JP4682759B2 - Playback apparatus, playback method, and playback program - Google Patents

Description

  The present invention relates to a playback apparatus, a playback method, and a playback program that can perform forward or reverse variable speed playback with higher image quality.

  2. Description of the Related Art A data recording / reproducing apparatus that records a digital video signal and a digital audio signal on a recording medium and reproduces the signal from the recording medium is known. As a recording medium for recording a digital video signal and a digital audio signal, a recording medium that performs serial access such as a magnetic tape has been conventionally used. However, in recent years, an optical disk, a hard disk, a semiconductor memory, etc. Randomly accessible recording media are often used for recording and reproducing digital video signals and digital audio signals.

  Since a digital video signal has an enormous data capacity, it is generally compressed and encoded by a predetermined method and recorded on a recording medium. In recent years, MPEG2 (Moving Picture Experts Group 2) system is known as a standard system for compression coding. In MPEG2, a digital video signal is compression-encoded using DCT (Discrete Cosine Transform) and motion compensation, and a data compression rate is increased using a variable-length code.

  The data stream structure of MPEG2 will be schematically described. MPEG2 is a combination of motion compensation predictive coding and compression coding by DCT. The data structure of MPEG2 has a hierarchical structure, and from the lower order is a block layer, a macroblock layer, a slice layer, a picture layer, a GOP layer, and a sequence layer. The block layer is composed of DCT blocks that are units for performing DCT. The macroblock layer is composed of a plurality of DCT blocks. The slice layer is composed of a header part and one or more macroblocks. The picture layer is composed of a header part and one or more slices. A picture corresponds to one screen.

  The GOP layer includes a header part, an I (Intra-coded) picture that is a picture based on intra-frame coding, and a P (Predictive-coded) picture B (Bi-directionally predictive coded) picture that is a picture based on predictive coding. It consists of. The I picture can be decoded only by its own information, and the P and B pictures require the previous or previous image as a reference image and are not decoded alone. For example, a P picture is decoded using an I picture or a P picture temporally prior to itself as a reference image. In addition, the B picture is decoded using two pictures, an I picture or a P picture before and after itself, as reference pictures. A group completed by itself including at least one I picture is called GOP (Group Of Picture), and is the smallest unit that can be independently accessed in an MPEG stream.

  A GOP is composed of one or more pictures. Hereinafter, for convenience, a GOP composed of only one I picture will be referred to as a single GOP, and a GOP composed of a plurality of pictures composed of an I picture and P and / or B pictures will be referred to as a long GOP. To do. In the single GOP, by configuring the GOP only from the I picture, editing in units of frames is facilitated, and since the predictive coding between frames is not performed, higher image quality can be obtained. On the other hand, long GOP has the advantage of good compression efficiency because it performs predictive coding between frames.

  In a long GOP, a closed GOP having a closed structure that can be completely decoded within the GOP, and an open GOP that can use information of the previous GOP in the coding order at the time of decoding. There are types. An open GOP can be decoded using more information than a closed GOP, so that a high image quality can be obtained and is generally used. In the following, when “GOP” is simply described, this open GOP is indicated unless otherwise specified.

  As a video signal format, an SD (Standard Definition) format having a bit rate of 25 Mbps (megabit second) is conventionally known. Particularly in video equipment used in broadcasting stations and the like, an SD format video signal is used in the single GOP described above to achieve a high image quality and a highly accurate editing environment. A fixed bit rate with a fixed bit rate for each frame is applied to an SD format video signal.

  On the other hand, in recent years, with the implementation of digital high-definition broadcasting and the like, the HD (High Definition) format, which has a higher resolution than the SD format, has come to be used. The HD format has a high bit rate with high resolution, and a single GOP cannot record for a long time on a recording medium. Therefore, an HD format video signal is used in the above-described long GOP. In the long GOP, inter-frame compression using predictive encoding is performed, so that the variable bit rate is different for each frame.

  By the way, when editing a video signal, cueing is performed in units of frames in order to determine editing points such as IN points and OUT points. For this purpose, variable-speed playback with a playback speed of 1 × or less is required in each of the forward and reverse playback directions. When a single GOP is used as in the SD format, each frame can be decoded independently, so that there is no particular problem with variable speed playback at 1 × speed or lower. That is, in the case of a single GOP, at least only the frame to be displayed needs to be decoded.

On the other hand, when a long GOP is used as in the HD format, each frame cannot be independently decoded as in the SD format described above. Decoding processing in the case of a long GOP will be described with reference to FIG. Here, it is assumed that 1 GOP is composed of a total of 15 pictures, one I picture, four P pictures, and 10 B pictures. As shown in FIG. 16A, the display order of the I, P, and B pictures in the GOP is “B ₀ B ₁ I ₂ B ₃ B ₄ P ₅ B ₆ B ₇ P ₈ B ₉ B ₁₀ P ₁₁ B is as ₁₂ B ₁₃ P ₁₄ ". The subscript indicates the display order.

In this example, the first two B ₀ and B ₁ pictures are predicted and decoded using the last P ₁₄ picture in the previous GOP and the I ₂ picture in this GOP. . The first P ₅ picture in the GOP is a picture predicted and decoded from the I ₂ picture. Other P ₈ picture, P ₁₁ picture and P ₁₄ are pictures decoded is predicted by using the preceding P-picture, respectively. Each B picture after the I picture is a picture predicted and decoded from the preceding and following I and / or P pictures.

  On the other hand, since B pictures are predicted and decoded using temporally preceding and following I or P pictures, the arrangement order of I, P, and B pictures on a stream or recording medium takes into account the decoding order in the decoder. It is necessary to decide. That is, an I and / or P picture for decoding a B picture must always be decoded before the B picture.

In the above example, the arrangement of each picture on the stream or the recording medium is “I ₂ B ₀ B ₁ P ₅ B ₃ B ₄ P ₈ B ₆ B ₇ P ₁₁ B ₉ B as illustrated in FIG. 16B. ₁₀ P ₁₄ B ₁₂ B ₁₃ ”and are input to the decoder in this order. The subscripts correspond to FIG. 16A and indicate the display order.

In the decoding process in the decoder, as shown in FIG. 16C, the I ₂ picture is first decoded, and the decoded I ₂ picture and the last P ₁₄ picture in the previous GOP (display order) are B _0. Predict and decode pictures and B ₁ pictures. Then, the B ₀ picture and the B ₁ picture are output from the decoder in the order of decoding, and then the I ₂ picture is output. Once the B ₁ picture is output, the P ₅ picture is then predicted and decoded using the I ₂ picture. Then, the B ₃ picture and the B ₄ picture are predicted and decoded using the I ₂ picture and the P ₅ picture. The decoded B ₃ picture and B ₄ picture are output from the decoder in the order of decoding, and then the P ₅ picture is output.

Hereinafter, similarly, the P or I picture used for prediction of the B picture is decoded before the B picture, the B picture is predicted and decoded using the decoded P or I picture, and the decoded B picture is decoded. Is output, the process of outputting the P or I picture used to decode the B picture is repeated. The picture arrangement as shown in FIG. 16B on the recording medium or in the stream is generally used, and requires a frame memory for four frames for decoding. Non-Patent Document 1 describes a method for decoding an MPEG2 elementary stream in this way.
Hiroshi Fujiwara, “Point Illustration / Latest MPEG Textbook”, first edition, ASCII, Inc., August 1, 1994, p. 106

  Such a 1 × speed reproduction in the forward direction when a long GOP is used for a video signal uses a decoder (called a 1 × speed decoder) that can obtain a decoding result of a picture of one frame in a time of one frame. Is possible.

  By the way, especially in the case of editing work or the like, in order to search for a necessary frame, it is required that the playback speed can be variably set to 1 × speed or less, and the playback direction can be freely switched between the forward direction and the reverse direction. Consider a case in which a long GOP is used for a video signal and variable speed playback is performed at a playback speed of 1 × speed or less in the forward and backward directions.

  Note that when a single GOP is used for a video signal, as described above, since a frame for display can be decoded independently, variable-speed playback at a forward speed and a forward speed of 1 × or lower, Even if the playback direction is switched in the reverse direction, no particular problem occurs.

  When a long GOP is used for a video signal, as described above, when decoding a frame for display, one or a plurality of pictures before and / or after the time are required. Playback at a playback speed of 1 × speed or less in the forward direction stops the input stream according to the playback speed so as not to update the frame memory, and repeatedly reads out the output video signal from the frame memory. This can be realized by using a 1 × speed decoder.

  On the other hand, when reverse playback is performed using a long GOP for a video signal, more pictures are often required to display one frame of images than in forward playback.

As an example, if the display order is backward play back the video stream illustrated in FIG. 16A, it must be output P ₁₄ picture first. As described above, in order to decode the P ₁₄ picture, it is necessary to decode the I ₂ picture, the P ₅ picture, the P ₈ picture, and the P ₁₁ picture. Therefore, when a stream is input in the arrangement as shown in FIG. 16B, a delay sufficient to perform decoding processing for at least four frames occurs. In addition, the I ₂ picture, the P ₅ picture, the P ₈ picture, and the P ₁₁ picture are used to decode the B picture, and thus need to be held in the memory.

Furthermore, the B ₁ picture and the B ₀ picture to be output at the end of the GOP are the I ₂ picture of the GOP and the GOP that is one previous in the original reproduction direction, that is, the GOP that is one after in the reverse reproduction. to be decoded is predicted by using the P ₁₄ picture, in the decoding processing of the GOP, it becomes necessary decoding of the GOP after one in display order in the further reverse playback.

  Here, consider a case where the playback direction is switched from the forward direction to the reverse direction, or from the reverse direction to the forward direction. For example, assuming an editing apparatus that can control the playback speed and playback direction with a jog dial or the like, this corresponds to a case where a desired frame is searched while switching the playback speed and playback direction around the point where the playback speed is zero. .

