JP2000217109A - Dynamic image reproducing device and reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dynamic picture reproducing device with which reverse reproduction is conducted with a uniform and smooth display time, without increasing the capacity of a frame memory, and to provide a reproduction method. SOLUTION: When a reverse reproduction direction detection means 10 detects a reverse reproduction sate, a frame number detection means 11 counts the number of reference frames required to reproduce each frame, and a decoding control means 12 controls a decoding means 13, so that the means 13 decodes a frame with less number of reference frames for decoding and displayed earlier in the display sequence of reverse reproduction after decoding a frame with many numbers of reference frames for decoding and displayed later in the display sequence.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for reproducing a moving image using digitally encoded image data, and more particularly to an apparatus and a method for improving the quality of screen display when performing reverse reproduction. Things.

[0002]

2. Description of the Related Art Conventionally, as a coding method for compressing a digital image signal, an MPEG (Moving Picture Experts Group) method specified in ISO / IEC11172-2 and 13818-2 has been proposed. FIG. 7 shows a typical data structure of the MPEG system. In this figure, a GOP, which is a unit of encoding obtained by dividing one sequence of a moving image, is composed of 1 frame for an I picture, 4 frames for a P picture, and 10 frames for a B picture, for a total of 15 frames. Here, an I picture is an intra-frame coded image, a P picture is an inter-frame forward prediction coded image, and a B picture is an inter-frame bi-directional predicted coded image. Specifically, as shown by the arrow in FIG. 7A, I2 is intra-frame coded only with I2 frame, P5 is inter-frame coded with reference to I2 and P8 with reference to P5, respectively. , And B0 and B1 are P "14 and I2
, And B3 and B4 are I2 and P5
, And has been subjected to inter-frame prediction coding. The actually encoded data is encoded in the order shown in FIG. 7 (b). The difference from the display order shown in FIG. 7A is that the frames required for decoding can be decoded first.

If the stream shown in FIG. 7 is to be played back from P14, for example, it is necessary to sequentially decode I2, P5, P8, P11 and P14 in order to display and decode P14. There is. Next, in order to display B13, in the same manner, I2, P5, P8, P11, P14, and B13 are sequentially decoded. By repeating such an operation, it becomes possible to reproduce image data compressed by the MPEG system in the reverse direction.

[0004] Here, when reproduction is performed in the reverse direction using the method described above, for example, the stream shown in FIG.
Assuming that reverse playback is started from I'2, to decode I'2, it is necessary to decode only one frame, that is, only I'2, but decode B'1 displayed after I'2. To do, I
Decoding of seven frames must be performed in the order of 2, P5, P8, P11, P14, I'2, B'1. That is, the decoding times of I'2 and B'1 are significantly different from each other even though they are adjacent frames. This is a problem caused by the MPEG data structure.

If the obtained frame is to be displayed immediately after the decoding at the time of the reverse reproduction as described above, the difference in the decoding time becomes the difference in the display time as it is. It becomes more unnatural appearance.

In order to equalize the difference in display time, it is necessary to match the display time with a frame having a large number of decoded images, and therefore the speed of reverse reproduction is significantly reduced as a whole. Also, by storing many I or P (hereinafter referred to as I / P) pictures as reference frames by having many frame memories, decoding time can be reduced and display time can be equalized. As a result, the amount of frame memory increases, which leads to an increase in circuit scale and power consumption.

[0007]

The conventional moving picture reproducing apparatus and the conventional reproducing method are constituted as described above, and the moving picture coded data which has been subjected to the compression processing by utilizing the inter-frame correlation in the time axis direction. If you want to play in reverse time,
There has been a problem that smooth reproduction cannot be performed without increasing the circuit scale. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and provides a moving image reproducing apparatus and a reproducing method capable of performing smooth reverse reproduction with a uniform display time without increasing the amount of frame memory. The purpose is to provide.

