JPH06276485A - Method for reproducing fast feed picture and fast returned picture from motion picture information subject to high efficiency coding - Google Patents

Abstract

PURPOSE:To obtain a reproduced picture with a smooth motion from motion picture information subject to high efficiency coding at the timer of reproduction of fast feed picture and fast returned picture. CONSTITUTION:When a picture of only I frame is selected and reproduced from a bit stream in which I, P, B frames or the like are in existence in mixture and a fast feed/fast returned picture is reproduced, the average interval between I mutual frames arranged in the bit stream is arranged so as to be a predetermined interval by which an interval of displayed pictures is made constant, and the retrieval of an I frame to be reproduced succeedingly to the reproduced I frame is started from a position resulting from subtracting a predetermined value K from an integer multiple of the predetermined interval in the case of reproduction of a fast feed picture and the retrieval of an I frame to be reproduced succeedingly to the reproduced I frame is started from a position resulting from adding a predetermined value M to an integer multiple of the predetermined interval in the case of reproduction of a fast returned picture. Thus, a time required to detect an object I frame is reduced, number of reproduced pictures per unit time is increased and a reproduced picture with smooth motion is easily obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing method for reproducing a fast-forward and fast-reverse image from moving image information which has been coded with high efficiency by the MPEG method.

[0002]

2. Description of the Related Art Video signals of moving images are highly efficiently compressed and transmitted,
Research for recording and reproducing has been actively conducted, and for example, recording of image data of a highly efficient compressed moving image on a small disk has also been attempted.
With the aim of creating an international standard for compressing image data by high-efficiency encoding video image signals, MPEG
(Moving Picture Coding Grou
p) sequentially proposes various data formats relating to highly efficient compressed image data, and image data highly efficiently compressed according to the data format proposed by MPEG (compressed image signal highly efficiently compressed by the MPEG system). Research and development has also been conducted on a practical device for transmitting, recording, and reproducing.

A moving picture information coding system (MPEG system) intended for a recording medium for recording digital data such as a CD-ROM employs a predictive coding method. An image in which image data is compressed by applying the inner prediction method {I picture (I
The image data is compressed by applying an inter-frame prediction method in which inter-frame prediction is performed based on image data of a frame (hereinafter, also referred to as an I frame) and image data of a past frame. Image {P picture (Predicted Pi
frames) (hereinafter also referred to as P-frames) and inter-frame prediction based on image data of both past frame image data and future frame image data Image whose image data has been compressed by applying the method {B picture (Bi-directional Pred
motion pictures) frame (hereinafter referred to as B
(Although it may be called a frame), each frame in three types of image modes is arranged in a predetermined arrangement on the time axis, and a predetermined header is added to the digital data to obtain image encoded data. .

In the MPEG system, the relationship between the image data compression rate in the I frame, the image data compression rate in the P frame, and the image data compression rate in the B frame is as follows. Compression rate) <(compression rate of image data in P frame) <(compression rate of image data in B frame)
The relationship is such that the reproduction is performed from the sequence header of the entry point at the time of reproduction, and the prediction is performed using the past image information and the image information of the future frame. In order to reproduce the image information of the B frame, the image information of the future P frame used for predicting the image information of the B frame needs to be recorded before the B frame.

FIG. 2 is a view for explaining the arrangement of data relating to the highly efficient compressed moving image information when the highly efficient compressed moving image information is recorded on an optical disc conforming to the CD (Compact Disc) standard. 2 (b) is an arrangement of recording data in a sequential sector portion in which data relating to moving image information compressed with high efficiency is recorded on an optical disc conforming to the CD (Compact Disc) standard. It shows the state. First, in FIG. 2A, following the MPEG system header portion in each sector shown in FIG.
The contents of the data to be recorded sequentially are recorded in one GOP.
(Group of Pictures) is illustrated. The GOP has a sequence header placed at the beginning of the GOP, a GOP header placed after the sequence header,
A sequential image frame is arranged subsequent to the GOP header.

2C to 2F show the concrete contents of the MPEG system header shown in FIG. 2B. PTS and DTS in the figure are: A time stamp, and one of the two types of time stamps PTS and DTS, PTS (pr
esentation time stamp) is information indicating the time when the image is actually displayed, and the other time stamp DT.
S (decoding time stamp) is time information indicating the time at which data is sent to the MPEG video decoder. By the way, there are many kinds of concrete contents of the MPEG system header as shown in (c) to (f) of FIG. 2 because the presence or absence of the time stamp included in the MPEG system header. In order to be able to indicate the content of the image information recorded in the sector in which the MPEG system header exists, the recording mode, etc., by distinguishing the type of existing time stamp, etc. Is.

The concrete contents of the MPEG system header are such that two types of time stamps PTS and DTS exist in the MPEG system header as shown in (c) and (d) of FIG. If so, the MPEG
I encoded in the sector where the system header is placed
This means that the frame or P frame starts, and in particular, the MPEG system header having the contents shown in FIG. 2C is as illustrated in FIG. It indicates that a plurality of GOPs are located in the first sector of each video sequence in the series. Further, as shown in (e) of FIG. 2, the time stamp PT is included in the MPEG system header.
If only S is present, it means that the encoded B frame starts in the sector in which the MPEG system header is placed, and further, (f) in FIG.
If neither of the time stamps PTS and DTS is present in the MPEG system header, as in the case of, the I-frame, P-frame or B-frame is stored in the sector in which the MPEG system header is placed. It means that it does not include the boundary of the beginning of the image frame.