  For example, when an arbitrary frame being played in the forward direction is displayed and the playback direction is switched to the reverse direction, the frame image one frame before the frame immediately before switching the playback direction from the forward direction to the reverse direction is displayed. If it remains in the frame memory, the first frame when the playback direction is switched in the reverse direction can be displayed using the frame image remaining in the frame memory.

However, for example, when the frame immediately before switching the playback direction to the reverse direction was P ₁₄ picture to be displayed at the end of the GOP, the frame to be displayed immediately after switching the playback direction to the reverse direction, of the GOP B ₁₃ picture. In order to decode the B ₁₃ picture, the P ₁₄ picture and the P ₁₁ picture are necessary. Further, in order to decode the P ₁₁ picture, the I ₂ picture, the P ₅ picture, and the P ₈ picture of the GOP Needed.

Therefore, in this case, at the moment when the reproduction direction is switched from the forward direction to the reverse direction, a delay corresponding to the decoding time of at least four pictures (I ₂ picture, P ₅ picture, P ₈ picture and P ₁₁ picture) occurs. There was a problem. In particular, when the switching between the forward direction and the reverse direction is frequently performed, this delay appears as a poor feeling of operation, which is a problem.

  That is, in order to apply the recording / reproducing apparatus to an editing operation or the like, it is necessary to always output a reproduction output result with a certain delay with respect to a command speed requested by a higher system such as the editing apparatus. If a delay occurs when the playback direction is switched from the forward direction to the reverse direction, it can be said that the editing operation is not appropriate.

  Several methods have been considered to solve this problem. As a first method, a method using a decoder having a decoding speed sufficiently higher than 1 × speed can be considered. For example, in the above example, it is conceivable to use a decoder capable of decoding pictures of four frames or more within one frame time. However, a decoder having a high decoding speed is more expensive than a 1 × speed decoder, and there is a problem that the cost increases.

  As a second method, there can be considered a method in which a picture that does not meet the decoding timing with respect to a predetermined display timing is dropped, that is, the picture is not decoded and displayed, and the reproduction is apparently continued. However, this method has a problem in display quality.

  As a third method, at the time of encoding, data that can be reproduced and output with a fixed delay is created based on the input video signal, such as lower resolution data in which the resolution is reduced with respect to the originally used video signal, and recorded on a recording medium. Record it. A method of performing display using the low-resolution data when the video signal that is originally used cannot be decoded in time for reproduction can be considered. This method also has a problem in terms of display quality because low-resolution pictures are mixedly displayed with pictures of video signals that are originally used.

  As a fourth method, after the command speed required from the host system is determined, a necessary picture is decoded, and when a picture is stored in the frame memory so that the playback operation is not delayed, actual playback is started. Can be considered. However, with this method, a delay occurs until the playback is started after the command speed is requested from the host system, and the above-mentioned problems cannot be solved.

  Accordingly, an object of the present invention is to provide variable speeds from forward 1 × speed playback to reverse 1 × speed playback when playback of a video signal subjected to interframe compression by predictive coding is performed using a 1 × speed decoder. It is an object of the present invention to provide a playback device, a playback method, and a playback program that can perform playback with a fixed delay.

In order to solve the above-mentioned problems, the present invention is directed to forward-reverse video data recorded on a random-accessible recording medium that has been compression-encoded using inter-frame compression by predictive encoding from reverse 1 × speed playback. a playback equipment which is adapted to play variable speed to 1-speed reproduction of, at least, be stored and the current target playback frame, and each frame adjacent back and forth in the display order for the current target frame a frame buffer that, when one of each frame is a new target playback frame, and a target pattern creation section that creates a target pattern of a frame buffer for new targets reproduction frame, the current target playback frame a comparator for comparing the state of the stored frame buffer with the target pattern, based on the comparison result by the comparison unit, the newly de Is a playback apparatus that have a frame buffer control unit for extracting unnecessarily Na Ru 1 frame in the current state of the frame buffer with the over de extracts one frame required.

The present invention also provides variable-speed video data recorded on a random-accessible recording medium that has been compression-encoded using inter-frame compression by predictive encoding, from reverse single-speed playback to forward single-speed playback. At least the current target playback frame and each frame adjacent to the current target frame in the order of display in the display order are stored in the frame buffer. when any is a new target playback frame, a target pattern generating step of generating a target pattern of a frame buffer for new targets reproduction frame, the current state of the framebuffer the target playback frame is stored a comparing step of comparing the target pattern, based on the comparison result of the comparing step, the newly decoded Is Pla how having a frame buffer control step of extracting unnecessary Na Ru 1 frame in the current state of the frame buffer are extracted one frame required.

The present invention also provides variable-speed video data recorded on a random-accessible recording medium that has been compression-encoded using inter-frame compression by predictive encoding, from reverse single-speed playback to forward single-speed playback. A playback program for causing a computer device to execute a playback method adapted to play back at least, wherein at least a current target playback frame and frames adjacent to each other adjacent to the current target frame in the display order stored in the frame buffer, when any of each frame is a new target playback frame, a target pattern generating step of generating a target pattern of a frame buffer for new targets playback frame, the current target playback frame a comparing step but comparing the status and the target pattern of the frame buffer stored, Based on the comparison result of the compare step, new computer playback method and a frame buffer control step of extracting unnecessary Na Ru 1 frame in the current state of the frame buffer with decoding to extract one frame required a reproduction program to be executed by device.

  As described above, the present invention creates a frame buffer target pattern capable of temporarily storing video data for a plurality of frames for a target playback frame to be played next, and the current frame buffer state and target Based on the result of comparison with the pattern, a new frame that needs to be decoded is extracted and a frame that is unnecessary in the current frame buffer state is extracted. At the time of playback up to 1 × speed playback in the direction, the number of updated frames in the frame buffer can always be one frame. As a result, the amount of delay from frame input to decoding is fixed, and variable-speed playback from 1x playback in the forward direction to 1x playback in the reverse direction does not drop frames with a fixed delay. In addition, it can be performed using a 1 × speed decoder.

  As described above, the present invention creates a frame buffer target pattern for a target playback frame to be reproduced next, and compares the created target pattern with the current frame buffer state. Based on the comparison result, a frame that needs to be newly decoded and a frame that becomes unnecessary in the current frame buffer state are extracted. Therefore, the number of frames updated in the frame buffer can always be one frame during playback from 1x playback in the forward direction to 1x playback in the reverse direction, and the delay amount from frame input to decoding is fixed. There is an effect that can be achieved.

  This also has the effect that variable speed playback from 1x playback in the forward direction to 1x playback in the reverse direction can be performed using a 1x speed decoder with a fixed amount of delay and no frame dropping. .

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 conceptually shows a reproduction control process according to the present invention. In step S1, a target playback frame to be played next is instructed. For example, if the playback speed is within 1 × speed in the forward direction or the reverse direction, the target playback frame is a range of frames adjacent in the display order to the target playback frame determined before one frame timing. The target playback frame is specified from, for example, a higher system and is supplied at each frame timing.

  When the target playback frame is designated, a target frame buffer pattern for the target playback frame is created (step S2). The target frame buffer pattern is a frame pattern that needs to be stored in a decoded state on the frame buffer in order to play back the target playback frame and continue playback in the reverse and forward directions. . In the next step S3, the created target frame buffer pattern is compared with the current frame buffer state. By this comparison, a picture that needs to be newly decoded with respect to the current frame buffer state is extracted (step S4), and an unnecessary picture is extracted with the current frame buffer state (step S5). The pictures extracted in step S4 and step S5 are always one picture.

  Up to here is the process of creating a target for actual decoding. Next, the decoder is actually controlled and the decoding process is started.

  In step S6, for example, a recording medium is accessed, and a predetermined picture is stream-input to the decoder based on the result extracted in step S4. The picture decoded by the decoder is overwritten in the unnecessary picture area extracted in step S5 described above on the frame buffer (step S7). When decoding for one picture is completed, it is output as a decoded output frame image (step S8).

  FIG. 2 schematically shows a configuration of an example of a playback apparatus 1 applicable to the embodiment of the present invention. The playback apparatus 1 uses the optical disc 10 as a recording medium. A CPU (Central Processing Unit) 14 is connected to a ROM (Read Only Memory) and a RAM (Random Access Memory) (not shown), and controls each part of the reproducing apparatus 1 according to a program stored in advance in the ROM. The RAM is used as a work memory for the CPU 14.

  The disk drive 11 reads data from a predetermined address of the loaded optical disk 10 based on the control of the CPU 14. The read data is temporarily stored in the cache memory 12. Based on an instruction from the CPU 14, a video stream is supplied from the cache memory 12 to the decoder 13, and the video stream input in response to the request is decoded using the frame memory 13A. The decoded output is output as a baseband video signal.

  The operation unit 15 is provided with various operators such as keys and switches, generates a control signal corresponding to an operation performed on the operator, and supplies the control signal to the CPU 14. The CPU 14 sends a command to each unit of the playback device 1 in accordance with the supplied control signal. For example, a jog dial 16 is provided in the operation unit 15. The jog dial 16 is configured to output a signal corresponding to the rotation angle. For example, the jog dial 16 is configured to output a control signal for designating a forward direction and a reverse direction with respect to the reproduction direction in accordance with a user operation. A control signal for instructing the reproduction speed in substantially real time is generated and supplied to the CPU 14.

  Note that the command for instructing the playback speed, the playback direction, and the like is not limited to a command based on an operation on the operation unit 15. For example, a command for instructing a playback speed and a playback direction can be transmitted from another device such as an editing device connected to the playback device 1 by a predetermined communication means (not shown). In this case, another device that transmits a command to the playback device 1 is a higher-order device with respect to the playback device 1.

