JP2003037816A - Moving picture coding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the response to an operation by reducing the amount of coding delay without reducing the amount of information transmitted to audience. SOLUTION: When start of coding is designated, it is determined in a step 101 whether usual reproduction is designated. If the usual reproduction is not continued, a sequence end processing is performed in a step 105. It is determined in a step 106 whether or not the coding is continued. When the coding is continued, since a special reproduction is instructed, special reproduction processing is started in a step 107. Also, in the case that it is determined that the usual reproduction is not designated, special reproduction is started in the step 107. In the step 107, a value of low- delay as a parameter is set at 1, and sequence start processing is started as GOP which does not include a B-picture. Then, input processing of an I-picture is performed, and the picture which is already inputted is coded in a step 108.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving picture coding method for switching between normal coding and low-delay coding depending on an operation mode of a source of a video signal to be coded. .

[0002]

2. Description of the Related Art When a video signal is transmitted via a wireless transmission line or a wired transmission line, it is common to encode the video signal with high efficiency in order to effectively utilize the limited transmission line capacity. High-efficiency coding causes a coding delay in the encoder and a decoding delay in the decoder, so that a video signal shifts between the video source side and the viewer side.

As an example, a case of the wireless transmission system shown in FIG. 16 is shown. FIG. 16 shows that the video signal reproduced by the moving image reproducing device 21 is highly efficiently encoded by the moving image encoding device 22, the encoded data is transmitted from the wireless transceiver 23 to the wireless transceiver 24, and the received encoded data is a moving image. The image is decoded by the image decoding device 25, and the viewer controls the moving image reproduction device 21 by the reproduction mode instruction means 26 (for example, a remote controller).

In the decoded video viewed by the viewer 27 in FIG. 16, the video output from the moving picture reproducing apparatus 21 is the coding delay in the moving picture coding apparatus 22 and the moving picture decoding apparatus 25.
The video is delayed by the decoding delay in. That is, at the same time, the video signal output from the moving image reproducing apparatus 21 is ahead of the decoded video viewed by the viewer 27 in time. The encoding delay and the decoding delay time vary greatly depending on the encoding method, the circuit mounting means, etc.
In the case of the MPEG video system defined by O / IEC13818-2, it is about 6 to 15 frames.

In such a situation, for example, when the viewer 27 searches for a desired video scene in high speed reproduction, when the viewer 27 specifies high speed reproduction by the reproduction mode instructing means 26, the command indicating high speed reproduction is a moving image decoding command. Device 25, wireless transmission line,
It is transmitted to the moving image reproducing device 21 via the moving image encoding device 22. Upon receiving the high speed reproduction command, the moving image reproduction device 21 outputs a high speed reproduction image. Then, when the viewer 27 finds a desired video scene and returns to normal reproduction, the reproduction mode instructing means 26 issues an instruction to return to normal reproduction. At this point, the viewer 27 performs normal reproduction in the moving image reproduction device 21. The scene is ahead of the scene to be started, and normal reproduction is performed from a scene prior to the video scene desired by the viewer 27. In other words, the viewer 27 will see the video of the instructed operation mode after a time corresponding to the encoding delay and the decoding delay after the instruction is given by the reproduction mode instructing means 26, and there is a problem that the operation response is poor. .

As a conventional technique for improving the operation response in a system which performs encoding and decoding in real time, there is an apparatus described in Japanese Patent Laid-Open No. 9-9233. JP-A-9-
Japanese Patent No. 9233 is a technique for improving the operation response in a video conference system, in which a screen area to be transmitted is made smaller than usual during a remote operation of a camera, and a transmission code amount is reduced to improve a frame rate. It realizes a reduction in coding delay.

[0007]

However, in the technique disclosed in Japanese Patent Laid-Open No. 9-9233, the video rate on the viewer side is limited to a part of the screen to improve the frame rate and reduce the coding delay. The amount of information transmitted to viewers is decreasing. Therefore, for example, a problem may occur in that the portion that the viewer wants to confirm is not updated on the screen.

An object of the present invention is to provide a moving picture coding method for reducing the coding delay amount and improving the operation response without reducing the amount of information transmitted to the viewer.

