JP2007300395A - Video stream decoding output device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video stream decoding output device capable of performing video output normally even when an image having different scenes of a top field and a bottom field in the same frame is output by the PAL system. <P>SOLUTION: The video stream decoding output device includes a decoding means 110, a frame rate converting means 120 having a skip counter 121 therein, a video synchronizing signal generating means 130, and a video output means 140. When a repeat/first/field signal indicates that video is output for a three-field period, decoded image data decoded by the decoding means 110 are thinned out by image data of two fields and when the repeat/first/field signal indicates that video is output for a two-field period, the decoded image data are not thinned out, thereby achieving normal video output in accordance with the repeat/first/field signal or a top/field/first signal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a video bitstream decoding output device that decodes an input video bitstream, performs frame rate conversion, and outputs a video.

  In recent years, interest in multimedia technology has increased due to the widespread use of DVD (Digital Video Disc) discs, digital televisions, and the like. For example, an apparatus that decodes and reproduces a video bitstream encoded by MPEG technology or the like is required to have higher image quality and higher functionality. The MPEG2 playback apparatus has a frame rate conversion function in order to output a bit stream having various frame rates in accordance with the output frame rate. For example, Patent Document 1 discloses a video data reproducing apparatus that can convert a video signal to be output into either the NTSC system or the PAL system according to the television system of the television monitor to be used.

  In order to output film material shot at 24 frames per second using the NTSC system that outputs 30 frames per second (= 60 fields), image data is repeated 12 fields per second (= 60-24 * 2). Output. Therefore, in this case, one field of image data is repeated every other frame, the first frame of the film is 3 fields, the second frame is 2 fields, the 3rd frame is 3 fields, the 4th frame is 2 fields, and thereafter 24 frames By repeating 3-2-3-2 until the eyes, 60 field images are output. This reproduction method is called 3: 2 pull-down.

  In order to realize the 3: 2 pull-down described above, in the MPEG2 standard, a video signal is output first as a repeat first field signal indicating a video output period of decoded image data in units of frames. It is defined that a top field first signal representing a field is given.

  FIG. 12 is a timing diagram when a film material of 3: 2 pull-down is output in the NTSC format. As shown in FIG. 12, when the repeat first field signal is “0” (for example, frame # 1), the video is output for two field periods, and when it is “1” (for example, frame # 2), the video is 3 When the top field first signal is “0” (eg, frame # 3), the bottom field of the decoded frame is output first, and when it is “1” (eg, frame # 3). In # 1), the top field is first video output. Accordingly, when the encoder encodes the film material to be output in the NTSC format that outputs 30 frames of video for one second, the top field first signal and the video signal are added to the video signal so as to perform 3: 2 pull-down playback. A repeat first field signal is added and encoded. The playback device outputs video according to these signals and performs 3: 2 pull-down playback.

The film material to which 3: 2 pull-down playback is applied with such a repeat first field signal and top field first signal is output in a PAL system that outputs 25 frames (= 50 fields) of video per second. In this case, it is necessary to repeatedly output the image data by 2 fields per second (= 50-24 * 2). However, conventionally, unlike the case of outputting by the NTSC system, the image data is shown in FIG. As described above, there is a reproduction method in which image data is repeatedly output by one field every 24 field outputs without using the repeat first field signal or the top field first signal given to the stream. It was common to be done. FIG. 13 is a timing chart when a 3: 2 pull-down film material is output by the PAL method. This reproduction method is based on the premise that the film material is an image having a progressive structure. In other words, in the case of an interlaced image, the sampled time differs between the top field and the bottom field, so it is necessary to output video according to the top field first signal given to the stream. This is because, since the sampled times of the top field and the bottom field are the same, the reverse of the video output on the time axis does not occur regardless of which field is put out first.
JP-A-9-284804

  By the way, the film material rarely has frames with different scenes in the top field and the bottom field. For example, as shown in FIGS. 14 and 15, a film material from which the scene until the bottom field of a certain frame (here, frame # 3) is the scene 1 and the scene 2 starts from the top field can be mentioned.

  Even in such a case, as shown in FIG. 14, if the image data is output based on the repeat first field signal and the top field first signal given in units of frames, the image is normally displayed. Can be output. However, as described above, when video is output by the PAL method, video may not be output based on the repeat first field signal and the top field first signal. Even if a frame with different scenes is included in the top field and the bottom field, it cannot be detected, and as shown in FIG. There is a problem of outputting one field.

  Specifically, in the case of a film material where scene 1 is the bottom field of a frame and scene 2 starts from the top field, when this frame is output from the top field, scene 2 is output first, and then the bottom field. Since the scene 1 is output, there is a problem that the scenes appear to be switched for a moment.

  The present invention has been made paying attention to the above-described problems, and when a film material including images having different top-field and bottom-field scenes in the same frame is output by the PAL method, the video is normally output. It is an object of the present invention to provide a video bitstream decoding output device capable of performing the above-described operation.

  In order to solve the above problems, a video bitstream decoding output device according to the present invention is a video bitstream decoding output device that decodes a video bitstream including encoded image data and outputs a video image. Video synchronization signal generation means for generating and outputting a video synchronization signal indicating output timing, and a frame rate signal representing the number of output frames per unit time of the image data is output per unit time obtained from the video synchronization signal Frame rate conversion means for outputting a thinned-out signal for thinning out the image data in synchronization with the video synchronizing signal so as to match the number of output frames per unit time obtained from the video synchronizing signal when the number of frames is larger Decoded image data obtained by decoding the input video bitstream The frame rate signal and a repeat first field signal indicating a video output period of the decoded image data included in the video bitstream indicate a 3-field period video output, and the decimation signal performs decimation. When instructing, the video is output for one field period, and when the repeat first field signal indicates video output for three field periods, and when the decimation signal does not indicate decimation, the video is output for three field periods, When the first field signal indicates a two-field period video output, the decoding means for outputting a video output field number signal to be output in two field periods in synchronization with the video synchronization signal, and the video output field number signal Based on the instructed video output period, the decoding A video output means for video output and multiplexing said video sync signal to the image data, and having a.