  The video stream handled by the playback apparatus 1 is a stream that has been compression-encoded in accordance with the MPEG2 (Moving Pictures Experts Group 2) standard, and the GOP (Group Of picture) has a long GOP and an open GOP. Suppose that

  FIG. 3 schematically shows an exemplary configuration of the decoder 13. The stream data read from the optical disk 10 and output from the disk drive 11 is, for example, MPEG-ES (MPEG Elementally Stream). This MPEG-ES is supplied to the stream decoder 20. The stream decoder 20 analyzes the input MPEG-ES packet and header information, and extracts various parameters necessary for decoding processing and picture data stored in the payload in the packet after compression encoding. Various parameters are supplied to the CPU 14, for example. The extracted picture data is stored in the stream buffer 21 in a predetermined manner.

  The MPEG decoder 22 requests the picture data stored in the stream buffer 21 from the stream decoder 20, decodes the picture data read from the stream buffer 21 in response to the request, and writes it into the frame memory 13A. The MPEG decoder 22 also performs a process of decoding other picture data (for example, a P picture or a B picture) using the picture data written in the frame memory 13A.

  Although details will be described later, the frame memory 13A has a necessary and sufficient capacity so that forward reproduction and backward reproduction can be executed with a fixed delay. For example, the frame memory 13A has a capacity that can store nine frames of decoded pictures. As an example, in the frame memory 13A, the storage area is divided into nine banks each capable of storing data for one frame, and access is controlled for each bank.

  The output data control unit 23 manages output video data. For example, the output data control unit 23 reads frame data to be displayed next from the frame memory 13 </ b> A based on an instruction of the CPU 14 according to an operation on the operation unit 15. The read frame data is output as a baseband video signal.

  FIG. 4 shows an example of the configuration of the decoder 13 more specifically. In FIG. 4, the same reference numerals are given to the portions common to FIG. 3 described above, and detailed description thereof is omitted. The MPEG-ES output from the disk drive 11 is supplied to a demultiplexer (DMUX) 30, and the packet is analyzed. MPEG ES and header information extracted from the packet are stored in the stream buffer 21. The packet header information is also supplied to the user data decoder 31, and various parameters are extracted. The extracted parameters are stored in the stream buffer 21 in a predetermined manner.

  The decoder 32 decodes the header information and MPEG ES stored in the stream buffer 21. The decoder 32 decodes the header information and extracts parameters necessary for decoding the picture. Based on the parameters extracted from the header information, the decoder 32 performs variable-length code decoding, inverse quantization, and inverse DCT (Discrete Cosine Transform) on the MPEG ES, and performs decoding for each picture. The picture data decoded by the decoder 32 is written into the frame memory 13A via the prediction restoration unit 33.

  The prediction restoration unit 33 uses the picture data written in the frame memory 13A to decode a picture that has been inter-frame compressed using predictive coding. The picture that has been subjected to the inter-frame compression is written again into the frame memory 13A as frame data.

  On the other hand, when the user operates the jog dial 16 for designating the reproduction direction and the reproduction speed, a control signal indicating the reproduction speed and the reproduction direction is generated in the operation unit 15 in a predetermined manner. This control signal is supplied to the CPU 14. The control signal indicating the reproduction direction and the reproduction speed is not limited thereto, and as described above, the control signal may be supplied to the CPU 14 as a command from a higher-level device via a communication unit (not shown).

  The CPU 14 issues a command to the video output unit 23 based on a control signal supplied from the operation unit 15 according to a program stored in advance in the ROM 35, and instructs a frame to be output. The RAM 36 is used as a work memory for the CPU 14 as necessary. The video output unit 23 reads the frame instructed from the frame memory 13A in response to this command.

  The read frame is supplied to the auxiliary data superimposing unit 34, and video index information, auxiliary data, etc. are superposed on the basis of the information stored in the stream buffer 21, and further a synchronization signal is added to the output video signal. Is output as

  Next, a recording medium applicable to one embodiment of the present invention will be described. First, an example of data arrangement in a disc-shaped recording medium will be described with reference to FIG. The data arrangement shown as an example in FIG. 5 is a general data arrangement in a disc-shaped recording medium capable of random access, such as a recordable optical disc or hard disk. The logical address space is an area where arbitrary data can be recorded / reproduced.

  In this embodiment, the recording medium is an optical disk. Note that the recording medium applicable to this embodiment is not limited to an optical disk. That is, this embodiment can be applied to other randomly accessible recording media such as a hard disk drive and a semiconductor memory.

  A file system FS is arranged at the leading and trailing ends of the logical address. Arbitrary data is recorded in a predetermined format generally called a file in the logical address space. Data on the recording medium is basically managed in file units. File management information is recorded in the file system FS. A file system layer of a system control unit (described later) of the recording / reproducing apparatus can manage various kinds of data on one recording medium by referring to and operating information of the file system FS. The file system FS uses, for example, UDF (Universal Disk Format) and manages files in units of 2 kB.

  A replacement area is arranged outside the logical address space. The spare area is an area that can be used as an alternative when a part of the recording medium cannot be physically read or written due to a defect. For example, when a defective area is recognized at the time of access to the recording medium (particularly at the time of recording), a replacement process is normally performed, and the address of the defective area is moved into the replacement area.

  The usage status of the spare area is stored as a defect list in a predetermined area, and is used by a drive control unit of the recording / reproducing apparatus and a lower hierarchy of the system control unit. In other words, in the lower layers of the drive control unit and system control unit described later, by referring to the defect list when accessing the recording medium, even when replacement processing is performed, access to an appropriate area is performed. It can be carried out. By this mechanism of the spare area, the host application can perform data recording / reproduction with respect to the recording medium without considering the presence / absence or position of the defective recording area on the recording medium.

  In the case of a disc-shaped recording medium, the replacement area is often arranged on the innermost or outermost side of the disc. When the disk rotation control is performed by zone control in which the rotation speed is changed stepwise in the radial direction of the disk, a replacement area may be provided for each zone. When the recording medium is not a disk-shaped recording medium such as a semiconductor memory, it is often arranged on the side having the smallest physical address or the largest physical address.

  In an application that handles audio data and video data (hereinafter collectively referred to as AV data), a group of data that is a unit that requires continuous synchronous reproduction, that is, reproduction that guarantees real-time reproduction is called a clip. For example, a group of data from the start to the end of shooting by the video camera is used as a clip. The entity of a clip consists of a single file or multiple files. In the present invention, a clip consists of a plurality of files. Details of the clip will be described later.

  For example, an NRT (Non Real Time) area in which an arbitrary file other than a clip can be recorded is arranged at the head side in the logical address space, and clips are sequentially packed from the next of the NRT area. The clip is arranged avoiding the defect position on the optical disk 10 so that the above-described replacement process is not performed. A header (H) and a footer (F) are added to each clip. In this example, the header and footer are arranged together on the rear end side of the clip.

  In the following description, it is assumed that the clip first recorded on the optical disc 10 is the clip # 1, and the clip numbers are subsequently increased as clip # 2, clip # 3,.

  In the logical address space, an area where no data is recorded or an area where data has been recorded in the past but is no longer needed is managed as an unused area in the file system FS. A recording area is allocated to a file newly recorded on the recording medium based on an unused area. The management information of the file is added to the file system FS.

  When a recordable optical disc is used as the recording medium, the present invention records the clip on the recording medium with an annual ring structure. The annual ring structure will be described with reference to FIGS. 6 and 7. FIG. 6A is an example showing one clip 100 on the timeline. In this example, the clip 100 includes seven files of video data 101, audio data 102A to 102D, auxiliary AV data 103, and real-time metadata 104.

  The video data 101 is video data obtained by compressing and coding baseband video data at a high bit rate of, for example, a bit rate of 50 Mbps (megabit second). As the compression encoding method, for example, MPEG2 (Moving Pictures Experts Group 2) method is used. As the audio data 102A, 102B, 102C, and 102D, baseband audio data is used, each of which is 2-channel audio data. However, the audio data 102A, 102B, 102C, and 102D may be audio data obtained by compression-coding baseband audio data at a high bit rate. The video data 101 and the audio data 102A to 102D are data to be actually broadcast and edited, and are referred to as main line data.

  The auxiliary AV data 103 is data obtained by compressing and multiplexing baseband video data and audio data at a lower bit rate than main line video data and audio data. As the compression encoding method, for example, the MPEG4 method is used, and main line AV data is generated by compression encoding so as to reduce the bit rate to, for example, several Mbps. The auxiliary AV data 103 is data used as a proxy for main line data in order to perform high-speed search reproduction, and is also referred to as proxy data.

  Metadata is high-order data related to certain data, and functions as an index for representing the contents of various data. The metadata includes real-time metadata 104 generated along the time series of the main AV data and non-time series meta data generated for a predetermined section such as for each scene in the main AV data. There are two types of data. The non-time series metadata is recorded in the NRT area described with reference to FIG.

  As shown in FIG. 6B, the clip 100 is divided on the basis of a predetermined reproduction time (for example, 2 seconds) and recorded on the optical disc as an annual ring structure. As an example is shown in FIG. 6C, one annual ring is a video data 101, audio data 102A to 102D, auxiliary AV data 103, and real-time metadata (RM) 104 so that the playback time zones correspond to each other. The data is divided into predetermined reproduction time units having a data size of one or more rounds, and the divided reproduction time units are sequentially arranged and recorded. That is, each data composing the clip 100 is interleaved in a predetermined time unit by the annual ring structure and recorded on the optical disc.

  Data forming the annual ring is referred to as annual ring data. The annual ring data has an amount of data that is an integral multiple of the smallest recording unit on the disc. The annual rings are recorded so that the boundaries coincide with the block boundaries of the recording units of the disc.

  FIG. 7 shows an example in which annual ring data is formed on the optical disc 10. For example, as described with reference to FIG. 6B, annual ring data # 1, # 2, # 3,... In which one clip is divided into predetermined playback time units from the inner circumference side to the outer circumference side of the optical disc 10. .. is recorded continuously. That is, the data is arranged so that the reproduction time series is continuous from the inner periphery side to the outer periphery side of the optical disc 10. Although not shown, the NRT region is arranged further on the inner peripheral side of the first annual ring data # 1 in the example of FIG.