[0009]

According to the present invention, a moving picture output means for outputting a video signal, a moving picture coding means for high efficiency coding the video signal, and a moving picture coding means for coding the moving picture coding means. And a moving picture decoding method for decoding the coded data, and an operation mode instructing means for instructing an operation mode to the moving picture output means. When the operation mode instructing means instructs special reproduction, the moving picture encoding means switches to an encoding method in which the encoding delay time and the decoding delay time are shortened.

The encoding method is an MPEG encoding method and may be characterized by a low delay mode, or the capacity of the encoding buffer may be reduced or the delay time in the encoding buffer may be shortened. It may be characterized by doing. The encoding method is an MPEG encoding method and may be characterized by encoding with a GOP configuration that does not use B pictures or B pictures and P pictures, or performs encoding in field units. That is, all the pictures are coded as P pictures and each P picture is
A part of the picture may be intra-coded, and the area to be intra-coded may be changed for each picture so that the entire area of the picture is intra-coded in a plurality of consecutive pictures.

Further, in the moving picture coding method of the present invention, the moving picture output means is composed of a moving picture recording / reproducing apparatus or a moving picture reproducing apparatus having a recording medium, and the special reproduction is still or frame advance reproduction or It can also be applied to slow or high speed playback.

Further, in the moving picture coding method of the present invention, the moving picture output means is a video camera, and the special reproduction is carried out by moving the main body of the video camera, moving the direction of the video camera, or photographing by the video camera. It can also be applied when zooming in and out of a range, or when changing the shooting parameters of a video camera.

In the present invention, when the video from the moving image output means is required to have real-time characteristics, the coding response and the decoding delay are shortened to improve the operation response.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

[First Embodiment] FIG. 1 is a block diagram showing a first embodiment of a video encoding / decoding apparatus used in a moving image encoding method according to the present invention. This figure shows a configuration in which a video reproduced by a VTR is encoded by an MPEG system, encoded data transmitted by radio is decoded by a viewer, and the viewer operates the VTR with a remote controller.

In FIG. 1, when the viewer 8 instructs the remote controller 7 to reproduce, the VTR (moving image output means) 1 starts the reproduction, and the reproduced image is reproduced by the MPEG encoder (moving image encoding means) 2. It is encoded with high efficiency and is decoded by the MPEG decoder (moving image decoding means) 6 via the wireless transceiver 3, the wireless transmission path 4, and the wireless transceiver 5. The viewer 8 controls the remote control (operation mode instruction means) 7 such as stop, play, fast forward, rewind, still, frame advance, slow play, and high speed play while watching the video decoded by the MPEG decoder 6. .
The instruction command from the remote controller 7 is received by the MPEG decoder 6, transmitted to the MPEG encoder 2 via the wireless transceiver 5, the wireless transmission path 4, and the wireless transceiver 3, and input to the VTR 1.

In normal reproduction, the MPEG encoder 2 performs encoding so as to obtain high image quality. That is, for example, in FIG.
As shown in FIG.
Of Pictures) are encoded. In Figure 2,
I is a picture to be intra-frame coded (hereinafter referred to as I picture), P is a coded I, P picture from which forward predictive coding is performed (hereinafter referred to as P picture), and B is already Pictures to be bidirectionally predictively coded from I and P pictures before and after being coded (hereinafter, referred to as B
It is called a picture). The numbers in parentheses 0
Reference numeral 14 indicates a frame number in the input order in the GOP.

FIG. 2B shows the coding order when the GOP shown in FIG. 2A is coded. Since the B picture is predictively encoded from the decoded image of the I picture or P picture that is input later, it is stored in the frame memory once,
The I picture or P picture to be input later is encoded and then encoded. Therefore, the encoding order is I (2),
B (0), B (1), P (5), ... The decoding order is as shown in FIG. 2 (c), which is the same as the coding order in FIG. 2 (b). FIG. 2D shows the output order of the decoded data. The output order must be the same as the input order in FIG. Therefore, the I picture and P picture are temporarily recorded in the frame memory, and the B picture decoded later is output first.

