JP2007124576A - Video-reproducing apparatus, video-reproducing method, video-reproducing program, and recording medium with video-reproducing program recorded thereon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video-reproducing apparatus capable of displaying video images at special reproduction at intervals to be as fixed as possible, even for any type of digital video data. <P>SOLUTION: A PTS comparison section 14 acquires display time information of a key frame, based on a random access table read from a storage medium 2 by a table analysis section 19 and specifies a key frame, to which a time being as long as or longer than a time after the lapse of a preset threshold time from the last output time as a display time set to the key frame outputted the last time and being closest to the time after the lapse of the threshold time from the output time is set as display time information. A video data reading section 15 reads the key frame specified by the PTS comparison section 14 from digital video data 32 on the storage medium 2 and outputs the read key frame as video data to be reproduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a video playback apparatus that enables special playback such as fast forward and fast reverse using random access information given to digital video data.

  In recent years, with the start of digital TV broadcasting, it has become widespread to record received digital video data on a large capacity recording medium that records DVD (digital versatile disk), HDV standard digital video data, and the like.

  Unlike analog video data, digital video data may include data that cannot be reproduced by a single frame. For example, digital video data encoded by the MPEG2 system currently used in BS / CS digital broadcasting is a P frame in which only the difference from the previous frame is encoded in order to increase the data compression rate, It is composed of a combination of a B frame in which a difference is encoded and an I frame that can be reproduced independently. An arbitrary P frame can be composed of one frame image by continuously reproducing from the most recent I frame in time series, but a single P frame cannot constitute an image. In the case of the B frame, a subsequent frame is further required to construct one frame of video.

  On the other hand, when the recorded video data is reproduced, there is a demand for special reproduction such as fast-forward and fast-reverse for shortening the viewing time or searching the viewing location. Here, when special playback of the above digital video data is performed at high speed, the viewer recognizes the content when the processing speed of the playback device cannot catch up or all the frames are decoded, or when the video is switched in a very short time. There is a problem that the original purpose cannot be achieved. Therefore, at the time of special reproduction of digital video data, it is necessary to reproduce by thinning out the frames.

  When the digital video data frame is thinned and reproduced, it is necessary to consider the type of frame to be reproduced for the reason described above. It is preferable to avoid a frame that cannot be played back alone, such as a P frame and a B frame in MPEG2, and extract and play back a frame that can be played back independently, such as an I frame, that is so-called random access.

  However, in video data that has been subjected to variable length encoding, such as MPEG2, it is not possible to know which frame is in which position of the entire video data, and to detect the position of a randomly accessible frame. Have difficulty.

  In order to solve this problem, in a medium such as a DVD-ROM in which creators pre-record digital video data and sell it, position information that can be randomly accessed is held in a table form separately from the video data. Yes.

  For example, according to the moving picture recording / reproducing apparatus disclosed in Patent Document 1, when recording video data transmitted as MPEG2-TS data on a storage medium such as a DVD-RAM, the random access table is similarly set. Can be created.

  By the way, it is desirable that the speed of special reproduction such as fast-forward and fast-reverse be possible in accordance with the needs of the viewer. For example, searching for a portion to be viewed from content of about 2 hours takes the worst 1 hour with only double-speed playback. On the other hand, when the position is narrowed to some extent, it is preferable to reduce the speed of special reproduction in order to detect the desired position with as little error as possible.

  As a method for realizing special reproduction at a plurality of speeds, the above-mentioned Patent Document 1 discloses a method of reproducing by appropriately thinning out entries based on entry information in a table. Specifically, it is as follows. First, an index number is assigned to each entry in order from the top of the entry in the table. Then, the variable TSKskipNs = 1 for double speed playback, and TskipNs = 2 for quadruple speed playback, an entry with the corresponding index number is read from the table for each TPSkipNs + 1, and video data is played back from the address indicated by the entry. Is done.

Further, Patent Document 2 discloses a method of outputting by thinning out the number of output video data units so as to be a reciprocal multiple of the playback speed during special playback.
JP 2001-16546 A (published on January 19, 2001) JP 2002-112194 A (published on April 12, 2002)

  However, the so-called key frame interval at which random access is possible differs depending on the encoder that creates the content and the video content. In the case of MPEG2, I frames are usually inserted at intervals of 0.5 to 2 seconds. However, in the case of 0.5 seconds and 2 seconds, the display interval is four times as long as equivalent entries are thinned out. There will be a difference.

  In order for the viewer to accurately grasp the contents, it is preferable that as many frames as possible be displayed without being thinned out in a display time that is visible. If the fast-forwarding speed is fast, for example, 100 times faster, even if key frames are included only every 2 seconds, if all key frames are displayed, the display time per frame is 1 / 50 seconds. Even if display is performed at such a display interval, it is very difficult for the viewer to grasp the displayed content. Under the same conditions, for a content with a key frame interval of 0.5 seconds, the display time per frame is 1/200 second.

  Here, in order to make it easier to grasp the display contents, if thinning is performed according to content with a short key frame interval, the key frame is thinned over a long time for content with a long key frame interval. become. Therefore, there is a problem that it is difficult for the viewer to specify a desired location when searching for a viewing location.

  As an example, FIG. 15 shows a time sequence diagram when seven key frames are thinned out, that is, every eight key frames are selected and output when the key frame interval is 0.5 seconds and 2 seconds. For content at 2 second intervals, the frame display is not updated for 4 times the 0.5 second interval. For example, when fast-forwarding is performed at the same speed to search for a frame at time A, the target frame is displayed for content with a key frame interval as narrow as 0.5 seconds, and the viewer can easily identify the search location. On the other hand, in a content having a wide key frame interval of 2 seconds, the target frame is not displayed even though the entry is included in the table. That is, in this case, the viewer cannot identify the search location.

  In addition, when the display interval is different within the content or between the content, the viewer easily misidentifies that the reproduction speed is unstable. As shown in FIG. 15, when the same number of thinning is performed between the content with a key frame interval of 0.5 seconds and the content with 2 seconds, the display interval is four times different. Even within one content, the interval between key frames can change. Different display intervals depending on the content or within the same content is easily recognized as a malfunction of the device, or when the display interval is free, an illusion that the playback speed is slow.

  Furthermore, content with different display intervals is difficult to view and may cause stress during viewing.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to enable video display during special playback to be performed at as constant intervals as possible for any digital video data. An object of the present invention is to provide a video playback device, a video playback method, a video playback program, and a recording medium on which the video playback program is recorded.

  Another object of the present invention is to perform playback using key frames with good reception when digital video data recorded on a recording medium is recorded by receiving radio waves. Video reproduction apparatus, video reproduction method, video reproduction program, and recording medium on which the video reproduction program is recorded.

  In order to solve the above problems, the video reproduction apparatus according to the present invention is composed of a plurality of frame data, and combines a key frame that can be reproduced with only one frame data and another frame data. A video playback device that reads information from a recording medium on which digital video data including frames that can be played back is recorded, and outputs the video data to be played back. The time closest to the time at which the threshold time has elapsed from the previous output time is set as the display time information that is equal to or greater than the time at which a preset threshold time has elapsed from the previous output time as the display time. A key frame specifying means for specifying a key frame; and a key frame specified by the key frame specifying means. A configuration in which an image data output means for outputting the over arm.

  In addition, in order to solve the above-described problem, the video playback method according to the present invention is composed of a plurality of frame data and combines a key frame that can be played back with only one frame data and another frame data. A video playback method in a video playback apparatus that reads information from a recording medium on which digital video data including frames that can be played back is recorded and outputs video data to be played back, The display time is the time that is equal to or greater than the time when the preset threshold time has elapsed from the previous output time as the display time set in the key frame and that is closest to the time when the threshold time has elapsed from the previous output time. A key frame specifying step for specifying a key frame set as information, and It is a method and an image data output step of outputting the key frame identified by step.

  In the above configuration or method, first, the threshold value is equal to or greater than the time when a preset threshold time has elapsed from the previous output time as the display time set in the key frame output last time, and the threshold value from the previous output time. A key frame in which the time closest to the elapsed time is set as the display time information is specified. The identified key frame is output.

  As described above, the interval between the key frames included in the digital video data varies depending on the encoder that generates the digital video data and the video content. On the other hand, according to the above configuration or method, the interval between the output key frames is substantially constant. Therefore, for example, the interval between key frames used for special reproduction or the like becomes substantially constant, so that the reproduction state can be made almost uniform for any digital video data.