In addition to the sequence header code, the sequence header is composed of the horizontal size and vertical size of the image, information on the aspect ratio, and various other information. The GOP header is a GOP (Group). of P
group start code, time code, information indicating whether or not it is a closed GOP, and broken link (if it is set to 1, its GOP header is added. A BOP existing between an I-frame and a P-frame constituting a GOP, which has a role of preventing the MPEG video decoder from performing a decoding operation), and other various information. Etc. The GOP is composed of an I-frame image data, a P-frame image data, and a B-frame image data group. However, immediately after the GOP header, the I-frame image data is always included. It is supposed to be located. Further, in a bit stream in which I frames, P frames, and B frames composed of moving image information highly efficient coded by the MPEG system are mixed, the I frames are arranged on the bit stream at substantially equal intervals on average. The encoding is performed in consideration of the above.

[0009]

By the way, when the image reproducing apparatus reproduces fast-forward and fast-reverse images from moving image information encoded by the MPEG system with high efficiency, the operator reproduces the image on the operation unit. When an input for operating in the fast-forward / fast-reverse image playback mode is performed, the central processing unit in the image playback device plays back the fast-forward / fast-reverse image from moving image information highly efficient encoded by the MPEG method. By sequentially controlling the operation of each component of the image reproducing apparatus according to each step in FIG. 3 exemplifying the procedure in the case, the I frame in which the sequence header and the GOP header are placed immediately before is selected. And then play
Perform control operations to obtain fast-forward and fast-reverse images. That is, the MPE is operated by the operation of each component in the image reproducing apparatus according to the procedure as shown in FIG.
When fast-forwarding and fast-rewinding images are reproduced from the moving image information that has been coded with high efficiency by the G system, the disk drive device equipped with the optical head seeks the optical head according to an instruction from the central processing unit. The operation is performed, the data read by the optical head is once stored in the buffer memory, the stored data is read from the buffer memory, and the bit stream is continuously supplied to the MPEG video decoder. The MPEG video decoder looks at the entire bit stream supplied to it, detects an I frame in the entire bit stream, and decodes the image information of the I frame, and the MPEG video decoder decodes the image information of a certain I frame. When it finishes the decoding operation for In processing apparatus, it gives a command to the disk drive device so as to seek the optical head to where you think that the next I-frame is present, operation as that is being that carried out.

Therefore, when fast-forwarding and fast-rewinding images are reproduced from moving image information that is highly efficient coded by the MPEG system as described above, the next reproduction is performed for each reproduction of the image information of the next I frame. Each time such as the time to skip to the position of the bit stream to start, the time to detect an I frame after starting the reproduction of the bit stream from the skipped position, the time to reproduce the entire detected I frame, etc. However, as described above, in a bit stream in which I frames, P frames, and B frames composed of moving image information highly efficient coded by the MPEG method are mixed, as described above. The intervals between successive I-frames in the are not constant, and there are wide variations in the intervals, so that the bit to start the next reproduction is Position the skip is performed as the position of the stream skips the advanced position with sufficient margin with respect to likely not exist I frame position,
In order to detect the I frame after starting the reproduction of the bit stream from the skipped position,
Since the time required for detecting the I frame as described above becomes long, and the number of reproduced images per unit time decreases, the smoothness of the motion of the reproduced images becomes insufficient. Therefore, improvement measures were required to minimize the above-mentioned time.

[0011]

According to the present invention, in a bit stream in which I frames, P frames, and B frames composed of moving image information highly efficient coded by the MPEG system are mixed, the I frames are on the bit stream. so,
Paying attention to the fact that encoding is performed with consideration given to being arranged at approximately equal intervals on average, an image frame whose image data has been compressed by applying the intra-frame prediction method is used. , MPE in which image frames in which image data is compressed by applying inter-frame prediction are mixed
When the fast-forward and fast-reverse images are reproduced by selectively reproducing only the image of the image frame in which the image data is compressed by applying the intra-frame prediction method from the moving image information encoded by the G method with high efficiency In the above, the average interval between the image frames in which the image data is compressed by applying the intra-frame prediction method is set to a predetermined interval so that the interval of the display images can be made constant. The image frame whose image data is compressed by applying the intra-frame prediction method described above is placed in advance in the bitstream, and when the fast-forward image is played back, the played intra-frame prediction method is applied to The search for an image frame whose image data has been compressed by applying the intra-frame prediction method, which should be reproduced next to the image frame that has been compressed, is determined in advance as described above. Constant value K from an integer multiple of the resulting distance
Starting from the position where is subtracted, and when playing back the fast-reverse image, the intra-frame prediction method that should be played next to the image frame in which the played intra-frame prediction method is applied and the image data is compressed High-efficiency encoding is performed by the MPEG method by starting the search for the image frame in which the image data is compressed by applying the fixed value M to the integer multiple of the predetermined interval described above. The present invention provides a reproducing method that can easily obtain a reproduced image with smooth movement when reproducing a fast-forward or fast-reverse image from the generated moving image information.