Looking at the delays in FIGS. 2A to 2D for I pictures, first, the input of I pictures in FIG. 2A is completed, and then the encoding is started in FIG. 2B. In order to
One frame of delay occurs, and decoding of the B picture is completed in FIG. Further, since the I picture is output after the B picture output is completed in FIG. 2D, a delay of 4 frames occurs. That is, a delay of 5 frames occurs only by encoding and decoding.

Further, the MPEG encoder 2 temporarily stores the encoded data in a buffer and then sends it to the wireless transceiver 3, the delay required for the transmission process in the wireless transceiver 3, and the reception in the wireless transceiver 5. Processing delay, MPE
A delay occurs because the G decoder 6 temporarily stores the encoded data in the buffer and then starts decoding.

In this embodiment, when the viewer 8 designates special reproduction such as high-speed reproduction, still picture, frame advance, and slow reproduction, the parameter for instructing the encoding method in the MPEG encoder 2 is changed. The method is characterized by switching to an encoding method in which the delay time is shortened compared to normal reproduction. The fact that the trick play is instructed means that the MPEG decoder 6 receives the command from the remote controller 7,
It is transmitted to the MPEG encoder 2 via the wireless transmission line 4 and the wireless transceiver 3. In this embodiment, when special reproduction is instructed, the MPEG encoder 2 uses the MPEG parameter lo.
The w_delay flag is set to 1. l
ow_delay = 1 indicates the low delay mode, and the GOP structure does not use B pictures. FIG. 3 shows an example of the GOP structure when special reproduction is instructed.

In the low delay mode, a GOP is composed of only I and P pictures without using B pictures. In this case, since neither the encoding side nor the decoding side needs to rearrange the pictures, the MPEG encoder 2 can immediately encode the input-completed frame, and the encoding delay becomes one frame.
The MPEG decoder 6 can immediately output the frame that has been decoded, so that the decoding delay becomes one frame. Therefore,
The delay time in the encoding / decoding processing is shortened from 5 frame periods during normal reproduction to 2 frame periods.

FIG. 4 is a flowchart showing the operation of the MPEG encoder 2 of this embodiment. In FIG. 4, when the start of reproduction is designated, it is determined in step 101 whether it is normal reproduction. In the case of normal reproduction, a sequence start process is performed in step 102. At this time, the value of low_delay is 0, and encoding is performed as a GOP including a B picture. Next, in step 103, input processing of one picture is performed, and the already input picture is encoded. Then, in step 104, it is determined whether or not the normal reproduction is continued.

While continuing normal reproduction, step 103,
Repeat step 104. When the normal reproduction is not continued, the sequence end process is performed in step 105. Then, in step 106, it is determined whether the encoding is continued. If the special reproduction is instructed to continue the encoding, the special reproduction process is started in step 107. Also, when it is determined in step 101 that the normal reproduction is not performed, the special reproduction process is started in step 107.

In step 107, the parameter l
The value of ow_delay is 1 and G does not include B picture.
Sequence start processing is performed as OP. Next, at step 108, input processing of one picture is performed, and the already input picture is encoded. Then, in step 109, it is determined whether or not the trick play is to be continued. Steps 108 and 109 are repeated while the trick play is continued. When the trick play is not continued, step 110
The sequence end processing is performed with. Then, in step 111, it is determined whether or not the encoding is continued. When encoding is continued, normal reproduction is instructed, so step 10
At 2, the normal reproduction process is started.

In the flowchart of FIG. 4, when the normal reproduction and the special reproduction are switched, the sequence ending process is performed and then the new sequence starting process is performed. This is an MPEG standard and is low_del in the same sequence.
There is a restriction that the values of ay must be the same,
This is because it is necessary to set a new sequence in order to change the value of low_delay.

With the above configuration and operation, it is possible to realize an encoding device using an encoding method that shortens the encoding delay during special reproduction as compared with normal reproduction. In the present embodiment, the coding delay time is shortened by eliminating the rearrangement of frames during special reproduction and by outputting the frame immediately after decoding is completed by setting the low delay mode. Therefore, the number of frames that make up the GOP and the number of I, P, and B pictures that make up the GOP are not limited to this example.
The number of frames forming a GOP may be different between normal reproduction and special reproduction.