  In order to solve the above problems, the video playback apparatus according to the present invention is composed of a plurality of frame data, and combines a key frame that can be played back with only one frame data and another frame data. A video playback apparatus that reads information from a recording medium on which digital video data including a frame that can be played back is recorded, and outputs video data to be played back. For each of a plurality of threshold times set sequentially from a reference time at a time interval, a key frame in which a time that is not less than the threshold time and that is closest to the threshold time is set as display time information is specified. Key frame specifying means and video data output for outputting the key frame specified by the key frame specifying means. A configuration in which a unit.

  In addition, in order to solve the above-described problem, the video playback method according to the present invention is composed of a plurality of frame data and combines a key frame that can be played back with only one frame data and another frame data. A video playback method in a video playback apparatus that reads information from a recording medium on which digital video data including a frame that can be played back is recorded and outputs video data to be played back. For each of a plurality of threshold times that are sequentially set from a reference time at a predetermined time interval, a key that is set to display time information that is equal to or more than the threshold time and that is closest to the threshold time A key frame specifying step for specifying a frame, and a key frame specified by the key frame specifying step. It is a method and an image data output step of outputting the over arm.

  In the above configuration or method, first, for each of a plurality of threshold times sequentially set from a reference time at predetermined time intervals that are set in advance, the threshold time is equal to or greater than the threshold time. A key frame whose time is set as display time information is specified. The identified key frame is output.

  As described above, the interval between the key frames included in the digital video data varies depending on the encoder that generates the digital video data and the video content. On the other hand, according to the above configuration or method, the interval between the output key frames is substantially constant. Therefore, for example, the interval between key frames used for special reproduction or the like becomes substantially constant, so that the reproduction state can be made almost uniform for any digital video data.

  Also, in the video reproducing apparatus according to the present invention, in the above configuration, the position information of the key frame included in the digital video data recorded on the recording medium on the recording medium, and the key frame Key frame group information including at least the display time information is recorded, key frame group information analyzing means for reading the key frame group information from the recording medium, and video data reading means for reading the digital video data from the recording medium The key frame specifying means obtains the display time information and position information of the key frame from the key frame group information analyzing means, and the position information of the key frame specified based on the display time information is Data reading means, and the video data reading means Based on the position information of the key frame which has been notified from the constant unit may be configured to read the key frame corresponding from the recording medium.

  According to the above configuration, the key frame specifying means specifies the key frame based on the key frame group information read from the recording medium, and the specified key frame is read from the recording medium by the video data reading means. become. Therefore, the key frame read from the recording medium by the video data reading means can be minimized, so that the processing amount can be reduced and the processing speed can be increased.

  The video reproduction apparatus according to the present invention further includes an instruction input unit that receives an instruction input from a user in the above configuration, and the instruction input unit is configured to input an instruction for reproduction at a speed different from normal reproduction. When accepted, the video data reading means may read the corresponding key frame from the recording medium based on the position information of the key frame notified from the key frame specifying means.

  According to the above configuration, when a playback instruction input at a speed different from that of normal playback is received, the key frame thinning process is performed. When playback is performed at a speed different from normal playback, it is necessary to extract key frames from the digital video data according to the playback speed. At this time, it is possible to make the interval between the extracted key frames almost constant regardless of the digital video data, so that good reproduction can be performed.

  In the video reproducing apparatus according to the present invention, in the above configuration, a key frame including at least position information on a recording medium of a key frame included in the digital video data recorded on the recording medium on the recording medium. Group information is recorded, and further comprises key frame group information analyzing means for reading the key frame group information from the recording medium, and video data reading means for reading digital video data from the recording medium. Means obtains key frame position information from the key frame group information analyzing means, reads the key frame from the digital video data recorded on the recording medium, and the key frame specifying means reads the video data; When displaying the key frame from the key frame read by the means To obtain information, the key frames identified based on the display time information may be configured to be output from the video data output unit.

  According to the above configuration, the video data reading means reads the key frame based on the key frame group information read from the recording medium, and the key frame specifying means acquires the display time information of the read key frame. Thus, the key frame to be output is specified, and the specified key frame is output. Therefore, it is possible to cope with the case where the key frame group information recorded on the recording medium does not include the display time information of each key frame.

  The video reproduction apparatus according to the present invention further includes an instruction input unit that receives an instruction input from a user in the above configuration, and the instruction input unit is configured to input an instruction for reproduction at a speed different from normal reproduction. If accepted, the key frame specifying means may output the specified key frame from the video data output means.

  According to the above configuration, when a playback instruction input at a speed different from that of normal playback is received, the key frame thinning process is performed. When playback is performed at a speed different from normal playback, it is necessary to extract key frames from the digital video data according to the playback speed. At this time, it is possible to make the interval between the extracted key frames almost constant regardless of the digital video data, so that good reproduction can be performed.

  In the video playback apparatus according to the present invention, in the above configuration, an instruction input unit that receives an instruction input from a user and an instruction input for playback at a speed different from that of normal playback are received by the instruction input unit. In this case, it may be configured to further include threshold setting means for setting the threshold time according to the instructed playback speed.

  According to the above configuration, the threshold time used for specifying the key frame is set according to the instructed playback speed. Therefore, at any playback speed, output is performed at key frame intervals suitable for the playback speed, and good playback can be performed.

  In order to solve the above problems, the video playback apparatus according to the present invention is composed of a plurality of frame data, and combines a key frame that can be played back with only one frame data and another frame data. A video playback device that performs processing for reading information from a recording medium on which digital video data including a frame that can be played back is recorded and outputting video data to be played back. Key frame group information analysis means for recording key frame group information including at least display time information of key frames included in the digital video data recorded on the recording medium and reading the key frame group information from the recording medium And a table of key frames sequentially read by the key frame group information analyzing means. A key frame group whose time information interval is equal to or greater than a preset threshold time and that is closest to the threshold time is extracted, and reconstructed key frame group information including the extracted key frame group is generated. And a memory for temporarily storing the reconstructed key frame group information generated by the reconstructed key frame group information composing means.

  In addition, in order to solve the above-described problem, the video playback method according to the present invention is composed of a plurality of frame data and combines a key frame that can be played back with only one frame data and another frame data. A video playback method in a video playback apparatus that reads information from a recording medium on which digital video data including frames that can be played back is recorded, and outputs video data to be played back. Key frame group information including at least display time information of key frames included in the digital video data recorded on the recording medium is recorded on the medium, and the key frame for reading the key frame group information from the recording medium The group information analysis step and the key frame group information analysis step sequentially A key frame group having an interval of display time information of the extracted key frame that is equal to or longer than a preset threshold time and that is closest to the threshold time is extracted, and consists of the extracted key frame group A reconstructing key frame group information composing step for generating reconstructing key frame group information; and a memory storing step for temporarily storing the reconstructing key frame group information generated by the reconstructing key frame group information composing step in a memory. Is the way you are.

  In the above configuration or method, first, key frame group information is read from the recording medium, and the interval between the display time information of the read key frames is equal to or greater than a preset threshold time, and the threshold time A key frame group having an interval closest to is extracted. Then, reconstructed key frame group information including the extracted key frame group is generated and temporarily stored in the memory.

  In order to solve the above problems, the video playback apparatus according to the present invention is composed of a plurality of frame data, and combines a key frame that can be played back with only one frame data and another frame data. A video playback device that performs processing for reading information from a recording medium on which digital video data including a frame that can be played back is recorded and outputting video data to be played back. Key frame group information analysis means for recording key frame group information including at least display time information of key frames included in the digital video data recorded on the recording medium and reading the key frame group information from the recording medium And the key frame group sequentially read by the key frame group information analyzing means. For each of a plurality of threshold times sequentially set from a reference time at a predetermined time interval set in advance, a time that is equal to or more than the threshold time and closest to the threshold time is set as display time information. A reconstructed key frame group information forming means for generating reconstructed key frame group information consisting of the extracted key frame groups, and a reconstructed key frame group information forming means for generating reconstructed key frame group information. And a memory that temporarily stores configuration key frame group information.

  In addition, in order to solve the above-described problem, the video playback method according to the present invention is composed of a plurality of frame data and combines a key frame that can be played back with only one frame data and another frame data. A video playback method in a video playback apparatus that reads information from a recording medium on which digital video data including frames that can be played back is recorded, and outputs video data to be played back. Key frame group information including at least display time information of key frames included in the digital video data recorded on the recording medium is recorded on the medium, and the key frame for reading the key frame group information from the recording medium The group information analysis step and the key frame group information analysis step sequentially Among the extracted key frames, each of a plurality of threshold times sequentially set from a reference time at a predetermined time interval set in advance is equal to or more than the threshold time and is closest to the threshold time A reconstructed key frame group information composition step for extracting a key frame group whose time is set as display time information and generating reconstructed key frame group information composed of the extracted key frame group, and the reconstructed key frame group A memory storage step of temporarily storing the reconstructed key frame group information generated by the information configuration step in a memory.