[0012]

According to the moving image information which is highly efficient coded by the MPEG system in which I frames, P frames, B frames and the like are mixed, only the I frame images are selectively reproduced and fast forward and fast reverse images are reproduced. In this case, the I-frames arranged in the bitstream are arranged in such a manner that the average interval between the I-frames becomes a predetermined interval so that the interval between the display images can be kept constant. Then, when the fast-forward image is reproduced, it should be reproduced next to the reproduced I frame,
The search for the I frame is started from a position obtained by subtracting a constant value K from the integral multiple of the above-mentioned predetermined interval, and when the fast-reverse image is reproduced, the I frame to be reproduced next to the reproduced I frame. The search is started from the position where a constant value M is added to the integral multiple of the above-mentioned predetermined interval.
As a result, it is possible to shorten the time until the I frame is detected after the reproduction of the bit stream is started from the skipped position, the number of reproduced images per unit time can be increased, and the reproduced image with smooth motion can be obtained. Can be easily obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The MPEG of the present invention will be described below with reference to the accompanying drawings.
Fast-forward from moving image information that is highly efficient coded by the method,
The specific content of the reproduction method for reproducing the fast-reverse image will be described in detail. FIG. 1 is a block diagram showing a schematic configuration of a reproducing apparatus to which a reproducing method for reproducing fast-forwarding and fast-reversing images from moving image information highly efficient coded by the MPEG system of the present invention is applied, and FIG. FIG. 3 is a data layout diagram for explaining a reproducing method for reproducing a fast-forward and a fast-reverse image from moving image information highly efficient coded by the MPEG system of the invention. FIG. 3 shows moving image information highly efficient coded by the MPEG system. FIG. 4 is a flowchart showing an example of a procedure for reproducing a fast-forward and fast-reverse image. FIG. 4 shows an example of actual measurement of the intervals between I frames existing in the bit stream and the number of appearances of each interval. It is a figure. In the reproducing apparatus shown in FIG. 1, 1 is a reproduction signal source, 2 is an interface, 3 is a buffer manager, 4 is a central processing unit, 5 is a buffer memory, 6 is an MPEG video decoder, 7 is an MPEG audio decoder, and 13 is a memory. is there.

In the reproducing apparatus shown in FIG. 1, the reproducing signal source 1 applies an image frame (I frame) in which image data is compressed by applying at least the intra-frame prediction method and inter-frame prediction. And time-series data including high-efficiency-coded moving image information and audio information data by the MPEG method in which image frames (P frames, B frames) in which image data is compressed are mixed. A data stream (bit stream) with a predetermined header that includes at least information on the type of each of the above-mentioned information, video information or audio information, and time information (time stamp) for each information. The data read from the information recording medium on which the data string to be reproduced in the recorded state is recorded, for example, an optical disc, a magneto-optical disc, or another recording medium. A structure that can send out a data train is used. In the following description, the reproduction signal source 1 is used for the highly efficient compressed audio information and MPEG.
It is said that the reproduction data can be output from an optical disc conforming to the CD (Compact Disc) standard in which moving image information highly efficiently compressed by the method is recorded.

The above-mentioned time-series bit stream containing the data of the moving picture information and the audio information which are highly efficient coded by the MPEG system in which the above-mentioned I frame, P frame and B frame are mixed, The header portion in the data string to be reproduced in the state in which the predetermined header is added as described later, which is configured to include at least the information of each information type and the time information of each information. Includes information indicating the type of each information such as acoustic information, image information, and other information, time information for each information, and various information such as a sector number. Various data such as audio information data, image information data, and other data form a bit stream. In the reproduction signal source 1 described above, under the control of the control signal provided from the central processing unit 4 via the transmission line 8 and the interface 2, for example, a data string reproduced from an optical disk, that is, at least data of acoustic information. Data to be reproduced in a state in which a header is added to a bit stream including data of image information and at least information of the type of each information and time information of each information. Row (playback data row)
Is transmitted to the transmission line 9.

Then, the reproduction data string transmitted to the transmission line 9 as described above is stored in the buffer memory 5 via the interface 2 and the buffer manager 3. The buffer manager 3 is controlled by a control signal supplied from the central processing unit 4 via the bus 10 and is reproduced from the reproduction signal source 1 to the transmission line 9 and the interface 2.
The reproduction data transmitted via the buffer memory 5 is sequentially written in the buffer memory 5, or the audio information data in the reproduction data string stored in the buffer memory 5 is read out and is transmitted via the bus 11. To supply to the MPEG audio decoder 7 or to read the image information data in the reproduction data sequence stored in the buffer memory 5 and supply it to the MPEG video decoder 7 via the bus 12. Each has a function that can be performed in real time.

When the reproducing apparatus is operating in the normal reproducing mode, the central processing unit 4 operates according to the program stored in the memory 13,
Information of the type of information included in the header part of the reproduction data string stored in the buffer memory 5 via the buffer manager 3 and time information of each information, that is, whether the data is acoustic information data or image information. In order to distinguish between the data and the information such as the reproduction time of the acoustic information and the image information, in response to the request from each MPEG decoder (6, 7) corresponding to each data, the buffer memory 5 is stored. Data for each type of information in the stored reproduction data is transferred via the buffer manager 3. The above-mentioned requests from the respective MPEG decoders (6, 7) are issued at timings such that the reproduction state is continuous, and the data is transferred accordingly, so that the reproduction signal continues on the time axis. The sex will be guaranteed by each MPEG decoder (6, 7). It should be noted that the MPEG decoder (6, 7) is provided with a means for starting the reproduction at a predetermined time at this time because the reproduction is discontinuous with the reproduction from the non-reproduction at the start. As a means for starting the reproduction at the above-mentioned predetermined time, the MPE from the central processing unit 4 via the bus 10 is used.
The data which is configured to be commanded to the G decoder (6, 7) and which includes the time stamp is transferred to the bus 1
1 or an MPEG decoder (6
7) and various MPEG decoders (6, 7) can start reproduction at a predetermined time based on the data including the time stamp.