In this embodiment, the MPEG decoder 6 receives the special reproduction instruction command from the remote controller 7,
Although it is transmitted to the MPEG encoder 2 via the wireless transceiver 5, the wireless transmission path 4, and the wireless transceiver 3, it may be transmitted directly from the remote controller 7 to the MPEG encoder 2 or the VTR 1.

[Second Embodiment] The block configuration of this embodiment is the same as that of the first embodiment shown in FIG.
In the first embodiment, the low delay mode is set at the time of special reproduction, but in the present embodiment, the coding delay is reduced by reducing the capacity of the coding buffer for storing the coded data or the delay time in the coding buffer. . In MPEG, an encoder is provided with an encoding buffer for accumulating encoded data, the amount of data input to the encoding buffer and the amount of code for each picture are controlled, and it is guaranteed that the decoder will perform decoding processing without delay. Is common. The encoding buffer capacity is an MPEG parameter vbv_buffer_siz.
e_value, the delay time in the encoding buffer is vb
It is specified by v_de1ay.

FIG. 5 shows an outline of the relationship between the encoding buffer capacity in the MPEG encoder 2 and the delay time in the encoding buffer. According to the MPEG standard, some of the headers of the encoded data do not accurately show details such as not affecting the value of vbv_delay. However, it is not necessary to explain the features of the present application, and therefore omitted. ing.

FIG. 5 shows the encoding buffer capacity and the buffer remaining amount, in which the code is input at a constant rate,
A model in which coded data of a picture disappears from the coding buffer is used. In FIG. 5, the encoding start time T
In the start, the remaining buffer amount is the same as the remaining buffer amount, and the remaining buffer amount decreases with time.
The buffer remaining amount becomes zero. Then, at the timing of T0, the encoded data (d1) of the first I picture disappears from the encoding buffer, and thereafter, the code is input at a constant rate, and the encoded data of one picture is output from the encoding buffer every one picture period. Repeat that it disappears. Then, the code amount of one picture is controlled so that the buffer remaining amount is always 0 or more and equal to or less than the encoding buffer capacity.

In FIG. 5, the delay time of the first I picture in the coding buffer is t (I), and the delay time of the next B picture in the coding buffer is t (B). The MPEG decoder 6 delays the encoded data in the buffer by the value indicated by the delay time in the encoding buffer and then starts decoding. This is also shown in FIG.
This is to maintain the relationship of the buffer remaining amount shown in, and to ensure that the encoding buffer does not overflow or underflow.

FIG. 6 shows the relationship between the encoding buffer capacity and the buffer remaining capacity during special reproduction. In FIG. 6, only the buffer capacity is smaller than that in FIG. By reducing the buffer capacity, both the delay time t (I) of the first I picture in the encoding buffer and the delay time t (B) of the next B picture in the encoding buffer are reduced. That is, the time required for the buffer in the MPEG decoder 6 to delay is reduced.

FIG. 7 is a flowchart showing the operation of the MPEG encoder 2 of this embodiment. In the flowchart of FIG. 7 and the flowchart showing the operation of the MPEG encoder 2 of the first embodiment of the present invention shown in FIG. 4, only steps 102 and 107 of FIG. The same number is attached to each and the description is omitted.

In FIG. 7, if it is determined in step 101 that normal reproduction is performed, step 121 is executed to start the sequence for normal reproduction. At this time, vbv_buffer
r_size sets a normal value A. Step 101
If it is not determined to be normal reproduction in step 122,
Starts the sequence during special playback with. On this occasion,
For vbv_buffer_size, a value B smaller than the value A set in step 121 is set. Step 1
Except 21 and 122, the same operation as the flowchart in FIG. 4 is performed.

Also in the flow chart of FIG. 7, when the normal reproduction and the special reproduction are switched, the sequence ending process is performed and then the new sequence starting process is performed. This is an MPEG standard and is vbv_buf in the same sequence.
This is because there is a restriction that the values of fer_size must be the same, and it is necessary to use a new sequence to change the value of vbv_buffer_size.