  As a result, even when film material is output in the PAL format, video can be output in accordance with the repeat first field signal or top field first signal contained in the stream, so the top field and bottom field in the same frame. It is possible to output video normally even for images having different scenes.

  Furthermore, in the video bitstream decoding output device of the present invention, when the decoding means does not instruct thinning-out when the decoded image data, the frame rate signal, and the thinning-out signal indicate the repetition first field. When the video output period indicated by the signal is output, the repeat fast field signal indicates the video output for the three field period, and the thinning signal indicates the thinning, the video is output for one field period, and the repeat first When the field signal indicates video output for a two-field period and the thinning signal indicates thinning, decoding is performed from the next frame without decoding the image data for one frame, and the repeat first Number of video output fields to be output during the period indicated by the field signal No. of, and outputs in synchronization with the video synchronization signal.

  As a result, even when film material is played back at high speed, video can be output according to the repeat first field signal or top field first signal contained in the stream, so the top field and bottom field scenes can be displayed in the same frame. It is possible to output video normally even for different images.

  Furthermore, in the video bitstream decoding output device of the present invention, the frame rate conversion means is configured such that when the frame rate signal is smaller than the number of output frames per unit time obtained from the video synchronization signal, the video synchronization signal Output a repetitive signal for repeatedly outputting the image data to match the number of output frames per unit time obtained from the decoding means, the decoding means, the decoded image data, the frame rate signal, When the repeat first field signal indicates a two-field period video output and the repeat signal indicates repetition, the four-field period video is output, and the repeat first field signal is output for a two-field period video. And the repetitive signal is repetitive When not instructed, the video output field number signal is output for two field periods, and when the repeat first field signal indicates a three field period video output, the video output field number signal to be output for three field periods is synchronized with the video synchronization signal. Output.

  As a result, even when film material is played back at a low speed, video can be output according to the repeat first field or top field first signal contained in the stream, so the top field and bottom field scenes in the same frame are different. It is possible to output video normally even for images.

  According to the video bitstream decoding output apparatus of the present invention, when a film material is output as a video by the PAL system, or when a video is output by converting the frame rate of the decoded image data for high speed playback or low speed playback. However, since video can be output according to the repeat first field signal or top field first signal included in the video bitstream, the video output order is reversed in frames with different top field and bottom field scenes. Thus, it is possible to prevent a problem such as a momentary change of scenes and to output video normally.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
In the present invention, when the film material is output in the PAL format, the video is output in accordance with the repeat first field signal or the top field first signal added to the video bitstream.

  In the video bitstream decoding output device, in order to output the video material of the 3: 2 pull-down playback by the PAL system, the video is output from the image data obtained by decoding the video bitstream encoded by the MPEG2 format. It is necessary to output video by thinning out image data so as to match the number of output frames per unit time.

  In the video bitstream decoding output device according to the first embodiment, a decimation signal indicating the timing for decimation of image data from the decoded image data is generated from the frame rate of the output video and the frame rate of the input stream. In addition, the number of video output fields indicating the video output period of the image data is determined according to the thinned signal and the repeat first field signal or the top field first signal, and from the decoded image data, The image data of the determined number of video output fields is thinned at every interval indicated by the thinning signal and output as video.

  Hereinafter, the video bitstream decoding output apparatus 100 according to the first embodiment will be described with reference to FIGS. FIG. 1 is a block diagram showing a configuration of a video bitstream decoding output apparatus 100 according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the video bitstream decoding output device 100 includes decoding means 110, frame rate conversion means 120, video synchronization signal generation means 130, and video output means 140.

  The decoding unit 110 is connected to the frame rate conversion unit 120 and the video output unit 140, decodes the input video bitstream, and sends the decoded image data to the video output unit 140. In addition to outputting, the attribute information signal included in the video bitstream is output to the frame rate conversion means 120. The attribute information signal in the first embodiment is a frame rate signal indicating the number of output frames per unit time of decoded image data in the sequence header in the MPEG2 format.

  Further, the decoding unit 110 uses the video output unit based on a decimation signal input from the frame rate conversion unit 120 at predetermined intervals and a repeat_first field signal of picture_coding_extension included in the video bitstream. The number of video output fields indicating the video output period for outputting the decoded image data from 140 is determined, and the value is output to the video output means 140.

  Here, the decimation signal is a signal indicating the timing of decimation of image data from the image data decoded by the decoding means 110. In the first embodiment, the decimation signal = “1” has two fields. It means a command for thinning out image data, and a thinning signal = “0” means a command for not thinning out image data.

  In the first embodiment, in order to reproduce a video as smoothly as possible, the number of video output fields is determined so that one field is necessarily output from the decoded image data of each frame. Therefore, when the repeat first field signal is “1” (3-field output), the number of video output fields is set to “3” when the thinning-out signal is “0”, that is, when the thinning-out signal is “0”. When “1”, the image data of 2 fields (= 1 frame) is thinned to set the number of video output fields to “1”, while the repeat first field signal is “0” (2 fields output) The instruction of the thinning signal is not followed, that is, the data is not thinned from the decoded image data, and the number of video output fields is always “2”.