  In the HD format, compression encoding at a variable length bit rate is possible. In addition, when a long GOP is used, the data size differs depending on the I picture, P picture, and B picture due to inter-frame compression coding using predictive coding. Therefore, access to a desired position is realized using a picture pointer file.

  The picture pointer is offset information of each frame position in the clip. That is, for example, in MPEG2, a variable bit rate that changes the data compression rate for each frame is possible. For example, a flat screen frame is compression-encoded at a higher compression rate, and a coarse screen frame is compression-encoded at a lower compression rate. Thus, by changing the compression rate according to the nature of the frame, higher resolution video data can be transmitted and recorded at a lower bit rate. In MPEG2, compression encoding is also performed using a variable length code.

  In such video data that is compression-encoded with a variable bit rate, the frame position and the GOP position at which reproduction is completed in a plurality of frames differ from frame to frame or from GOP to jump to a desired position. . Therefore, in order to facilitate access to the variable length bit rate, the offset information of each frame position in the clip is tabulated as a picture point to form a non-time series metadata file, which is arranged corresponding to each clip. For example, when the disc is inserted into the drive, this picture point is read in a predetermined manner, so that a desired position in the clip can be accessed at high speed.

  This will be described in more detail with reference to FIGS. FIG. 8 shows an example of a data structure in the MPEG2 long GOP. For example, as shown in FIG. 8A, one long GOP file is composed of one clip. As shown in FIG. 8B, the long GOP file has a structure called a video MXF (Material Exchange Format) file OP-Atom. From the top, a header partition pack (HPP) and header metadata are arranged, and header information is stored. After that, an essence container in which the main body of video data is stored is arranged. A footer partition pack (FPP) is arranged at the end of the file.

  The essence container has a configuration in which GOPs are arranged as shown in FIG. 8C. The contents of each GOP are a set of pictures as shown in FIG. 8D, and the contents of one picture are arranged with KL (Key, Length) information at the head, as shown in FIG. The main body of the I, P or B picture is arranged, and further KL information is arranged. A filler is arranged at the end of the picture as necessary, and the end is aligned in byte units.

  In such a configuration, in the MPEG2 long GOP, the information amount of each picture, that is, the values of the sizes of the I, P, and B pictures shown in FIG. 8E are uncertain. Therefore, for example, when playback is to be started from a certain frame in the long GOP video file, the start position of the picture corresponding to that frame in the long GOP video file cannot be specified by the byte position or the like.

  Therefore, with respect to each picture included in the long GOP video file with reference to the file address (see FIG. 8F) indicated in bytes from the head position of the long GOP video file, the file address, size and picture type (I, P or (B picture) and information indicating whether or not the picture is the head picture of the GOP are prepared as picture pointer information. This picture pointer information is prepared for each long GOP video file.

  Note that the filler arranged at the end of the picture shown in FIG. 8E is adjusted so that the boundary of each picture is a multiple of a predetermined byte such as 2048 bytes when viewed from the file address. As an example, it is preferable to adjust using a filler so that the boundary of each picture coincides with the boundary of the minimum access unit such as a sector of the optical disk 10 because access to each picture becomes easy.

  FIG. 9 shows a more specific example of a picture pointer table in which picture pointer information is described. In this example, the picture pointer table describes data in units of 8 bytes. The first 8 bytes store the reserved area and version information of this picture pointer table. Hereinafter, 8 bytes are allocated to one frame, that is, one picture, and this 8-byte information is arranged by the number of pictures included in the long GOP video file. Each picture is arranged in the order of display frames.

  Data for each picture will be described. The first 1 bit is a flag indicating whether or not the picture is the first picture of the GOP. For example, assuming that there are a plurality of I pictures in one GOP, the boundary of the GOP cannot be specified only by the position of the I picture. If the GOP boundary cannot be specified, the position of the sequence header (Sequence Header) defined in MPEG2 cannot be known, and there is a possibility that there is no sequence header at the head of the stream input to the decoder. Such a state can be avoided by providing each picture with a flag indicating whether or not this is a GOP head picture. During playback, the stream is input to the coder based on this flag.

  The next 23 bits store picture size information as shown in FIG. 8E. By securing 23 bits as size information, it is possible to cope with a data size up to 8 MB (megabytes), and it is also possible to cope with MPEG profile 422 @ HL.

The next two bits indicate the picture type. For B pictures, reference direction information is also shown. More specifically, the picture type is described as follows, for example.
00: I picture 10: P picture 01: B picture restored by referring to the forward (future) frame. This is, for example, a B picture at the beginning of a long GOP video file in the case of an open GOP, or a B picture at the beginning of each GOP in the case of a closed GOP.
11: B picture restored by referring to the front and rear frames.

  The next 38 bits indicate a file address in the long GOP video file of the picture. By assigning 38 bits to the file address, a long GOP video file having a size up to 256 GB (gigabytes) can be supported. For example, it is possible to cope with the optical disc 10 in which up to eight recording layers having a recording capacity of 27 GB are formed in one layer.

  This picture pointer table is recorded as a picture pointer file in the NRT area of the recording medium, for example, together with non-time series metadata. When the optical disk 10 is loaded into the disk drive 11, the non-time series metadata and the picture pointer file recorded in this NRT area are read by the disk drive 11, and the optical disk 10 is mounted on the system of the playback device 1. Is done. The read non-time-series metadata and picture pointer file are held in, for example, a RAM included in the CPU 14. The CPU 14 can access any picture in the clip recorded on the optical disk 10 by referring to the picture pointer table held in the RAM.

  Next, the reproduction control process according to the embodiment of the present invention will be described in more detail. First, the creation of the target frame buffer pattern described in step S2 of FIG. 1 will be described. First, a frame buffer size necessary for reproducing an arbitrary target reproduction frame and frames before and after adjacent to the target reproduction frame in display order are obtained.

FIG. 10 shows an example of the necessary buffer amount when decoding a frame one frame after or one frame before in the display order with respect to the current frame (for example, the target reproduction frame). In FIG. 10, the output frame (current frame) is indicated by “0”, the frame that is forward in the display order, that is, the future (back) from the present, is “+”, and the reverse direction in the display order, that is, the past (front). The frame is indicated by “−”. In the figure, “M” indicates the number of moving pictures from the reference picture to the next reference picture when there is a B picture between them, and “N” indicates the number of pictures in one GOP. For example, when the GOP is composed of 15 pictures of “I ₂ B ₀ B ₁ P ₅ B ₃ B ₄ P ₈ B ₆ B ₇ P ₁₁ B ₉ B ₁₀ P ₁₄ B ₁₂ B ₁₃ ”, M = 3 N = 15.

  FIG. 10A shows an example in which playback is advanced by one frame in the forward direction. In this case, when M = 3, the buffer is most necessary when the target playback frame is a B picture forward in the display order of adjacent B pictures. In this case, it moves from the target playback frame to the next B picture at the next frame timing.

That is, in this case, the B ₄ picture and the B ₅ picture are decoded using the I ₃ picture and the P ₆ picture, respectively. Until the decoding of the B ₅ picture is completed, the I ₃ picture cannot be discarded from the buffer, and the P ₆ picture is displayed next to the B ₅ picture, and thus is held in the buffer. Therefore, a buffer for M + 1 = 4 pictures is required.

FIG. 10B shows an example of the case where playback is advanced (returned) by one frame in the reverse direction. In the case of a general M = 3 and N = 15 open GOP, the buffer is most needed when the target playback frame is an I ₃ 'picture. In this case, at the next frame timing, it moves from the target playback frame to the rear B ₂ 'picture in the display order.

That is, in this case, 'in order to decode the picture, I _3' B ₂ and the picture, B ₂ 'is required and the previous P ₁₅ picture in the display order of the pictures, in order to decode the P ₁₅ picture The I ₃ picture, P ₆ picture, P ₉ picture, and P ₁₂ picture in the GOP to which the P ₁₅ picture belongs are sequentially required. Therefore, a buffer for N / M + 2 = 7 pictures is required. Here, N / M corresponds to the number of I pictures and P pictures included in the GOP.

FIG. 10C shows an example in which transition of one frame in either the forward direction or the reverse direction is considered. In the case of a general M = 3 and N = 15 open GOP, the buffer is most needed when the target playback frame is an I ₃ 'picture. In this case, at the next frame timing, it moves to the next B ₄ 'picture in the display order of the I ₃ ' picture or the previous B ₂ 'picture in the display order.

That is, in this case, the above example of FIG. 10A and the example of FIG. 10B are combined, and in order to decode the next B ₄ ′ picture in the display order of the I ₃ ′ picture that is the target playback frame, An I ₃ 'picture and a P ₆ ' picture that is a reference picture that appears next to the I ₃ 'picture are required. Furthermore, in order to decode the picture 'before B ₂ in the display order of the pictures' the I _3, the I ₃ 'picture and, the I _3' I ₃ pictures in the previous GOP of the GOP belongs picture, P ₆ picture , P ₉ picture, P ₁₂ picture and P ₁₅ picture are sequentially required. Therefore, a buffer for N / M + M + 1 = 9 pictures is required.

  As described above, when moving from the target playback frame to the adjacent frames in the display order, a buffer for 9 pictures is required.

  In one embodiment of the present invention, a buffer update pattern is created in the frame buffer so that the previous and subsequent pictures adjacent to the target playback frame in the display order can always be displayed with a fixed delay. That is, a frame adjacent to the target playback frame decoded and existing on the buffer in the display order is always decoded and exists on the buffer. Further, all the frames necessary for continuing the backward reproduction and the frames necessary for continuing the forward reproduction are always decoded and stored in the buffer. Such a pattern on the buffer is created for all patterns in which the target playback frame is moved frame by frame.