With the above configuration and operation, it is possible to realize an encoding device using an encoding method that reduces the encoding delay during special reproduction as compared with normal reproduction. The present embodiment is characterized in that the capacity of the encoding buffer is reduced during the special reproduction or the delay time in the encoding buffer is shortened. In this embodiment, only the capacity of the encoding buffer is changed, and the code amount of each picture is not changed. That is, the encoding control is the same for normal reproduction and special reproduction, but the encoding control method is not limited to this example. For example, the encoding buffer capacity is made smaller, and each picture is adjusted according to the small encoding buffer capacity. You may perform the encoding control which controls a code amount.

[Third Embodiment] The block configuration of this embodiment is the same as that of the first embodiment shown in FIG.
In the first embodiment, the low delay mode is set during special playback, but in the present embodiment, only the GOP configuration is changed without setting the low delay mode. G during normal reproduction in this embodiment
The OP configuration, the encoding order, and the decoding order are also the same as in the first embodiment shown in FIG. FIG. 8 shows the GOP structure, the encoding order, and the decoding order during special playback. The delay in the data output stage of (d) is different from the GOP configuration, the encoding gradient, and the decoding order in the special reproduction in the first embodiment shown in FIG. In the low-delay mode, since it is known in advance that there are only I and P pictures, it is not necessary to rearrange the frames, and it is possible to immediately output the decoded pictures. However, when the mode is not the low-delay mode, B-pictures may be included, so it is necessary to perform control in consideration of frame rearrangement. That is, the I and P pictures are
Alternatively, it is necessary to output after the P picture is decoded. This is the same control as the normal reproduction. Therefore, the delay at the decoder at the time of special reproduction of this embodiment is 2 frames, and the total delay at the encoder and the decoder is 3 frames. That is, the delay time is shorter by 2 frames than the 5 frames in the normal mode.

FIG. 9 is a flowchart showing the operation of the MPEG encoder 2 of this embodiment. In the flowchart of FIG. 9 and the flowchart of FIG. 4 showing the operation of the MPEG encoder 2 of the first embodiment of the present invention, only the operation corresponding to steps 102 and 107 of FIG. 4 is different (step 231). , 232, 235, 236),
The difference is that the processing order of steps 105 and 106 and steps 110 and 111 is switched (steps 233, 234, 237, and 238, respectively), but otherwise the operation is the same, so steps that perform the same operation are not The same numbers are attached and the description is omitted.

In FIG. 9, when it is determined in step 101 that the normal reproduction is performed, step 231 is executed to start the sequence for the normal reproduction. Then, in step 232, processing is performed as a GOP with a B picture. When it is determined in step 104 that the normal reproduction is not continued,
In step 233, it is determined whether the encoding is continued,
When it is determined that the encoding is not continued, step 234
The sequence end processing is performed with and the processing ends.

If it is not determined in step 101 that the normal reproduction is performed, step 235 is executed to start the sequence for special reproduction. Then, in step 236, processing is performed as a GOP without B picture. And step 10
If it is determined in step 9 that the trick play is not to be continued, it is determined in step 237 whether or not the encoding is to be continued. If it is determined that the encoding is not to be continued, the sequence ending process is performed in step 238 to perform the process. finish. The other steps perform the same operations as in the flowchart of FIG.

In the flowchart of FIG. 9, when the normal reproduction and the special reproduction are switched, the sequence ending process is not performed and the encoding is continued as the same sequence. This is because the MPEG standard does not limit the GOP structure of the same sequence to be fixed.

With the above configuration and operation, it is possible to realize an encoding device using an encoding method for reducing the encoding delay during special reproduction as compared with normal reproduction. Note that the present embodiment is characterized in that the coding delay time is shortened by eliminating the rearrangement of frames during special reproduction. Therefore, GO
Number of frames forming P, I, P, B forming GOP
The number of pictures is not limited to this example. Also, GO
The number of frames forming P may be different between normal reproduction and special reproduction.

[Fourth Embodiment] The block configuration of this embodiment is the same as that of the first embodiment shown in FIG.
In the first embodiment, the low-delay mode is used during special reproduction, but in the present embodiment, it is encoded as a field picture. The GOP configuration, the encoding order, and the decoding order during normal reproduction of this embodiment are also the same as those of the first embodiment shown in FIG.