[0008]

According to a first aspect of the present invention, there is provided a moving picture reproducing apparatus for temporally reversing moving picture coded data which has been subjected to compression processing using inter-frame correlation in a time axis direction. In a moving image reproducing apparatus having a function of reproducing in the direction, the reproduction direction detecting means for detecting whether or not the reproduction of the encoded data is temporally reverse, and the reproduction direction detecting means, A decoding reference frame number detecting means for detecting, for each frame to be reproduced, the number of reference frames necessary for decoding the frame to be reproduced, when it is determined that the reproduction in the reverse direction is performed; Decoding means for decoding a frame to be reproduced with reference to a reference frame, and a reference frame of a reproduction target frame to be reproduced later in time, receiving an output of the decoding-time reference frame number detecting means. Is larger than the number of reference frames of the reproduction target frame to be reproduced earlier in time, the decoding of the reference frame of the frame to be reproduced later in time is performed for the frame to be reproduced earlier in time. Decoding control means for controlling the decoding means so as to precede the decoding.

According to a second aspect of the present invention, in the moving image reproducing apparatus according to the first aspect, the compression processing is performed by using an MPEG method. The frame displayed earlier in the display order of time is a coding unit obtained by dividing one sequence of a moving image.
The first intra-frame coded image (I-picture) of (GOP), and the frame displayed temporally later is the GO in reverse playback order.
This is the frame to be displayed next to the first I picture of P.

According to a third aspect of the present invention, in the moving image reproducing apparatus according to the second aspect, the decoding control means determines that the next frame to be displayed is the first IOP of the GOP. In the case of a picture, some of the I or P pictures of the immediately preceding GOP are decoded first, and then the leading I picture of the GOP is decoded.

According to a fourth aspect of the present invention, in the moving image reproducing apparatus according to the third aspect, the decoding control means determines that the next frame to be displayed is the first IOP of the GOP. If it is not a picture, and if the currently displayed frame is the first I picture in the GOP, decode the next display frame from the previously decoded next I or P picture. It is.

Further, a moving picture reproducing apparatus according to claim 5 of the present invention reproduces coded moving picture data which has been subjected to compression processing using a correlation between frames in a time axis direction in a temporally reverse direction. Video playback device with
A playback direction detecting means for detecting whether or not the playback of the encoded data is in the reverse direction in time; and a playback in the case where the playback direction detection means determines that the playback in the backward direction is to be performed. Decoding reference frame number detecting means for detecting the number of reference frames required to decode the target frame for each frame to be reproduced, and decoding the frame to be reproduced with reference to the reference frame. Receiving means for receiving the output of the decoding reference frame number detecting means, the reference frame number of the reproduction target frame to be reproduced temporally later, and the reference frame of the reproduction target frame to be reproduced earlier in time. Decoding control means for controlling the output from the decoding means so that the display start of the target frame to be reproduced earlier in time is delayed for a predetermined time when the number is larger than the number. A.

According to a sixth aspect of the present invention, there is provided a moving image reproducing method for reproducing moving image encoded data which has been subjected to a compression process in a temporally reverse direction by utilizing inter-frame correlation in a time axis direction. In the moving picture reproducing method, the step of detecting whether or not the reproduction of the encoded data to be performed is temporally reverse, and it is determined in the above step that the temporally reverse reproduction is performed. In this case, the step of detecting the number of reference frames necessary for decoding the frame to be reproduced for each frame to be reproduced, and the step of detecting the number of reference frames of the frame to be reproduced later in time, When the number of frames to be reproduced earlier is larger than the number of reference frames, the decoding of the frame to be reproduced temporally later is performed before the decoding of the frame to be temporally performed earlier. Cormorant is intended to include a step.