  In this state, when the target playback frame is moved and updated by one frame, the data that needs to be newly decoded is always one frame regardless of the playback direction regardless of the forward direction or the reverse direction. Therefore, variable speed playback at a playback speed within 1 × speed when the playback direction is either the forward direction or the reverse direction can be realized using the 1 × speed decoder.

  Further, in this state, a playback output result can be obtained with a fixed delay between the reverse 1x speed playback and the forward 1x speed command speed.

  FIG. 11 shows an update pattern of an example of the target frame buffer created based on the above-described idea. The example of FIG. 11 relates to the case of a long GOP where (N = 15, M = 3). Since 1 GOP is composed of 15 pictures (frames), it consists of 15 patterns. As shown in each row in FIG. 11, when the target playback frame is moved one frame at a time in a state where the frame corresponding to the target playback frame is stored in the frame buffer, the updated frame is Only one frame is required, and variable-speed reproduction within the 1 × speed in the forward and reverse directions can be performed using a 1 × speed decoder.

  Note that I, P, and B in FIG. 11 are frames based on the I picture, P picture, and B picture, respectively, and the added numbers indicate the display order in the GOP. A frame by a picture belonging to a reference GOP (current GOP) is not added a symbol. A minus sign (-) is added to a frame of a picture belonging to the GOP immediately before the current GOP (referred to as GOP (-)). A plus sign (+) is added to a frame of a picture belonging to the GOP (referred to as GOP (+)) immediately after the current GOP.

  In the update pattern of FIG. 11, the direction from the upper side to the lower side in the drawing indicates playback in the forward direction, and the direction from the lower side to the upper side indicates playback in the reverse direction. That is, the target playback frame advances by one frame from the upper side to the lower side in FIG. 11, and the target playback frame returns by one frame by going from the lower side to the upper side by one row. Further, the update pattern of FIG. 11 is cyclic, and when the target playback frame returns by one frame from the first row, the storage pattern of the frame buffer on the 15th row is shifted to.

  In the frame buffer update pattern of FIG. 11, the first row is an example of a pattern in the case where the target playback frame is the frame “I3”. The frames required to advance one frame in the forward direction from the target playback frame “I3” are the frame “B4” and the frame “P6”. Also, the frames required to return one frame in the reverse direction from the target playback frame are the frame “B2”, the frame “P15-”, the frame “P12-”, the frame “P9-”, the frame “P6-”, and Frame “I3-”.

  The second row is an example of a pattern when the target reproduction frame is the frame “B4”. Frames required to advance one frame in the forward direction from the target reproduction frame “B4” are the frame “B5” and the frame “P6”. Also, the frames required to return one frame in the reverse direction from the target playback frame are the frame “I3”, the frame “P15-”, the frame “P12-”, the frame “P9-”, the frame “P6-”, and Frame “I3-”.

  The third row is an example of a pattern when the target reproduction frame is the frame “B5”. The frames required to advance one frame in the forward direction from the target playback frame “B5” are the frame “P6” and the frame “P9”. Also, the frames required to return one frame in the reverse direction from the target playback frame are frame “B4”, frame “I3”, frame “P12-”, frame “P9-”, frame “P6-”, and frame "I3-".

  The fourth line is an example of a pattern when the target reproduction frame is the frame “P6”. The frames required to advance one frame in the forward direction from the target reproduction frame “P6” are the frame “B7” and the frame “P9”. Also, the frames required to return one frame in the reverse direction from the target playback frame are the frame “B5”, the frame “I3”, the frame “P12-”, the frame “P9-”, the frame “P6-”, and the frame "I3-".

  The fifth line is an example of a pattern when the target reproduction frame is the frame “B7”. The frames required to advance one frame from the target reproduction frame “B7” in the forward direction are the frame “B8” and the frame “P9”. Also, the frames required to return one frame in the reverse direction from the target playback frame are the frame “P6”, the frame “I3”, the frame “P12-”, the frame “P9-”, the frame “P6-”, and the frame "I3-".

  The sixth line is an example of a pattern when the target reproduction frame is the frame “B8”. The frames required to advance one frame from the target playback frame “B8” in the forward direction are the frames “P9” and “P12”. Also, the frames required for returning one frame from the target playback frame in the reverse direction are the frame “B7”, the frame “P6”, the frame “I3”, the frame “P9-”, the frame “P6-”, and the frame “ I3- ".

  The seventh line is an example of a pattern when the target reproduction frame is the frame “P9”. The frames required to advance one frame in the forward direction from the target reproduction frame “P9” are the frame “B10” and the frame “P12”. Also, the frames required to return one frame in the reverse direction from the target playback frame are the frame “P6”, the frame “I3”, the frame “P9-”, the frame “P6-”, and the frame “I3-”. .

  The eighth line is an example of a pattern when the target reproduction frame is the frame “B10”. Frames required to advance one frame in the forward direction from the target reproduction frame “B10” are the frame “B11” and the frame “P12”. Also, the frames required to return one frame in the reverse direction from the target playback frame are the frame “P9”, the frame “P6”, the frame “I3”, the frame “P9-”, the frame “P6-”, and the frame “ I3- ".

  The ninth line is an example of a pattern when the target reproduction frame is the frame “B11”. Frames required to advance one frame in the forward direction from the target reproduction frame “B11” are the frame “P12” and the frame “P15”. Also, the frames required to return one frame in the reverse direction from the target playback frame are the frame “B10”, the frame “P9”, the frame “P6”, the frame “I3”, the frame “P6-”, and the frame “I3”. -".

  The 10th line is an example of a pattern when the target reproduction frame is the frame “P12”. The frames required to advance one frame from the target playback frame “P12” in the forward direction are the frame “B13” and the frame “P15”. Also, the frames required to return one frame from the target playback frame in the reverse direction are the frame “B11”, the frame “P9”, the frame “P6”, the frame “I3”, the frame “P6-”, and the frame “I3”. -".

  The eleventh line is an example of a pattern when the target reproduction frame is the frame “B13”. Frames required to advance one frame in the forward direction from the target reproduction frame “B13” are the frame “B14” and the frame “P15”. Also, the frames required to return one frame in the reverse direction from the target playback frame are the frame “P12”, the frame “P9”, the frame “P6”, the frame “I3”, the frame “P6-”, and the frame “I3”. -".

  The twelfth line is an example of a pattern when the target reproduction frame is the frame “B14”. Frames required to advance one frame in the forward direction from the target reproduction frame “B14” are the frame “P15” and the frame “I3 +”. Also, the frames required to return one frame in the reverse direction from the target playback frame are the frame “B13”, the frame “P12”, the frame “P9”, the frame “P6”, the frame “I3”, and the frame “I3- It is.

  The 13th line shows an example of a pattern when the target reproduction frame is the frame “P15”. The frames required to advance one frame in the forward direction from the target playback frame “P15” are the frame “B1 +” and the frame “I3 +”. Also, the frames required to return one frame from the target playback frame in the reverse direction are the frame “B14”, the frame “P12”, the frame “P9”, the frame “P6”, the frame “I3”, and the frame “I3- It is.

  The 14th line is an example of a pattern when the target reproduction frame is the frame “B1 +”. The frames required to advance one frame in the forward direction from the target reproduction frame “B1 +” are the frame “B2 +” and the frame “I3 +”. Also, the frames required to return one frame in the reverse direction from the target playback frame are the frame “P15”, the frame “P12”, the frame “P9”, the frame “P6”, the frame “I3”, and the frame “I3- It is.

  The 15th line shows an example of a pattern when the target reproduction frame is the frame “B2 +”. The frames required to advance one frame in the forward direction from the target reproduction frame “B2 +” are the frame “I3 +” and the frame “P6 +”. Also, the frames required to return one frame from the target playback frame in the reverse direction are the frame “B1 +”, the frame “P15”, the frame “P12”, the frame “P9”, the frame “P6”, and the frame “I3”. is there.

  In this manner, in the frame buffer update pattern shown in FIG. 11, only one frame is updated between the update patterns for each frame. This will be described more specifically with some examples.

  As a first example, a case where the target playback frame is a frame “P6” based on a P picture will be described. In this case, in the playback speed range within 1 × speed in the forward and reverse directions, a frame that may become a new target playback frame after one frame timing of the target playback frame is the frame “P6”, The frame “B5” and the frame “B7” are adjacent to the frame “P6” in the display order.

  In a state where the target playback frame is the frame “P6”, a frame decoded according to the target frame buffer pattern created based on the target playback frame as described above is stored in the frame buffer (the fourth row in FIG. 11). The target reproduction frame “P6”, the frames “B5” and “B7” before and after the target reproduction frame are stored in the frame buffer in a state where they have already been decoded.

  When the target playback frame is shifted to the frame “B5” or the frame “B7” from this state, a newly required frame is decoded based on a new target frame buffer pattern for the transferred target playback frame. To store in the frame buffer.

  The other area of the frame buffer in which these data are stored holds the immediately preceding data. That is, in the example of FIG. 11, when the target playback frame is the frame “P6”, the frame “P6” and the same GOP as the frame “P6” are stored in the frame buffer as shown in the fourth row. The frame “I3”, the frame “P9”, the frame “B5”, the frame “B7”, and the frame “I3-” and the frame “P6” that belong to the previous GOP with respect to the GOP to which the frame “P6” belongs. -", Frame" P9- "and frame" P12- "are stored.

  When the target playback frame is frame “P6”, when the target playback frame shifts by one frame in the forward direction, the new target playback frame becomes frame “B7”. In addition, a frame that may become a new target playback frame after one frame timing with respect to this new target playback frame is adjacent to the frame “B7” and the frame “B7” in the display order. The frame “P6” and the frame “B8” are set.

  Note that if the playback speed is within 1 × speed in the forward and reverse directions, the same frame may be output continuously at two frame timings. In this case, the target playback frame does not change even when moving to the next frame timing.