  In the above configuration or method, first, key frame group information is read from the recording medium, and the interval between the display time information of the read key frame and the reference time is equal to or greater than a preset threshold time, and A key frame group having an interval closest to the threshold time is extracted. Then, reconstructed key frame group information including the extracted key frame group is generated and temporarily stored in the memory.

  Normally, data read processing from a recording medium outside the video playback device takes longer to access than a memory provided in the video playback device such as ROM or RAM, and the access processing load is also large. Therefore, in order to realize a high-speed special reproduction operation, it is desirable to hold key frame group information with a high access frequency in a storage device provided inside the video reproduction apparatus. That is, as in the configuration or method described above, high-speed processing can be realized by building key frame group information in the memory and reading the key frame group information from the memory, for example, during special playback operation.

  As described above, the interval between key frames included in digital video data varies depending on the encoder that generates the digital video data and the video content. On the other hand, according to the above configuration or method, the interval between the key frames in the key frame group information reconstructed in the memory is substantially constant. In other words, the interval between the key frames in the reconstructed key frame group information can be made almost uniform for any digital video data.

  In order to solve the above problems, the video playback apparatus according to the present invention is composed of a plurality of frame data, and combines a key frame that can be played back with only one frame data and another frame data. A video playback device that performs processing for reading information from a recording medium on which digital video data including a frame that can be played back is recorded and outputting video data to be played back. Key frame group information including at least display time information of key frames included in digital video data recorded on the recording medium, and digital video data recorded on the recording medium were recorded by receiving radio waves If it is, the reception status information at the time of recording is stored together with the recorded time information. A state identification table is recorded, key frame group information analysis means for reading out the key frame group information from the recording medium, identification table analysis means for reading out the reception state identification table from the recording medium, and the key frame group The key frame display time information sequentially read by the information analysis means is compared with the reception state identification table read by the identification table analysis means, and a key frame group having a good reception state is extracted and extracted. Reconstructed key frame group information generating means for generating reconstructed key frame group information comprising the reconstructed key frame group, and a memory for temporarily storing the reconstructed key frame group information generated by the reconstructed key frame group information configuring means It is the structure equipped with.

  In addition, in order to solve the above-described problem, the video playback method according to the present invention is composed of a plurality of frame data and combines a key frame that can be played back with only one frame data and another frame data. A video playback method in a video playback apparatus that reads information from a recording medium on which digital video data including frames that can be played back is recorded, and outputs video data to be played back. The medium receives key frame group information including at least display time information of key frames included in the digital video data recorded on the recording medium, and the digital video data recorded on the recording medium receives radio waves. If it was recorded by the, the reception status information at the time of recording is recorded as the recorded time information. A reception state identification table held together with the key frame group information analysis step for reading the key frame group information from the recording medium, and an identification table analysis step for reading the reception state identification table from the recording medium, By comparing the display time information of the key frames sequentially read by the key frame group information analysis step with the reception state identification table read by the identification table analysis step, a key frame group having a good reception state is compared. A reconstructed key frame group information composition step for extracting and generating reconstructed key frame group information composed of the extracted key frame groups, and reconstructed key frame group information generated by the reconstructed key frame group information composition step Memory storage step for temporarily storing in memory Is a method to have.

  In the above configuration or method, first, the key frame group information and the reception state identification table are read from the recording medium, and the key frame group having a good reception state is extracted. Then, reconstructed key frame group information including the extracted key frame group is generated and temporarily stored in the memory.

  Normally, data read processing from a recording medium outside the video playback device takes longer to access than a memory provided in the video playback device such as ROM or RAM, and the access processing load is also large. Therefore, in order to realize a high-speed special reproduction operation, it is desirable to hold key frame group information with a high access frequency in a storage device provided inside the video reproduction apparatus. That is, as in the configuration or method described above, high-speed processing can be realized by building key frame group information in the memory and reading the key frame group information from the memory, for example, during special playback operation.

  In addition, when the digital video data recorded on the recording medium is recorded by receiving radio waves, a frame incompletely received may be recorded as a key frame. On the other hand, according to the configuration or method described above, incomplete key frame information that is difficult to use for reproduction is eliminated, and reconstructed key frame group information including as many complete key frame information as possible is stored inside the apparatus. It becomes possible to read into the memory.

  The video playback device may be realized by a computer. In this case, a video playback program for causing the video playback device to be realized by a computer by operating the computer as each of the means, and a program for recording the same Computer-readable recording media are also within the scope of the present invention.

  As described above, the video playback device according to the present invention is equal to or more than the time when a preset threshold time has elapsed from the previous output time as the display time set in the key frame output last time, and the previous time. Key frame specifying means for specifying a key frame whose time closest to the time when the threshold time has elapsed from the output time is set as display time information, and video data output for outputting the key frame specified by the key frame specifying means And means. As a result, for example, since the interval between key frames used for special playback is substantially constant, the playback state can be made almost uniform for any digital video data. Play.

  The video reproduction apparatus according to the present invention includes a key frame group information analyzing unit that reads the key frame group information from the recording medium, and display time information of the key frames sequentially read by the key frame group information analyzing unit. Reconstruction that extracts a key frame group whose interval is equal to or longer than a preset threshold time and that is closest to the threshold time, and generates reconstructed key frame group information including the extracted key frame group The key frame group information constituting unit and a memory for temporarily storing the reconstructed key frame group information generated by the reconstructed key frame group information constituting unit. As a result, high-speed processing can be realized, and there is an effect that the interval between the key frames in the reconstructed key frame group information can be made almost uniform for any digital video data. .

  The video reproduction apparatus according to the present invention includes a key frame group information analyzing unit that reads the key frame group information from the recording medium, an identification table analyzing unit that reads the reception state identification table from the recording medium, and the key frame. Compare the display time information of the key frames sequentially read by the group information analysis means with the reception state identification table read by the identification table analysis means, and extract a key frame group having a good reception state, Reconstructed key frame group information forming means for generating reconstructed key frame group information composed of the extracted key frame groups, and reconstructed key frame group information generated by the reconstructed key frame group information forming means are temporarily stored. And a memory. As a result, high-speed processing can be realized, information on incomplete key frames that are difficult to use for reproduction is eliminated, and reconstructed key frame group information including as many complete key frame information as possible is stored in the apparatus. There is an effect that it can be read into the memory.

  An embodiment of the present invention is described below with reference to the drawings.

[Embodiment 1]
(Configuration of video playback system)
FIG. 1 is a block diagram showing a schematic configuration of a video reproduction system according to this embodiment. As shown in the figure, the video playback system includes a video playback device 1 and a display device 3. The video reproduction device 1 reads the digital video data 32 recorded on the storage medium (recording medium) 2 and performs a reproduction process, and then performs a process of outputting the reproduction data to the display device 3. The display device 3 performs processing for displaying the playback data received from the video playback device 1 on the screen. The display device 3 may be any display device that can display a moving image, such as a liquid crystal display device, a plasma display device, or a CRT (Cathode Ray Tube). Can be mentioned.

  The video reproduction apparatus 1 includes an instruction input unit (instruction input unit) 11, a threshold setting unit (threshold setting unit) 12, a table analysis unit (key frame group information analysis unit) 13, a PTS comparison unit (key frame identification unit) 14, A video data reading unit (video data reading unit) 15, a decoding processing unit (video data output unit) 16, a threshold recording unit 21, and a current PTS recording unit 22 are provided.

  The instruction input unit 11 performs a process of accepting an instruction input by the user for the video playback device 1. Examples of the instruction input include a video playback instruction, a stop instruction, a pause instruction, a fast forward instruction, a fast reverse instruction, a slow playback instruction, and a frame advance instruction. The instruction input is received by, for example, an input using a button provided on the main body of the video reproduction apparatus 1 or an input by a remote controller.

  The table analysis unit 13 reads a random access table (key frame group information) 31 from the storage medium 2 and analyzes entries constituting the random access table 31. More specifically, the table analysis unit 13 analyzes the entry information of the random access table 31, and notifies the PTS comparison unit 14 of the PTS, the position information of the key frame, and the size of the key frame group. Details of the configuration of the random access table 31 will be described later.

  The PTS comparison unit 14 is a key frame to be read from the digital video data 32 recorded on the storage medium 2 when special playback operations such as fast forward, fast reverse, slow playback, and frame advance playback are performed. Process to identify. Details of processing in the PTS comparison unit 14 will be described later.