According to a seventh aspect of the present invention, there is provided a moving image reproducing method for reproducing compressed moving image data which has been subjected to compression processing in a temporally reverse direction by utilizing inter-frame correlation in a time axis direction. In the moving picture reproducing method, the step of detecting whether the reproduction of the encoded data is in the reverse direction in time and the reproduction direction detecting means determine that the reproduction in the reverse direction in time is performed. Detecting the number of reference frames required to decode the frame to be played back for each frame to be played back, and determining the number of reference frames of the frame to be played back later in time. The display start of the target frame to be reproduced earlier in time is delayed by a predetermined time when the number of reference frames to be reproduced earlier is larger than the number of reference frames.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) Hereinafter, a moving image reproducing apparatus according to Embodiment 1 of the present invention will be described. FIG. 1 is a block diagram showing the configuration of a moving image reproducing apparatus according to the present invention. In FIG. 1, reference numeral 10 denotes a reproducing direction detecting means to which a reproduction instruction signal is input.
0 indicates whether the reproduction is in the normal direction or in the reverse direction. Numeral 11 denotes a frame number detecting means for counting the number of reference frames necessary for reproducing each frame from the input coded data when the reproduction direction is reverse reproduction.
13 is decoding means for decoding the input coded data, 12 receives the output of the frame number detecting means 11,
According to the number of reference frames of the frame to be decoded,
The decoding control unit controls the decoding unit 13 so that the order of the frames decoded by the decoding unit 13 is changed.

FIG. 2 is a diagram showing a circuit-level configuration of a reproducing apparatus for realizing the moving image reproducing method of the present invention. In this figure, the stream analyzing unit 21 converts the picture header of the input moving image encoded data into a picture header. The control unit 27 performs detection and extracts a picture type indicating whether each picture is an I picture, a P picture, or a B picture, and information on a temporal reference indicating the display order of each picture in the GOP. To supply. VLC decoding unit 22, IQ unit 2
3. In the IDCT unit 24, VLC (Va
liable Length Code), inverse quantization, and inverse DCT (Di
screte Cosine Transform). And the inverse DCT
The converted data is added to the output from the motion compensation unit 25 according to the picture type, and is added to the frame memory 2.
6 is written. The data in the frame memory 26 is output in display order. The control unit 27 performs decoding control and frame memory management at the time of reverse reproduction. Depending on a frame to be displayed next, the control unit 27 performs a part of decoding processing of a display frame two frames later, and performs frame-by-frame This is to equalize the decoding time.

FIG. 4 is a flow chart for explaining the operation of the control unit 27 of FIG. This flow is used for each process of decoding an image to be displayed next in reverse reproduction. Hereinafter, the operation will be described. In step S300, when processing for a certain image is started,
First, it is determined whether or not the next image to be displayed is the first I picture of the GOP (step S301), and if "YES", the frame can be decoded quickly, so that the next display Decode N I / P pictures of the GOP immediately before the GOP containing the I picture to be decoded, and store the decoding result in a frame memory other than the frame memory in which the currently displayed frame is stored ( Step S302). Here, N is a predetermined positive integer. Then, the next I picture to be displayed is decoded (step S3
03) and display the I picture (step S304)
The process ends (step S310). On the other hand, step S3
If it is “NO” in the determination of whether the image to be displayed next is the first I picture of the GOP in step S305, it is determined whether the currently displayed frame is the first I picture of the GOP (step S305). Then, if “YES”, the necessary I / P picture is decoded beforehand.
Decode the I / P picture and the frame to be displayed next (
(Step S306) After the decoding is completed, the display frame is displayed.
(Step S307), the process ends (Step S310). Also, in step S305, the currently displayed frame is a GOP.
If the determination is "NO" in the determination as to whether or not the frame is the first I picture, the necessary I / P picture and the frame to be displayed next are decoded (step S308). Then (step S309), the process ends (step S310).

