JP3521066B2 - Video-on-demand system and method for deleting inter-coded picture after cut switching for the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video-on-demand system which enables video codes registered in a video server to be efficiently edited and distributed as a new video program.

[0002]

2. Description of the Related Art A moving picture program editing method is disclosed in Japanese Unexamined Patent Publication No. 9-70009 as an example of a system capable of efficiently providing a new program code by editing a video code registered in a video server. Has been done.

In the above-described conventional moving picture program editing method, with respect to the video code registered in the video server, the start position and the end position of each video code necessary for a new program and the reproduction order of each video code are edited. When a new program is to be distributed in the video server, the video server sends the video code in the reproduction order from the start position to the end position of the video code based on the information.

Now, the screen structure of the moving image code will be described. As an example of a moving image code encoded by using information for a certain reproduction time as a unit for encoding / decoding, a case of MPEG (Moving Picture Experts Group) which is an international standard will be described. MPEG has a structure called GOP (Group of Picture) in which a plurality of screens (pictures) are grouped. There are three types of pictures, I / B / P. The I picture is a picture (intra-frame coded picture) that can be decoded only with the code of the picture, and the B / P
A picture is a picture (interframe coded picture) that cannot be decoded only by the code of the picture. P pictures are forward inter-frame coded pictures, and B pictures are bidirectional inter-frame coded pictures. Usually 1
One GOP is a group of about 0.5 seconds (15 screens), and the number of screens included in the GOP is constant.

In order to edit the above-mentioned moving picture code by the above-mentioned conventional moving picture program editing method, the start position and the end position are designated in units of approximately seconds. In that case, since the start position of the video code is always always the head of the GOP, it can be decoded as it is.

[0006]

The above-described conventional moving picture program editing method has the following problems. That is, when a scene suddenly changes when encoding a video code, a video code edited by a conventional moving image program editing method is decoded with respect to a video code encoded so as to improve image quality. Then, the video is disturbed by the breaks in the successive video codes.

The reason for this is that, when editing is performed in units of seconds, if the encoding is performed so that the image quality is improved when the scene changes suddenly, the editing start position will not be the head of the GOP.

As shown in FIG. 3, usually, in a picture forming one GOP, I / B / P are periodically arranged. As described above, the I picture can be decoded only with the code of the picture, but the B / P picture is predicted and coded based on the codes of the preceding and subsequent pictures, and therefore can be decoded only with the code of the picture. Can not. If the scene changes abruptly, the prediction accuracy decreases, and if the B / P picture is used for encoding, the image quality deteriorates.

Therefore, as shown in (2) of FIG. 4, when the scene suddenly changes, the image quality can be improved by encoding that part with an I picture. However, in such a case, the number of pictures forming one GOP is not constant.

When the start position and the end position are designated in units of seconds and the number of pictures making up the GOP is constant, the boundaries of different cuts in the edited code after editing are always GOP as shown in FIG. It will start from the beginning of
If the number of pictures that make up a GOP is not constant,
As shown in FIG.
It will not start from the beginning of the OP. In the example of FIG.
Six pictures from the boundary are the last six pictures of GOP12, and the picture of GOP13 starts from the seventh picture.

The boundary between the cuts of consecutive video codes is G
If it does not start at the beginning of the OP, it will be decoded in the middle of the GOP and cannot be completely decoded, so the video will be disturbed.

It is an object of the present invention to provide a video demand system having a video server for editing and transmitting moving picture codes of a plurality of cuts, and a video demand system in which an image is not disturbed at a cut boundary.

[0013]

[0014]

Video-On with the present invention, in order to solve the problems]
The demand system transfers the edited video code to the block.
Server to send in units of video and video code of the transfer block
Video with client for decoding video signal
In the on-demand system, the server transfers the transfer
Indicates that there is a cut switch for each block
Cut switching information addition means for adding a flag to the video code
Comprises a step, said client is provided with said flag
Between frames at the beginning of the transfer block that includes that flag in
The cut switching information adding means further adds offset information indicating the number of pictures to be deleted to the video code, and the deleting means uses the offset information to activate the flag. In this case, the inter-frame coded picture at the beginning of the transfer block including the flag is deleted.

Further, the video-on-demand system according to the present invention is the above video-on-demand system,
The video code is of the MPEG system.

[0016]

Inter-frame code after cut switching according to the present invention
The method to delete the encoded picture is to transfer the edited video code.
Server for sending in units of blocks and video of the transfer block
A video provided with a client that decodes a video signal from a code
Frame after cut switching for on-demand system
In the method for deleting inter-coded pictures, performed by the server
When there is a cut switching for each of the transfer blocks
Cut off to add a flag indicating that to the video code
Replacement information adding step, and before being performed by the client
If there is a flag, the transfer block that includes that flag
A deletion step that deletes the inter-coded picture at the beginning
Tsu have up, the when the further adds offset information indicating the number of pictures to be removed in cutting the switching information adding step to said video coding, wherein the deleting step the flag by using the offset information is active It is characterized in that the inter-frame coded picture at the beginning of the transfer block including the flag is deleted.

Further, the inter-frame coded picture deleting method after cut switching is characterized in that, in the above-mentioned inter-frame coded picture deleting method after cut switching, the video code is of the MPEG system.

[0019]

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

Referring to FIG. 1, one embodiment of the video-on-demand system of the present invention comprises a video server 1 and a client 2, which are connected by a network 3. The video server 1 includes edit information 11, and the client 2 includes a code receiving unit 21, a deleting unit 22, a decoding unit 23, and a requesting unit 24.