  The current PTS recording unit 22 records the value of the current PTS used in the processing of the PTS comparison unit 14.

  The threshold setting unit 12 performs a process of setting a threshold used in the process of the PTS comparison unit 14. The threshold is set according to the content of the special reproduction instruction accepted by the instruction input unit 11. Details of the threshold setting process by the threshold setting unit 12 will be described later. The threshold set by the threshold setting unit 12 is recorded in the threshold recording unit 21.

  The video data reading unit 15 reads the video data from the digital video data 32 according to the key frame position information and the key frame group size information notified from the PTS comparison unit 14 and transmits them to the decoding processing unit 16. The decoding processing unit 16 performs a process of decoding the video data and outputting it to the display device 3 as reproduction data.

  The storage medium 2 may be any recording medium that can record digital video data. Examples of the storage medium 2 include an optical disk recording medium such as a DVD, a magnetic recording medium such as a hard disk, a tape recording medium, and a semiconductor memory.

  The threshold recording unit 21 and the current PTS recording unit 22 are configured by a recording medium capable of recording data at least temporarily in the video reproduction device 1. Examples of such a recording medium include a semiconductor memory such as a RAM (Random Access Memory).

(Configuration of random access table)
The random access table 31 has a structure as shown in FIG. In the example shown in the figure, the random access table 31 includes a table header 51 and an entry group 52. The table header 51 includes information related to the entire random access table 31 such as the size of the entire random access table 31 and the number of entries. The entry group 52 includes a key frame position 53 indicating position information of a randomly accessible key frame, a key frame group size 54 indicating the size of a key frame or a frame group starting from the key frame, and a PTS ( This is a set of entries 56 including Presentation Time Stamp (display time information) 55.

  The random access table 31 is created so as to be paired with the digital video data 32. That is, the key frame position 53 and the key frame group size 54 indicate the position information of the key frame in the digital video data 32 and the size of the key frame group. The entry 56 corresponds to any key frame included in the digital video data 32.

(Processing flow in the PTS comparison unit)
Next, the flow of processing in the PTS comparison unit 14 when special reproduction is performed will be described with reference to the flowchart shown in FIG. First, in step 31 (hereinafter referred to as S31), a process of initializing the variable currentPTS recorded in the currentPTS recording unit 22 is performed as an initialization process. In this example, currentPTS is set to 0, but an initial value of currentPTS may be set as appropriate according to the situation.

  Next, in S32, it is determined by the PTS comparison unit 14 whether or not the special reproduction operation is finished. The PTS comparison unit 14 performs the above determination by receiving information indicating that an instruction to end the special reproduction operation has been received from the instruction input unit 11. If YES in S32, that is, if it is determined that the special reproduction operation has ended, the process ends. On the other hand, if NO in S32, that is, if it is determined that the special reproduction operation has not ended, the process proceeds to S33.

  In S33, the PTS comparison unit 14 receives the key frame position information, the size of the key frame group, and the PTS from the table analysis unit 13. Then, the PTS comparison unit 14 compares the received PTS with the most recent current PTS recorded in the current PTS recording unit 22, and the interval between them (the absolute value of the difference between them) is determined in advance for each special playback speed. It is determined whether or not the threshold value Th is not less than (S34). The PTS comparison unit 14 reads the value of the threshold Th from the threshold recording unit 21. If NO in S34, that is, if the absolute value of the difference between the PTS and the current PTS is smaller than the threshold Th, the processing returns to S32.

  On the other hand, if YES in S34, that is, if the absolute value of the difference between the PTS and the current PTS is greater than or equal to the threshold Th, the PTS comparison unit 14 sets the key frame position information and the key frame group size to the video data reading unit. 15 is notified. Further, the PTS comparison unit 14 changes the current PTS to the value of the PTS at that time and records it in the current PTS recording unit 22 (S35). Thereafter, the processing returns to S32.

(Processing of threshold setting unit)
Next, threshold setting processing by the threshold setting unit 12 will be described. As described above, the threshold value Th is used as a comparison target of the absolute value of the difference between the PTS and the current PTS in the PTS comparison unit 14. The threshold value setting unit 12 determines the threshold value Th by the following formula (1), for example, assuming that the special reproduction speed is N times and the output interval of the desired key frame is D seconds.

Th = | N | × D (1)
| N | indicates the absolute value of N, which is a multiple of the speed of special playback. When playback is performed in the reverse direction, such as fast rewinding, N is a value smaller than 0.

(Processing flow in the video playback device)
Next, the flow of processing when performing special playback in the video playback device 1 will be described with reference to the flowchart shown in FIG. First, in S41, the threshold value setting unit 12 determines the threshold value Th according to the designated speed according to the equation (1). Here, the threshold setting unit 12 specifies the designated speed by receiving information on the designated speed of special reproduction designated at that time from the instruction input unit 11.

  Next, in S42, as in S32 described above, the PTS comparison unit 14 determines whether or not the special reproduction operation has ended. If YES in S42, that is, if it is determined that the special reproduction operation has ended, the process ends. On the other hand, if NO in S42, that is, if it is determined that the special reproduction operation has not ended, the process proceeds to S43.

  In S43, the table analysis unit 13 sequentially reads and analyzes the entries 26 from the top of the random access table 31 of the storage medium 2. As a result, the table analysis unit 13 acquires the PTS, key frame position information, and key frame group size recorded in the entry.

  Thereafter, in S44, as in the process in S34 described above, the PTS comparison unit 14 performs a comparison process regarding the difference between the PTS and the current PTS. If NO in S44, that is, if the absolute value of the difference between the PTS and the current PTS is smaller than the threshold Th, the processing returns to S42.

  On the other hand, if YES in S44, that is, if the absolute value of the difference between the PTS and the current PTS is greater than or equal to the threshold Th, the PTS comparison unit 14 displays the position information of the key frame and the size of the key frame group as the video data reading unit. 15 is notified.

  When the video data reading unit 15 receives the key frame position information and the size of the key frame group from the PTS comparison unit 14, the video data reading unit 15 performs a process of reading the key frame group of the corresponding position and size from the digital video data 32 (S45). . The key frame group read by the video data reading unit 15 is transmitted to the decryption processing unit 16, and the decryption processing unit 16 performs the decryption process (S46). The decoding processing unit 16 outputs the decoded video data to the display device 3 (S47). Thereafter, the processing returns to S42.

(Key frame sequence during special playback)
FIG. 5 shows a time sequence diagram of each key frame of digital video data during special playback by the video playback device 1. In the figure, the upper diagram schematically shows the key frame interval when playing back content with a key frame interval of 0.5 seconds, and the lower diagram when playing back content with 2.0 seconds. In the figure, key frames output from the decryption processing unit 16 and displayed are indicated by hatching. In any case, the reproduction speed is 4 ×, and the key frame output interval D in the equation (1) is 1 second.

  In the example shown in FIG. 15, since both contents are thinned out by the same number of key frames, the difference between the key frame intervals of the contents is directly reflected in the display interval of special reproduction. Therefore, depending on the key frame interval, there is a problem that it is difficult for the viewer to grasp the playback content, or the display interval differs depending on the content. On the other hand, according to the video playback apparatus 1 according to the present embodiment, even if the key frame interval of the content is different, the influence on the playback frame interval is small, and both contents are output at the same key frame interval. Is possible.

  In the method described above, the threshold value Th is fixed, the PTS (current PTS) of the key frame output immediately before is used as a reference, and the difference between the PTS and the current PTS is compared with the threshold value Th as shown in FIG. Regardless of the frame interval, the playback frame interval is substantially constant. However, the threshold Th may be increased based on the PTS of the first key frame for special playback. In S35 of FIG. 3, instead of replacing the current PTS with the PTS, the threshold Th may be replaced with the equation (2).

Th = Th + | N | × D (2)
By setting an appropriate value such as PTS of the first key frame for special reproduction in current PTS and sequentially replacing Th by Equation (2), the same effect can be obtained by thinning out the key frames as appropriate.

  In the present embodiment, the digital video data 32 is described as being played back from the beginning. However, even if playback is performed midway, special playback at equal intervals can be performed in the same procedure.

  When normal playback is performed by the video playback device 1, the video data reading unit 15 sequentially reads video data including frames other than the key frame from the digital video data 32, and the decoding processing unit 16 appropriately decodes the display data. 3 is output.

  In this embodiment, the random access table structure shown in FIG. 2 is described as an example. However, if the entry includes key frame position information, key frame group size, and PTS, the same operation is performed. It is possible and is not limited to this configuration.

