JP2003087800A - Moving image transmission and reception system, moving image transmitter, and moving image receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that an image can be outputted to a monitor after waiting additional time even if a state where a stream after the reduction of a refresh period can be decoded and the picture can be outputted to a monitor concerning a conventional moving image receiver. SOLUTION: A moving image transmitter 61 is provided with a refresh control part 203 for controlling a refreshing period to be shorten based on refreshing instruction from the moving image receiver, a refresh information generation part 204 for generating refresh information by which the end image of the first refreshing period after becoming short can be specified, and a multiplexing part 205 for multiplexing the refresh information to a moving image. Then, the moving image receiver is provided with a display control part for displaying the moving image on a prescribed display device from one of images after the end image based on the refresh information obtained from the moving image transmitter 61.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving image transmitting apparatus for transmitting a moving image, a moving image receiving apparatus for receiving a moving image, and a moving image transmitting / receiving system having the moving image transmitting apparatus and the moving image receiving apparatus. .

[0002]

2. Description of the Related Art In recent years, a video conference using a technique in which a transmitting device compresses and encodes a moving image to transmit encoded data, and a receiving device decodes the encoded data from the transmitting device to restore the moving image. The system is realized. MPEG (Moving Picture coding) is used for compression coding of moving images.
MPEG2 devised by a group called Experts Group)
A compression encoding method called (MPEG Phase2) is used.

In moving image compression by MPEG2, each frame or each field forming a moving image is divided into a plurality of rectangular blocks of 16 pixels × 16 pixels called macroblocks, and compression coding is performed in macroblock units. At that time, for each macroblock of the image to be compressed, the correlated macroblock is extracted from the temporally and spatially preceding and succeeding images, and the spatial distance and direction to the extracted macroblock are expressed. The difference between the motion vector and the extracted macroblock is calculated. Then, the calculated motion vector and difference information are subjected to DCT, quantization, and variable length coding to be compressed into a bit stream.

Due to the difference in the method of extracting macroblocks described above, each frame or field has an intra-coded image (I-picture) that is intraframe-predictively coded.
Predictive that is interframe forward predictive coded
An e-coded image (P picture) and bidirectionally predictive-coded Bidirectionally predictive
A ve encoded image (B picture) is classified into one of three types.

By the way, performing the predictive coding between the frames temporally preceding and following by the above-described bidirectional predictive coding is an advantage for improving the image quality of the restored image.
It is necessary to change (reorder) the order of encoding the images at the time of encoding, and the delay time from encoding to decoding becomes long. Therefore, in order to reduce the delay time from encoding to decoding, the B picture that needs to be subjected to the bidirectional predictive encoding is not used, and a moving image is composed of only I and P pictures. A low delay mode for encoding is used.

However, since the I picture is an image (picture) that is predictively coded within a frame, the amount of coded data for the I picture is significantly larger than the amount of coded data for the P picture. Such as video conferencing systems
When a moving image is transmitted in real time, the information transfer rate is a predetermined constant rate, so it is necessary to suppress the fluctuation in the amount of encoded data of each frame or each field forming the moving image and keep it constant.

Therefore, in order to equalize the amount of coded data of each frame or each field, a method of using intra slices is adopted without using not only B pictures but also I pictures. The intra slice is
It is a slice in which each macroblock forming a band-shaped image provided in a part of an image (picture) that is a P picture as a whole is intraframe predictively coded.

In the encoding method using the intra slice, as described above, neither the B picture nor the I picture is used, and only the P picture including the intra slice or the P picture and the intra slice including the intra slice are used. The moving picture is encoded so that the moving picture is configured with a P picture that does not include.

The P picture including this intra slice will be further described with reference to FIG. FIGS. 1A and 1B show a case where a moving image is composed of only P pictures including intra slices (each P picture including intra slices in the case of FIG. 1 has a frame structure).
A part of a plurality of continuous images is shown. In addition, in FIG. 1, a band-shaped black portion on each image is a band-shaped image based on an intra slice. The numbers above each image in FIG. 1 indicate the order of the images.

As shown in FIG. 1, when a moving picture is composed of only P pictures including intra slices, the positions of the intra slices in each successive picture are sequentially gradually shifted downward in the picture. It shifts. Then, as shown in FIG. 1, when the intra slice is located at the bottom of the image, the intra slice is located at the top of the image in the next image. In this way, the position of the intra slice on the image moves cyclically. The cycle in which the location of the intra slice on the image moves is called the refresh cycle. For example, in the case of FIG. 1A, the refresh cycle is a period of 4 frames.
In the case of (b), the refresh cycle is a period of 6 frames.

Note that the coded data at the same location in the image next to the location where the intra slice is provided is not the intraframe predictive coding but the interframe forward predictive coding. Images can be restored by using intra slices.
Therefore, if the encoded data for one refresh cycle is prepared, the subsequent image can be decoded.

As described above, by constructing a moving picture only with P pictures including intra slices, the amount of encoded data for each picture can be made uniform, and even if I pictures are not used, in the middle of the stream. Can be decrypted from. Similarly, even if a moving picture is composed of P pictures that include intra slices and P pictures that do not include intra slices, the amount of encoded data for each picture is I
The picture can be made uniform as compared with the case of using a picture, and if the coded data for one refresh cycle is aligned, decoding can be performed from the middle of the stream.

Below, the moving image transmitting apparatus encodes the moving image so that the moving image is composed only of P pictures including intra slices, and transmits the encoded data, and the moving image receiving apparatus transmits from the moving image transmitting apparatus. 2 shows a conventional moving image transmitting / receiving system for receiving and decoding encoded data of FIG.
~ It demonstrates using FIG. In the following description, each P picture including an intra slice has a frame structure for convenience of description.

FIG. 2 is a diagram showing an example of the overall configuration of a conventional moving image transmitting / receiving system. As shown in FIG. 2, the conventional moving image transmitting / receiving system includes, for example, a moving image transmitting device 21, a moving image transmitting device 22, and a moving image receiving device 5.

The moving image transmitting device 21 is a device for encoding the input moving image 11 captured by the camera 51 and outputting the stream 31, and the moving image transmitting device 22 is the same as the moving image transmitting device 21. This is a device that encodes the input moving image 12 captured by the camera 52 and outputs a stream 32. The moving image receiving apparatus 5 receives the stream 31 from the moving image transmitting apparatus 21 and the stream 32 from the moving image transmitting apparatus 22, and selects either the stream 31 or the stream 32 by the channel switching instruction 7. It is a device that outputs the output image 6 to the monitor 8 by performing the decoding. In the following, the stream 31 is set to CH1.
The stream 31 of (channel 1) is described, and the stream 32 is described as the stream 32 of CH2 (channel 2).

The most typical example of the moving image transmission / reception system is a remote monitoring system in which a plurality of sets of cameras and moving image transmission devices are installed. In FIG. 2, for simplification of description, only two sets of a camera and a moving image transmission device are shown, but three or more sets may be used.

FIG. 3 is a block diagram of a moving picture transmitting apparatus 21 which constitutes the conventional moving picture transmitting / receiving system. The encoding unit 201 converts the input moving image 11 from the camera 51 into
As shown in FIG. 1A, compression encoding is performed so that the P picture includes only intra slices, and the stream 31 of CH1 is output. Then, when the refresh control unit 202 receives the refresh instruction 41 requesting the shortening of the refresh cycle from the moving image receiving apparatus 5, the refresh control unit 202 controls the coding performed by the coding unit 201 so as to shorten the refresh cycle. To do. The moving image transmitting apparatus 22 has the same configuration as the moving image transmitting apparatus 21.

FIG. 4 is a block diagram of a moving image receiving apparatus 5 which constitutes the above-mentioned conventional moving image transmitting / receiving system. The switch 304 selects one of the CH1 stream 31 and the CH2 stream 32 based on the channel switching instruction 7 from the user, and the decoding unit 301 decodes the stream selected by the switch 304. . The switch 305 selects the frame memory 302 or the frame memory 303 as the storage destination of the stream decoded by the decoding unit 301 based on the channel switching instruction 7. The display control unit 307
Is the switch 3 based on the channel switching instruction 7.
By switching 06, the frame memory 302 or the frame memory 303 is selected, the image accumulated in the selected frame memory is output to the monitor 8 as the output image 6, and the output image 6 is displayed by the monitor 8.

Here, for example, by the switch 304, C
While the stream 31 of H1 is selected, its C
It is assumed that the user gives a channel switching instruction 7 so that the stream 32 of CH2 is selected while the stream 31 of H1 is decoded and output to the monitor 8 as the output image 6.