FIG. 3A is a diagram showing frame memory write / read timings when the stream shown in FIG. 7 is reproduced in reverse. Here, assuming that the frame of B'3 is currently displayed, the next display frame is I'2, but before decoding of I'2, necessary for decoding of B'1.
Decode I2, P5 and P8 necessary to decode P14 (N = 3
in the case of) . At this time, a frame memory other than the frame memory in which the currently displayed B'3 is stored (FM1 in FIG. 1)
And FM2) are alternately written with the decoding result. And P8
After decoding of, the frame to be displayed next is I'2
Is decrypted and displayed. Next, the frame to be output next to I'2 is B'1, but when decoding I'2, since it has already been decoded up to P8, the I / P picture next to P8 is used. A certain P11, P14, I'2 is decoded and B'1 is decoded and displayed.

On the other hand, conventionally, as shown in FIG. 3B, if the frame of B'3 in the frame memory FM0 is currently displayed, the next display frame is I'2.
After decoding I'2 and storing the decoding result in the frame memory FM1, I'2 is displayed. Then, the frame displayed after I'2 is B'1, but since the reference frame of B'1 is P'14 and I2 of the immediately preceding GOP, to decode the reference frame, 1 After starting decoding from I2 of the previous GOP and storing it in frame memory FM2, P5 (FM0), P8 (FM2), P11
(FM0), P14 (FM2), I'2 (FM0), and then decode the reference frame, and finally decode B'1 and store it in FM1.
Display B'1. When decoding and displaying are performed in such a method, the display time of the frames varies, resulting in an unnatural reverse reproduction.

On the other hand, in the present embodiment, the decoding time for each frame can be effectively used, and I 'can be decoded quickly.
Before P2, P14 required for time-consuming decoding of B'1
By decoding I2, P5, P8 necessary to decode the, the displayed frame interval becomes more even,
Smooth reverse reproduction can be performed.

As described above, according to the first embodiment, decoding of a frame having a small number of reference frames to be decoded, which is displayed first in the display order of reverse reproduction, is displayed later in the display order. , Decoding after decoding the reference frames of a frame with a large number of reference frames leads to equalization of the decoding time, resulting in equalization of the display time and smooth reverse playback. become.

In the first embodiment, the frame memory is composed of three planes. However, the number of the frame memories is not limited to this, and may be any number. By this I / P
Since many pictures can be stored in the frame memory, high-speed reverse playback is possible.

In the first embodiment, the head of the GOP is
Although the example of decoding first only with I picture is shown, GOP
The same is possible for I / P / B pictures other than the first one. As a result, the encoding time between the other frames is also equalized, so that smoother reverse reproduction is possible.

(Embodiment 2) Next, a moving image reproducing apparatus and a reproducing method according to Embodiment 2 will be described.
For the basic configuration and the configuration to realize the device,
1 and 2 except that the flow of the decoding control means 12 in FIG. 1 (the control unit 27 in FIG. 2) is different. That is, the control unit 27 performs decoding control and management of the frame memory at the time of reverse reproduction. Depending on the next frame to be displayed, the control unit 27 delays the display of the frame so that the display time becomes equal.

FIG. 5 shows a control unit 27 according to the second embodiment.
FIG. 4 is a diagram showing a flowchart of the above. This flow is used for each process of decoding an image to be displayed next in reverse reproduction. When the processing for a certain image is started in step S400, first, it is determined whether the next image to be displayed is the first I picture of the GOP (step S40).
If 1), "YES", the next I picture to be displayed is decoded (step S402), and N I / P pictures of the GOP immediately before the GOP including the next I picture to be displayed are decoded. The decryption is performed (step S403). Here, N is a predetermined positive integer. Thereafter, the first I picture of the GOP decoded in step S402 is displayed (step S404). Then, after the display, the frame to be displayed next to the first I picture of the currently displayed GOP is set to the first I picture of the currently displayed GOP.
The necessary I / P picture that exists next to the I / P picture that has been decoded before the picture is displayed,
The next frame to be displayed is decoded (step
(S405), and display the frame to be displayed next (step
(S406), the process ends (step S409). On the other hand, in step S401, the image to be displayed next is the first image in the GOP.
If the determination result is "NO" instead of the I picture, the necessary I / P picture and the frame to be displayed next are decoded (step S407), and the frame to be displayed next is displayed (step S407). (S408), the process ends (step S409).