  Among these, since the frame “P6” is the current target reproduction frame, it already exists on the frame buffer. Further, in order to decode the frame “B8”, the frame “P6” and the frame “P9” are required. Since the frames “P6” and “P9” are used to decode the frame “B7”, they already exist on the frame buffer. Frame “B8” is decoded using these frames “P6” and “P9”.

  On the other hand, when the target playback frame shifts to the frame “B7”, the frame “B5” which is the adjacent frame in the reverse display order in the state of the frame “P6” is discarded because it is unnecessary. The The newly decoded frame “B8” is stored in the area of the discarded frame “B5” on the frame buffer, and the frame buffer is updated.

  When the playback is returned by one frame in the reverse direction, the new target playback frame becomes the frame “B5”, and there is a possibility that the new target playback frame becomes a new target playback frame after one frame timing. The frames are a frame “B5”, a frame “B4”, and a frame “P6”. Since the frame “P6” is the current target playback frame, it already exists on the frame buffer. Further, in order to decode the frame “B4”, the frame “I3” and the frame “P6” are required. The frame “I3” is held on the frame buffer. Frame “B4” is decoded using these frames “I3” and “P6”.

  On the other hand, when the target playback frame shifts from the frame “P6” to the frame “B5”, the frame “B7” that is the adjacent frame on the forward direction side in the state where the target playback frame is “P6” becomes unnecessary. Discarded. The newly decoded frame “B4” is stored in the area of the discarded frame “B7” on the frame buffer, and the frame buffer is updated.

  As described above, when the target reproduction frame advances by one frame in the forward direction from the state of the frame “P6”, the frame is updated only for one frame from the frame “B5” to the frame “B8”. Even when the target playback frame is returned by one frame in the reverse direction from the state of frame “P6”, the frame is updated only for one frame from frame “B7” to frame “B4”.

  As a second example, a case where the target playback frame is a frame “B7” based on a B picture will be described. In this case, in the playback speed range within 1 × speed in the forward and reverse directions, a frame that may become a new target playback frame after one frame timing of the target playback frame is the frame “B7”, The frames “P6” and “B8” are adjacent to the frame “B7” in the display order.

  In the state where the target playback frame is the frame “B7”, the frame decoded according to the target frame buffer pattern created based on the target playback frame as described above is stored in the frame buffer (the fifth row in FIG. 11). The target reproduction frame “B7”, the frames “P6” and “B8” before and after the target reproduction frame are stored in the frame buffer in a state where they have already been decoded.

  When the target playback frame is shifted to frame “P6” or frame “B8” from this state, a newly required frame is decoded based on a new target frame buffer pattern for the transferred target playback frame. To store in the frame buffer.

  The other area of the frame buffer in which these data are stored holds the immediately preceding data. That is, in the example of FIG. 11, when the target playback frame is the frame “B7”, the frame “B7” and the frame “B7” belong to the same GOP as the frame “B7” as shown in the fifth row. The frame “I3”, the frame “P9”, the frame “B8”, the frame “I3-”, the frame “P6-”, and the frame “P9” that belong to the previous GOP with respect to the GOP to which the frame “B7” belongs. -"And frame" P12- "are stored.

  When the target playback frame is frame “B7”, when the target playback frame shifts by one frame in the forward direction, the new target playback frame becomes frame “B8”. In addition, a frame that may become a new target playback frame after one frame timing with respect to the new target playback frame is displayed before and after the frame “B8” and the frame “B8” in the display order. The adjacent frames are “B7” and “P9”.

  Among these, since the frame “B7” is the current target reproduction frame, it already exists on the frame buffer. Further, in order to decode the frame “B8”, the frame “P6” and the frame “P9” are required. Since the frames “P6” and “P9” are frames necessary for decoding the frame “B7”, they already exist on the frame buffer. Frame “B8” is decoded using these frames “P6” and “P9”. Also, the frame “P9” already exists on the frame buffer.

  In this case, the frame “P6” that was the adjacent frame in the reverse display order in the state where the target playback frame is the frame “B7” is used for decoding the frame “B8” and is not discarded. Further, the frame “P12” used when the playback progresses by one frame in the forward direction is decoded using the frame “P9”. Also, among the frames belonging to the earliest GOP existing in the buffer memory, the frame “P12−” that is present in the buffer memory and is the newest frame in the display order is discarded, and the decoded frame “P12” is stored. To do.

  When the playback is returned by one frame in the reverse direction, the new target playback frame becomes the frame “P6”, and there is a possibility that the new target playback frame becomes a new target playback frame after one frame timing. The frames are a frame “P6”, a frame “B5”, and a frame “B7”. Since the frame “B7” is the current target playback frame, it already exists on the frame buffer. Further, in order to decode the frame “B5”, the frame “I3” and the frame “P6” are required. The frame “I3” is held on the frame buffer. Frame “B5” is decoded using frame “I3” and frame “P6”.

  On the other hand, when the target playback frame shifts from the frame “B7” to the frame “P6”, the frame “B8” that is the adjacent frame on the forward direction side in the state where the target playback frame is “B7” becomes unnecessary. Discarded. The newly decoded frame “B5” is stored in the area of the discarded frame “B8” on the frame buffer, and the frame buffer is updated.

  In this way, when the target playback frame advances one frame in the forward direction from the state of frame “B7”, the frame is updated only for one frame from frame “P12−” to frame “P12”. Even when the target playback frame is returned by one frame in the reverse direction from the state of the frame “B7”, the frame is updated only for one frame from the frame “B8” to the frame “B5”.

  As a third example, a case where the target playback frame is a frame “I3” based on an I picture will be described. In this case, in the playback speed range within 1 × speed in the forward and reverse directions, a frame that may become a new target playback frame after one frame timing of the target playback frame is the frame “I3”, The frame “B2” and the frame “B4” are adjacent to the frame “I3” in the display order.

  In the state where the target playback frame is the frame “I3”, the data decoded in accordance with the target frame buffer pattern created based on the target playback frame as described above is stored in the frame buffer (the first row in FIG. 11). The target reproduction frame “I3”, the frames “B2” and “B4” before and after the target reproduction frame are stored in the frame buffer in a decoded state.

  When the target playback frame is shifted to the frame “B2” or the frame “B4” from this state, a newly required frame is decoded based on a new target frame buffer pattern for the transferred target playback frame. To store in the frame buffer.

  The other area of the frame buffer in which these data are stored holds the immediately preceding data. That is, in the example of FIG. 11, when the target playback frame is “I3” as shown in the first row, the frame “I3” belongs to the same GOP as the frame “I3” and the frame “I3”. The frame “P6”, the frame “B2”, the frame “B4”, the frame “I3-”, the frame “P6-”, and the frame “P9” that belong to the previous GOP with respect to the GOP to which the frame “I3” belongs. ”,“ P12− ”, and“ P15 ”are stored.

  When the target playback frame is frame “I3”, when the target playback frame shifts by one frame in the forward direction, the new target playback frame becomes frame “B4”. Further, a frame that may become a new target playback frame after one frame timing with respect to the new target playback frame is a frame that is adjacent to the frame “B4” in the display order. “I3” and frame “B5”.

  Among these, since the frame “I3” is the current target playback frame, it already exists on the frame buffer. Further, in order to decode the frame “B5”, the frame “I3” and the frame “P6” are required. Since the frame “P6” is used to decode the frame “B4”, it already exists on the frame buffer. Frame “B5” is decoded using these frames “I3” and “P6”.

  In this case, the frame “B2” which is the target reproduction frame on the reverse direction side in the state where the target reproduction frame is “I3” is unnecessary and is discarded. The decoded frame “B5” is stored in the area of the frame “B2” to be discarded on the frame buffer, and the frame buffer is updated.

  When playback is returned by one frame in the reverse direction, the new target playback frame becomes frame “B2”, and a frame that may become a new target playback frame after one frame timing with respect to this new target playback frame is , “B2”, “B1”, and “I3”. Since the frame “I3” is the current target playback frame, it already exists on the frame buffer. Further, in order to decode the frame “B1”, the frame “I3” and the frame “P15−” belonging to the GOP immediately before the GOP to which the frame “I3” belongs are necessary. Frame “B1” is decoded using these frames “P15-” and “I3”.

  On the other hand, when the target playback frame shifts from the frame “I3” to the frame “B2”, the frame “B4” that is the forward adjacent frame in the state of the frame “I3” is not necessary, Discarded. The newly decoded frame “B1” is stored in the area of the discarded frame “B4” on the frame buffer, and the frame buffer is updated.

  Thus, when the target playback frame advances one frame in the forward direction from the state of frame “I3”, the frame is updated only for one frame from frame “B2” to frame “B5”. Even when the target playback frame is returned by one frame in the reverse direction from the state of the frame “I3”, the frame is updated only for one frame from the frame “B4” to the frame “B1”.

As described above, when the target playback frame is transferred to another frame, one frame stored in the buffer memory is discarded, and one new frame is decoded and stored in the discarded frame area. The buffer memory is updated. At this time, a frame to be discarded from the buffer memory can be determined based on the following rule.
(1) Discards the target playback frame and the B picture frame other than the frame adjacent to the target playback frame in the display order.
(2) If there is no frame based on the B picture to be discarded in accordance with the rule (1) above, a frame based on the I or P picture that satisfies the following condition (2a) or (2b) is present on the buffer memory. Discard.
(2a) In the case of a target playback frame transition in the forward direction, the last I or P picture belonging to the GOP in the GOP farthest in the reverse direction from the GOP in which the target playback frame exists.
(2b) In the case of a target playback frame transition in the reverse direction, in the GOP farthest in the forward direction from the GOP in which the target playback frame exists, the last I or P picture belonging to that GOP.

  As described above, if data is stored in the buffer memory according to the update pattern of the buffer memory according to the embodiment of the present invention, the current target reproduction frame is a frame based on I picture, a frame based on P picture, and a frame based on B picture. In either case, only one frame of data marching on the buffer memory is required for movement of one frame in an arbitrary direction. Therefore, variable speed reproduction within 1 × speed in the forward and reverse directions can be executed with a fixed delay using the 1 × speed decoder.