In that case, based on the channel switching instruction 7, the stream 3 of CH2 is switched by the switch 304.
2 is selected. However, as mentioned above, CH
The stream 32 of No. 2 is the input moving image 1 from the camera 52.
Since 2 is coded data that is coded so that it is composed of only P pictures including intra slices, if the coded data for one refresh cycle is not available, the coded data after that is decoded and the image is decoded. Can't play. Therefore, the display control unit 3 continues until the encoded data for one refresh cycle is decoded by the decoding unit 301.
07 cannot output the output image 6 based on the stream 32 of CH2 to the monitor 8. During that time, the image stored in the frame memory 302 is output to the monitor 8 as the output image 6. That is, the stream 3 of CH1 immediately before the channel switching instruction 7 is given.
The image based on 1 is output to the monitor 8.

Therefore, as described in Japanese Patent Laid-Open No. 10-304382, in order to output the output image 6 based on the stream selected by the channel switching instruction 7 to the monitor 8 as soon as possible, conventionally, FIG. As shown, the refresh instructing unit 308 having the functions described below.
Was provided in the moving image receiving apparatus 5. The refresh instructing unit 308 is means for issuing a refresh instruction to shorten the refresh cycle of the stream selected by the channel switching instruction 7. That is, the refresh instructing unit 308 determines that CH1 stream 31 and CH
When the output image 6 based on one of the two streams 32 is output to the monitor 8, the user outputs the output image 6 based on the other of the stream 31 of CH1 and the stream 32 of CH2 to the monitor 8. When a channel switching instruction 7 to the effect is issued (step 50 in FIG. 5)
1), a refresh instruction requesting reduction of the refresh cycle of the other stream is transmitted to the moving image transmitting apparatus corresponding to the other stream (step 502 in FIG. 5).

For example, as described above, when the output image 6 based on the stream 31 of CH1 is output to the monitor 8, the user outputs the output image 6 based on the stream 32 of CH2 to the monitor 8. It is assumed that the channel switching instruction 7 is performed. In that case, the refresh instruction unit 308 transmits the refresh instruction 42 requesting the shortening of the refresh cycle of the CH2 stream 32 to the moving image transmitting apparatus 22 corresponding to the CH2 stream 32.

Then, in the moving image transmission device 22, the refresh control unit 202, based on the refresh instruction 42, as shown in FIG. The encoding performed by the encoding unit 201 is controlled so as to shorten the period. Note that, as shown in FIG. 6B, for example, after the channel switching instruction 7 is performed, the refresh instruction 42 is transmitted to the moving image transmitting device 22 after the period of one frame has passed, and based on the refresh instruction 42, The refresh cycle is shortened by one refresh cycle from the image immediately after the refresh instruction 42 is received.

Based on this rule, the case where the channel switching instruction 7 is issued when the image two before the channel switching instruction 7 shown in FIG. 6 is displayed (at the time of (n-2)) is shown. Suppose. In that case, when an image immediately before the channel switching instruction 7 shown in FIG. 6 is displayed after a period of one frame has elapsed from the time when the channel switching instruction 7 was issued ((n-1)). At that time), the refresh instruction 42 is transmitted to the moving image transmission device 22. Then, based on the refresh instruction 42, the refresh cycle is shortened by one refresh cycle from the time when the image immediately after the channel switching instruction 7 shown in FIG. 6 is transmitted (from the time of n).

As described above, conventionally, the refresh cycle of the stream selected by the channel switching instruction 7 is shortened.

[0026]

As described above, conventionally, for example, the channel switching instruction 7 is performed and the refresh instruction 42 is transmitted to the moving image transmitting device 22 after the lapse of a period of one frame, and the refresh instruction is transmitted. Based on 42, the refresh cycle is shortened by one refresh cycle from the image (picture) immediately after the refresh instruction 42 is received. However, this is an example, and for example, the refresh cycle may be shortened from the image (picture) two frames after the refresh instruction 42 is received, and conventionally, at the start of shortening the refresh cycle, It wasn't decided.

In the above-mentioned example, the refresh cycle is shortened from the period of 6 frames to the period of 3 frames, but this is also an example, and conventionally, the shortening of the refresh period is uniform. Was not decided.

As described above, conventionally, the moving image transmitting apparatus 22 is used.
Is uncertain when to shorten the refresh cycle,
It was also unknown at the end of the first refresh cycle after shortening. Therefore, since the moving image receiving apparatus 5 cannot know the end time of the refresh cycle after shortening, the refresh instruction unit 308 notifies the display control unit 307 when transmitting the refresh instruction 42 to the moving image transmitting apparatus 22. On the other hand, a predetermined value that can count a predetermined time t ₀ (see FIG. 6) sufficient to complete the shortening of the refresh cycle is set (step 503 in FIG. 5) and the value is counted up to that value ( Step 504 of FIG. 5). Then, the display control unit 307 waits for the end of the count up to that value (step 505 in FIG. 5), that is, the predetermined time t ₀ determined in advance, and then the stream selected by the channel switching instruction 7. An image (picture) based on is output to the monitor 8 and displayed (step 506 in FIG. 5).

For example, as shown in FIG. 6 (d), CH1
It is assumed that, while the output image 6 based on the stream 31 is output to the monitor 8, the user issues a channel switching instruction 7 so that the output image 6 based on the CH2 stream 32 is output to the monitor 8. In that case, FIG.
As shown in (d), a predetermined time t ₀ sufficient to complete the shortening of the refresh cycle of the CH2 stream 32.
Waiting for, the image based on the stream 32 of CH2 was output to the monitor 8 and displayed on the monitor 8. That is, from the time when the eighth image (picture) is output to the monitor 8 (after (n + 8)) after the channel switching instruction 7 is given, the stream 32 of CH2 is started.
An image based on is output to the monitor 8 and displayed on the monitor 8. It should be noted that until the 7th image is output to the monitor 8 after the channel switching instruction 7 is given (until (n + 7)), it is output to the monitor 8 immediately after the channel switching instruction 7 is given. The displayed image will continue to be displayed.

By the way, as shown in FIG. 6C, the stream of CH2 from the image (picture) to be decoded fourth (from the image to be decoded at (n + 4)) after the channel switching instruction 7 is given. The entire image based on 32 can be decoded. In other words, from the time the fifth image is output to the monitor 8 (after (n + 5)) after the channel switching instruction 7 is given, the image based on the CH2 stream 32 is output to the monitor 8 and displayed on the monitor 8. It becomes possible.

However, as described above, it is unknown when the refresh cycle will be shortened, and at the end of the first refresh cycle after the shortening. Therefore, conventionally, the end time of the first refresh cycle after the change cannot be known, and the display control unit 307
The start of the output of the image (picture) based on the CH2 stream 32 selected by the channel switching instruction 7 to the monitor 8 is completed, and the refresh cycle of the changed CH2 stream 32 based on the channel switching instruction 7 has been shortened. There was a problem that we had to wait until the extra time passed.

Further, as shown in FIG. 7, when the output image 6 based on the CH2 stream 32 is output to the monitor 8, the user outputs the output image 6 based on the CH1 stream 31 to the monitor 8. Even when the channel switching instruction 7 is performed in this manner, the same problem as described above occurs. That is, as shown in FIG. 7D, the display control unit 307 causes the output image 6 based on the stream 31 of CH1.
It means that it has to wait until the extra time elapses after the completion of the shortening of the refresh cycle of the CH1 stream 31 after the change based on the channel switching instruction 7 before the start of the output to the monitor 8 of is there.

Further, in the moving picture transmitting / receiving system including the moving picture transmitting apparatus 21 and the moving picture receiving apparatus 50 similar to the moving picture receiving apparatus 5 as shown in FIG. The same challenges exist. The challenge is
When the moving image transmitting apparatus 21 is transmitting the CH1 stream 31 and the moving image receiving apparatus 50 has not received the CH1 stream 31, the moving image receiving apparatus 50 receives the moving image based on the new connection instruction 9 from the user. The device 50 is the CH
It occurs when the reception of the stream 31 of 1 is started.

That is, since the moving image receiving apparatus 50 has not received the CH1 stream 31 from the moving image transmitting apparatus 21 until receiving the new connection instruction 9 from the user, the CH1 stream 31 is immediately received. It cannot be decrypted. This is because the stream 31 of CH1 includes only the P picture including the intra slice and the input moving image 11
This is because the input moving image 11 is encoded data so that Therefore, in order to be able to decode the stream 31 of CH1 as soon as possible, as shown in FIG. 8 and FIG.
0 immediately receives a new connection instruction 9 from the user,
The refresh instruction 41 requesting the shortening of the refresh cycle of the stream 31 of CH1 is transmitted to the moving image transmitter 21.

On the basis of the refresh instruction 41, the moving image transmitting apparatus 21 shortens the refresh cycle from a period of 4 frames to a period of 2 frames and inputs the refresh period, as shown in FIG. 9A. The moving image 11 is encoded and the encoded data is transmitted.