As described above, when the audio information data is transferred from the buffer memory 5 to the MPEG audio decoder 7 via the buffer manager 3 and the bus 11 under the control of the buffer manager 3, the MPEG audio decoder 7 receives the audio information data. The reproduced acoustic information signal obtained by decompressing the acoustic information data obtained by compressing the acoustic information signal supplied thereto is output, and the buffer memory 5 and the buffer manager 3 and the bus 12 are controlled by the buffer manager 3. The image information data is transferred to the MPEG video decoder 7 via
Then, the MPEG video decoder 7 outputs the reproduced image information signal obtained by decoding the image information data obtained by compressing the image information signal supplied thereto. Therefore, the reproduced audio information signal is continuously output on the time axis from the MPEG audio decoder 7, and the image information signal is continuously output on the time axis from the MPEG video decoder 7. Output

As described above, on a bit stream in which I frames, P frames, and B frames composed of moving image information highly efficient coded by the MPEG system are mixed, the I frames are approximately equal to each other on average. Encoding is performed with consideration given to the arrangement at intervals, but conventionally, when attention is paid to the above point, when fast-forwarding and fast-rewinding images are reproduced from moving image information that is highly efficient encoded by the MPEG method. At
The above points have not been utilized to shorten the frame search time, and conventionally, when fast-forwarding and fast-rewinding images are reproduced from moving image information that is highly efficient coded by the MPEG system, one after another. Since it took a lot of time to search for the I frame, it was difficult to increase the number of reproduced images per unit time at the time of reproducing fast-forward and fast-reverse images, but the MPEG method of the present invention was used. In the reproducing method for reproducing the fast-forward and fast-reverse images from the moving image information encoded by high efficiency, the I frame, the P frame, and the B frame composed of the moving image information encoded by the high efficiency MPEG are mixed. In the bitstream, encoding is performed so that the I frames are arranged on the bitstream at substantially equal intervals on average.
That is, it is effective to arrange the above-mentioned I-frames in the bitstream in advance so that the average interval between the I-frames becomes a predetermined interval so that the interval between the display images can be made constant. When the fast-forwarding image is reproduced, the search for the I frame to be reproduced next to the reproduced I frame is started from a position obtained by subtracting a constant value K from the integral multiple of the predetermined interval, and When the fast-reverse image is reproduced, the search for the I frame to be reproduced next to the reproduced I frame is started at the position where the constant value M is added to the integral multiple of the above-mentioned predetermined interval. As described above, fast-forwarding and fast-rewinding from a bitstream in which I-frames, P-frames, and B-frames composed of moving image information highly efficient coded by the MPEG system are mixed. When reproducing an image, the time required to skip to the position of the bitstream where the next reproduction should be started, which is required for each reproduction of the image information of the next I frame, and the reproduction of the bitstream is started from the skipped position. Time to detect an I frame after
In each time such as the time for reproducing the entire detected I frame, the time until the I frame is detected after the reproduction of the bit stream is started from the skipped position can be greatly shortened. I did.

FIG. 4 shows a reproducing method for reproducing fast-forwarding and fast-reversing images from moving image information coded with high efficiency according to the MPEG method of the present invention. The average interval between I frames is a constant interval between display images. For one of the practical examples in which the above-mentioned I frames are arranged in advance in the bitstream so as to have a predetermined interval that can be achieved, the interval value between the I frames in the bitstream (unit of interval) Shows the number of appearances (the number of appearances) of 1 sector length = 2296 bytes). In the case of the above example, the spacing between I-frames in the bitstream has a slight variation between the interval value corresponding to 36 sector length and the corresponding 43 sector length, The average interval corresponds to 39.86 sector length.
By the way, according to the MPEG standard, the storage capacity of the buffer memory in the MPEG decoder is defined as 40 kilobytes. Therefore, if the variation of the data amount due to the variation of the interval of the I sector in the bit stream is within ± 20 kilobytes. Good. The amount of change in the data amount due to the variation in the I sector interval in the bit stream shown in FIG. 4 is within ± 9 kilobytes.

For example, the spacing between I-frames in a bitstream is as illustrated in FIG.
When the minimum value of the interval is a value corresponding to the length of 36 sectors and the maximum value of the interval is a value corresponding to the length of 43 sectors, in order to select the next I frame, the I currently being reproduced is selected. If a position away from the head of the frame by 36 sector length is accessed, in the worst case, the next I within 7 sector length between 36 sector length and 43 sector length
The frame will appear. Therefore, the MPE of the present invention
In a reproducing method for reproducing a fast-forward and a fast-reverse image from moving image information encoded by the G method with high efficiency, the average interval between I frames is a predetermined interval such that the interval of display images can be made constant. As described above,
I when the frame is arranged in advance in the bitstream
When the average interval between the frames corresponds to the 39.86 sector length as in the example of FIG. 4 described above, during fast-forward playback, when playing back one I frame, In order to select the next I frame, from the position of the head of the I frame currently being reproduced, the above-mentioned average interval between the I frames and the corresponding sector length 39.
N times 86 + 36 sector length (where N is a number that shows a larger value as the rapid feed rate increases, N = 0, 1,
If the positions are distant by 2, 3, ...), the next I frame aimed within the 7-sector length will appear in the worst case, and the average interval between I frames will be the same as the above. The average interval between I-frames when the I-frames are previously arranged in the bitstream so that the intervals between the display images can be set to a predetermined interval, for example, as shown in FIG. In the case of the one corresponding to the 39.86 sector length as in the example of 1), it is necessary to select the next I-frame at the time of fast-reverse playback when the next I-frame is selected. From the position of the head of the I frame being reproduced, the above-mentioned average interval between the I frames and the corresponding sector length 39.
N times 86 + 43 sector length (where N is a number that shows a larger value as the fast-reverse rate increases, N = 0, 1,
If the positions are distant by (2, 3 ...), the next I frame aimed at will appear within 7 sector length in the worst case.