FIG. 10 shows the GOP structure, encoding order, and decoding order during special reproduction. In the present embodiment, each of the two fields constituting the frame at the time of special reproduction is encoded as one picture (field picture). Figure 10
(A) shows that two fields, a first field and a second field, are input in one frame period. Figure 10
The coding order and the coding timing are shown in (b). In the case of the field picture, the encoding can be started when the first fields of the I and P frames are input, so that the encoding can be started by a half frame period earlier than the case of encoding the frame picture. FIG. 10D shows the output order and output timing. As for the output timing, in the case of a field picture, the output can be started when the decoding of one field forming a frame is completed, so that the output can be performed by a half frame period earlier than the case of decoding a frame picture. Therefore, the coding delay at the time of special reproduction in this embodiment is 4 frames, which is one frame shorter than the 5 frames in the normal mode.

FIG. 11 shows the MPEG encoder 2 of this embodiment.
The operation of is shown in a flowchart. The flowchart of FIG. 11 is the MPEG of the third embodiment of the present invention shown in FIG.
Although the operation is almost the same as the flowchart showing the operation of the encoder 2, only the portions corresponding to steps 232 and 236 in FIG. 9 are different from those in FIG. 11 (steps 241 to 24).
2), the same numbers are given to the steps that perform the same operation, and the description thereof will be omitted.

In FIG. 11, when it is determined in step 101 that the normal reproduction is performed, step 231 is executed to start the sequence for the normal reproduction. Then, in step 241, encoding processing is performed as a frame picture. Step 10
If it is not determined to be normal reproduction in step 1, step 2
At 35, the start processing of the sequence during special reproduction is performed. Then, in step 242, encoding processing is performed as a field picture. The other steps perform the same operations as in the flowchart of FIG.

With the above configuration and operation, an encoding device using an encoding method that reduces the encoding delay during special reproduction as compared with normal reproduction can be realized. It should be noted that the present embodiment is characterized in that the coding delay time is shortened by using a field picture during special reproduction. Therefore, GOP
The number of frames that make up G, and the number of I, P, and B pictures that make up GOP are not limited to this example.

[Fifth Embodiment] The block configuration of this embodiment is the same as that of the first embodiment shown in FIG.
In the first embodiment, the low-delay mode is set during special reproduction, but in the present embodiment, P pictures are encoded as intra slices. FIG. 12 shows an outline of intra slice coding. In the intra slice, all are coded as P pictures, and part of the pictures is intra-frame coded. Then, the position for intra-frame encoding is shifted for each picture, and regarding a certain portion, intra-frame encoding is performed once in a plurality of frames.

In FIG. 12, in the picture P (0), P
It is encoded as a picture, and the upper part of the picture (the intra slice and the hatched portion shown) is intra-frame encoded.
The next picture P (1) is also encoded as a P picture, and the portion below the portion that has been intra-coded with the picture P (0) is intra-frame encoded. In this way, the position for intra-frame coding is shifted for each picture. The operation in normal reproduction of this embodiment is the same as that of the first embodiment.

FIG. 13 shows the relationship between the encoding buffer capacity and the buffer remaining capacity during special reproduction. In intra slice coding, since all P pictures are coded, the generated code amount for each picture does not change significantly. Therefore, the encoding buffer capacity can be further reduced. For example, in the relationship between the coding buffer capacity and the buffer remaining capacity of the second embodiment shown in FIG. 6, the code amount d1 of an I picture is larger than the code amounts of other pictures, and the coding buffer capacity is d.
Although it cannot be made smaller than 1, in the present embodiment, the generated code amounts of all pictures are easily equalized, so that a smaller buffer capacity can be obtained. As a result, the delay time t (p) in the encoding buffer becomes smaller.

FIG. 14 shows the MPEG encoder 2 of this embodiment.
The operation of is shown in a flowchart. 1 is a flowchart of the MPEG encoder 2 of the second embodiment shown in FIG.
In the flowchart showing the operation of the MPEG encoder 2 of the present embodiment shown in FIG. 4, steps 121 and 122 of FIG.
However, the same numbers are given to the steps that perform the same operation, and the description thereof will be omitted.