However, in the past, the moving image transmitting apparatus 2 was used.
Since it is unknown when 1 shortens the refresh cycle, the moving image receiving apparatus 50 sets the preset time sufficient to complete the shortening of the refresh cycle (see FIG. 9).
It was necessary to wait for the predetermined time t _{0 in} (c). That is, as shown in FIG. 9B, from the image to be decoded third after the new connection instruction 9 is given (from the image to be decoded at (n + 3)), the entire image based on the stream 31 of CH1 From the time when the fourth image can be output to the monitor 8 (from (n + 4)) after the new connection instruction 9 is made and the image based on the stream 31 of CH1 is output to the monitor 8. Although it is possible to display the image on the monitor 8, the moving image receiving apparatus 50 outputs the image to the monitor 8 and displays the image on the monitor 8 according to the new connection instruction 9. It was necessary to wait until the time when the eighth image was output to the monitor 8 (until (n + 8)).

That is, conventionally, the moving image receiving devices 5 and 50 have been used.
Issues a refresh instruction, and even if the moving image transmitters 21 and 22 transmit the stream by shortening the refresh cycle based on the refresh instruction, the end time of the first refresh cycle after shortening is unknown. Even if the moving image receiving apparatuses 5 and 50 are ready to output the image to the monitor 8 by decoding the stream after the refresh period has been shortened, the moving image receiving apparatus 5 and 50 have to wait an extra time before outputting the image. . This problem also occurs when an image (picture) has a field structure.

Therefore, in consideration of the above-mentioned conventional problems, the present invention shortens the refresh cycle based on a refresh instruction from the outside to generate encoded data, and at the end of the first refresh cycle after the shortening. It is an object of the present invention to provide a moving image transmission apparatus that transmits refresh information that can specify the above-mentioned encoded data together with the encoded data.

Further, according to the present invention, the end time of the first refresh cycle after shortening which is transmitted together with the above-mentioned coded data from the moving picture transmitting apparatus which shortens the refresh cycle and transmits the coded data is specified. An object of the present invention is to provide a moving image receiving apparatus capable of displaying an image on the external display device from the tail image of the first refresh cycle after shortening based on the refresh information that can be obtained.

Further, according to the present invention, there is provided a moving image transmitting apparatus for transmitting refresh information capable of specifying the end time of the first refresh cycle after the above shortening together with encoded data, and a moving image transmitting apparatus from the moving image transmitting apparatus. An image is displayed on an external display device from the tail image of the first refresh cycle after shortening based on the refresh information that can specify the end time of the first refresh cycle after shortening that is transmitted together with the encoded data. It is an object of the present invention to provide a moving image transmitting / receiving system having a moving image receiving device capable of performing the same.

[0041]

In order to solve this problem, the moving image transmitting / receiving system of the present invention has an inter-frame forward prediction in which the positions of intra slices on an image are sequentially shifted for each successive image. It is premised that a moving image transmitting apparatus that transmits a moving image including at least a part of the encoded image and a moving image receiving apparatus that receives the moving image from the moving image transmitting apparatus are included.

Then, based on the refresh instruction from the moving image receiving device, the moving image transmitting device interframe forward prediction code so that the refresh cycle in which the location where the intra slice is provided moves is shortened. A refresh control unit for controlling the generation of the modified image; a refresh information generation unit for generating refresh information capable of specifying the tail image of the first refresh cycle after the refresh cycle is shortened; And a multiplexing unit that multiplexes the moving image.

On the other hand, based on a predetermined instruction, the moving image receiving apparatus is instructed to the moving image transmitting apparatus to perform the refresh instruction for shortening the refresh cycle in which the place where the intra slice is provided moves. A refresh instructing unit for performing the display and a display control unit for displaying the moving image on a predetermined display device from any one of the images after the trailing image based on the refresh information obtained from the moving image transmitting device are provided. To be

According to such a moving image transmitting / receiving system, the moving image receiving apparatus waits an extra time when it becomes possible to decode the stream after the refresh cycle is shortened and output the image to a predetermined display device. It is possible to immediately output and display the image without the need.

Further, the moving picture transmitting apparatus of the present invention is capable of moving pictures including at least a part of inter-frame forward prediction coded pictures which are sequentially shifted for each successive picture in which the intra slice is provided. It is supposed to be sent.

Then, the moving picture transmitting apparatus of the present invention, based on a refresh instruction from the outside, makes the interframe forward predictive coded image such that the refresh cycle in which the location where the intra slice is provided moves is shortened. A refresh control unit that controls generation, a refresh information generation unit that generates refresh information that can specify a tail image of the first refresh cycle after the refresh cycle is shortened, and the refresh information to the moving image. And a multiplexing unit for multiplexing.

When such a moving picture transmitting device is used, when the moving picture receiving device is ready to decode the stream after the refresh cycle is shortened and output the image to a predetermined display device, the moving picture receiving device is set to the moving picture receiving device. It is possible to immediately output and display an image without waiting for extra time.

Further, the moving image receiving apparatus of the present invention is an interframe forward predictive coded image from a predetermined moving image transmitting apparatus, which is sequentially shifted for each successive image where the intra slice on the image is provided. It is assumed that a moving image including at least a part of is received.

Then, the moving image receiving apparatus of the present invention issues a refresh instruction to the moving image transmitting apparatus based on a predetermined instruction in order to shorten the refresh cycle in which the place where the intra slice is provided moves. Based on refresh information for performing a refresh instruction unit and refresh information that can be specified from the moving image transmission device and that can identify the tail image of the first refresh cycle after the refresh cycle has become shorter, any of the tail images and subsequent pictures. And a display control unit for displaying the moving image on a predetermined display device from the image.

When such a moving picture receiving device is ready to decode the stream after the refresh cycle is shortened and output the image to a predetermined display device, it immediately outputs and displays the image without waiting extra time. It becomes possible.

[0051]

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

(Embodiment 1) First, FIG. 10 shows the configuration of a moving image transmitting / receiving system according to Embodiment 1 of the present invention. As shown in FIG. 10, the moving image transmitting / receiving system according to the first embodiment is similar to the conventional moving image transmitting / receiving system shown in FIG. 2, and has a moving image transmitting device 61, a moving image transmitting device 62, and a moving image receiving device. And device 70.

The moving image transmitting device 61 is a device for encoding the input moving image 11 photographed by the camera 51 and outputting the stream 31 of CH1 forming each image shown in FIG. The image transmission device 62 is a device that encodes the input moving image 12 captured by the camera 52 and outputs the CH2 stream 32 that constitutes each image shown in FIG. 1B. The moving image receiving device 70 includes a moving image transmitting device 61.
Stream 31 of CH1 from the video transmission device 62
From the CH2 stream 32 from the CH2 stream, select either the CH1 stream 31 or the CH2 stream 32 by the channel switching instruction 7, and decode the stream.
The device outputs the output image 6 to the monitor 8.

FIG. 11 shows the configuration of the moving image transmitting apparatus 61 that constitutes the moving image transmitting / receiving system of the first embodiment.
In the moving image transmitting apparatus 61, as in the case of the conventional moving image transmitting apparatus 21, the encoding unit 201 includes the input moving image 11 from the camera 51 including an intra slice as shown in FIG. Compression encoding is performed so as to include only P pictures, and a stream 31 of CH1 is generated. For convenience of explanation, in the present embodiment, each P picture including an intra slice has a frame structure.

Then, the refresh instruction 41 requesting the shortening of the refresh cycle by the moving image receiving device 70.
If it is done, the refresh control unit 203 determines that CH1
The encoding performed by the encoding unit 201 is controlled so that the refresh cycle of the stream 31 is shortened, for example, from the period of 4 frames to the period of 2 frames. At that time, the refresh control unit 203 controls the encoding performed by the encoding unit 201 so that the width of the intra slice is widened for an image (picture) whose refresh cycle is shortened. In addition, the refresh control unit 203
The refresh information generation unit 204 is controlled to generate refresh information that specifies the tail image of the first refresh cycle after shortening (at the end of the first refresh cycle after shortening).

Under the control of the refresh control unit 203, the refresh information generation unit 204 generates refresh information, and the multiplexing unit 205 encodes the refresh information generated by the refresh information generation unit 204 by the encoding unit 201. The multiplexed CH1 stream 31 is multiplexed and the refresh information multiplexed CH1 stream 31 is output to the outside (moving image receiving apparatus 70).

The structure of the moving image transmitting apparatus 62 is similar to that of the moving image transmitting apparatus 61. However, in the moving image transmitting apparatus 62, the CH2 stream 32 compression-coded so as to be composed of only P pictures including intra slices is generated as shown in FIG. When the refresh instruction 42 is issued by
The refresh cycle of the H2 stream 32 is, for example, 6
The period for one frame is shortened to the period for three frames.