  By the way, in the above description, in order to facilitate processing in the video output means 140 at the subsequent stage, when the thinning signal is “1”, image data of 2 fields (= 1 frame) is thinned out from the decoded image data. However, the number of fields to be thinned out is not limited to this, and for example, one field of image data may be thinned out. As described above, when the image data of one field is thinned out when the thinning signal is “1”, the decoding is performed in accordance with the thinning signal command even when the repeat first field signal is “0”. Thin out image data from image data. Further, when the image data of one field is thinned out when the thinning signal is “1”, the subsequent video output means 140 performs processing so that there is no deviation in the image data constituting one frame by two fields. There is a need.

  Hereinafter, a series of operations of the decoding unit 110 described above will be described with reference to FIG. FIG. 2 is a flowchart showing a series of operations of the decoding means in the first embodiment. Here, a case where image data of two fields (= 1 frame) is thinned out from decoded image data in the case of the thinning signal “1” will be described as an example.

  First, in step S <b> 201, a frame rate signal is read from the input video bitstream and output to the frame conversion unit 120.

  In step S202, a repeat first field signal is acquired from the input video bitstream. In step S203, the value of the repeat first field signal read in step S202 is evaluated.

  If the repeat first field signal is “1” in step S203, the value of the thinned signal input from the frame rate conversion means 120 is evaluated in step S204, and the thinned signal is “1”. In this case, the number of video output fields is set so as to thin out two fields of image data from the decoded image data, and in the case of “0”, the number of video output fields according to the repeat first field signal is set. To do. That is, if the decimation signal is “0” in step S204, the video output field number signal is set to “3” and is output to the video output means 140 (step S207). When “1” is “1”, since thinning is instructed, thinning out of 2 fields from 3 field output, “1” is set in the video output field number signal, and the result is output to the video output means 140 (step) S205). After the step S205, the thinning signal is changed from “1” to “0” (step S206).

  If the repeat first field signal is “0” in step S203, the video output field number signal is set to “2” regardless of the value of the decimation signal output from the frame rate conversion means 120. Set and output to the video output means 140.

  Thus, after outputting the number of video output fields to the video output means 140 and setting the video output period, one frame is decoded in step S209, and the decoded image data is sent to the video output means 140. Output.

  Then, the decoding unit 110 is activated again after the period indicated by the video output field number signal, and performs the processing of steps S201 to S209 described above.

  As a result, the decoding means 110 can perform decimation of decoded image data based on the repeat first field signal, so that normal video output is possible.

  The frame rate conversion unit 120 includes therein a skip counter 121 that holds a value of the thinning interval t1 determined by the frame rate conversion unit 120 and decrements the value in field units. 110 and the video synchronization signal generating means 130. Then, the frame rate conversion means 120 outputs a frame rate signal (attribute information signal) of the decoded image data input from the decoding means 110 and a video output input from the video synchronization signal generation means 130. A thinning interval t1 is determined based on the number of output frames per unit time determined from a video output method (NTSC method, PAL method, etc.) obtained from a video synchronization signal indicating timing, and for each thinning interval t1, the thinning interval t1 is determined. A decimation signal is output to the decoding means 110.

  Here, the thinning interval t1 is the number of output frames (frame rate) per unit time of the decoded image data decoded by the decoding unit 110, and the output per unit time obtained from the video synchronization signal. In order to match the number of output frames per unit time obtained from the video synchronization signal when the number is larger than the number of frames, this indicates an interval at which image data is thinned out from the decoded image data. It is calculated by (Formula 1).

Thinning interval t1
= (Frame rate of video output method /
| Frame rate indicated by frame rate signal−frame rate of video output system |) * 2 (Expression 1)

For example, it is determined that the frame rate of the bit stream input from the decoding unit 110 is 30 and the video output method is the PAL method (25 Hz) from the video synchronization signal input from the video synchronization signal generation unit 130. The thinning interval t1 is
Thinning interval t1 = (25 / | 30-25 |) * 2 = 10
It becomes. Accordingly, in this case, a value “9” obtained by subtracting 1 from the thinning interval t1 is set in the skip counter 121, and a thinning signal is output from the frame rate conversion means 120 every 10 fields.

Hereinafter, a series of operations of the frame rate conversion means 120 will be described with reference to FIG. FIG. 3 is a flowchart showing a series of operations of the frame rate conversion means.
First, in step S301, a thinning interval t1 is determined from a frame rate signal that is an attribute information signal input from the decoding unit 110 and a video synchronization signal input from the video synchronization signal generation unit 130.

  Next, in step S302, it is determined whether or not playback is started. If it is determined that playback is started, in step S303, the skip counter 121 is set to 1 from the thinning interval t1 determined in step S301. The subtracted value is set and the skip counter 121 is initialized.

  On the other hand, if it is determined in step S302 that it is not the time to start playback, the process proceeds to step S304, where the value of the skip counter 121 is evaluated. Since it is not the thinning-out timing, the value of the skip counter 121 is decremented by 1 (step S307). On the other hand, when the value of the skip counter 121 is “0” in step S304, it is necessary to perform thinning out of the image data of two fields. Therefore, in step S305, the thinning signal is set to “1” and decoding is performed. After output to the means 110, the value of the skip counter 121 is initialized to "9" in step S306.

  Thereby, the frame conversion means 120 can output a decimation signal instructing decimation of image data at a timing according to the frame rate of the output video.