That is, the average interval between I-frames arranged in advance in the bit stream is shown in FIG.
In the case of fast-forward reproduction in the case where the frame length corresponds to the 39.86 sector length as in the above example, from the position of the head of the I frame currently being reproduced, f {39.86 × N-3.86} sector length ... (FF) However, f {n} is a maximum natural number smaller than n.
Also, during fast-reverse reproduction, from the position of the head of the I-frame currently being reproduced, g {39.86 × N + 3.14} sector length (FB), where g {n} is a minimum natural number larger than n. .
Then, N in the above-mentioned formulas (FF) and (FB)
Is a number showing a larger numerical value as the magnification for fast forward and fast return increases, N = 1, 2, 3, ... Therefore, by accessing the positions separated by the intervals represented by the formulas (FF) and (FB), the desired I frame can be searched immediately. Generally speaking, the above-mentioned formulas (FF) and (FB) are written as the following formulas (F)
Formula F1) and a general formula at the time of fast reverse reproduction are expressed by the following formula (FB1). f {N × (average interval value between I-frames that is determined corresponding to a predetermined interval such that the interval between display images can be made constant) −K} ... (FF1) where f {n} is n It is the smaller maximum natural number. g {N × (average interval value between I-frames that is determined corresponding to a predetermined interval such that the interval between display images can be made constant) + M} ... (FB1) where g {n} is greater than n It is a large minimum natural number. In the formulas (FF1) and (FB1) described above, N is a number that shows a larger numerical value as the magnification of fast forward and fast reverse increases, N = 1, 2, 3, ... And K is K = ( (Average interval value between I-frames, which is determined corresponding to a predetermined interval such that the interval between display images can be made constant)-
(The minimum value of the interval values between the I frames), and M is M = (the maximum value of the interval values between the I frames)-(so that the interval of the display image can be constant. Is an average interval value between I-frames, which is determined corresponding to a predetermined interval.

[0023]

As is clear from the above description, the reproduction method for reproducing a fast-forward or fast-reverse image from moving image information highly efficient coded by the MPEG method of the present invention is I frame and P frame. In the bit stream, when only the I-frame image is selectively reproduced and fast-forwarding and fast-reversing images are reproduced from the moving image information that is highly efficient encoded by the MPEG method in which frames, B frames, and the like are mixed. When the fast-forwarding images are played back, the I-frames reproduced are arranged so that the average interval between the arranged I-frames is a predetermined interval so that the intervals of the display images can be kept constant. The search for the I frame to be reproduced next is started from the position obtained by subtracting a constant value K from the integral multiple of the above-mentioned predetermined interval, and when the fast-reverse image is reproduced, To be reproduced next to I-frames,
Since the search for the I frame is started from the position where the constant value M is added to the integral multiple of the above-mentioned predetermined interval, the I frame is detected after the reproduction of the bit stream is started from the skipped position. It is possible to shorten the time until, the number of reproduced images per unit time can be increased, and it is possible to easily obtain a reproduced image with good smooth motion.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a reproducing apparatus to which a reproducing method for reproducing a fast-forward and a fast-reverse image from moving image information highly efficient coded by the MPEG system of the present invention is applied.

FIG. 2 is a data layout diagram for explaining a reproduction method for reproducing a fast-forward and fast-reverse image from moving image information that has been highly efficiently coded by the MPEG system of the present invention.

FIG. 3 is a flowchart showing an example of a procedure for reproducing a fast-forward and fast-reverse image from moving image information that has been coded with high efficiency by the MPEG method.

FIG. 4 is a diagram showing an example of actual measurement of intervals between I frames existing in a bitstream and the number of appearances of each interval described above.

[Explanation of symbols]

1 ... Playback signal source, 2 ... Interface, 3 ... Buffer manager, 4 ... Central processing unit, 5 ... Buffer memory, 6 ... MPEG video decoder, 7 ... MPEG audio decoder, 13 ... Memory,

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[Procedure amendment]

[Submission date] April 21, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Title of invention

[Correction method] Change

[Correction content]

Title: Playback method for playing back fast-forward and fast-reverse images from moving image information encoded with high efficiency

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction content]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproduction method for reproducing a fast-forward and fast-reverse image from moving image information encoded with high efficiency, and in particular, an image in which image data is compressed by applying an intra-frame prediction method. From moving image information that is highly efficient coded by a highly efficient compression coding method that has a signal configuration in which frames and image frames in which image data is compressed by applying interframe prediction are mixed The present invention relates to a reproducing method for selectively reproducing only an image of an image frame in which image data is compressed by applying the intra-frame prediction method and reproducing a fast-forward or fast-reverse image.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art Video signals of moving images are highly efficiently compressed and transmitted,
Researches for recording and reproducing have been actively conducted, and various high-efficiency compression methods have been conventionally proposed. As one of the high-efficiency compression methods for the moving image signal, the intra-frame An image frame in which image data is compressed by applying the prediction method and an image frame in which image data is compressed by applying the inter-frame prediction are mixed. An efficient compression coding method has also been proposed. Then, for example, it has been attempted to record highly efficient compressed moving image data on a small disc, but an international standard for compressing image data by highly efficient encoding of a moving image signal is defined as an international standard. Aiming to make, MPEG (Moving Picture)
es Expert Group) sequentially proposes various data formats related to high-efficiency compressed image data, and highly efficiently compresses image data according to a data format proposed by MPEG (compressed image highly efficient compressed by MPEG method). Research and development of practical devices for transmitting, recording, and reproducing signals are also underway.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