[Embodiment 2]
(Configuration of video playback system)
FIG. 6 is a block diagram showing a schematic configuration of the video reproduction system according to the present embodiment. As shown in the figure, the video playback system according to the present embodiment is different in the configuration of the video playback device 1 from the video playback system according to the first embodiment. Other configurations are the same as those described above, and thus the description thereof is omitted here.

  The video playback apparatus 1 according to the present embodiment includes the same blocks as the blocks included in the video playback apparatus 1 described in the first embodiment, but the data flow is different, and accordingly, the table analysis unit 13, the video The processing contents of the data reading unit 15 and the PTS comparison unit 14 are different. Other blocks included in the video reproduction apparatus 1 are the same as those described above, and thus the description thereof is omitted here.

  The table analysis unit 13 reads the random access table 31 from the storage medium 2 and analyzes the entry information of the random access table 31. Then, the table analysis unit 13 notifies the video data reading unit 15 of the key frame position information and the key frame group size.

  Here, the configuration of the random access table 31 in the present embodiment will be described with reference to FIG. As shown in the figure, unlike the random access table 31 in the first embodiment, the random access table 31 in the present embodiment is a table that does not include PTS information in the entry 56. Unlike the table analysis unit 13 of the first embodiment, the table analysis unit 13 does not analyze the PTS, and the destination of notifying the position information of the key frame obtained as a result of the analysis and the size of the key frame group is the PTS comparison unit 14. Instead, it becomes the video data reading unit 15.

  The video data reading unit 15 sequentially reads the key frame video data from the digital video data 32 according to the key frame position information and the key frame group size information notified from the table analysis unit 13, and transmits them to the PTS comparison unit 14. . That is, the video data reading unit 15 in this embodiment is different from the first embodiment in the transmission source of the position information of the key frame and the size information of the key frame group, and the transmission destination of the video data. The same as in the first embodiment.

  The PTS comparison unit 14 performs a process of specifying a key frame to be output from the video data based on the video data transmitted from the video data reading unit 15 when the special reproduction operation is performed.

(Processing flow in the PTS comparison unit)
Next, the flow of processing in the PTS comparison unit 14 when special reproduction is performed will be described with reference to the flowchart shown in FIG. First, in S81, as an initialization process, a process for initializing the current PTS recorded in the current PTS recording unit 22 is performed. In this example, currentPTS is set to 0, but an initial value of currentPTS may be set as appropriate according to the situation.

  Next, in S82, it is determined by the PTS comparison unit 14 whether or not the special reproduction operation has ended. The PTS comparison unit 14 performs the above determination by receiving information indicating that an instruction to end the special reproduction operation has been received from the instruction input unit 11. If YES in S82, that is, if it is determined that the special reproduction operation is completed, the process is terminated. On the other hand, if NO in S82, that is, if it is determined that the special reproduction operation has not ended, the process proceeds to S83.

  In S83, the PTS comparison unit 14 acquires the PTS from the video data transmitted from the video data reading unit 15. Then, the PTS comparison unit 14 compares the acquired PTS with the current PTS recorded in the current PTS recording unit 22, and the absolute value of the difference between the two is equal to or greater than a threshold Th that is predetermined for each special playback speed. It is determined whether or not (S84). If NO in S84, that is, if the absolute value of the difference between PTS and current PTS is smaller than the threshold Th, the processing returns to S82.

  On the other hand, if YES in S84, that is, if the absolute value of the difference between the PTS and the current PTS is equal to or greater than the threshold Th, the PTS comparison unit 14 transmits the video data to the decoding processing unit 16. Further, the PTS comparison unit 14 changes the current PTS to the value of the PTS at that time and records it in the current PTS recording unit 22 (S35). Thereafter, the processing returns to S82.

(Processing flow in the video playback device)
Next, the flow of processing when performing special playback in the video playback device 1 will be described with reference to the flowchart shown in FIG. First, in S91, the threshold setting unit 12 determines the threshold Th according to the specified speed according to the equation (1). Here, the threshold setting unit 12 specifies the designated speed by receiving information on the designated speed of special reproduction designated at that time from the instruction input unit 11.

  Next, in S92, as in S82 described above, the PTS comparison unit 14 determines whether or not the special reproduction operation has ended. If YES in S92, that is, if it is determined that the special reproduction operation has ended, the process ends. On the other hand, if NO in S92, that is, if it is determined that the special reproduction operation has not ended, the process proceeds to S93.

  In S93, the table analysis unit 13 reads and analyzes the entries 26 sequentially from the top of the random access table 31 of the storage medium 2. Accordingly, the table analysis unit 13 acquires the position information of the key frame recorded in the entry and the size of the key frame group.

  Next, the video data reading unit 15 sequentially reads the key frame video data from the digital video data 32 in accordance with the key frame position information and the key frame group size information notified from the table analysis unit 13 (S94). The read video data is transmitted to the PTS comparison unit 14.

  Thereafter, in S95, the PTS comparison unit 14 acquires the PTS based on the acquired video data, and the PTS comparison unit 14 performs the comparison process regarding the difference between the PTS and the current PTS as in the process in S84 described above. If NO in S95, that is, if the absolute value of the difference between the PTS and the current PTS is smaller than the threshold Th, the processing returns to S92.

  On the other hand, if YES in S95, that is, if the absolute value of the difference between the PTS and the current PTS is equal to or greater than the threshold Th, the PTS comparison unit 14 transmits the video data to the decoding processing unit 16.

  The decoding processing unit 16 performs a decoding process on the received video data (S96). Then, the decoding processing unit 16 outputs the decoded video data to the display device 3 (S97). Thereafter, the processing returns to S92.

  As can be seen by comparing FIG. 4 of the operation flowchart in the first embodiment and FIG. 9 of the operation flowchart in the second embodiment, the operations performed by the video reproduction apparatus 1 are similar between the first and second embodiments. The video playback apparatus 1 according to the first embodiment suitably realizes the special playback operation when the PTS of the key frame is recorded in the random access table 31. That is, in the first embodiment, there is no step of reading PTS from the video data, and the video data reading unit 15 is a digital video data in which only the video data of the key frame instructed from the PTS comparison unit 14 is recorded in the storage medium 2. 32 will be read. Therefore, compared with the second embodiment, the video playback device 1 in the first embodiment has a smaller processing amount.

  On the other hand, according to the second embodiment, a special reproduction operation in which the frame display interval is almost constant regardless of the content can be realized for the random access table in which the PTS of the key frame is not recorded as in the first embodiment.

  Also in the present embodiment, as in the first embodiment, the threshold Th is increased by the formula (2) based on the PTS of the first key frame for special playback, that is, instead of replacing the current PTS with the PTS in S85 of FIG. In addition, by replacing the threshold Th with the equation (2), the same effect as when the threshold Th is set to a fixed value with the equation (1) and the current PTS is sequentially replaced with the PTS can be obtained.

  When normal playback is performed in the video playback device 1 according to the second embodiment, the video data reading unit 15 sequentially reads the digital video data 32 including frames other than key frames and outputs the digital video data 32 to the PTS comparison unit 14. The PTS comparison unit 14 does not acquire the PTS and transmits all the video data to the decoding processing unit 16 as they are. The decoding processing unit 16 appropriately decodes the received video data and outputs it to the display device 3.

[Embodiment 3]
In the random access table that creates an entry for each key frame, as the length of the content increases, the number of entries increases in proportion thereto, and the size of the random access table increases. For example, in the case of the MOI (Media Object Information) table of the ISDB-T mobile video specification (SD Specification Part 8) published by the SD association, the size of one entry is 12 bytes. However, if entries are created at intervals of 0.5 seconds, the number of entries created per hour is 120 and the size is 1440 bytes. If the content length is 2 hours or 3 hours, the size of the MOI table can be 3k, 4kBytes. The third embodiment described below describes a video playback apparatus that can save memory resources by appropriately thinning out entries in a random access table in view of such a problem.

(Configuration of video playback system)
FIG. 10 is a block diagram showing a schematic configuration of the video reproduction system according to the present embodiment. As shown in the figure, the video playback system according to the present embodiment is different in the configuration of the video playback device 1 from the video playback system according to the first embodiment. Other configurations are the same as those described above, and thus the description thereof is omitted here.

  The video playback apparatus 1 according to the present embodiment includes a table reconstruction unit (reconstruction key frame group information configuration unit) 17 and a RAM (memory) 18 in addition to the configuration of the video playback apparatus 1 illustrated in the first embodiment. It has a configuration with. Other configurations are the same as those described above, and thus the description thereof is omitted here.