FIG. 6 is a diagram showing the timing of writing / reading the frame memory when the stream shown in FIG. 7 is reproduced in reverse. Assuming that the frame of B'3 is currently displayed, the next display frame is I'2. Where I '
After decrypting 2, decode I'2 instead of displaying I'2.
, The next output frame is decoded. Specifically, I2 is decoded, and then I'2 is displayed and P5, P8, P11,
Decode P14, I'2, B'1 and display B'1.

As described above, according to the second embodiment, the processing time of a frame with a small number of reference frames for decoding a display frame and the processing time of a frame with a large number of reference frames for decoding a frame By delaying the display start time of a frame having a short decoding processing time so that the decoding time becomes equal, the display time of the reproduced frame is equalized, and a smooth reverse reproduction can be performed.

In the second embodiment, the frame memory is composed of three planes. However, the number of frame memories is not limited to this, and may be any number. For example, when the frame memory has four or more frames, it is possible to display a frame at an arbitrary timing.

Also, in the second embodiment, the head of the GOP
The example in which the display is delayed only for the I picture has been described. However, the same configuration can be applied to the case where the I / P / B picture other than the head of the GOP is delayed. As a result, the display time between the other frames can be equalized, so that smoother reverse reproduction can be achieved.

[0030]

As described above, according to the moving picture decoding apparatus according to the first aspect of the present invention, the moving picture coded data which has been subjected to the compression processing using the inter-frame correlation in the time axis direction is temporally converted. When decoding in the reverse direction, the decoding of the reference frame of the frame having the small number of reference frames to be displayed earlier in the display order of the reverse playback and the decoding of the reference frame displayed later in the display order is performed. Is performed after decoding a reference frame of a frame having a large number of reference frames, so that encoded data that has been subjected to compression processing using frame correlation in the time axis direction is reproduced in a temporally reverse direction. In this case, the display time is equalized even with the minimum necessary number of frame memories, and a smooth reverse reproduction can be achieved.

Further, by delaying the display start time of a frame whose decoding processing time is short, the processing time of a frame having a small number of reference frames for decoding a display frame and the number of reference frames for decoding a frame are reduced. Since the display time difference from the processing time of a large number of frames is reduced, the display time of the reproduced frame is equalized, and the effect that smooth reverse reproduction can be performed is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a moving image reproducing device according to Embodiments 1 and 2 of the present invention.

FIG. 2 is a diagram illustrating a circuit-level configuration of the moving image reproducing apparatuses according to the first and second embodiments of the present invention.

FIG. 3 is a diagram showing write / read timings of a frame memory at the time of reverse reproduction in the moving picture reproduction device according to the first embodiment.

FIG. 4 is a diagram showing a control flowchart at the time of reverse playback in the moving picture playback device according to the first embodiment.

FIG. 5 is a diagram illustrating a control flowchart of a moving image reproducing apparatus according to a second embodiment of the present invention.

FIG. 6 is a diagram showing write / read timings of a frame memory at the time of reverse playback in the moving picture playback device according to the second embodiment.

FIG. 7 is a diagram showing an inter-frame structure in MPEG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Reproduction direction detection means 11 Frame number detection means 12 Decoding control means 13 Decoding means 21 Stream analysis part 22 VLC decoding part 23 IQ part 24 IDCT part 25 Motion compensation part 26 Frame memory 27 Control part

Claims (7)