FIG. 12 shows the configuration of the moving image receiving apparatus 70 that constitutes the moving image transmitting / receiving system of the first embodiment.
In the moving image receiving apparatus 70, as in the case of the conventional moving image receiving apparatus 5, the switch 304 selects one of the CH1 stream 31 and the CH2 stream 32 based on the channel switching instruction 7 from the user. The decoding unit 301 selects and decodes the stream selected by the switch 304.

The switch 305 selects the frame memory 302 or the frame memory 303 as the storage destination of the stream decoded by the decoding unit 301 based on the channel switching instruction 7.

Then, the display control unit 309 selects the frame memory 302 or the frame memory 303 by switching the switch 306 based on the channel switching instruction 7, and the image stored in the selected frame memory ( The picture) is output to the monitor 8 as the output image 6, and the output image 6 is displayed on the monitor 8.

The frame memories 302 and 303 store image data based on the stream currently decoded by the decoding unit 301. Then, when the channel switching instruction 7 is given, it is based on the stream newly selected by the channel switching instruction 7 in a different frame memory from the one used before the channel switching instruction 7 is given. Image data is stored.

Here, for example, as shown in FIG. 13D, the stream 31 of CH1 is selected by the switch 304, and the stream 31 of CH1 is decoded and output to the monitor 8 as the output image 6 and displayed. It is assumed that the user has issued the channel switching instruction 7 so that the stream 32 of CH2 is selected during this time (step 601 in FIG. 14).

In that case, based on the channel switching instruction 7, the stream 304 of CH2 is switched by the switch 304.
2 is selected and the refresh instruction unit 308
Transmits a refresh instruction 42 requesting shortening of the refresh cycle of the CH2 stream 32 to the moving image transmitter 62 corresponding to the CH2 stream 32 (FIG. 1).
4 step 602).

In the moving image transmitting apparatus 62, the refresh control unit 203, as shown in FIG. 13B, based on the refresh instruction 42 from the moving image receiving apparatus 70,
The encoding performed by the encoding unit 201 is controlled so that the refresh cycle of the stream 32 of CH2 is shortened from the period of 6 frames to the period of 3 frames, for example.
Further, the refresh control unit 203 controls the refresh information generation unit 204 so as to generate refresh information that specifies the tail image of the shortened first refresh cycle.

Under the control of the refresh control unit 203, the refresh information generation unit 204 specifies the identifier of an image in which the first shortened refresh cycle starts and the shortened refresh cycle (for example, a period of 3 frames). Generates refresh information consisting of a value and.
By the identifier of the image in which the first refresh cycle after the shortening starts and the value of the refresh cycle after the shortening, FIG.
After the channel switching instruction 7 shown in 3 (c) is given, the fourth decoded image (the image decoded at (n + 4)) can be specified as the trailing image of the first refresh cycle after shortening. .

Then, the multiplexing unit 205 replaces the refresh information generated by the refresh information generating unit 204 with
C in which the refresh information is multiplexed in the CH2 stream 32 encoded by the encoding unit 201
The stream 32 of H2 is transmitted to the moving image receiving device 70.

Here, the position in the stream 32 of CH2 where the refresh information is multiplexed will be described with reference to FIG. FIG. 15 is a diagram showing the data structure of the CH2 stream 32. As shown in FIG. 15, the data of the CH2 stream 32 has a hierarchical structure. Then, as shown in FIG. 15, in the first embodiment, the refresh information is stored in the user data (User Data) area of the first picture of the first refresh cycle after shortening in the hierarchical structure, and CH
2 streams 32 are multiplexed. In addition, here
Although the structure of the stream 32 of CH2 and the method of multiplexing the refresh information on the stream 32 of CH2 have been described, the structure of the stream 31 of CH1 has also been described above.
The configuration of the stream 32 is the same as that of the stream 32 of FIG.
The refresh information is similar to how CH2 is multiplexed on the stream 32.

The user data area is an area where a user data start code of 32 bits can be freely stored by the user every 8 bits until the next start code starts. Since the user data area is used for various purposes, an identifier for discriminating that the refresh information is stored is added. The length of the identifier is, for example, 16 bits. Therefore, in this case, the user data start code of 32 bits and 16
56-bit refresh information composed of a 8-bit refresh information identifier and a 8-bit refresh period value is multiplexed on the CH2 stream 32.

Now, the multiplexing unit 205 of the moving image transmitting apparatus 62.
However, when the stream 32 of CH2 in which the refresh period is shortened by multiplexing the refresh information is transmitted, the stream 32 of CH2 is received by the moving image receiving apparatus 70.

In the moving image receiving apparatus 70, the refresh information extraction unit 310 analyzes the CH2 stream 32,
When the user data area is detected during the analysis (step 603 in FIG. 14), refresh information is extracted from the user data area (step 604 in FIG. 14), and the first picture of the first refresh cycle after shortening (first refresh after shortening). Information of the first image of the cycle) and the value of the refresh cycle after shortening are acquired. Then, the refresh information extraction unit 310 sets the obtained value of the refresh cycle to
The counter in the display control unit 309 is set (step 605 in FIG. 14), and the counter in the display control unit 309 counts in synchronization with the decoding process performed by the decoding unit 301 on a picture-by-picture basis (see FIG. 14). Step 606). That is, the above-mentioned counter takes the timing of counting in picture units (image units), not in time. When the display control unit 309 has finished counting by the counter (step 607 in FIG. 14), the switch 306 switches the extraction destination of the output image 6 from the frame memory 302 to the frame memory 303 (step 60 in FIG. 14).
8).

By switching the output destination of the output image 6 in this way, as shown in FIG. 13D, the refresh is completed at the time of (n + 4) shown in FIG.
CH2 after the image decoded at 4) (the image decoded fourth after the channel switching instruction 7 is given)
The output image 6 based on the stream 32 is output to the monitor 8 from the time of (n + 5) and displayed on the monitor 8.

As shown in FIG. 13D, it is not possible to output an image obtained by decoding the entire image of the CH2 stream 32 from the time the channel switching instruction 7 is issued to the time (n + 4). Therefore, the image displayed on the monitor 8 continues to be displayed when the channel switching instruction 7 is issued.

Conventionally, as described with reference to FIG. 6, the moving image receiving apparatus 5 cannot know the tail image (at the end) of the shortened refresh cycle. Therefore, the conventional moving image receiving apparatus 5 outputs an image based on the stream 32 of CH2 selected by the channel switching instruction 7 to the monitor 8 and causes the monitor 8 to start displaying the image. After the completion of the shortening of the refresh cycle of the CH2 stream 32 after the change based on No. 7, an extra time had to be waited. That is, conventionally, as shown in FIG. 6 (d), an image based on the stream 32 of CH2 having a shortened refresh cycle can be output to the monitor 8 from the time of (n + 5) and displayed by the monitor 8. However, it was output to the monitor 8 from the time of (n + 8) and displayed on the monitor 8.

On the other hand, in the first embodiment, when the refresh instruction requesting the shortening of the refresh cycle is issued, the moving image transmitting apparatus 62 specifies the refresh information for specifying the tail image of the first refresh cycle after shortening. Is transmitted, the moving image receiving apparatus 70 can know the end time of the shortened refresh cycle. Therefore, the moving image receiving apparatus 70 of the first embodiment outputs the image based on the stream 32 of CH2 selected by the channel switching instruction 7 and starts displaying the image. Stream 32
Stream of CH2 from the image at the end, that is, the tail image of the first refresh cycle after shortening, without waiting for an extra time after the shortening of the refresh cycle of
The output image based on is displayed on the monitor 8.
Therefore, as is clear from comparison between FIG. 13 (d) and FIG. 6 (d), in the first embodiment, the image based on the CH2 stream 32 in which the refresh cycle is shortened is equivalent to three frames. From (n + 5) before the period of, the effect of being output to and displayed on the monitor 8 is obtained.

In the first embodiment described above, CH2
Although the case of channel switching from the stream 32 of CH1 to the stream 31 of CH1 has been described, the same effect as in the above case can be obtained in the case of channel switching from the stream 31 of CH1 to the stream 32 of CH2. That is, as shown in FIG. 16, after finishing the shortening of the refresh cycle of the stream 31 of CH1 after the change based on the channel switching instruction 7, the image at the end, that is, the first after shortening, is not waited for. The output image 6 based on the stream 31 of CH1 is output to the monitor 8 from the tail image of the refresh cycle of, and can be displayed on the monitor 8.

Further, in the above-described first embodiment, when the refresh control unit 203 receives the refresh instruction 42, the refresh information generation unit 204, based on the control by the refresh control unit 203, causes the first refresh after the shortening. As information that can identify the tail image of the cycle,
It is assumed that the refresh information including the identifier of the image where the first refresh cycle after shortening starts and the value of the refresh cycle after shortening that specifies the refresh cycle after shortening is generated. That is, the refresh information generation unit 204
Is composed of the above-mentioned identifier as an example of information specifying the leading image of the shortened first refresh cycle, and the value of the refresh cycle as an example of information specifying the length of the shortened refresh cycle. Suppose you want to generate refresh information.