  In the above description, an example has been described for each of the I picture, the P picture, and the B picture that constitute the GOP as the current target playback frame. However, other frames that are not described here are the current target playback frame. Similarly, in the case of a playback frame, only one frame of data on the buffer memory is updated with respect to movement of one frame in an arbitrary direction.

  Next, a method of creating an example of the target frame buffer pattern as described above will be described with reference to the flowchart of FIG. In the following description, it is assumed that a target frame (referred to as a current frame) is a B picture frame.

First, in step S10, an I picture (I ₀ ) of the current GOP to which the current frame belongs is acquired. As shown in FIG. 13A, an I picture is searched from the picture corresponding to the current frame in the reverse direction in the order on the recording medium. At this stage, no frame of the target frame buffer pattern has been determined (see FIG. 14A).

When the first I picture (I ₀ ) picture of the current GOP is acquired, in step S 11, the position after the position advanced by two frames from the current frame in the forward direction on the recording medium from the picture corresponding to the current frame. An I picture or a P picture (P ₀ ) is searched (see FIG. 13B). At this stage, no frame of the target frame buffer pattern is determined (see FIG. 14B).

In step S12, I and / or P pictures from the picture (I ₀ ) to the picture (P ₀ ) acquired in steps S10 and S11 described above are searched from the recording medium. For example, as shown in FIG. 13C, the picture (I ₀ ) retrieved in step S10 is determined as a frame to be used for the target frame buffer pattern. Further, the next P picture (P) is searched from the picture (I ₀ ) in the forward direction in the order on the recording medium. The retrieved P picture is determined as a frame to be used for the target frame buffer pattern. As described above, the frame of the current GOP used for the target frame buffer pattern is sequentially determined based on the P or I picture searched sequentially from the recording medium (see FIG. 14C).

  When the frame based on the I and P pictures of the current GOP is determined as a frame to be used for the target frame buffer pattern in step S12, in step S13, the current frame is changed from the frame immediately before the current frame in the order on the recording medium. A B picture existing until the next frame is searched (see FIG. 13D). The searched B picture frame is determined as the frame of the current GOP used in the target frame buffer pattern (see FIG. 14D).

  That is, depending on the I and / or P pictures used to decode the B picture existing between the previous frame of the current frame and the next frame of the current frame in steps S11 and S12 described above. A frame is determined as a frame used for the target frame buffer pattern. In step S13, the determined frame based on the B picture decoded using the frame based on the I and / or P picture is determined as a frame to be used for the target frame buffer pattern.

When all the frames used for the target frame buffer pattern of the current GOP are determined by the processing up to step S13, the first I picture (I ₋₁ ) in the GOP immediately before the current GOP is searched in step S14. (See FIG. 13E). For example, starting from the first I picture (I ₀ ) of the current GOP, the I picture is searched in the reverse direction in the order on the recording medium, and on the recording medium based on the searched I picture (I ₋₁ ). The P picture is searched in the forward direction in the order (see FIG. 13F). Then, the frame based on the I and / or P picture of the GOP immediately preceding the searched current GOP is determined as the frame used for the target frame buffer pattern (see FIG. 14F).

  The processes from step S14 to step S15 described above are repeated until the buffer memory is filled (step S16).

  The position and type (I picture, P picture, and B picture) of a picture recorded on the recording medium can be known by referring to the picture pointer file described with reference to FIG. For example, when playback of a certain frame is instructed from the system or a higher system, the CPU 14 searches the picture pointer file using the frame instructed to be played as the target playback frame and the GOP to which the target playback frame belongs as the current GOP. The position of the I picture of the current GOP is acquired. As described above, the picture pointer file describes the picture type, the flag indicating whether or not the picture is the first picture of the GOP, the size information of the picture, and the start address. It is possible to search for a desired picture on the recording medium.

  When the target frame buffer pattern is determined based on the target playback frame and the frame buffer is filled with the decoded frame in accordance with the determined target frame buffer pattern, the operation described with reference to FIG. Playback is performed within a single speed in the forward and reverse directions with a predetermined fixed delay.

  Although the description has been given here assuming that the target playback frame is a B picture, the processing described with reference to the flowchart of FIG. 12 can also be applied to the case where the current frame is an I picture and a P picture.

  Further, a target frame buffer pattern corresponding to the target playback frame is created according to the flowchart of FIG. 12 described above, with a frame for which playback has been instructed by the system or a higher system as a target playback frame. This process is performed each time a target playback frame is instructed, for example. Based on the instruction of the first target playback frame, it may be created for all frames in the GOP. The created target frame buffer pattern is stored in the RAM 36, for example.

  Not limited to this, if the GOP configuration of a clip to be played back is known in advance, the processing shown in the flowchart of FIG. 12 is performed on each picture constituting the GOP, as shown in FIG. It is also possible to create a frame buffer update pattern in advance. If the GOP configuration applicable to the playback apparatus 1 is determined, an update pattern can be created in advance and stored in the ROM 35.

  The CPU 14 refers to the update pattern corresponding to the output frame in response to a reproduction instruction within the normal speed within the forward direction or within the normal speed within the reverse direction with respect to the operation unit 15, and the picture read from the optical disk 10 at each frame timing To update the frame buffer.

  Next, the reproduction control operation based on the frame buffer update pattern will be described. The reproduction control is synchronized at the frame timing and is sequentially performed for each frame. FIG. 15 schematically shows synchronization control according to an embodiment of the present invention. In the example of FIG. 15, video data for one frame is decoded with a period of three frames, and video data for one frame on the frame buffer is output in synchronization with this decoding.

  First, in the first frame, the frame information currently stored in the frame buffer is obtained from the frame buffer information acquired by the CPU 14, the read information in the disk drive 11, and the target speed information. Is determined (step S20). The read information is information on pictures that have already been read from the optical disk 10 and stored in the cache memory 12 of the disk drive 11. The target speed information is information indicating the playback speed and direction supplied to the CPU 14 by an operation on the operation unit 15 or a command from a higher-order application.

  When the target playback frame is determined, the picture to be transferred to the decoder 22 is determined (step S21). That is, based on the frame buffer update pattern described with reference to FIG. 11, the picture to be decoded is determined as the target playback frame is determined.

  For example, in the example of the fourth row in FIG. 11, if the playback direction is the forward direction, the new target playback frame for the current target playback frame “P6” is the frame “B7” or the frame “ P6 "is determined. Which of the frame “B7” and the frame “P6” is determined as the new target playback frame is uniquely determined based on the target speed information, the timing of the instruction, and the like. Here, a description will be given on the assumption that a new target playback frame is determined to be frame “B7”.

  Further, the frame buffer information in the fourth row is compared with the frame buffer information in which the new target playback frame is the target playback frame, and a frame that needs to be newly decoded and a frame that becomes unnecessary are determined. Extracted. In this example where the new target playback frame is frame “B7”, the frame buffer information in the fourth row is compared with the frame buffer information in the next fifth row, and the frame “B5” becomes unnecessary, It can be seen that frame “B8” needs to be decoded.

  When the picture to be transferred is determined in step S21, the picture is transferred to the decoder 22 at the timing of the next second frame (step S22). For example, the CPU 14 requests the disk drive 11 to read from the optical disk 10 a picture whose transfer has been confirmed. In response to this request, the disk drive 11 reads a picture (in the above example, a picture corresponding to the frame “B8”) from the optical disk 10. The read picture is transferred to the decoder 22, and when there is another frame necessary for decoding the read picture, the other frame is read from the frame buffer and transferred to the decoder 22. Is done.

  In this example of decoding the frame “B8”, the picture corresponding to the frame “B8” and the other frames “P6” and “P9” for decoding the frame “B8” are transferred to the decoder 22.

  Actually, the transfer of the picture whose transfer has been confirmed is performed by accessing the cache memory 12 of the disk drive 11 as described above, and the DMA (Direct Memory Access) transfer is performed without going through the CPU 14.

  Transfer of pictures from the disk drive 11 to the decoder 22 is performed in synchronization with the timing of the next second frame (step S22). Further, with the determination of the transfer picture in step S21, the decoding information for the picture is determined (step S23). For example, parameters necessary for decoding extracted from the header information of the determined transfer picture and information on other frames necessary for decoding are determined as decoding information. The determined decoding information is passed to the decoder 22.

  Based on the decoding information transferred in step S23, the decoder 22 starts decoding the picture transferred in step S22 in synchronization with the timing of the next third frame (step S24). The decoded picture (frame) is written to a predetermined bank of the frame buffer, and the frame buffer is updated. In the example of the fourth row in FIG. 11 described above, the decoded data of the frame “B8” is overwritten on the bank in which the frame “B5” is written on the buffer memory (the fifth row in FIG. 11). See line).

  On the other hand, when the target playback frame is determined in step S20 described above, information of the video data to be output is determined (step S25). In the example of the fourth row in FIG. 11 described above, the frame “P6” is determined as the output video data. Information on the determined output video data is passed to the output data control unit 23. Based on the received information, the output data control unit 23 sets video output by the start timing of the third frame (step S26). Based on this setting, the frame “P6” is output in synchronization with the third frame (step S27).

  In the forward playback at a speed less than 1 × speed, for example, in step S20 described above, whether or not the target playback frame is advanced to the next frame is controlled according to playback speed information supplied from a higher-level application or the like. Is possible. As an example, when reproduction is performed in the forward direction at a half speed, it is only necessary to update the output frame by one frame every two frame timings. This is possible, for example, by updating the target playback frame at a rate of once every two frames. If the target playback frame is not updated, the processing is performed based on the same frame buffer pattern as the previous processing, and thus the same frame as the previous frame timing is output. At this time, it is preferable that the access operation to the optical disk 10 by the disk drive 1 and the decoding operation of the decoder 22 are stopped.