  Furthermore, the video synchronization signal generation means 130 is connected to the frame rate conversion means 120, the video output means 140, and a television (not shown), and outputs video according to the video output method of the connected television. A video synchronization signal indicating the timing is generated and output to the frame rate conversion means 120 and the video output means 140. For example, if the television is an NTSC system, a video synchronization signal of 29.97 Hz is generated, and if the television is a PAL system, a video synchronization signal of 25 Hz is generated and output.

  The video output unit 140 is connected to the decoding unit 110 and the video synchronization signal generation unit 130, and the number of fields (video output period) indicated by the video output field number signal output from the decoding unit 110. The video synchronization signal output from the video synchronization signal generation unit 130 is multiplexed with the decoded image data output from the decoding unit 110 and output.

  Hereinafter, an operation in the case of playing back a film material of 3: 2 pull-down playback with PAL video output in the video bitstream decoding output device 100 configured as described above will be described with reference to FIG. FIG. 4 is a diagram showing the operation timing of the video bitstream decoding output device when the film material is output in the PAL format in the first embodiment.

  First, the frame rate conversion unit 120 receives the frame rate signal included in the video bitstream from the decoding unit 110 and the video synchronization signal from the video synchronization signal generation unit 130, and determines the thinning interval t1. Here, since the frame rate signal is “30” and the PAL frame rate obtained from the video synchronization signal is “25”, the decimation interval t1 is “10”. On the other hand, a thinning signal for thinning out image data in units of 10 fields is output. Specifically, “9” is set in the skip counter 121 in the frame rate conversion means 120, the value of the skip counter 121 is decremented in field units (see FIG. 4B), and the value is 0. At this time, the decimation signal is output from “0” to “1” to the decoding means 110 (see FIG. 4C).

  The decoding unit 110 includes a decimation signal output from the frame rate conversion unit 120 (see FIG. 4C), and a repeat first field signal added to the video bitstream (see FIG. 4G). The video output field number is determined in accordance with the video bit stream, one frame of the video bit stream is decoded, and the decoded output image data and the video output field number signal are transmitted to the video output unit 140. Output (see FIGS. 4D and 4E).

  Here, the thinning-out processing is performed only when the thinning-out signal = “1” and the repeat first field signal = “1”. That is, when the thinning signal “1” and the repeat first field signal = “1”, the video output field number signal = “1”, the thinning signal “0” and the repeat first field signal = “1”. In this case, the video output field number signal = “3” is output to the video output means 140 when the repeat first field signal = “0”.

  The video output means 140 receives the video output field number signal and the video synchronization signal described above, and multiplexes the decoded image data of the number of fields designated by the video output field number signal with the video synchronization signal. It outputs (refer FIG.4 (f)).

  As described above, according to the first embodiment, even when a film material is output to a PAL monitor, the image data is thinned out from the decoded image data in accordance with the repeat first field signal in the video bitstream. Since the PAL video output is performed, it is possible to normally output the video even for images having different scenes in the top field and the bottom field in the same frame.

  In the above description, by using the repeat first field signal in the video bitstream, the thinning interval for thinning out the image data from the decoded image data and the number of video output fields are calculated, and normal video output is performed. As described above, even if the top field first signal in the video bitstream is used, the thinning interval and the number of video output fields can be calculated and normal video output can be performed. FIG. 5 is a diagram showing the relationship between the top field first signal and the repeat first field signal added to the video bitstream. As shown in FIG. 5, when the current repeat first field signal is “0”, the top field first signal of the next frame has the same value as the current repeat first field signal, This is because when the repeat first field signal is “1”, the top field first signal of the next frame is a value obtained by inverting the current repeat first field signal. That is, if the current top field first signal is compared with the previous top field first signal, the value of the current repeat first field signal can be obtained, that is, the previous top field first value. If the first signal and the current top field first signal are the same, the current repeat first field signal is “0”, and the previous top field first signal and the current top field first signal are the same. If the signal is different, the current repeat first field signal is “1”. Therefore, even if the repeat first field signal in the video bitstream is used, the image data to be thinned out from the decoded image data can be calculated and the normal video output can be performed in the same manner as described above.

(Embodiment 2)
In the first embodiment, image data is thinned out so that one field of the decoded image data of each frame is always video output. Specifically, repeat first field signal = “1” and thinned signal = Only in the case of “1”, the case where the image data of 2 fields is thinned out from the decoded image data is given as an example. In this case, the playback speed of the output video is at most,
(2 + 3) / (2 + 1) = 5/3 times.

In the second embodiment, a video bitstream decoding output device capable of reproducing output video at a higher reproduction speed will be described.
Here, a case where a film material is played back at double speed with NTSC video output will be described as an example.

The configuration of the video bitstream decoding output apparatus according to the second embodiment is similar to that of the first embodiment in that the decoding means 110, the frame rate conversion means 120 including the skip counter 121 therein, and the video synchronization signal generation Means 130 and video output means 140 are provided. In the apparatus of the second embodiment, the operations of the frame rate conversion means 120, the video synchronization signal generation means 130, and the video output means 140, excluding the decoding means 110, are the same as in the first embodiment. is there.
Accordingly, only the operation of the frame rate conversion means 120 will be described here.

  In the first embodiment, when the repeat first field signal is “1” (3 field output) in the decoding unit 110, the image data of 2 fields is decoded from the decoded image data in accordance with the instruction of the thinning signal. In the second embodiment, even when the repeat first field signal is “0” (2 field output), the image data is thinned according to the instruction of the thinning signal.