However, the refresh information generator 2
When generating the refresh information, 04 may generate, as the refresh information, information that directly specifies the tail image of the first refresh cycle after the shortening.

Alternatively, the refresh information generator 204
As the refresh information, only the information that specifies the leading image of the shortened first refresh cycle may be generated as the refresh information. However, in this case, although the leading image of the first refresh cycle after shortening is known, it is unclear which image is the trailing image of the first refresh cycle after shortening. Therefore, the length of the refresh cycle after shortening (for example, the number of frames or time) is determined in advance, and as shown in FIG. 17, the storage unit 311 that stores the predetermined length of the refresh cycle after shortening. Is provided in the moving image receiving apparatus 70. Then, the display control unit 309
Is based on the predetermined length of the shortened refresh cycle stored in the storage unit 311 and uses information from the refresh information extraction unit 310 that specifies the leading image of the shortened first refresh cycle. Then, the tail image of the first refresh cycle after shortening is specified, and the images after the tail image are output to the monitor 8 and displayed.

Even in this case, the image based on the stream newly selected by the channel switching instruction 7 is output to the monitor 8 and the monitor 8 starts the display.
The output image based on the newly selected stream is output to the monitor 8 from the tail image of the first refresh cycle after shortening without waiting for an extra time after the shortening of the refresh cycle of the newly selected stream is completed. It can be output and displayed.

Further, in the above-described first embodiment, FIG.
And as shown in FIG. 15, refresh instructions 41, 42
Is issued, the refresh cycle of only the encoded data for one refresh cycle immediately after that is shortened as compared with that until then. However, the shortening of the refresh cycle is performed immediately after the refresh instructions 41 and 42 are issued. Is not limited to the encoded data for one refresh cycle. When the refresh instructions 41 and 42 are issued, the refresh cycle may continue to be shortened in the subsequent streams. In short, when the refresh instructions 41 and 42 are issued, it is only necessary that the refresh cycle of the coded data for at least one refresh cycle be shortened as compared with that before.

When the shortened refresh cycle is restored, the moving image transmitters 61 and 62 may restore the shortened refresh cycle at any time after one cycle has elapsed. Further, the moving image receiving apparatus 70 may instruct when to restore the refresh cycle, and based on the instruction, the moving image transmitting apparatuses 61 and 62 may restore the shortened refresh cycle.

Further, in the above-described first embodiment, CH1
Stream 31 and CH2 stream 32 are shown in FIG.
As described above, it is assumed that the input moving image 11 or the input moving image 12 is encoded data that is compression-encoded so that it is composed of only P pictures including intra slices. However, CH1 stream 31 or CH2
The stream 32 may be compression-coded so as to be composed of P pictures that include intra slices and P pictures that do not include intra slices. In that case, when the refresh instructions 41 and 42 are issued, the coded data of the P picture including the intra slice is output as soon as possible for at least one refresh cycle, and the refresh cycle is shorter than the length of the refresh cycle at the normal time. It is necessary to become.

Further, in the above-described first embodiment, CH1
The case where the channel switching instruction 7 from the channel 1 to the channel 2 is performed using the stream 31 of 3 and the stream 32 of CH2 has been described. However, the number of streams is not limited to two, the stream 31 of CH1 and the stream 32 of CH2. When there are three or more streams, the stream of the channel selected according to the channel switching instruction 7 is selected by the switch 304, and a refresh instruction is issued to the moving image transmitting apparatus that is transmitting the selected streams. Then, the moving image transmitting apparatus to which the refresh instruction is issued shortens the refresh cycle as in the moving image transmitting apparatus 61 or the moving image transmitting apparatus 62, and
The stream is transmitted with refresh information for identifying the tail image of the first refresh cycle after shortening added. Then, the moving image receiving apparatus can output the image from the trailing image of the first refresh cycle after shortening to the monitor and display it on the monitor by using the refresh information.

In the first embodiment described above, FIG.
As described above, the refresh information is stored in the user data area and multiplexed in the stream. Since the user data area is an area that can be freely mounted, when the conventional moving image transmitting apparatuses 21 and 22 that cannot add refresh information to the stream and the moving image transmitting apparatuses 61 and 62 according to the first embodiment are combined. But
The moving image receiving apparatus 70 according to the first embodiment does not malfunction.

(Second Embodiment) Next, a moving image transmitting / receiving system according to a second embodiment of the present invention will be described.

The second embodiment differs from the above-described first embodiment only in the content of refresh information. That is,
In the second embodiment, as the refresh information, the picture number that identifies the tail image of the refresh cycle after shortening is used, and the tail image of the first refresh cycle after shortening is identified using that refresh information. Therefore, the configurations of the moving image transmitting / receiving system, the moving image transmitting device, and the moving image receiving device according to the second embodiment are the same as those in the first embodiment, and the description thereof will be omitted.

FIG. 18 shows the position and structure of the refresh information multiplexed in the stream by the moving picture transmitting apparatus according to the second embodiment of the present invention. In the second embodiment, as the refresh information, the picture number that identifies the tail image of the first refresh cycle after shortening is used, and the refresh information is stored in the user data area of the first picture of the first refresh cycle after shortening. And is multiplexed in the stream.

The temporal reference of the picture layer is used as the picture number for specifying the tail image of the first refresh cycle after the above shortening. The temporal reference is 1024 consecutive numbers from 0 to 1023 reset in the GOP layer. Since the GOP header that requires an I picture later cannot be used in a stream that is refreshed by intra slice, the temporal reference is a value sufficient to notify the end of the first refresh cycle after shortening. . The temporal reference is 10-bit data. Therefore, in the second embodiment, the refresh information includes a 32-bit user data start code, a 16-bit refresh information identifier, and a 10-bit refresh information identifier.
This is 58-bit information composed of a picture number that specifies the tail image of the first refresh cycle after the shortening of the bit.

The operation of the moving image transmitting / receiving system according to the second embodiment will be described below with reference to the flowchart shown in FIG. Note that, also in the second embodiment, as in the case of the first embodiment, as shown in FIG. 13D, the stream 31 of CH1 is selected by the switch 304, and the stream 31 of CH1 is decoded. It is assumed that the user gives a channel switching instruction 7 so that the stream 32 of CH2 is selected when the output image 6 is output to the monitor 8 and is displayed on the monitor 8 (see FIG. 19). Step 701).

In this case, in the moving image receiving apparatus 70, the switch 304 selects the CH2 stream 32 based on the channel switching instruction 7, and the refresh instruction unit 308 shortens the refresh cycle of the CH2 stream 32. Refresh instruction 4 requesting
2 is transmitted to the moving image transmitter 62 corresponding to the stream 32 of CH2 (step 702 in FIG. 19).

In the moving image transmitting apparatus 62, the refresh control unit 203, as shown in FIG. 13B, based on the refresh instruction 42 from the moving image receiving apparatus 70,
The encoding performed by the encoding unit 201 is controlled so that the refresh cycle of the CH2 stream 32 is shortened from the period of 6 frames to the period of 3 frames. Also,
The refresh control unit 203 causes the refresh information generation unit 204 to generate the refresh information described above.
To control.

Under the control of the refresh controller 203, the refresh information generator 204 generates the above-mentioned refresh information. From the refresh information, the image decoded at (n + 4) shown in FIG. 13C can be specified as the tail image of the first refresh cycle after shortening.

When the refresh information is generated as described above, the multiplexing unit 205 causes the refresh information generating unit 204 to
The refresh information generated by the
The CH2 stream 32 encoded by is multiplexed and the CH2 stream 32 in which the refresh information is multiplexed is transmitted to the moving image receiving apparatus 70.

The CH2 stream 32 is received by the moving image receiving apparatus 70, and in the moving image receiving apparatus 70, the refresh information extracting section 310 analyzes the CH2 stream 32. When the refresh information extraction unit 310 detects the user data area during the analysis (step 703 in FIG. 19), the refresh information extraction unit 310 extracts the refresh information from the user data area (step 70 in FIG. 19).
4) Obtain a picture number that specifies the tail image of the first refresh cycle after shortening.

The picture number is sent to the display control unit 309, and the display control unit 309 compares the sent picture number with the picture number of the image decoded by the decoding unit 301 (FIG. 19). 705), the selection of the switch 306 is switched so that the image having the picture number equal to the sent picture number is output to the monitor 8 as the output image 6 and displayed by the monitor 8 (step 706 in FIG. 19). . This completes the channel switching process.