[Claims] 1. A moving picture reproducing apparatus having a function of reproducing moving picture coded data which has been subjected to compression processing by utilizing inter-frame correlation in a time axis direction in a temporally reverse direction. Playback direction detecting means for detecting whether or not the playback is in the reverse direction in time. If the playback direction detection means determines that the playback in the reverse direction in time is to be performed, the playback is performed. Decoding reference frame number detection means for detecting the number of reference frames necessary for decoding a frame for each frame to be reproduced; and decoding for decoding the frame to be reproduced with reference to the reference frame. Means for receiving the output of the decoding-time reference frame number detecting means, wherein the reference frame number of the reproduction target frame to be reproduced temporally later is set to the reference frame of the reproduction target frame to be reproduced temporally earlier. When the number is larger than the number, the decoding unit is controlled so that the decoding of the reference frame of the frame to be reproduced temporally later is performed prior to the decoding of the frame to be temporally performed earlier. A moving picture reproducing apparatus comprising: a decoding control unit. 2. The moving picture reproducing apparatus according to claim 1, wherein the compression processing is performed using an MPEG method, and a frame displayed earlier in a display order during reverse reproduction is temporally earlier. , A coding unit (G
OP) is the first intra-coded image (I picture), and the frame displayed later in time is GO in reverse playback order.
A moving picture reproducing apparatus characterized by being a frame to be displayed next to a leading I picture of P. 3. The moving picture reproducing apparatus according to claim 2, wherein said decoding control means, when the next frame to be displayed is the first I-picture of the GOP, temporally immediately preceding the GOP. A moving picture reproducing apparatus characterized in that I or some of the inter-frame forward prediction coded pictures (P pictures) are decoded first, and then the first I picture of the GOP is decoded. 4. The moving picture reproducing apparatus according to claim 3, wherein the decoding control means is configured to determine that the next frame to be displayed is not the first I-picture of the GOP, and that the currently displayed frame is GO.
A moving picture reproducing apparatus for decoding a next display frame from the first I or P picture decoded in the case of the first I picture of P. 5. A moving picture reproducing apparatus having a function of reproducing moving picture coded data, which has been subjected to compression processing by utilizing inter-frame correlation in a time axis direction, in a temporally reverse direction. Playback direction detecting means for detecting whether or not the playback is in the reverse direction in time. If the playback direction detection means determines that the playback in the reverse direction in time is to be performed, the playback is performed. Decoding reference frame number detection means for detecting the number of reference frames necessary for decoding a frame for each frame to be reproduced; and decoding for decoding the frame to be reproduced with reference to the reference frame. Receiving the output of the decoding reference frame number detecting means, and setting the reference frame number of the reproduction target frame to be reproduced temporally later to the reference frame number of the reproduction target frame to be reproduced earlier in time. Decoding control means for controlling the output from the decoding means so as to delay the display start of the target frame to be reproduced earlier in time if the number is larger than the predetermined number. Video playback device. 6. A moving picture reproducing method for reproducing moving picture coded data, which has been subjected to compression processing using inter-frame correlation in the time axis direction, in a temporally reverse direction. A step of detecting whether or not the reproduction is temporally reverse, and decoding the frame to be reproduced when it is determined in the above step that reproduction in the temporal direction is performed. Detecting the required number of reference frames for each frame to be played back, wherein the number of reference frames of the frame to be played back temporally later is larger than the number of reference frames of the frame to be played back earlier in time. Decoding the reference frame of the frame to be reproduced temporally later, prior to the decoding of the frame to be temporally performed, if the number is large. Video playback method. 7. A moving picture reproducing method for reproducing moving picture coded data, which has been subjected to compression processing by utilizing inter-frame correlation in a time axis direction, in a temporally reverse direction. A step of detecting whether or not the reproduction is temporally backward; and a step of decoding the frame to be reproduced when the reproduction direction detection means determines that reproduction in the temporally reverse direction is performed. Detecting the number of reference frames required for each reproduction target frame, and the number of reference frames of the reproduction target frame to be reproduced later in time is made larger than the number of reference frames of the reproduction target frame to be reproduced earlier in time. And delaying the display start of the target frame to be reproduced earlier in time by a predetermined time when there are many moving images.