Hereinafter, a series of operations of the decoding unit 110 will be described with reference to FIG. FIG. 6 is a flowchart showing a series of operations of the decoding means in the second embodiment.
First, in step S <b> 201, a frame rate signal is read from the input video bitstream and output to the frame conversion unit 120.

  In step S202, a repeat first field signal is acquired from the input video bitstream. In step S203, the value of the repeat first field signal read in step S202 is evaluated.

  If the repeat first field signal is “1” in step S203, the value of the thinned signal input from the frame rate conversion means 120 is evaluated in step S204, and the thinned signal is “1”. In this case, two fields are thinned out from the decoded image data, and when “0”, thinning is not performed. That is, in step S204, if the thinning signal is “0”, since thinning is not instructed, the video output field number signal is set to “3” and output to the video output means 140 (step S207). On the other hand, if the decimation signal is “1”, decimation is instructed, so that 2 fields are decimation from 3 field output, and “1” is set in the video output field number signal, and the video output means After output to 140 (step S205), the thinning signal is changed from “1” to “0” (step S206). Thereafter, in step S209, one frame is decoded, and the decoded image data is output to the video output means 140 as decoded image data.

  In the second embodiment, even when the repeat first field signal is “0” in step S203, the value of the decimation signal input from the frame rate conversion means 120 is evaluated in step S210. If the decimation signal is “1”, two fields are decimation from the decoded image data, and if “0”, decimation is not performed. That is, if the thinning signal is “0” in step S210, since thinning is not instructed, the video output field number signal is set to “2” and output to the video output means 140 (step S210). S208), in step S209, one frame is decoded, and the decoded image data is output as decoded image data to the video output means 140. If the thinning signal is “1”, thinning is instructed. Therefore, after 2 fields are thinned out from the 2 field output and the video output field number signal is set to “0” and output to the video output means 140 (step S211), the image data for one frame is skipped. (Step S212), the thinning signal is changed from “1” to “0” (step S213).

  The decoding means 110 is started again after the period indicated by the video output field number signal. Accordingly, when the video output field number signal = “0”, the decoding unit 110 is activated immediately after the process of step S213 is completed, and performs the processes of steps S201 to S213 described above.

  In this case, since the decimation signal = “0” is set in step S213, the process proceeds to step S207 or step S208 to determine the number of video output fields in accordance with the next repeat first field signal, and one frame decoding is performed in step S209. To output decoded image data.

  As a result, the decoding means 110 can perform the decimation of the decoded image data based on the repeat first field signal, so that a normal video can be reproduced at high speed.

  Hereinafter, an operation in the case of playing back a film material of 3: 2 pull-down playback at double speed with NTSC video output in the video bitstream decoding output device 100 configured as described above will be described with reference to FIG. . FIG. 7 is a diagram showing the operation timing of the video bitstream decoding output apparatus when the film material is played back at double speed by the NTSC system in the second embodiment.

It should be noted that the thinning interval t1 in the second embodiment is based on (Equation 1) described above.
t1 = (30 / | (30/2) -30 |) * 2 = 4
It is.

  First, the frame rate conversion means 120 receives the frame rate signal of the video bit stream from the decoding means 110 and the video synchronization signal from the video synchronization signal generation means 130, and determines the thinning interval t1. Here, since the frame rate signal is “30” and the frame rate for double speed reproduction in the NTSC system obtained from the video synchronization signal is “15”, the thinning interval t1 is “4”. A decimation signal for decimation of decoded image data in units of 4 fields is output to the decoding unit 110. Specifically, “3” is set in the skip counter 121 in the frame rate conversion means 120, the value of the skip counter 121 is decremented in field units (see FIG. 7B), and the value is 0. Then, the decimation signal is output from “0” to “1” to the decoding means 110 (see FIG. 7C).

  The decoding unit 110 includes a decimation signal output from the frame rate conversion unit 120 (see FIG. 7C), and a repeat first field signal added to the video bitstream (see FIG. 7G). The video output field number is determined in accordance with the video bit stream, one frame of the video bit stream is decoded, and the decoded output image data and the video output field number signal are transmitted to the video output unit 140. The data is output (see FIGS. 7D and 7E). More specifically, when the thinning signal “0” and the repeat first field signal = “1”, the video output field number signal = “3”, the thinning signal “1” and the repeat first field signal = When “1”, the video output field number signal = “1”, and when the decimation signal “0” and the repeat first field signal = “0”, the video output field number signal = “2”. When the signal is “1” and the repeat first field signal = “0”, the video output field number signal = “0” is output to the video output means 140.

  The video output means 140 receives the video output field number signal and the video synchronization signal described above, multiplexes the video synchronization signal with the decoded image data of the field number designated by the video output field number signal, and outputs the video. (See FIG. 7 (f)).

  Here, unlike Embodiment 1 described above, since the video output field number signal is determined according to the thinned signal, the decoded image is also obtained when the thinned signal = “1” and the repeat first field signal = “0”. Two fields of image data are thinned out from the data. Therefore, when the decimation signal = “1” and the repeat first field signal = “0”, the decoding means 110 skips the image data for one frame without decoding and decodes from the next frame. Start the conversion. In this way, double-speed reproduction can be realized by thinning out the image data of two fields from the decoded image data in accordance with the thinning signal.