As described above, in the second embodiment, as in the above-described first embodiment, the refresh information is multiplexed in the stream by using the user data area, and the moving image receiving apparatus is based on the refresh information. Since the stream switching timing is set as described above, it is possible to achieve channel switching without waiting for an unnecessary time.

Further, unlike the above-described first embodiment, the above-described second embodiment has an advantage that the switching timing of the output image 6 can be set without using a counter, so that the processing can be simplified.

In the second embodiment described above, the picture number for specifying the tail image of the first refresh cycle after shortening is used as the refresh information. Even if the picture number that identifies the first image of is used as the refresh information, the same effect as the above case can be obtained. In short, the refresh information is only required to identify the tail image of the first refresh cycle after shortening,
The same effect as in the case of the second embodiment described above can be obtained.

(Third Embodiment) Next, a moving image transmitting / receiving system according to a third embodiment of the present invention will be described.

The third embodiment differs from the first and second embodiments described above only in the content of the refresh information. In the third embodiment, as the refresh information, an identifier that identifies the leading image of the shortened refresh cycle is used, and the refresh information is used to determine the tail image of the shortened first refresh cycle by a method described later. Identify. Therefore, the configurations of the moving image transmitting / receiving system, the moving image transmitting device, and the moving image receiving device according to the third embodiment are the same as those in the first embodiment, and the description thereof is omitted.

FIG. 20 shows the position and structure of refresh information multiplexed in a stream by the moving picture transmitting apparatus according to the third embodiment of the present invention. In the third embodiment, as the refresh information, only the identifier that identifies the leading image of the shortened first refresh cycle is used, and the refresh information is stored in the user data area of the leading picture of the shortened first refresh cycle. And is multiplexed in the stream.

Therefore, in the third embodiment, the refresh information is 48 bits which is composed of the user data start code of 32 bits and the identifier of 16 bits.
Information.

The operation of the moving image transmitting / receiving system according to the third embodiment will be described below with reference to the flowchart shown in FIG. Note that, also in the third embodiment, as in the case of the first and second embodiments described above, FIG.
As shown in (d), when the stream 31 of CH1 is selected by the switch 304, the stream 31 of CH1 is decoded and output to the monitor 8 as the output image 6 and displayed on the monitor 8. It is assumed that the user gives the channel switching instruction 7 so that the stream 32 of CH2 is selected (step 801 in FIG. 21).

In this case, in the moving image receiving apparatus 70, the switch 304 selects the CH2 stream 32 based on the channel switching instruction 7, and the refresh instruction unit 308 shortens the refresh cycle of the CH2 stream 32. Refresh instruction 4 requesting
2 is transmitted to the moving image transmitter 62 corresponding to the stream 32 of CH2 (step 802 in FIG. 21).

In the moving image transmitting apparatus 62, the refresh control unit 203, as shown in FIG. 13B, based on the refresh instruction 42 from the moving image receiving apparatus 70,
The encoding performed by the encoding unit 201 is controlled so that the refresh cycle of the stream 32 of CH2 is shortened from the period of 6 frames to the period of 3 frames, for example.
In addition, the refresh control unit 203 controls the refresh information generation unit 204 so as to generate the above-mentioned refresh information (the above-mentioned identifier).

Then, the multiplexing unit 205 replaces the refresh information generated by the refresh information generating unit 204 with
C in which the refresh information is multiplexed in the CH2 stream 32 encoded by the encoding unit 201
The stream 32 of H2 is transmitted to the moving image receiving device 70.

The CH2 stream 32 is received by the moving image receiving apparatus 70, and in the moving image receiving apparatus 70, the refresh information extracting section 310 analyzes the CH2 stream 32. Refresh information extraction unit 310
Detects a user data area during its analysis (see Figure 2
In step 803 of 1), a value of the shortened refresh cycle that specifies a predetermined shortened refresh cycle is set in a counter in the display control unit 309 (step 804 in FIG. 21). As described in Embodiment 1 above, the counter in the display control unit 309 counts in synchronization with the decoding process performed by the decoding unit 301 on a picture-by-picture basis (step 805 in FIG. 21). And
When the counting by the counter is completed (step 806 in FIG. 21), the display control unit 309 causes the switch 306.
The switching destination of the output image 6 is switched from the frame memory 302 to the frame memory 303 (step 807 in FIG. 21).

Then, as shown in FIG. 13 (d),
The output image 6 based on the stream 32 of CH2 after the image that is refreshed and decoded at (n + 4) shown in FIG. 13C is output to the monitor 8 from the time (n + 5) and is displayed on the monitor 8. .

As described above, in the third embodiment, as in the first and second embodiments described above, the refresh information is multiplexed in the stream. The stream switching timing can be set based on the above, and as a result, channel switching can be realized without waiting for an unnecessary time.

The advantages of the third embodiment described above are as follows.
That is, the information of user data to be multiplexed in the stream can be implemented in the simplest manner.

(Fourth Embodiment) Next, a moving image transmitting / receiving system according to a fourth embodiment of the present invention will be described.

In the fourth embodiment, unlike each of the above-described embodiments, the refresh information is not stored in the user data area, but the sequence header is inserted only in the first picture of the shortened refresh cycle. so,
This is to realize refresh information. Therefore,
Since the configurations of the moving image transmitting / receiving system, the moving image transmitting device, and the moving image receiving device according to the fourth embodiment are the same as those in the first embodiment, the description thereof will be omitted.

FIG. 22 shows the position of refresh information multiplexed in a stream by the moving picture transmitting apparatus according to the fourth embodiment of the present invention. In the fourth embodiment, the sequence header is used as refresh information as described above. The sequence header is usually used for the purpose of finding the beginning of a chapter, etc., but in the fourth embodiment, the sequence header is inserted only in the head picture of the refresh cycle after shortening, as described below.

The operation of the moving picture transmitting / receiving system according to the fourth embodiment will be described below with reference to the flowchart shown in FIG. Note that, also in the fourth embodiment, as in the case of each of the above embodiments, as shown in FIG. 13D, the stream 31 of CH1 is selected by the switch 304, and the stream 31 of CH1 is decoded. When the output image 6 is output to the monitor 8 and is displayed on the monitor 8, the user gives a channel switching instruction 7 so that the stream 32 of CH2 is selected (step 901 in FIG. 23). .

Then, in the moving image receiving apparatus 70, the switch 304 is operated based on the channel switching instruction 7.
CH2 stream 32 is selected by
The refresh instructing unit 308 uses the stream 32 of CH2.
The refresh instruction 42 requesting the shortening of the refresh cycle is transmitted to the moving image transmitter 62 corresponding to the stream 32 of CH2 (step 902 in FIG. 23).

In the moving image transmitting apparatus 62, the refresh control unit 203, as shown in FIG. 13B, based on the refresh instruction 42 from the moving image receiving apparatus 70,
The encoding performed by the encoding unit 201 is controlled so that the refresh cycle of the stream 32 of CH2 is shortened from the period of 6 frames to the period of 3 frames, for example.
Also, the refresh control unit 203 controls the refresh information generation unit 204 so as to generate the sequence header as the above-mentioned refresh information.

Then, the multiplexing unit 205 multiplexes the sequence header as the refresh information generated by the refresh information generating unit 204 into the stream 32 of CH2 encoded by the encoding unit 201, and the sequence as the refresh information. CH with multiplexed header
The second stream 32 is transmitted to the moving image receiving device 70.

The CH2 stream 32 is received by the moving image receiving apparatus 70, and in the moving image receiving apparatus 70, the refresh information extracting section 310 analyzes the CH2 stream 32. Refresh information extraction unit 310
Detects a sequence header during its analysis (see Figure 2
3 in step 903), based on the information that the sequence header has been detected, a counter in the display control unit 309 is set with a value of the refresh cycle after shortening that specifies a predetermined refresh cycle after shortening. (Step 904 in FIG. 23). As described in the first embodiment, the counter in the display control unit 309 is
The decoding unit 301 starts counting in synchronization with the decoding process performed in picture units (step 90 in FIG. 23).
5). Then, when the counting by the counter is completed (step 906 in FIG. 23), the display control unit 309
The switch 306 switches the extraction destination of the output image 6 from the frame memory 302 to the frame memory 303 (step 907 in FIG. 23).

Then, as shown in FIG. 13D,
The output image 6 based on the stream 32 of CH2 after the image that is refreshed and decoded at (n + 4) shown in FIG. 13C is output to the monitor 8 from the time (n + 5) and is displayed on the monitor 8. .

As described above, in the fourth embodiment, the sequence header as the refresh information is multiplexed in the stream in the leading picture of the first refresh cycle after shortening, and the moving image receiving apparatus stores the sequence header. As the stream switching timing is taken as a basis,
The effect is that channel switching can be realized without waiting for useless time.