  The table reconstruction unit 17 reads the random access table 31 recorded on the storage medium 2 and performs processing for reconstructing information in the random access table. The RAM 18 records the random access table reconstructed by the table reconstructing unit 17. The RAM 18 is constituted by a semiconductor memory such as a RAM. However, the RAM 18 is not limited to this, and the video playback apparatus 1 can record data at least temporarily and can store data in the storage medium 2. Any recording medium may be used as long as it can be accessed at higher speed than access.

(Processing flow in the table reconstruction unit)
Next, the flow of processing in the table reconstruction unit 17 will be described with reference to the flowchart shown in FIG. First, in S111, as initialization processing, processing for initializing currentPTSA, counter, and n recorded in the parameter recording unit 23 is performed. In this example, currentPTSA, counter, and n are set to 0, but an initial value may be appropriately set according to the situation. After the initialization process is performed, reading of the random access table information from the random access table 31 is started.

  Next, in S112, it is determined whether all information recorded in the random access table 31 has been read. If YES in S112, that is, if it is determined that all the information recorded in the random access table 31 has been read, the process ends. On the other hand, if NO in S112, that is, if it is determined that not all information recorded in the random access table 31 has been read, the process proceeds to S113.

  In S113, it is determined whether or not the value of counter recorded in the parameter recording unit 23 is larger than a predetermined constant MAX_NUM. Here, MAX_NUM is a value obtained by subtracting 1 from the total number of entries that can be recorded in the RAM 18, is preset according to the capacity of the RAM 18, and is recorded in the parameter recording unit 23.

  If YES in S113, that is, if it is determined that the value of counter is larger than a predetermined constant MAX_NUM, a process of increasing the threshold ThA by an appropriate constant k is performed in S118. Thereafter, the processing from S111 is started again. On the other hand, if NO in S113, that is, if it is determined that the value of counter is equal to or less than a predetermined constant MAX_NUM, the process proceeds to S114.

  In S114, the table reconstruction unit 17 reads Entry [n], which is the (n + 1) th entry, from the random access table 31 of the storage medium 2, and analyzes the PTS of the entry. Then, the table reconstruction unit 17 compares the PTS obtained by analysis with the current PTSA, and determines whether or not the absolute value of the difference between the two is greater than or equal to the threshold ThA (S115). If NO in S115, that is, if the absolute value of the difference between PTS and current PTSA is smaller than the threshold ThA, n is incremented by 1 in S117, and the process returns to S112.

  On the other hand, if YES in S115, that is, if the absolute value of the difference between the PTS and the current PTSA is greater than or equal to the threshold ThA, the table restructuring unit 17 uses RecEntry [counter, which is an entry of the random access table to be reconfigured on the RAM 18. ] (Counter = 0 to MAX_NUM), Entry [n] is recorded. After recording, the counter is incremented by one. Further, the table reconstruction unit 17 changes the current PTSA to the PTS value at that time and records it in the parameter recording unit 23 (S116). Thereafter, n is incremented by 1 in S117, and the process returns to S112.

The threshold value ThA is set in advance according to the storage capacity of the RAM 18 and the key frame interval required at the minimum during the special reproduction operation. When the total playback time is included in the table header 51 of the random access table 31, ThA may be determined according to the total playback time TD. For example, ThA may be determined as shown in the following formula (3).
ThA = TD / (MAX_NUM + 1) (3)
In this case, since the counter does not exceed MAX_NUM, the processing of S113 and S118 described above can be omitted.

  The operation of the table reconstruction unit 17 is performed before the reproduction is started prior to the special reproduction operation described in the first and second embodiments. That is, during the special reproduction operation, the random access table information is read from the RAM 18 in the processing during the special reproduction operation shown in the first embodiment. Specifically, it is as follows.

  The table analysis unit 13 reads the random access table reconstructed by the table reconstruction unit 17 from the RAM 18 and analyzes the entry information. Then, the table analysis unit 13 notifies the PTS comparison unit 14 of the PTS and key frame position information obtained by the analysis and the size of the key frame group.

  The operations in the PTS comparison unit 14, the video data reading unit 15, and the decoding processing unit 16 are the same as those described in the first embodiment. That is, as in the first embodiment, even if the content key frame interval is different, there is little influence on the playback frame interval, and both contents can be output at the same key frame interval.

  In the above-described method, the threshold ThA is fixed, the PTS (current PTSA) of the key frame recorded immediately before in the RAM 18 is used as a reference, and the difference between the PTS and the current PTSA is compared with the threshold ThA, thereby making the random access table the key frame. The data is thinned at an interval not depending on the interval and read into the RAM 18. However, the threshold ThA may be increased with reference to the PTS of the key frame at the head of the video data. In S116 of FIG. 11, instead of replacing currentPTSA with PTS, the threshold value ThA may be replaced with equation (4).

ThA = ThA + TD / (MAX_NUM + 1) (4)
By setting an appropriate value such as PTS of the first key frame of the video data in currentPTSA and sequentially replacing ThA by the equation (4), the same effect can be obtained by thinning out the key frames as appropriate.

  Note that the operation of the table reconstruction unit 17 in the present embodiment reads a random access table from the storage medium 2 to the RAM 18 in the video reproduction apparatus 1, similar to the key frame thinning process performed in the PTS comparison unit 14. It is applied to the case.

  Normally, the process of reading data from the storage medium 2 by the video playback device 1 takes longer to access than the storage device provided in the video playback device 1 such as ROM or RAM, and the access processing load is also large. Therefore, in order to realize a high-speed special reproduction operation, it is desirable to hold a random access table having a high access frequency in a storage device provided in the video reproduction apparatus 1. That is, as in the present embodiment, a random access table is constructed in the RAM 18 and information in the random access table is read from the RAM 18 during the special reproduction operation, whereby high speed processing of the special reproduction operation can be realized.

[Embodiment 4]
For example, when a mobile terminal such as a mobile terminal receives video data transmitted wirelessly such as a television broadcast and performs recording, the mobile terminal is not always placed in a stable reception environment. For example, since the mobile device moves with the owner, during recording, the mobile device moves from an environment with a good reception condition of an outdoor broadcast radio wave to an environment with a poor reception condition such as a basement or a shadow of a building, or vice versa. There are cases. As described above, when the reception environment changes abruptly during recording, a frame incompletely received may be recorded as a key frame. Incomplete key frames cannot be reproduced normally, and there is a high possibility that they cannot be used for viewing location searching or shortening the viewing time, which is the purpose of special reproduction.

  Here, when the key frame is thinned out as described above, if the remaining key frame is received in an incomplete state, normal reproduction by the key frame cannot be performed, and the resource Is not fully available.

  The fourth embodiment described below shows an example of a video reproduction apparatus that preferentially thins out key frames at a location where the reception state of the broadcast radio wave is bad at the time of recording in view of the above problems.

(Configuration of video playback system)
FIG. 12 is a block diagram showing a schematic configuration of the video reproduction system according to the present embodiment. As shown in the figure, the video playback system according to the present embodiment is different from the video playback system according to the third embodiment in that the reception state identification table 33 is recorded in the storage medium 2 and the video playback. The difference is that the apparatus 1 includes an identification table analysis unit (identification table analysis means) 19. Other configurations are the same as those described above, and thus the description thereof is omitted here.

  The reception state identification table 33 includes a reception state identification table header 61 and an entry group 62 as shown in FIG. The reception status identification table header 61 includes information related to the entire table such as the size of the entire reception status identification table 33 and the number of entries. The entry group 62 is a set of entries 67 including information on the reception state type 63, the start position 64 of the reception state section, the start time 65 of the reception state section, and the duration 66 of the reception state section. The reception state identification table 33 is created so as to be paired with the digital video data 32 and the random access table 31, and the start position 64 of the reception state section is information indicating a position in the digital video data 32.

  The identification table analysis unit 19 reads the reception state identification table 33 from the storage medium 2, analyzes the entry 67 constituting the reception state identification table 33, and performs processing for extracting position information of a section with a bad reception state. Then, the identification table analysis unit 19 notifies the table reconstruction unit 17 of the position information of the section with a poor reception state.

(Processing flow in the table reconstruction unit)
Next, the flow of processing in the table reconstruction unit 17 will be described with reference to the flowchart shown in FIG. First, in S141, as initialization processing, processing for initializing currentPTSA, counter, and n recorded in the parameter recording unit 23 is performed. In this example, currentPTSA, counter, and n are set to 0, but an initial value may be appropriately set according to the situation. After the initialization process is performed, reading of the random access table information from the random access table 31 is started.

  Next, in S142, it is determined whether all the information recorded in the random access table 31 has been read. If YES in S142, that is, if it is determined that all the information recorded in the random access table 31 has been read, the process ends. On the other hand, if NO in S142, that is, if it is determined that all the information recorded in the random access table 31 has not been read, the process proceeds to S143.