Even in a moving image information coding system (MPEG system) intended for a recording medium for recording digital data such as a CD-ROM, image data can be compressed by applying the above-mentioned intra-frame prediction method. Similar to the high-efficiency compression method of the image signal of the moving image having the signal structure in which the image frame being performed and the image frame in which the image data is compressed by applying the inter-frame prediction are mixed. ,
An image in which high-efficiency compression of a moving image signal is performed by using a predictive coding method and image data is compressed by applying an intra-frame prediction method as a prediction method {I picture (Intra Pictures) } An image in which image data is compressed by applying an inter-frame prediction method in which inter-frame prediction is performed based on image data of a frame (hereinafter, also referred to as I frame) and image data of a past frame. {P picture (Predic
inter-frame prediction based on image data of both the image data of the past frame and the image data of the future frame. An image in which image data is compressed by applying a prediction method {B picture (Bi-direction
al Prediction Pictures)} frame (hereinafter, also referred to as B frame), and the digital data in a state in which each frame in three types of image modes is arranged in a predetermined arrangement manner on the time axis,
A predetermined header is added to the image coded data.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

Since the above-mentioned MPEG method is also standardized by CCITT, in the following description, an image frame in which image data is compressed by applying the intra-frame prediction method and inter-frame prediction are applied. The MPEG system will be described as an example of a high-efficiency compression system of a moving image signal having a signal configuration in which image frames in which image data is compressed are mixed. In the MPEG system, the relationship between the compression rate of image data in the I frame, the compression rate of image data in the P frame, and the compression rate of image data in the B frame is (compression rate of image data in I frame). <(Compression ratio of image data in P frame) <
(The compression ratio of the image data in the B frame) has a relation of size, and the reproduction is performed from the sequence header of the entry point, the past image information and the image information of the future frame. In order to reproduce the image information of the B frame for which the prediction is performed using and, the image information of the future P frame used for the prediction of the image information of the B frame is recorded before the B frame. Need to be

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

Therefore, when fast-forwarding and fast-rewinding images are reproduced from moving image information that is highly efficient coded by the MPEG system as described above, the next reproduction is performed for each reproduction of the image information of the next I frame. Each time such as the time to skip to the position of the bit stream to start, the time to detect an I frame after starting the reproduction of the bit stream from the skipped position, the time to reproduce the entire detected I frame, etc. However, as described above, in a bit stream in which I frames, P frames, and B frames composed of moving image information highly efficient coded by the MPEG method are mixed, as described above. The intervals between successive I-frames in the are not constant, and there are wide variations in the intervals, so that the bit to start the next reproduction is Position the skip is performed as the position of the stream skips the advanced position with sufficient margin with respect to likely not exist I frame position,
In order to detect the I frame after starting the reproduction of the bit stream from the skipped position,
Since the time required for detecting the I frame as described above becomes long, which reduces the number of reproduced images per unit time, the smoothness of the motion of the reproduced images becomes insufficient. This point includes an image frame in which the image data is compressed by applying the intra-frame prediction method including the above-mentioned MPEG system, and an image frame in which the image data is compressed by applying the inter-frame prediction. This is a problem that similarly occurs in a high-efficiency compression method of a video signal of a moving image having a mixed signal structure, and when a fast-forward or fast-reverse image is reproduced from high-efficiency-coded moving image information, a frame Improvement measures have been sought in order to minimize the time for detecting the image frame in which the image data is compressed by applying the inner prediction method.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

[0011]

According to the present invention, an image frame in which image data is compressed by applying the intra-frame prediction method and an image in which image data is compressed by applying inter-frame prediction are used. An image frame in which image data is compressed by applying the intra-frame prediction method from moving image information that has been efficiently coded by a highly efficient compression coding method that has a signal configuration in which frames are mixed When selecting and playing back only the images in the fast forward and fast reverse images, the average interval between image frames where the image data is compressed by applying the intra-frame prediction method is An image frame in which image data has been compressed by applying the above-described intra-frame prediction method so as to have a predetermined interval that can be made constant is previously set in a bit stream. Lay location, when playing fast forward image to be reproduced next to the image frame by applying the intra-frame prediction method of reproducing the image data compression is being performed,
The search for the image frame in which the image data is compressed by applying the intra-frame prediction method is started from the position where a constant value K is subtracted from the integral multiple of the above-mentioned predetermined interval, and the fast-reverse image is also displayed. The image to be reproduced next to the image frame in which the image data is compressed by applying the reproduced intra-frame prediction method when the image is reproduced. The image in which the image data is compressed by applying the intra-frame prediction method. A frame search is started at a position where a constant value M is added to an integer multiple of the above-mentioned predetermined interval, and fast-forwarding and fast-returning images are obtained from high-efficiency-coded moving image information. It provides a reproducing method for reproducing.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

[0012]