  In the above description, by using the repeat first field signal in the video bitstream, the thinning interval for thinning out the image data from the decoded image data and the number of video output fields are calculated, and normal video output is performed. As described with reference to FIG. 5 in the first embodiment, if the current top field first signal is compared with the previous top field first signal, Since it is possible to obtain the value of the current repeat first field signal, the top field first signal in the video bitstream is used to calculate the thinning interval and the number of video output fields, so that normal video can be obtained. Can be reproduced at high speed.

  As described above, according to the second embodiment, even when a film material is played back at a speed of 5/3 times or more, decoding is performed according to the repeat first field signal or the top field first signal in the video bitstream. Since the video data is output by thinning out the image data from the image data, the video can be normally reproduced while following the repeat first field signal or the top field first signal added to the video bitstream. It becomes possible.

(Embodiment 3)
In the first and second embodiments, when the number of output frames per unit time indicated by the frame rate of the input video bit stream is larger than the number of output frames per unit time at the time of video output, or the video bit stream In the third embodiment, the video bitstream decoding output device that outputs the video by thinning out the decoded image data when performing high-speed playback has been described. In the third embodiment, the number of output frames per unit time of the video bitstream A video bitstream decoding and output device capable of performing a low-speed reproduction of the video bitstream when the number of output frames per unit time at the time of video output is smaller than the above will be described.

  In order to perform low-speed playback in a video bitstream decoding output device, the same frame of image data is set at regular intervals so that the decoded image data matches the number of output frames per unit time when video is output. It is necessary to output video repeatedly.

Here, an apparatus that operates a film material at 6/7 times speed will be described as an example.
Hereinafter, the video bitstream decoding output apparatus 200 according to the third embodiment will be described with reference to FIGS. FIG. 8 is a block diagram showing a configuration of a video bitstream decoding output apparatus according to Embodiment 3 of the present invention.

  As shown in FIG. 8, the video bitstream decoding output device 200 includes a decoding unit 210, a frame rate conversion unit 220, a video synchronization signal generation unit 130, and a video output unit 140.

  The decoding unit 210 is connected to the frame rate conversion unit 220 and the video output unit 140, decodes the input video bitstream, and sends the decoded image data to the video output unit 140. In addition to outputting, the attribute information signal included in the video bitstream is output to the frame rate conversion means 220. Note that the attribute information signal in the third embodiment is a frame rate signal indicating the number of output frames per unit time of decoded image data in the sequence header in the MPEG2 format.

  Further, the decoding unit 210 uses the repetition signal input at predetermined intervals from the frame rate conversion unit 220 and the repeat_first field signal of the picture_coding_extension included in the video bitstream. The number of video output fields indicating the video output period for outputting the decoded image data from 140 is determined, and the value is output to the video output means 140.

  Here, the repetitive signal is a signal indicating the timing for repeating the image data decoded by the decoding means 210. In the third embodiment, the repetitive signal = “1” repeats the image data of two fields. This means a command, and a repetition signal = "0" means a command that does not repeat image data.

  In the third embodiment, when the repeat first field signal is “1” (3 field period output), the decoded image data is not repeated regardless of the value of the repetition signal. This is because, even when the repeat first field signal is “1”, if the image data is repeated according to the repetitive signal, the same frame is output for a period of 5 fields, and the smoothness of the motion during video playback is lost. Is to prevent. Accordingly, when the repeat first field signal is “0” (2 field output), the decoded image data of 2 fields (= 1 frame) is followed according to the command of the repetition signal, that is, when the repetition signal is “1”. Is repeated to set the number of video output fields to “4”, and when the repeat signal is “0”, the number of video output fields is set to “3”, while the repeat first field signal is “1” (3-field output). In this case, the number of video output fields is always set to “3” without repeating the repetitive signal, that is, the decoded image data is not repeated.

  By the way, in the above description, in order to facilitate the processing in the video output means at the subsequent stage, in the case of the repetitive signal “1”, the decoded image data is repeatedly output by 2 fields (= 1 frame). The number of repeated fields is not limited to this. For example, the decoded image data may be output by repeating one field. However, in the case where the decoded image data is configured to be repeatedly output by one field when the repetition signal is “1”, the video output means 140 in the subsequent stage does not cause a shift in the image data constituting one frame by two fields. Need to be processed.

  Hereinafter, a series of operations of the above-described decoding unit 210 will be described with reference to FIG. FIG. 9 is a flowchart showing a series of operations of the decoding means in the third embodiment. Here, a case where the decoded image data of 2 fields (= 1 frame) is repeatedly output when the repetitive signal is “1” will be described as an example.

  First, in step S 401, a frame rate signal is read from the input video bitstream and output to the frame conversion means 220.

  In step S402, a repeat first field signal is acquired from the input video bitstream. In step S403, the value of the repeat first field signal read in step S402 is evaluated.

  If the repeat first field signal is “0” in step S403, the value of the repetitive signal output from the frame rate converting means 220 is evaluated in step S404, and the repetitive signal is “1”. In this case, the number of video output fields is set so that the decoded image data is repeatedly output by two fields, and in the case of “0”, the number of video output fields according to the repeat first field signal is set. . That is, if the repetition signal is “0” in step S404, “2” is set in the video output field number signal and output to the video output means 140 (step S407), while the repetition signal is When the signal is “1”, since repetition is instructed, two fields are added to the two-field output, the video output field number signal is set to “4”, and output to the video output means 140 ( Step S405). After step S405, the repetitive signal is changed from “1” to “0” (step S406).

  In step S403, if the repeat first field signal is “1”, the video output field number signal is set to “3” regardless of the repetitive signal output from the frame rate conversion means 220. The video is output to the video output means 140.