  In S143, it is determined whether or not the counter value recorded in the parameter recording unit 23 is larger than a predetermined constant MAX_NUM. Here, MAX_NUM is a value obtained by subtracting 1 from the total number of entries that can be recorded in the RAM 18, is preset according to the capacity of the RAM 18, and is recorded in the parameter recording unit 23.

  If YES in S143, that is, if it is determined that the value of counter is larger than a predetermined constant MAX_NUM, a process of increasing the threshold ThA by an appropriate constant k is performed in S140. Thereafter, the processing from S141 is started again. On the other hand, if NO in S143, that is, if it is determined that the value of counter is equal to or smaller than a predetermined constant MAX_NUM, the process proceeds to S144.

  In S144, the table reconstruction unit 17 reads the (n + 1) th entry Entry [n] from the random access table 31 of the storage medium 2 and analyzes the start position of the key frame. Next, it is determined whether or not the analyzed key frame position matches the position information of the section with a bad reception state notified from the identification table analysis unit 19 (S145). If YES in S145, that is, if it is determined that the analyzed key frame position matches the position information of the section with poor reception, n is incremented by 1 in S149, and the process returns to S142.

  On the other hand, if NO in S145, that is, if it is determined that the analyzed key frame position is different from the position information of the section having a poor reception state, the table reconstruction unit 17 analyzes the PTS of the entry (S146). Then, the table reconstruction unit 17 compares the PTS obtained by analysis with the current PTSA, and determines whether or not the absolute value of the difference between the two is greater than or equal to the threshold ThA (S147). If NO in S147, that is, if the absolute value of the difference between PTS and currentPTSA is smaller than the threshold ThA, n is incremented by 1 in S149, and the process returns to S142.

  On the other hand, if YES in S147, that is, if the absolute value of the difference between the PTS and the current PTSA is equal to or greater than the threshold ThA, the table restructuring unit 17 uses RecEntry [counter, which is an entry of the random access table to be reconfigured on the RAM 18. ] (Counter = 0 to MAX_NUM), Entry [n] is recorded. After recording, the counter is incremented by one. Further, the table reconstruction unit 17 changes the current PTSA to the PTS value at that time and records it in the parameter recording unit 23 (S148). Thereafter, n is incremented by 1 in S149, and the process returns to S142.

The threshold value ThA is set in advance according to the storage capacity of the RAM 18 and the key frame interval required at the minimum during the special reproduction operation. Further, when the total playback time is included in the table header 51 of the random access table 31, ThA may be determined according to the total playback time TD and the time TB indicating the total duration of the section in which the reception state is bad. . For example, ThA may be determined as shown in the following formula (3).
ThA = (TD−TB) / (MAX_NUM + 1) (5)
In this case, since the counter does not exceed MAX_NUM, the processing of S143 and S140 described above can be omitted.

  The operation of the table reconstruction unit 17 is performed before the start of reproduction prior to the special reproduction operation, as in the third embodiment.

  In the above-described method, the threshold ThA is fixed, the PTS (current PTSA) of the key frame output immediately before is used as a reference, and the difference between the PTS and the current PTSA is compared with the threshold ThA, so that the random access table is set to the key frame interval. The data is thinned at an unreliable interval and read into the RAM 18. However, as in the third embodiment, the threshold value ThA may be increased based on the PTS of the key frame at the top of the video data. In S116 of FIG. 11, instead of replacing currentPTSA with PTS, the threshold value ThA may be replaced with equation (6).

ThA = ThA + (TD−TB) / (MAX_NUM + 1) (6)
By setting an appropriate value such as the PTS of the first key frame of the video data in currentPTSA and sequentially replacing ThA by equation (6), the key frames can be thinned out appropriately, and the same effect can be obtained.

  In this embodiment, when the random access table is read from the external storage medium 2 into the internal RAM 18 of the apparatus, incomplete key frame information that is difficult to use for reproduction is eliminated, and as many complete key frame information as possible is obtained. It is intended to be read.

  In Embodiments 3 and 4, the video playback apparatus 1 performs special playback using the reconstructed random access table. However, the reconstructed random access table starts normal playback. It may be used for other purposes such as position determination. For example, when normal playback is started from a place other than a key frame, data necessary for composing a video is not prepared, so that an image is not normally displayed. On the other hand, this can be avoided by starting reproduction from the position of the key frame recorded in the reconstructed random access table. Thus, a random access table reconfigured for uses other than special reproduction may be used.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  Finally, each block included in the video reproduction apparatus 1, particularly the threshold setting unit 12, the table analysis unit 13, the PTS comparison unit 14, the video data reading unit 15, the decoding processing unit 16, the table reconstruction unit 17, and the identification table analysis The unit 19 may be configured by hardware logic, or may be realized by software using a CPU as follows.

  That is, the video reproduction apparatus 1 includes a CPU (central processing unit) that executes instructions of a control program that realizes each function, a ROM (read only memory) that stores the program, and a RAM (random access memory) that expands the program. And a storage device (recording medium) such as a memory for storing the program and various data. An object of the present invention is a recording medium on which a program code (execution format program, intermediate code program, source program) of a control program of the video reproduction apparatus 1 which is software for realizing the above-described functions is recorded so as to be readable by a computer. This can also be achieved by supplying the video reproduction apparatus 1 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  Further, the video reproduction device 1 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Also, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  The video playback device according to the present invention is applicable to a video playback device that plays back digital video data recorded on a large-capacity recording medium such as a DVD. Further, the present invention can also be applied to a video playback device that receives digital broadcasts and records them.

1 is a block diagram showing a schematic configuration of a video reproduction system according to an embodiment of the present invention. It is a figure which shows an example of the structure of a random access table. It is a flowchart which shows the flow of a process in the PTS comparison part in case special reproduction is performed. It is a flowchart which shows the flow of a process in the case of performing special reproduction | regeneration in a video reproducing device. It is a time sequence diagram of each key frame of digital video data at the time of special playback by the video playback device. It is a block diagram which shows schematic structure of the video reproduction system which concerns on other embodiment of this invention. It is a figure which shows an example of the structure of a random access table. It is a flowchart which shows the flow of a process in the PTS comparison part in case special reproduction is performed. It is a flowchart which shows the flow of a process in the case of performing special reproduction | regeneration in a video reproducing device. It is a block diagram which shows schematic structure of the video reproduction | regeneration system which concerns on further another embodiment of this invention. It is a flowchart which shows the flow of a process in a table reconstruction part. It is a block diagram which shows schematic structure of the video reproduction | regeneration system which concerns on further another embodiment of this invention. It is a figure which shows an example of the structure of a reception status identification table. It is a flowchart which shows the flow of a process in a table reconstruction part. It is a time sequence figure of each key frame of digital video data at the time of special playback by a conventional video playback device.

Explanation of symbols

1 Video playback device 2 Storage media (recording media)
3 Display device 11 Instruction input unit (instruction input means)
12 Threshold setting unit (threshold setting means)
13 Table analysis unit (Key frame group information analysis means)
14 PTS comparison part (key frame specifying means)
15 Video data reading unit (Video data reading means)
16 Decoding processing unit (video data output means)
17 Table reconstruction unit (reconstruction key frame group information configuration means)
18 RAM (memory)
19 Identification table analysis unit (identification table analysis means)
21 threshold recording unit 22 current PTS recording unit 23 parameter recording unit 26 entry 31 random access table 32 digital video data 33 reception state identification table 51 table header 52 entry group 53 key frame position 54 key frame group size 55 PTS
56 entry 61 reception status identification table header 62 entry group 63 reception status type 64 start position 65 start time 66 duration 67 entry

Claims (17)