Further, in the above-described fourth embodiment, the difference between the moving image transmitting apparatus of the fourth embodiment and the conventional moving image transmitting apparatus lies in whether or not to process the sequence header. There is also an advantage that the moving image transmitting apparatus according to the fourth embodiment requires less modification than the conventional moving image transmitting apparatus.

It should be noted that in each of the embodiments described above, FIG.
As described above, in the moving image receiving apparatus 70, the refresh instructing unit 308 performs the refresh instruction based on the channel switching instruction 7 from the user. However, the refresh instructing unit 308 is not limited to the one that issues the refresh instruction based on the channel switching instruction 7 from the user.

For example, as shown in FIG. 24, CH1 to C
When four streams of H4 are received by the moving image receiving apparatus 70, and the channel switching control unit 313 issues a channel switching instruction 7 from the user, the above CH1 to CH4.
It is assumed that the switch 304a is controlled so as to sequentially switch the four streams every 30 seconds. Then, the channel switching control unit 313 uses the switch 304a.
On the other hand, when controlling the switching of the four streams of CH1 to CH4, a refresh instruction for shortening the refresh cycle is issued to the moving image transmitting apparatus that transmits the stream selected by the switching of the switch 304a. The refresh instructing unit 308 is instructed. In that case, the refresh instruction unit 308 does not give a refresh instruction based on the channel switching instruction 7 from the user, but rather the channel switching control unit 31.
The refresh instruction is given based on the instruction from 3.

In each of the above-mentioned embodiments, FIG.
As described above, the moving image transmitting / receiving system is configured to include the moving image transmitting device 61, the moving image transmitting device 62, and the moving image receiving device 70. However, FIG.
As shown in FIG. 5, the moving image transmitting / receiving system may include a moving image transmitting device 61 and a moving image receiving device 70, as in the conventional moving image transmitting / receiving system described with reference to FIG.

In this case, when the moving image transmitting apparatus 61 is transmitting the CH1 stream 31 and the moving image receiving apparatus 70 has not received the CH1 stream 31, the user is instructed to make a new connection 9 by the user. Based on this, consider a situation in which the moving image receiving apparatus 70 starts receiving the CH1 stream 31 and outputs an image based on the CH1 stream 31 to the monitor 8.

At that time, since the moving image receiving apparatus 70 has not received the CH1 stream 31 from the moving image transmitting apparatus 61 until receiving the new connection instruction 9 from the user, the CH1 stream 31 is immediately transmitted. Can not be decrypted. Therefore, in order to be able to decode the stream 31 of CH1 as soon as possible, the moving image receiving apparatus 70 transmits to the moving image transmitting apparatus 61 a refresh instruction 41 requesting shortening of the refresh cycle of the stream 31 of CH1.

On the basis of the refresh instruction 41, the moving image transmitting apparatus 61 shortens the refresh cycle from, for example, four frame periods to two frame periods, as shown in FIG. The image 11 is encoded and the above-mentioned refresh information is multiplexed on the stream 31 of CH1 and transmitted.

Then, as shown in FIG. 26 (c),
By using the refresh information, the moving image receiving apparatus 70, as in each of the above-described embodiments,
The tail image of the first refresh cycle after shortening can be known. As a result, if the trailing image can be decoded, the moving image receiving apparatus 70 can output the image of the stream 31 of CH1 after the trailing image to the monitor 8 and display it on the monitor 8. As a result, as is clear from comparison with FIG. 9, the time in which the disordered image is displayed at the start of display is shorter than in the conventional case.

Further, in each of the above-described embodiments, the multiplexing of refresh information into a stream is performed when the refresh cycle is shortened, but it may be performed not only when the refresh cycle is changed but also at all times. I don't care.

In each of the above embodiments, CH1
In the stream 31 of No. 4, the refresh cycle is a period of four frames until a refresh instruction is given, and when the refresh instruction is given, the refresh cycle is shortened to a period of two frames. In the stream 32 of CH2, the refresh cycle is refreshed. It is assumed that there is a period of 6 frames until the instruction is given, and the period is shortened to 3 frames when the refresh instruction is given. However, the length of the refresh cycle after shortening can be arbitrarily set in the moving image transmitting apparatus. Therefore, for example, in the case of the stream 32 of CH2, when the refresh instruction is issued, the refresh cycle may be shortened from the period of 6 frames to the period of 2 frames, and the length of the refresh period after the shortening is Not limited.

Further, in each of the above-mentioned embodiments, each P picture including the intra slice has the frame structure for convenience of description, but may have the field structure.

As described above, each P including the intra slice
When the picture has a field structure, the moving image transmission apparatus sets the refresh cycle to a period of, for example, 8 fields as shown in FIG. 27A until the user issues a channel switching instruction 7. Odd field (1T) of the first → even field (1B) of the first →
A stream is configured in the order of the second odd field (2T) → the second even field (2B) → the third odd field (3T) → the third even field (3B) → ... Send each field. Note that, in FIG. 27, a band-shaped black portion on each field indicates an image based on an intra slice, and a band-shaped hatched portion indicates an image based on a slice subjected to interframe forward prediction coding. The blank slices that are not blackened and are not shaded indicate that no data exists.

In such a case, when the user issues a channel switching instruction 7 and the moving image receiving apparatus issues a refresh instruction accordingly, the moving image transmitting apparatus, for example, as shown in FIG. , The refresh cycle is shortened to, for example, a period of 6 fields, and each field constituting the stream is transmitted in order. that time,
As described in each of the above-described embodiments, the moving image transmitting apparatus also transmits refresh information that specifies the tail image of the shortened first refresh cycle. That is, FIG.
In the example of FIG. 7 (b), the picture 3'B picture is the tail image (tail field) of the first refresh cycle after shortening.
The moving image transmitting apparatus transmits the refresh information indicating that

As described above, when the moving image transmitting apparatus receives the refresh instruction, the moving image transmitting apparatus shortens the refresh cycle more than before and also transmits the refresh information for specifying the trailing image of the first refresh cycle after the shortening. The moving image receiving apparatus can know the trailing image of the first refresh cycle after shortening. Therefore, the moving image receiving apparatus outputs the image (field) based on the stream selected by the channel switching instruction 7 to the monitor and displays the image on the monitor in order to complete the shortened refresh cycle of the selected stream. After that, you don't have to wait extra time. That is, in this case, the moving image receiving apparatus outputs the image (field) based on the stream from the tail image (picture 3'B which is the tail field) of the first refresh cycle after shortening to the monitor and displays it. It will be possible.

Further, not only when the channel switching instruction 7 is given, but also when the new connection instruction 9 is given,
Similar to the above, the moving image transmitting apparatus transmits the refresh information, and the moving image receiving apparatus outputs the image (field) based on the stream from the trailing image (rear field) of the first refresh cycle after shortening to the monitor. Then, it becomes possible to display it on the monitor.

Further, each component of the moving image transmitting devices 61, 62 and the moving image receiving device 70 in each of the above-mentioned embodiments may be constituted by hardware or software. .

Furthermore, a program for causing a computer to function as all or a part of the components of the moving image transmitting devices 61 and 62 and the moving image receiving device 70 in each of the above-described embodiments is applied to a predetermined computer, The computer can also implement the functions of all or some of the constituent elements of the moving image transmitting devices 61 and 62 and the moving image receiving device 70 in the above-described embodiments. As a specific example of an embodiment of using the program, recording the program in a recording medium such as a CD-ROM, transferring the recording medium in which the program is recorded, or communicating means on the Internet or the like It includes communication of the above-mentioned program. It also includes installing the program on a computer.

[0138]

As is apparent from the above description, according to the present invention, the refresh cycle is shortened based on the refresh instruction from the outside to generate the encoded data, and the first refresh cycle after the shortening is completed. It is possible to provide a moving image transmission device that transmits refresh information that can specify a time together with the encoded data.

Further, according to the present invention, the end time of the first refresh cycle after shortening which is transmitted together with the above-mentioned coded data from the moving picture transmitting apparatus which shortens the refresh cycle and transmits the coded data is specified. It is possible to provide a moving image receiving device capable of displaying an image on the external display device from the tail image of the first refresh cycle after shortening based on the refresh information that can be obtained.

Further, according to the present invention, there is provided a moving image transmitting apparatus for transmitting refresh information capable of specifying the end time of the first refresh cycle after the above shortening together with encoded data, and a moving image transmitting apparatus from the moving image transmitting apparatus. An image is displayed on an external display device from the tail image of the first refresh cycle after shortening based on the refresh information that can specify the end time of the first refresh cycle after shortening that is transmitted together with the encoded data. It is possible to provide a moving image transmitting / receiving system having a moving image receiving apparatus capable of performing the above.