  Thus, after outputting the number of video output fields to the video output means 140 and setting the video output period, one frame is decoded in step S209, and the decoded image data is sent to the video output means 140. Output.

  Then, the decoding unit 210 is activated again after a period of time indicated by the video output field number signal, and performs the processes of steps S401 to S409 described above.

  As a result, the decoding means 210 can repeat the decoded image data based on the repeat first field signal, so that normal video can be reproduced at low speed.

  The frame rate conversion means 220 includes therein a repeat counter 221 that holds the value of the repetition interval t2 determined by the frame rate conversion means 220 and decrements the value in field units. 210 and the video synchronization signal generating means 130. Then, the frame rate conversion means 220 outputs a frame rate signal (attribute information signal) of the decoded image data inputted from the decoding means 210 and a video output inputted from the video synchronization signal generating means 130. A repetition interval t2 is determined based on the number of output frames per unit time determined from a video output method (NTSC method, PAL method, etc.) obtained from a video synchronization signal indicating timing, and for each repetition interval t2, the repetition interval t2 is determined. A repetitive signal is output to the decoding means 210.

  Here, the repetition interval t2 indicates that the number of output frames (frame rate) per unit time of the decoded image data decoded by the decoding unit 210 is an output per unit time obtained from the video synchronization signal. When the number of frames is smaller than the number of frames, this indicates the interval at which the decoded image data is repeated in order to match the number of output frames per unit time obtained from the video synchronization signal. ).

Repeat interval t2
= (Frame rate of video output method /
| Frame rate indicated by frame rate signal−frame rate of video output system |) * 2 (Expression 2)

For example, when the frame rate of the bit stream input from the decoding unit 210 is reproduced at 6/7 times speed, the repetition interval t2 is
Repeat interval t2 = (30 / | (30 / (6/7))-30 |) * 2 = 12.
It becomes. Accordingly, in this case, the repeat counter 221 is set to a value “11” obtained by subtracting 1 from the repeat interval t2, and the frame rate conversion means 220 outputs a repeat signal every 12 fields.

Hereinafter, a series of operations of the frame rate conversion means 220 will be described with reference to FIG. FIG. 10 is a flowchart showing a series of operations of the frame rate conversion means.
First, in step S501, the repetition interval t2 is determined from the frame rate signal, which is an attribute signal input from the decoding unit 210, and the video synchronization signal input from the video synchronization signal generation unit 130.

  Next, in step S502, it is determined whether or not playback is started. If it is determined that playback is started, 1 is subtracted from the repeat interval t2 determined in step S501 in the repeat counter 221 in step S503. Then, the repeated counter 221 is initialized.

  On the other hand, if it is determined in step S502 that the playback is not started, the process proceeds to step S504, where the value of the repeat counter 221 is evaluated. Since it is not the timing to repeat, the value of the repeat counter 221 is decremented by 1 (step S507). On the other hand, if the value of the repeat counter 221 is “0” in step S504, it is necessary to repeat the image data of two fields. Therefore, in step S505, the repetition signal is set to “1” for decoding. After output to the means 210, the value of the repeat counter 221 is initialized to "11" in step S506.

  As a result, the frame conversion means 220 can output a repetitive signal instructing repetitive image data at a timing according to the frame rate of the output video.

  Note that the configurations and operations of the video synchronization signal generation unit 130 and the video output unit 140 are the same as those in the above-described embodiment, and thus description thereof is omitted here.

  In the following, the operation in the video bitstream decoding / output device 200 configured as described above when a film material of 3: 2 pull-down playback is played back at 6/7 times speed with NTSC video output will be described with reference to FIG. To do. FIG. 11 is a diagram showing the operation timing of the video bitstream decoding output device when the film material is played back at 6/7 times speed in the NTSC system in the third embodiment.

  First, the frame rate conversion unit 220 receives the frame rate signal included in the video bitstream from the decoding unit 210 and the video synchronization signal from the video synchronization signal generation unit 130, and determines the repetition interval t2. Here, since the frame rate signal is “30” and the frame rate for 6 / 7-speed reproduction of the NTSC system obtained from the video synchronization signal is “35”, the thinning interval t1 is “12”. A repetition signal for repeating the image data in units of 12 fields is output to the decoding unit 210. Specifically, “11” is set in the repeat counter 221 inside the frame rate conversion means 220, the value of the repeat counter 221 is decremented in field units (see FIG. 11B), and the value is 0. Then, the repetitive signal is output from “0” to “1” to the decoding means 210 (see FIG. 11C).

  The decoding unit 210 includes a repetitive signal (see FIG. 11C) output from the frame rate conversion unit 220, and a repeat first field signal added to the video bitstream (see FIG. 11G). The video output field number is determined in accordance with the video bit stream, one frame of the video bit stream is decoded, and the decoded output image data and the video output field number signal are transmitted to the video output unit 140. It outputs (refer FIG. 11 (d), (e)). More specifically, when the repeat first field signal = “1”, the video output field number signal = “3”, the repeat signal “1”, and the repeat first field signal = “1” regardless of the repeat signal. In the case of “0”, the video output field number signal = “4”, and in the case of the repeat signal “1” and the repeat first field signal = “0”, the video output field number signal = “2”. Each is output to the video output means 140. The video output means 140 receives the video output field number signal and the video synchronization signal described above, and outputs the decoded image data having the number of fields designated by the video output field number signal in synchronization with the video synchronization signal. (See FIG. 11 (f)).

  As described above, when the repeat signal is “1” and the repeat first field signal is “0”, 6 / 7-speed reproduction can be realized by repeating the image data of two fields.