Digital video data including a plurality of frame data and a key frame that can be reproduced by only one frame data and a frame that can be reproduced by combining another frame data is recorded. A video playback device that performs processing for reading information from a recording medium and outputting video data to be played back,
The time closest to the time when the threshold time elapses from the previous output time is greater than or equal to the time when the preset threshold time has elapsed from the previous output time as the display time set for the key frame output last time. Key frame specifying means for specifying a key frame set as display time information;
And a video data output means for outputting the key frame specified by the key frame specifying means. Digital video data including a plurality of frame data and a key frame that can be reproduced by only one frame data and a frame that can be reproduced by combining another frame data is recorded. A video playback device that performs processing for reading information from a recording medium and outputting video data to be played back,
For each of a plurality of threshold times sequentially set from a reference time at a predetermined time interval set in advance, a time that is equal to or more than the threshold time and closest to the threshold time is set as display time information. A key frame specifying means for specifying the key frame being,
And a video data output means for outputting the key frame specified by the key frame specifying means. On the recording medium, key frame group information including at least the position information on the recording medium of the key frame included in the digital video data recorded on the recording medium and the display time information of the key frame is recorded. With
Key frame group information analyzing means for reading the key frame group information from the recording medium;
Video data reading means for reading digital video data from the recording medium,
The key frame specifying means acquires key frame display time information and position information from the key frame group information analyzing means, and notifies the video data reading means of the key frame position information specified based on the display time information. And
3. The video reproducing apparatus according to claim 1, wherein the video data reading means reads the corresponding key frame from the recording medium based on the position information of the key frame notified from the key frame specifying means. . An instruction input means for receiving an instruction input from a user;
When the instruction input means accepts a reproduction instruction input at a speed different from normal reproduction, the video data reading means is based on the key frame position information notified from the key frame specifying means, 4. The video reproducing apparatus according to claim 3, wherein the corresponding key frame is read from the recording medium. On the recording medium, key frame group information including at least position information on the recording medium of the key frame included in the digital video data recorded on the recording medium is recorded,
Key frame group information analyzing means for reading the key frame group information from the recording medium;
Video data reading means for reading digital video data from the recording medium,
The video data reading means acquires key frame position information from the key frame group information analyzing means, reads the key frame from digital video data recorded on the recording medium,
The key frame specifying means acquires the display time information of the key frame from the key frame read by the video data reading means, and the key frame specified based on the display time information is sent from the video data output means. 3. The video reproducing apparatus according to claim 1, wherein the video reproducing apparatus outputs the video. An instruction input means for receiving an instruction input from a user;
The key frame specifying unit causes the specified key frame to be output from the video data output unit when the instruction input unit receives a playback instruction input at a speed different from normal playback. The video reproduction apparatus according to claim 5. An instruction input means for receiving an instruction input from a user;
A threshold setting means for setting the threshold time according to the instructed reproduction speed when the instruction input means accepts an instruction for reproduction at a speed different from that of normal reproduction; The video playback apparatus according to claim 1 or 2, characterized in that: Digital video data including a plurality of frame data and a key frame that can be reproduced by only one frame data and a frame that can be reproduced by combining another frame data is recorded. A video playback device that performs processing for reading information from a recording medium and outputting video data to be played back,
Key frame group information including at least display time information of key frames included in the digital video data recorded on the recording medium is recorded on the recording medium, and
Key frame group information analyzing means for reading the key frame group information from the recording medium;
A key frame group is extracted in which the display time information intervals of the key frames sequentially read out by the key frame group information analyzing means are equal to or longer than a preset threshold time and are closest to the threshold time. Reconstructed key frame group information forming means for generating reconstructed key frame group information consisting of the extracted key frame groups;
A video reproduction apparatus comprising: a memory for temporarily storing reconstructed key frame group information generated by the reconstructed key frame group information composing means. Digital video data including a plurality of frame data and a key frame that can be reproduced by only one frame data and a frame that can be reproduced by combining another frame data is recorded. A video playback device that performs processing for reading information from a recording medium and outputting video data to be played back,
Key frame group information including at least display time information of key frames included in the digital video data recorded on the recording medium is recorded on the recording medium, and
Key frame group information analyzing means for reading the key frame group information from the recording medium;
Among the key frames sequentially read out by the key frame group information analyzing means, each of a plurality of threshold times sequentially set from a reference time at a predetermined time interval set in advance is equal to or greater than the threshold time. A reconstructed key frame group information configuration for extracting a key frame group in which the time closest to the threshold time is set as display time information and generating reconstructed key frame group information composed of the extracted key frame group Means,
A video reproduction apparatus comprising: a memory for temporarily storing reconstructed key frame group information generated by the reconstructed key frame group information composing means. Digital video data including a plurality of frame data and a key frame that can be reproduced by only one frame data and a frame that can be reproduced by combining another frame data is recorded. A video playback device that performs processing for reading information from a recording medium and outputting video data to be played back,
Key frame group information including at least display time information of key frames included in the digital video data recorded on the recording medium and the digital video data recorded on the recording medium receive radio waves on the recording medium. A reception status identification table that holds the reception status information at the time of recording together with the recorded time information when it is recorded by
Key frame group information analyzing means for reading the key frame group information from the recording medium;
Identification table analysis means for reading the reception status identification table from the recording medium;
By comparing the display time information of the key frames sequentially read by the key frame group information analysis unit with the reception state identification table read by the identification table analysis unit, a key frame group having a good reception state is obtained. Reconstructed key frame group information configuring means for extracting and generating reconstructed key frame group information composed of the extracted key frame groups;
A video reproduction apparatus comprising: a memory for temporarily storing reconstructed key frame group information generated by the reconstructed key frame group information composing means. Digital video data including a plurality of frame data and a key frame that can be reproduced by only one frame data and a frame that can be reproduced by combining another frame data is recorded. A video playback method in a video playback apparatus that performs processing of reading information from a recording medium and outputting video data to be played back,
The time closest to the time when the threshold time elapses from the previous output time is greater than or equal to the time when the preset threshold time has elapsed from the previous output time as the display time set for the key frame output last time. A key frame specifying step for specifying a key frame set as display time information;
And a video data output step of outputting the key frame specified by the key frame specifying step. Digital video data including a plurality of frame data and a key frame that can be reproduced by only one frame data and a frame that can be reproduced by combining another frame data is recorded. A video playback method in a video playback apparatus that performs processing of reading information from a recording medium and outputting video data to be played back,
For each of a plurality of threshold times sequentially set from a reference time at a predetermined time interval set in advance, a time that is equal to or more than the threshold time and closest to the threshold time is set as display time information. A key frame identification step for identifying a key frame that is present,
And a video data output step of outputting the key frame specified by the key frame specifying step. Digital video data including a plurality of frame data and a key frame that can be reproduced by only one frame data and a frame that can be reproduced by combining another frame data is recorded. A video playback method in a video playback apparatus that performs processing of reading information from a recording medium and outputting video data to be played back,
Key frame group information including at least display time information of key frames included in the digital video data recorded on the recording medium is recorded on the recording medium, and
A key frame group information analysis step of reading the key frame group information from the recording medium;
A key frame group is extracted in which the display time information interval of the key frames sequentially read out by the key frame group information analysis step is equal to or longer than a preset threshold time and is closest to the threshold time. A reconstructed key frame group information configuration step for generating reconstructed key frame group information consisting of the extracted key frame groups;
And a memory storage step for temporarily storing the reconstructed key frame group information generated in the reconstructed key frame group information composing step in a memory. Digital video data including a plurality of frame data and a key frame that can be reproduced by only one frame data and a frame that can be reproduced by combining another frame data is recorded. A video playback method in a video playback apparatus that performs processing of reading information from a recording medium and outputting video data to be played back,
Key frame group information including at least display time information of key frames included in the digital video data recorded on the recording medium is recorded on the recording medium, and
A key frame group information analysis step of reading the key frame group information from the recording medium;
Of the key frames sequentially read out by the key frame group information analysis step, each of a plurality of threshold times sequentially set from a reference time at a predetermined time interval set in advance is equal to or greater than the threshold time. A reconstructed key frame group information configuration for extracting a key frame group in which the time closest to the threshold time is set as display time information and generating reconstructed key frame group information composed of the extracted key frame group Steps,
And a memory storage step for temporarily storing the reconstructed key frame group information generated in the reconstructed key frame group information composing step in a memory. Digital video data including a plurality of frame data and a key frame that can be reproduced by only one frame data and a frame that can be reproduced by combining another frame data is recorded. A video playback method in a video playback apparatus that performs processing of reading information from a recording medium and outputting video data to be played back,
Key frame group information including at least display time information of key frames included in the digital video data recorded on the recording medium and the digital video data recorded on the recording medium receive radio waves on the recording medium. A reception status identification table that holds the reception status information at the time of recording together with the recorded time information when it is recorded by
A key frame group information analysis step of reading the key frame group information from the recording medium;
An identification table analysis step of reading the reception status identification table from the recording medium;
By comparing the display time information of the key frames sequentially read by the key frame group information analysis step with the reception state identification table read by the identification table analysis step, a key frame group having a good reception state is compared. A reconstructed key frame group information configuration step for extracting and generating reconstructed key frame group information consisting of the extracted key frame groups;
And a memory storage step for temporarily storing the reconstructed key frame group information generated in the reconstructed key frame group information composing step in a memory.   A video playback program for operating the video playback device according to any one of claims 1 to 10, wherein the program causes a computer to function as each of the above means.   The computer-readable recording medium which recorded the video reproduction program of Claim 16.

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