In FIG. 14, if it is determined in step 101 that normal reproduction is performed, step 141 is executed to start the sequence for normal reproduction. At this time, vbv_buff
er_size is set to a normal value A and is encoded with a GOP structure including I, P, and B pictures. If it is not judged as normal reproduction in step 101, step 142
Starts the sequence during special playback with. On this occasion,
For vbv_buffer_size, a value C that is smaller than the value A set in step 141 is set, all of which are P pictures to configure a GOP, and intra slice coding is performed. Except for steps 141 and 142, the same operation as the flowchart in FIG. 7 is performed.

Also in the flowchart of FIG. 14, when the normal reproduction and the special reproduction are switched, the sequence ending process is performed and then the new sequence starting process is performed. This is a standard of MPEG29, and vbv in the same sequence.
This is because a new sequence is required to change the value of _buffer_size.

With the above configuration and operation, an encoding device using an encoding method that reduces the encoding delay during special reproduction as compared with normal reproduction can be realized.

[Sixth Embodiment] FIG. 15 shows a sixth embodiment of the present invention.
2 shows a block diagram of an embodiment of FIG. The present embodiment is a modification of the first to fifth embodiments. Although the VTR is used as the moving image output means in the first embodiment, the video camera 11 is used in the present embodiment shown in FIG. In addition, in the first to fifth embodiments, the special reproduction is special reproduction such as still, slow, frame-advance, and high-speed reproduction, but in the present embodiment, movement of the video camera body, movement of the video camera direction, video camera The zoom-in and zoom-out of the shooting range, focus adjustment, and change of shooting parameters of the video camera dedicated to white balance. Other than that, the present embodiment and the first to fifth embodiments perform the same operation.

[Modifications of First to Sixth Embodiments] First to First
In all of the sixth embodiments, the coding response is reduced during special reproduction to improve the operation response. In the first embodiment, the low-delay mode is set to reduce the coding delay, and in the second embodiment, the coding buffer capacity or the delay time in the coding buffer is shortened to reduce the coding delay. In the third embodiment, the coding delay is reduced by changing the GOP structure, and in the fourth embodiment, the coding delay is reduced by coding as a field picture. Since these can be controlled independently, not only a single control but a plurality of controls may be performed simultaneously. For example, the low-delay mode may be set during high-speed reproduction, and the encoding buffer capacity may be reduced. Alternatively, the mode may be set to the low-delay mode, the capacity of the coding buffer may be reduced, and the field picture may be coded.

Further, in the second and fifth embodiments, when the normal reproduction and the special reproduction are switched, the sequence up to then is ended and a new sequence is performed for processing, but the value of vbv_buffer_size is changed. It is possible to reduce only the value of vbv_delay without changing it. In that case, it is not necessary to end the sequence, and normal reproduction and special reproduction can be switched in the same sequence. Furthermore, since the present invention is characterized in that the coding delay is reduced during special reproduction, the transmission between the encoder and the decoder is not limited to the wireless transmission path as in this example, and it is not limited to the Internet. A wired transmission line may be used.

[0059]

According to the present invention, since the encoding is shortened during the special reproduction, the time difference between the image output from the moving image re-outputting means and the decoded image in the moving image decoding means is reduced. , The operation response during special playback is improved. Since the frame rate and the screen area to be encoded are not changed even during special reproduction, the amount of information transmitted to the viewer is not lost, and only the operation response can be improved without visual deterioration. Further, since the coding delay is reduced only in the special reproduction, it is possible to realize the high-quality coding in which the coding parameters are not limited in the normal reproduction. Further, the encoding delay is reduced only in special reproduction, and in general, the demand for high image quality in special reproduction is loose. Therefore, even if the encoding parameters are limited during special reproduction, no visual problem occurs. Furthermore, if the coding delay is reduced, it may not be possible to display part of the video at the change point of the coding delay, and if the coding delay is increased, there may be no video to be displayed at the change point. Occurs at the timing of switching between normal playback and special playback, so there is an effect that it does not cause a visual problem.

Further, according to the present invention, since the coding delay is reduced in accordance with the MPEG standard, no special circuit is required in the decoder. Further, the encoder only changes the encoding parameter, and generally has the effect that it can be realized by software processing without the need for a special circuit.

Further, according to the present invention, when encoded as a field picture, overflow / underflow determination of the encoding buffer can be performed for each field. That is, there is an effect that finer control can be performed and the buffer capacity and the delay amount in the encoding buffer can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of a video encoding / decoding device used in a moving image encoding method according to the present invention.