  In the above description, the process when the playback direction is the forward direction has been described, but the same process is performed when the playback method is the reverse direction. In the first frame, a target playback frame is determined from the frame buffer information, read information, and target speed information (step S20). When the target playback frame is determined, the picture to be transferred to the decoder 22 is determined (step S21). In the example of the fourth row in FIG. 11, since the reproduction direction is the reverse direction, the target reproduction frame is determined to be either the frame “B5” or the frame “P6”. Here, it is assumed that the target reproduction frame is determined to be the frame “B5”. Further, the frame buffer information in the fourth row is compared with the frame buffer information in the third row in which the target playback frame is the output frame, so that the frame “B7” becomes unnecessary and the frame “B4” You can see that it needs to be decoded.

  When the picture to be transferred is determined in step S21, the picture is transferred to the decoder 22 in synchronization with the timing of the next second frame (step S22). At this time, if there is another picture necessary for decoding the picture, the other picture is also read from the frame buffer and transferred to the decoder 22. In this example of decoding frame “B4”, frames “I3” and “P6” used to decode frame “B4” are also forwarded to decoder 22. Frames “I3” and “P6” already exist on the frame buffer, as shown in the fourth row of FIG.

  As the transfer picture is determined in step S21, decoding information for the picture is determined (step S23). The determined decoding information is passed to the decoder 22. Based on the decoding information transferred in step S23, the decoder 22 starts decoding the picture transferred in step S22 in synchronization with the timing of the next third frame (step S24). The decoded picture (frame) is written to a predetermined bank of the frame buffer, and the frame buffer is updated. In the example of the fourth row in FIG. 11 described above, the data of the decoded frame “B4” is overwritten on the bank in which the frame “B7” in the buffer memory is written (the third row in FIG. 11). See line).

  On the other hand, when the target playback frame is determined in step S20 described above, information of the video data to be output is determined (step S25). In the example of the fourth row in FIG. 11 described above, the frame “P6” is determined as the output video data. Information on the determined output video data is passed to the output data control unit 23. Based on the received information, the output data control unit 23 sets video output by the start timing of the third frame (step S26). Based on this setting, the frame “P6” is output in synchronization with the third frame (step S27).

  Note that, regardless of whether the reproduction direction is the forward direction or the reverse direction, the processing described in step S20 to step S27 described above is sequentially performed for each frame timing. That is, in synchronization with the first frame, the target playback frame is determined by the process in step S20 described above. With the determined target playback frame as a new output frame, a new target playback frame determination process corresponding to the new output frame is started in synchronization with the next second frame.

  Since the transfer process of the new target playback frame from the disk drive 11 to the decoder 22 is performed in synchronization with the next third frame, it does not interfere with the previous process. Similarly, since the decoding process by the decoder 22 is performed in synchronization with the fourth frame (not shown), there is no interference with the previous process.

  As described above, according to the present invention, in variable speed playback ranging from forward 1 × speed playback to reverse 1 × speed playback, frame dropping is performed with a fixed delay with respect to a given playback speed and playback direction instruction command. The reproduction output without the above can be realized by using a 1 × speed decoder.

  In the sequence of FIG. 15 described above, after the target playback frame is determined in step S20, until the target playback frame is video output in step S27 with a fixed delay after the target playback frame is determined, It is necessary that the data transfer process in step S22 and the decoding process in step S24 each average within one picture / frame time. In other words, if the data transfer process in step S22 and the decoding process in step S24 are within one picture / frame time on average, there is no need to fix each processing time to one frame time. .

  When a 1x speed decoder is used to decode a picture and playback within 1x speed in the forward and reverse directions is performed with a fixed delay by the control based on the target frame buffer pattern as described above, the target playback is performed as described above. Each time a frame shifts, one frame is decoded, and one frame on the buffer memory is discarded accordingly. For this reason, the data transfer process in step S22 and the decoding process in step S24 each shift so as to converge to a process of 1 picture / frame time, and as a whole, converge to a 3-frame cycle as shown in FIG.

  As described above, according to the present invention, in variable speed playback ranging from forward 1 × speed playback to reverse 1 × speed playback, frame dropping is performed with a fixed delay with respect to a given playback speed and playback direction instruction command. The reproduction output without the above can be realized by using a 1 × speed decoder.

  In the above description, the present invention is applied to the case where an optical disk is used as a recording medium and a clip is recorded with an annual ring structure, but this is not limited to this example. For example, the recording format on the recording medium is not limited to the annual ring structure, and may be another format. Further, the recording medium is not limited to an optical disk, and may be a hard disk drive or a semiconductor memory. Further, the present invention has been described as being applied to data reproduced from a recording medium. However, this is not limited to this example, and the stream can be supplied from the outside if the stream can be stably supplied. The present invention can also be applied to a decoder device that decodes the stream data.

  In the above description, the playback device 1 is described as dedicated hardware for playing back video data recorded on the optical disc 10, but this is not limited to this example, and a general-purpose computer device such as a personal computer is used. (Not shown) can also be used as the playback apparatus 1. In this case, the function of the playback device 1 can be realized by a program installed in the computer device. In this case, the video data decoding process may be performed by the CPU by software processing, or dedicated hardware may be installed in the computer apparatus.

It is a basic diagram which shows notionally the reproduction | regeneration control processing by this invention. It is a block diagram which shows roughly the structure of an example of the reproducing | regenerating apparatus applicable to one Embodiment of this invention. It is a block diagram which shows roughly the structure of an example of a decoder. It is a block diagram which shows more specifically the structure of an example of a decoder. It is a basic diagram which shows an example data arrangement | positioning in a disk-shaped recording medium. It is a basic diagram for demonstrating a clip. It is a basic diagram which shows the mode of an example in which annual ring data was formed with respect to the optical disk. It is a basic diagram which shows the data structure of an example in the long GOP of MPEG2. It is a basic diagram which shows the more specific example of the picture pointer table in which picture pointer information is described. It is a basic diagram which shows the example of the required buffer amount in the case of decoding the flame | frame after 1 frame in the display order with respect to the current frame, or 1 frame before. It is a basic diagram which shows the update pattern of an example of the target frame buffer by one Embodiment of this invention. It is a flowchart which shows the creation method of an example of the pattern of a target frame buffer. It is a basic diagram for demonstrating the production method of an example of the pattern of a target frame buffer. It is a basic diagram for demonstrating the production method of an example of the pattern of a target frame buffer. It is a basic diagram which shows roughly the synchronous control by one Embodiment of this invention. It is a basic diagram for demonstrating the decoding process in the case of long GOP.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Playback apparatus 10 Optical disk 11 Disk drive 12 Cache memory 13 Decoder 13A Frame memory (frame buffer)
14 CPU
22 MPEG decoder 23 Output data control unit 33 Prediction restoration unit 35 ROM
36 RAM

Claims (7)

Video data that is compression-encoded using inter-frame compression by predictive encoding and recorded on a randomly accessible recording medium is played back at variable speeds from 1x playback in the reverse direction to 1x playback in the forward direction. a playback equipment,
At least, the current target playback frame, a frame buffer that stores the respective frame adjacent back and forth in the display order with respect to the current target frame,
When said one of each frame is a new target playback frame, and a target pattern creation section that creates a target pattern of the frame buffer to said new targets playback frame,
A comparison unit for comparing the above SL framebuffer the current target playback frame is stored state and the target pattern,
Re that having a frame buffer control unit on the basis of the comparison result by the comparison unit, and extracts a frame unnecessarily ing the state of the current frame buffer extracts the new 1 frame require decoding Raw equipment. The one frame that needs to be newly decoded is any frame that is adjacent to the new target playback frame in the order of display,
When the frame is already stored in the frame buffer, the frame buffer control unit selects one frame stored in the frame buffer, which is the newest frame in the display order or the oldest frame in the display order. The playback apparatus according to claim 1, wherein one frame is unnecessary. The frame buffer control unit determines one unnecessary frame according to a predetermined rule,
According to the predetermined rule, one frame that is not adjacent to the new target playback frame in the order of display in the display order and is decoded on the basis of other frames before and / or after in time becomes unnecessary. The playback device according to claim 1, wherein the playback device is determined as a frame. Start the input of the new decoded necessary frame extracted by the upper Symbol frame buffer control unit, decodes the frame input is started to a region of the frame becomes unnecessary above on the frame buffer The playback apparatus according to claim 1, further comprising a decoding control unit that controls to store the data. The above goal pattern is
Previously created playback apparatus according to any one of claims 1 to 4 that have been stored in the storage medium. Video data that is compression-encoded using inter-frame compression by predictive encoding and recorded on a randomly accessible recording medium is played back at variable speeds from 1x playback in the reverse direction to 1x playback in the forward direction. A playback method ,
At least the current target playback frame and the frames adjacent to the current target frame in the display order are stored in the frame buffer.
When said one of each frame is a new target playback frame, a target pattern generating step of generating a target pattern of the frame buffer to said new targets playback frame,
Upper SL and the current state of the frame buffer where the target playback frame is stored a comparison step of comparing the target pattern,
Based on the comparison result of the comparing step, that newly having a frame buffer control step of extracting one frame unnecessarily ing the state of the current frame buffer with decoding to extract one frame required playback method. Video data that is compression-encoded using inter-frame compression by predictive encoding and recorded on a randomly accessible recording medium is played back at variable speeds from 1x playback in the reverse direction to 1x playback in the forward direction. A playback program for causing a computer device to execute a playback method ,
At least the current target playback frame and the frames adjacent to the current target frame in the display order are stored in the frame buffer.
When said one of each frame is a new target playback frame, a target pattern generating step of generating a target pattern of the frame buffer to said new targets playback frame,
Upper SL and the current state of the frame buffer where the target playback frame is stored a comparison step of comparing the target pattern,
Reproducing method and a frame buffer control step on the basis of the comparison result of the comparing step, to extract one frame unnecessarily ing the state of the current frame buffer extracts the new 1 frame require decoding reproduction program for causing a computer to execute the device.

Images