As described above, according to the present invention, the moving picture transmitting apparatus multiplexes the refresh information in the encoded data,
The moving image receiving device extracts the refresh information from the encoded data and controls the display timing, so that the image based on the encoded data corresponding to the channel switching or the new connection can be displayed in a short time at the time of the channel switching or the new connection. The advantageous effect of being displayable is obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an intra slice.

FIG. 2 is a block diagram of a conventional moving image transmitting / receiving system.

FIG. 3 is a block diagram of a conventional moving image transmission device.

FIG. 4 is a block diagram of a conventional moving image receiving apparatus.

FIG. 5 is a flowchart showing a conventional channel switching procedure.

FIG. 6 is a first diagram showing a transition of a picture at the time of conventional channel switching.

FIG. 7 is a second diagram showing the transition of pictures at the time of conventional channel switching.

FIG. 8 is a block diagram of a conventional moving image transmitting / receiving system.

FIG. 9 is a diagram showing a transition of a picture when a conventional new connection is made.

FIG. 10 is a configuration diagram of a moving image transmitting / receiving system according to an embodiment of the present invention.

FIG. 11 is a block diagram of a moving image transmitting apparatus according to an embodiment of the present invention.

FIG. 12 is a block diagram of a moving image receiving apparatus according to an embodiment of the present invention.

FIG. 13 is a first diagram showing a picture transition at the time of channel switching according to the embodiment of the present invention.

FIG. 14 is a flowchart showing a channel switching procedure according to the first embodiment of the present invention.

FIG. 15 is a diagram showing the position and structure of refresh information according to the first embodiment of the present invention.

FIG. 16 is a second diagram showing a picture transition at the time of channel switching according to the embodiment of the present invention.

FIG. 17 is a block diagram of a moving image receiving apparatus according to an embodiment of the present invention.

FIG. 18 is a diagram showing the position and structure of refresh information according to the second embodiment of the present invention.

FIG. 19 is a flowchart showing a channel switching procedure according to the second embodiment of the present invention.

FIG. 20 is a diagram showing the position and structure of refresh information according to the third embodiment of the present invention.

FIG. 21 is a flowchart showing a channel switching procedure according to the third embodiment of the present invention.

FIG. 22 is a diagram showing the position and structure of refresh information according to the third embodiment of the present invention.

FIG. 23 is a flowchart showing a channel switching procedure according to the third embodiment of the present invention.

FIG. 24 is a block diagram of a moving image receiving apparatus according to an embodiment of the present invention.

FIG. 25 is a configuration diagram of a moving image transmitting / receiving system according to an embodiment of the present invention.

FIG. 26 is a diagram showing a transition of a picture when a new connection is made in the embodiment of the present invention.

FIG. 27 is a diagram illustrating a display start field when a refresh cycle of a stream composed of fields is shortened according to the embodiment of this invention.

[Explanation of symbols]

6 output image 7-channel switching instruction 8 monitors 11,12 Input moving image 31 CH1 stream 32 CH2 stream 41, 42 Refresh instruction 51,52 camera 61,62 Moving image transmitter 70 Video image receiving device 201 encoder 203 Refresh control unit 204 refresh information generator 205 Multiplexer 301 Decoding unit 302,303 frame memory 304, 305, 306 switch 308 Refresh instruction section 309 Display control unit 310 Refresh information extraction unit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Nobuhiko Yamada             2-6-1, Sakae, Naka-ku, Nagoya-shi, Aichi             Kawa Building Annex 5th floor Matsushita Electric Information Co., Ltd.             Stem Nagoya Institute F-term (reference) 5C059 KK22 MA05 MA23 MC11 ME01                       NN01 NN21 PP06 RC12 RC24                       SS06 SS07 TA00 TB01 TC00                       TC45 UA02 UA05 UA36 UA38                 5C063 AA01 AB03 AB07 AC01 AC10                       CA23 CA36 DA07 DA13 DB10                 5J064 AA00 BA04 BC01 BC02 BC25                       BC29 BD02 BD04

Claims (12)

[Claims] 1. A moving picture transmitting apparatus for transmitting a moving picture including at least a part of inter-frame forward predictive coded pictures, which are sequentially shifted for each successive picture where intra slices are provided on the picture, and In a moving image transmitting / receiving system having a moving image receiving device that receives the moving image from a moving image transmitting device, the intra slice is provided in the moving image transmitting device based on a refresh instruction from the moving image receiving device. The refresh control unit that controls the generation of the inter-frame forward prediction coded image and the trailing image of the first refresh period after the refresh period is shortened are specified so that the refresh period in which the refresh position is moved is shortened. And a refresh information generating unit that generates refresh information that can generate the refresh information. And a multiplexing unit for multiplexing, wherein the moving image receiving apparatus is configured to refresh the moving image transmitting apparatus based on a predetermined instruction to shorten a refresh cycle in which a location where the intra slice is provided moves. A refresh instruction unit for giving an instruction, and a display control unit for displaying the moving image on a predetermined display device from any of the images after the trailing image based on the refresh information obtained from the moving image transmitting device, Video transmission / reception system equipped with. 2. A moving picture transmitting apparatus for transmitting a moving picture including at least a part of inter-frame forward prediction coded pictures, which are sequentially shifted for each of consecutive pictures where intra slices are provided on the picture, On the basis of a refresh instruction from, a refresh control unit that controls the generation of the inter-frame forward prediction coded image so that the refresh cycle in which the location where the intra slice is provided moves becomes shorter, and the refresh cycle becomes shorter. A moving image transmitting apparatus comprising: a refresh information generating unit that generates refresh information that can specify a tail image of a first refresh cycle after the refreshing; and a multiplexing unit that multiplexes the refresh information with the moving image. 3. The moving image according to claim 2, wherein the refresh control unit controls generation of an inter-frame forward prediction coded image based on the refresh instruction so that the width of the intra slice becomes wider. Image transmitter. 4. The moving image transmitting apparatus according to claim 2, wherein the refresh information is information that specifies a tail image of a first refresh cycle after the refresh cycle is shortened. 5. The refresh information is information composed of information specifying a leading image of a first refresh cycle after the refresh cycle is shortened and information of the shortened refresh cycle length. The moving image transmitting apparatus according to claim 2. 6. The moving image transmitting apparatus according to claim 2, wherein the refresh information is information that specifies a leading image of a first refresh period after the refresh period is shortened. 7. A moving image including, from at least a part of a predetermined moving image transmitting device, at least a part of inter-frame forward-prediction-coded images which are sequentially shifted for each image in which the locations where intra slices are provided on the image are continuous. In the moving image receiving device for receiving, based on a predetermined instruction, to the moving image transmitting device,
A refresh instruction unit for issuing a refresh instruction for shortening a refresh cycle in which the place where the intra slice is provided moves, and a first refresh cycle after the refresh cycle is shortened, which is obtained from the moving image transmitting apparatus. Based on the refresh information that can identify the tail image,
A moving image receiving apparatus, comprising: a display control unit that displays the moving image on a predetermined display device from any of the images after the trailing image. 8. The moving image receiving apparatus according to claim 7, wherein the refresh information is information that specifies a tail image of a first refresh cycle after the refresh cycle is shortened. 9. The refresh information is information composed of information that specifies a leading image of a first refresh cycle after the refresh cycle is shortened and information about a shortened length of the refresh cycle. The moving image receiving apparatus according to claim 7. 10. A storage unit that stores information on the length of a refresh cycle when the refresh cycle is shortened, wherein the refresh information is a first refresh cycle after the refresh cycle is shortened. Information for identifying a leading image, wherein the display control unit also uses information on the length of the refresh cycle stored in the storage unit, from any of the images after the tail image, The moving image receiving apparatus according to claim 7, wherein a moving image is displayed on the display device. 11. A program for transmitting a moving image including at least a part of inter-frame forward predictive encoded images, which are sequentially shifted for each of continuous images in which a location where an intra slice is provided on the image, is transmitted from the outside. A refresh control unit that controls the generation of the inter-frame forward prediction coded image so that the refresh cycle at which the intra slice is provided moves based on the refresh instruction, and the refresh cycle is shortened. A refresh information generation unit that generates refresh information that can specify a tail image of a subsequent first refresh cycle, and a program that causes a computer to function as a multiplexing unit that multiplexes the refresh information with the moving image. 12. A moving image from at least a part of a predetermined moving image transmitting apparatus, the moving image including at least a part of inter-frame forward-prediction-coded images sequentially shifted for each of continuous images at locations where intra slices are provided on the image. In the program for receiving, based on a predetermined instruction, to the moving image transmitting device,
A refresh instruction unit for issuing a refresh instruction for shortening a refresh cycle in which the place where the intra slice is provided moves, and a first refresh cycle after the refresh cycle is shortened, which is obtained from the moving image transmitting apparatus. Based on the refresh information that can identify the tail image,
A program for causing a computer to function as a display control unit for displaying the moving image on a predetermined display device from any one of the images after the trailing image.