FIG. 2 is a diagram showing a GOP configuration, a coding order, and a decoding order during normal reproduction according to the first embodiment.

FIG. 3 is a diagram showing a GOP structure, an encoding order, and a decoding order at the time of special playback in the first embodiment.

FIG. 4 is a flowchart showing an operation of the MPEG encoder of the first embodiment.

FIG. 5 is a diagram illustrating a coding buffer capacity and a delay time in the coding buffer during normal reproduction.

FIG. 6 is a diagram illustrating a coding buffer capacity and a delay time in the coding buffer during special reproduction.

FIG. 7 is a flowchart showing an operation of the MPEG encoder 2 of the second embodiment.

FIG. 8 is a diagram showing a GOP structure, an encoding order, and a decoding order during trick play in the third embodiment.

FIG. 9 is a flowchart showing the operation of the MPEG encoder 2 of the third embodiment.

FIG. 10 is a GOP during special playback according to the fourth embodiment.
It is a figure which shows a structure, an encoding order, and a decoding order.

FIG. 11 is a flowchart showing an operation of the MPEG encoder 2 of the fourth embodiment.

[Fig. 12] Fig. 12 is a diagram for describing the outline of intra slice encoding.

FIG. 13 is a diagram illustrating an encoding buffer capacity and a delay time in the encoding buffer at the time of special reproduction in the fifth embodiment.

FIG. 14 is a flowchart showing an operation of the MPEG encoder of the fifth embodiment.

FIG. 15 is a block diagram showing a sixth embodiment of a video encoding / decoding device used in the moving image encoding method according to the present invention.

FIG. 16 is a block diagram showing a video encoding / decoding device used in a conventional moving image encoding method.

[Explanation of symbols]

1 VTR 2 MPEG encoder 3 wireless transceiver 4 wireless transmission path 5 wireless transceiver 6 MPEG decoder 7 remote control 8 viewers 11 video camera

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5C053 FA21 GB29 GB37 HA22 HA23                       HA24 KA04 LA01 LA15                 5C059 KK11 MA00 PP05 PP06 PP07                       SS06 SS12 SS14 SS16 SS17                       TA17 TA25 TB03 TB06 TC45                       UA02 UA33

Claims (8)

[Claims] 1. A moving image output means for outputting a video signal,
A moving picture coding means for coding the video signal with high efficiency, a moving picture decoding means for decoding the coded data coded by the moving picture coding means, and an operating mode to the moving picture output means. A moving image encoding method used in a video encoding / decoding device configured with an operation mode instruction unit, wherein the operation mode instruction unit instructs special reproduction,
The moving picture coding method, wherein the moving picture coding means switches to a coding method in which a coding delay time and a decoding delay time are shortened. 2. The moving image encoding method according to claim 1, wherein the encoding method is an MPEG encoding method and a low delay mode. 3. The encoding method according to claim 1, wherein the encoding method is an MPEG encoding method, and the capacity of the encoding buffer is reduced or the delay time in the encoding buffer is shortened. Video coding method. 4. The moving image code according to claim 1, wherein the encoding method is an MPEG encoding method, and encoding is performed with a GOP structure that does not use B pictures or B pictures and P pictures. Method. 5. The moving picture coding method according to claim 1, wherein the coding method is a coding method of an MPEG system, and the coding is performed in field units. 6. The encoding method is an MPEG encoding method, in which all pictures are encoded as P pictures, a part of each P picture is intra-frame encoded, and an area for intra-frame encoding is performed for each picture. The moving picture coding method according to claim 1, characterized in that the whole area of the picture is intra-coded in a plurality of consecutive pictures. 7. The moving image output means is composed of a moving image recording / reproducing device or a moving image reproducing device having a recording medium, and the special reproduction is still, frame-by-frame reproduction, slow reproduction or high-speed reproduction. The moving image encoding method according to claim 1. 8. The moving image output means is a video camera, and the special reproduction is performed by moving the main body of the video camera, moving the orientation of the video camera, zooming in and out of a shooting range of the video camera, or the video camera. 7. The moving picture coding method according to claim 1, wherein the shooting parameter is changed.