  In the above description, a normal video output is performed by calculating the repeat interval of repeating decoded image data and the number of video output fields using the repeat first field signal in the video bitstream. As described with reference to FIG. 5 in the first embodiment, if the current top field first signal is compared with the previous top field first signal, the current repeat is obtained. -Since the value of the first field signal can be obtained, the repetition interval and the number of video output fields are calculated using the top field first signal in the video bitstream, and normal video is reproduced at low speed. It is also possible to do.

  As described above, according to the third embodiment, even when the film material is played back at a low speed, the decoded image data is repeated according to the repeat first field signal or the top field first signal in the video bitstream. Since the video output is performed, it is possible to normally reproduce the video while following the repeat first field signal or the top field first signal added to the video bitstream.

  The video bitstream decoding output device of the present invention includes frames in which the top and bottom field scenes are different when the film material is output in the PAL format, or when high-speed playback or low-speed playback is performed. Even if it is displayed, it is useful as a device that can output normal video.

It is a figure which shows the structure of the video bit stream decoding output device in Embodiment 1 of this invention. It is a flowchart which shows a series of operation | movement of the decoding means in Embodiment 1 of this invention. It is a flowchart which shows a series of operation | movement of the frame rate conversion means in Embodiment 1 of this invention. It is an operation | movement timing diagram of the video bit stream decoding output apparatus at the time of carrying out the video output of the film material by the PAL system in Embodiment 1 of this invention. It is a figure explaining the relationship between the repeat first field signal contained in a video bit stream, and a top field first signal. It is a flowchart which shows a series of operation | movement of the decoding means in Embodiment 2 of this invention. It is an operation | movement timing diagram of the video bit stream decoding output apparatus at the time of performing double speed reproduction | regeneration of a film material in Embodiment 2 of this invention. It is a figure which shows the structure of the video bit stream decoding output device in Embodiment 3 of this invention. It is a flowchart which shows a series of operation | movement of the decoding means in Embodiment 3 of this invention. It is a flowchart which shows a series of operation | movement of the frame rate conversion means in Embodiment 3 of this invention. It is an operation | movement timing diagram of the video bit stream decoding output apparatus at the time of performing 6/7 speed reproduction | regeneration of a film material in Embodiment 3 of this invention. It is an operation | movement timing diagram in the case of outputting the image | video of the film material in the conventional NTSC system. It is an operation | movement timing diagram in the case of outputting the image | video of a film material in the conventional PAL system. FIG. 10 is an operation timing chart when a film material including frames having different scenes in the top field and the bottom field is output to the NTSC system. FIG. 10 is an operation timing chart in the case where a film material including frames having different scenes in the top field and the bottom field is output in the PAL system.

Explanation of symbols

100, 200 Video bit stream decoding output device 110, 210 Decoding means 120, 220 Frame rate conversion means 121 Skip counter 130 Video synchronization signal generation means 140 Video output means 221 Repeat counter

Claims (3)

A video bitstream decoding output device for decoding and outputting a video bitstream including encoded image data,
Video synchronization signal generating means for generating and outputting a video synchronization signal indicating the timing of video output;
When the frame rate signal representing the number of output frames per unit time of the image data is larger than the number of output frames per unit time obtained from the video synchronization signal, the output frames per unit time obtained from the video synchronization signal Frame rate conversion means for outputting a thinning signal for thinning out the image data so as to match the number in synchronization with the video synchronization signal;
Decoded image data obtained by decoding the input video bitstream;
The frame rate signal; and
When a repeat first field signal indicating a video output period of the decoded image data included in the video bitstream indicates a three-field period video output, and the thinning signal indicates thinning, one field period Video output,
When the repeat first field signal indicates video output for 3 field periods and the thinning signal does not indicate thinning, video is output for 3 field periods;
When the repeat first field signal indicates a two-field period video output, a video output field number signal to be output in a two-field period video,
Decoding means for outputting in synchronization with the video synchronization signal;
Video output means for multiplexing and outputting the video synchronization signal to the decoded image data based on the video output period indicated by the video output field number signal;
A video bitstream decoding output device characterized by the above. The video bitstream decoding output device according to claim 1,
The decoding means includes
The decoded image data;
The frame rate signal; and
When the thinning signal does not instruct thinning, the video output period indicated by the repeat first field signal is output as video,
When the repeat first field signal indicates a three-field period video output and the thinning signal indicates a thinning-out, the one-field period video is output,
When the repeat first field signal indicates video output for a two-field period and the thinning signal indicates thinning, decoding is performed from the next frame without decoding the image data for one frame, A video output field number signal for outputting a video image during a period indicated by the repeat first field signal,
Outputting in synchronization with the video synchronization signal,
A video bitstream decoding output device characterized by the above. The video bitstream decoding output device according to claim 1,
When the frame rate signal is smaller than the number of output frames per unit time obtained from the video synchronization signal, the frame rate conversion means matches the number of output frames per unit time obtained from the video synchronization signal. Outputting a repeated signal for repeatedly outputting the image data,
The decoding means includes
The decoded image data;
The frame rate signal; and
When the repeat first field signal indicates a 2-field period video output and the repeat signal indicates repetition, the 4-field period video is output,
If the repeat first field signal indicates a two-field period video output, and the repeat signal does not indicate repetition, the two-field period video output,
When the repeat first field signal indicates a three-field period video output, a video output field number signal to be output for a three-field period video,
Outputting in synchronization with the video synchronization signal,
A video bitstream decoding output device characterized by the above.

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