According to the present invention, an inter-frame prediction method for performing inter-frame prediction based on image data (I frame) in which image data is compressed by applying the intra-frame prediction method and past frame image data is provided. An image frame (P frame) to which image data has been applied and compressed
And an image in which the image data is compressed by applying an inter-frame prediction method in which the inter-frame prediction is performed based on both the image data of the past frame and the image data of the future frame. From the moving image information that is highly efficient encoded by the highly efficient compression encoding method that has a signal configuration in which frames (B frames) are mixed,
When only the I-frame image is selectively played back and fast-forward and fast-reverse images are played back, the average interval between I-frames arranged in the bitstream can be set in advance so that the interval between the display images can be made constant. It is placed in an arrangement manner so as to have a predetermined interval. And when playing fast-forward images,
The search for the I frame to be reproduced next to the reproduced I frame is started from the position obtained by subtracting the constant value K from the integral multiple of the predetermined interval described above, and is reproduced when the fast-reverse image is reproduced. The search for the I frame to be reproduced next to the I frame is started from the position where the constant value M is added to the integral multiple of the predetermined interval described above. As a result, it is possible to shorten the time until the I frame is detected after the reproduction of the bit stream is started from the skipped position, the number of reproduced images per unit time can be increased, and the reproduced image with smooth motion can be obtained. Can be easily obtained.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The specific contents of a reproducing method for reproducing fast-forwarding and fast-reversing images from highly efficient coded moving image information according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a block diagram showing a schematic configuration of a reproducing apparatus to which a reproducing method for reproducing a fast-forward and a fast-reverse image from high-efficiency-coded moving image information of the present invention is applied, and FIG. A data layout diagram for explaining a reproduction method for reproducing a fast-forward and fast-reverse image from the efficiency-encoded moving image information. FIG. 3 shows a fast-forward and fast-reverse image from the high-efficiency-encoded moving image information by the MPEG method. FIG. 4 is a flowchart showing an example of a procedure for reproduction, and FIG. 4 is a diagram showing an example of actual measurement of the intervals between I frames existing in the bitstream and the number of appearances of each interval described above. In the reproducing apparatus shown in FIG. 1, reference numeral 1 denotes a reproduction signal source. From the reproduction signal source 1, an image frame in which image data is compressed by applying the intraframe prediction method and an image frame by applying interframe prediction are used. A highly efficient compression bit stream of moving image information is reproduced by a highly efficient compression method of an image signal of a moving image having a signal structure in which image frames in which data is compressed are mixed. In the following description, it is assumed that the reproduction signal source 1 is reproducing the bit stream of the moving image information which is highly efficiently compressed by the MPEEG method described above. In the reproducing apparatus shown in FIG. 1, 2 is an interface, 3 is a buffer manager, 4 is a central processing unit, 5 is a buffer memory, 6 is an MPEG video decoder, 7 is an MPEG audio decoder, and 13 is a memory.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

As described above, on a bit stream in which I frames, P frames, and B frames composed of moving image information highly efficient coded by the MPEG system are mixed, the I frames are approximately equal to each other on average. Encoding is performed with consideration given to the arrangement at intervals, but conventionally, when attention is paid to the above point, when fast-forwarding and fast-rewinding images are reproduced from moving image information that is highly efficient encoded by the MPEG method. At
The above points have not been utilized to shorten the frame search time, and conventionally, when fast-forwarding and fast-rewinding images are reproduced from moving image information that is highly efficient coded by the MPEG system, one after another. Since it took a lot of time to search for the I frame, it was difficult to increase the number of reproduced images per unit time at the time of reproducing fast-forward and fast-reverse images, but the high efficiency of the present invention is high. In the playback method of playing fast-forward and fast-reverse images from encoded moving image information,
I frame composed of moving image information encoded with high efficiency, P
In a bitstream in which frames and B frames are mixed, encoding is performed with consideration for arranging I frames on the bitstream at substantially equal intervals, that is, I frames. Effectively utilizing that the above-mentioned I frames are pre-arranged in the bit stream so that the average interval between them is a predetermined interval so that the intervals of the display images can be made constant,
At the time of reproducing the fast-forwarding image, the search for the I-frame to be reproduced next to the reproduced I-frame is started from the position where a constant value K is subtracted from the integral multiple of the above-mentioned predetermined interval, and the fast-reverse image is reproduced. At the time of reproduction, the search for the I frame to be reproduced next to the reproduced I frame is started from the position where the constant value M is added to the integral multiple of the above-mentioned predetermined interval. Like, MP
When fast-forwarding and fast-rewinding images are played back from a bitstream in which I-frames, P-frames, and B-frames, which consist of moving-image information that has been highly efficiently coded by the EG method, are played back, the image information of successive I-frames is played back. The time required to skip to the position of the bitstream where the next reproduction should be started, the time required to detect an I frame after the reproduction of the bitstream is started from the skipped position, the detected I frame Of the entire playback time, etc., the time required to detect an I frame after the playback of the bit stream is started from the skipped position can be greatly shortened.

[Procedure Amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

FIG. 4 shows a reproduction method for reproducing a fast-forward and a fast-reverse image from high-efficiency-coded moving image information, which is determined in advance so that the average interval between I-frames can keep the interval between display images constant. With respect to one example of the case where the above-mentioned I frames are arranged in advance in the bitstream so as to have the predetermined intervals, the interval value between the I frames in the bitstream (the interval unit is 1 sector length = 2296).
This is an example of the number of appearances (the number of appearances) of a byte.
In the case of the above example, the spacing between I-frames in the bitstream has a slight variation between the interval value corresponding to 36 sector length and the corresponding 43 sector length, The average interval corresponds to 39.86 sector length. By the way, for example, according to the MPEG standard, the storage capacity of the buffer memory in the MPEG decoder is specified to be 40 kilobytes, so that the variation of the data amount due to the variation of the interval of the I sector in the bitstream is within ± 20 kilobytes. Good. The amount of change in the data amount due to the variation in the I sector interval in the bit stream shown in FIG. 4 is within ± 9 kilobytes.

[Procedure Amendment 13]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

For example, the spacing between I-frames in a bitstream is as illustrated in FIG.
When the minimum value of the interval is a value corresponding to the length of 36 sectors and the maximum value of the interval is a value corresponding to the length of 43 sectors, in order to select the next I frame, the I currently being reproduced is selected. If a position away from the head of the frame by 36 sector length is accessed, in the worst case, the next I within 7 sector length between 36 sector length and 43 sector length
The frame will appear. Therefore, when the above-mentioned I frames are arranged in advance in the bit stream so that the average interval between the I frames becomes a predetermined interval so that the intervals between the display images can be made constant, When the average interval corresponds to 39.86 sector length as in the example of FIG. 4 described above,
In fast-forward playback, when playing back a certain I frame, the next I frame is selected by selecting the average interval between the I frames described above from the head position of the I frame currently being played back. Corresponding sector length 39.86 times N times +36 sector length (where N is a number that shows a larger value as the fast-forward ratio increases, N = 0, 1, 2, 3
, The next I-frame which is aimed within 7 sector length will appear in the worst case, and the average interval between I-frames is the same as the above. The average interval between the I-frames when the above-mentioned I-frames are arranged in advance in the bitstream so that the intervals can be made constant, for example, in the example of FIG. Like 3
If it corresponds to the 9.86 sector length, in order to select the next I frame during reproduction of a certain I frame during fast reverse reproduction, the I frame currently being reproduced is selected. From the position of the head, the above-mentioned average interval between I-frames and the corresponding sector length 39.86 times N times +43 sector length (where N is a number showing a larger value as the fast-reverse rate increases, N = Accessing positions apart by 0, 1, 2, 3, ...) Will cause the next I frame to appear within 7 sector lengths in the worst case.

[Procedure Amendment 14]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

[0023]

As is apparent from the above detailed description, the intra-frame prediction method is applied to the reproduction method for reproducing the fast-forward and fast-reverse images from the high-efficiency-coded moving image information of the present invention. The image data is compressed by applying an inter-frame prediction method in which the inter-frame prediction is performed based on the image frame (I frame) in which the image data is compressed by the image data and the image data of the past frame. Image frame (P frame) and the image data of the past frame and the image data of the future frame based on both the image data Video coded by a high-efficiency compression coding method having a signal configuration in which image frames (B frames) that have been compressed are mixed. From the image information, when selecting and playing only the I-frame image to play fast-forward and fast-reverse images,
The I-frames arranged in the bitstream are arranged such that the average interval between the I-frames is a predetermined interval so that the interval between the display images can be made constant,
At the time of reproducing the fast-forwarding image, the search for the I-frame to be reproduced next to the reproduced I-frame is started from the position where a constant value K is subtracted from the integral multiple of the above-mentioned predetermined interval, and the fast-reverse image is reproduced. At the time of reproduction, the search for the I frame to be reproduced next to the reproduced I frame is skipped by starting from the position where the constant value M is added to the integral multiple of the predetermined interval described above. It is possible to shorten the time required to detect an I frame after starting the reproduction of a bitstream from a position, increase the number of reproduced images per unit time, and easily obtain a reproduced image with good smooth motion. You can

[Procedure Amendment 15]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a reproducing apparatus to which a reproducing method for reproducing a fast-forward and a fast-reverse image from high-efficiency-coded moving image information of the present invention is applied.

FIG. 2 is a data layout diagram for explaining a reproduction method for reproducing a fast-forward and fast-reverse image from moving image information that has been coded with high efficiency according to the present invention.

FIG. 3 is a flowchart showing an example of a procedure for reproducing a fast-forward and fast-reverse image from moving image information that has been coded with high efficiency by the MPEG method.

FIG. 4 is a diagram showing an example of actual measurement of intervals between I frames existing in a bitstream and the number of appearances of each interval described above.

[Description of Codes] 1 ... Playback signal source, 2 ... Interface, 3 ... Buffer manager, 4 ... Central processing unit, 5 ... Buffer memory, 6 ... MPEG video decoder, 7 ... MPEG audio decoder, 13 ... Memory,

Claims (1)

[Claims] 1. An image frame in which image data is compressed by applying an intra-frame prediction method and an image frame in which image data is compressed by applying inter-frame prediction are mixed. In the case where only the image of the image frame in which the image data is compressed by applying the intra-frame prediction method is selected from the moving image information which is highly efficiently encoded by the MPEG system and the fast-forward and fast-reverse images are reproduced. In the above, the average interval between the image frames in which the image data is compressed by applying the intra-frame prediction method is set to a predetermined interval so that the interval of the display images can be made constant. An image frame whose image data has been compressed by applying the intra-frame prediction method described above is placed in advance in the bit stream, and when playing back a fast-forward image, the frame Should be played next to the image frame where the image data is compressed by applying the intra-frame prediction method,
The search for the image frame in which the image data is compressed by applying the intra-frame prediction method is started from the position where a constant value K is subtracted from the integral multiple of the above-mentioned predetermined interval, and the fast-reverse image is searched. At the time of reproduction, an image frame whose image data has been compressed by applying the intra-frame prediction method that should be reproduced next to the image frame whose image data has been compressed by applying the reproduced intra-frame prediction method. Is started from a position where a constant value M is added to an integral multiple of the above-mentioned predetermined interval, fast-forwarding and fast-rewinding from moving image information highly efficient coded by the MPEG system. Playback method to play the image.