The video server 1 further comprises a storage means 12 for storing the video code, a transmission means 13 for transmitting the stored video code to the clients, and a request receiving means 14 for receiving a distribution request from each client. , The video code is sent to each client 2 through the network 3.

Further, the code receiving means 21 of the client 2
Is arranged as an input unit from the network and receives the video code transmitted from the video server 1.

The deleting means 22 determines from the received video code
Detects the editing boundary of the video code that has been transmitted continuously,
A code that cannot be correctly decoded at the edit boundary, that is, a picture immediately after the edit boundary to a picture before the P picture is deleted, and the video signal after the deletion is passed to the decoding means 23.

The decoding means 23 expands the code signal of the video code if it is compressed, decodes it if it is encrypted, converts it to the code structure in the state stored in the video server 1, and decodes it. And play.

Next, the overall operation of this embodiment will be described in detail with reference to the flow charts of FIGS. 1, 6 and 2.

In the video server 1, the edit information 11 has, as the edit code of the new cut, the start position and the end position of the video code forming the new cut, and the reproduction order. The video server 1 sends out the video code based on the editing information 11. At this time, as shown in FIG. 6, the video code manages 15 screens designated by the start position and the end position as one edit unit and transfer block. When transmitting the video code, the cut switching information adding means 15 stores, in the header information, for each transfer block, if the transfer block is a transfer block immediately after switching of the cut, a cut switching flag indicating that. Further, the cut switching information adding means 15 also stores offset information indicating the position of the last picture among the pictures to be deleted by the client 2 in the header information. Pictures to be deleted are inter-frame coded pictures such as P pictures and B pictures. The offset information can also be regarded as the number of pictures to be deleted.

For example, the edited program is composed of the start position 5a of the video code 5 to the end position 5b and the start position 6a of the video code 6 to the end position 6b. Edit information 1 to play in order
I have one. In the video server 1, the editing information 1
1, the start position 5a of the video code 5 to the end position 5
The codes up to b are transmitted, and then the start position 6 of the video code 6
The codes from a to the end position 6b are transmitted. The cut switching information adding unit 15 sets the cut switching flag and the offset information in the header information of the block when transmitting the code of the first transfer block of the video code 6.

In the client 2, the code receiving means 21 receives the code sent from the video server (step 1 in FIG. 2). The code receiving means 21 passes the received code to the deleting means 22 in units of transfer blocks. Deletion means 22
Determines whether or not the transfer block is the first block for cut switching by determining whether or not there is a cut switching flag in the header information of the transferred transfer block (step 2 in FIG. 2). When the current transfer block is not the block immediately after the cut switching, the deleting unit 22
The transfer block is passed as it is to the decoding means 23 (step 4 in FIG. 2). If the current transfer block is not the block immediately after the cut switching, the first picture of the transfer block to the picture specified by the offset information (code 6c that cannot be correctly decoded in FIG. 6) is deleted, and the subsequent codes are decoded. It is passed to the means 23 (step 4 in FIG. 2). The decoding means 23 decodes and reproduces the passed code (step 5 in FIG. 2).

[0029]

As described above, according to the present invention, the undecodable picture at the beginning of the transfer block can be deleted, so that the image reproduced by the client is not disturbed at the cut boundary.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a video on demand system according to an embodiment of the present invention.

FIG. 2 is an operation flowchart of a client of a video on demand system according to an exemplary embodiment of the present invention.

FIG. 3 is a diagram showing a structure of 1 GOP in which a plurality of screens are grouped.

[Fig. 4] Fig. 4 is a diagram showing a change in structure of one GOP when encoding is performed to further improve image quality when a scene suddenly changes.

FIG. 5 is a diagram showing a structure of an edit code when a video code is edited in the case of a normal GOP structure.

FIG. 6 is a diagram showing a structure of an edit code when a video code that has been encoded so as to improve the image quality is edited when a scene suddenly changes.

[Explanation of symbols]

1 Video server 2 clients 3 network 11 Editing information 12 Storage means 13 Transmission means 14 Request receiving means 15 Cut switching information addition means 21 code receiving means 22 Deletion means 23 Decoding means 24 Requesting means

Claims (4)

(57) [Claims] 1. A transfer block unit for editing an edited video code.
And the server that sends the video signal from the video code of the transfer block.
Video-on-demand system with client
The server has a cut switch for each transfer block.
Sometimes a flag indicating that is added to the video code
A cut switching information adding unit is provided, and the client can set the flag when the flag is present.
Inter-frame coding picture at the beginning of the transfer block including
The cut switching information adding means further adds offset information indicating the number of pictures to be deleted to the video code, and the deleting means uses the offset information to activate the flag. A video-on-demand system characterized in that an inter-frame coded picture at the beginning of a transfer block including the flag is deleted at times. 2. The video-on-demand system according to claim 1 , wherein the video code is of an MPEG system. 3. The edited video code is transferred in block units.
And the server that sends the video signal from the video code of the transfer block.
For video-on-demand systems with clients
The method for deleting inter-coded pictures after switching
The cut of each transfer block performed by the server.
When there is a replacement, a flag indicating that is added to the video code
The cut switching information adding step to be added, and when there is the flag performed by the client,
Interframe code at the beginning of the transfer block including the flag
A deletion step of deleting the encoded picture, and in the cut switching information adding step, offset information indicating the number of pictures to be deleted is further added to the video code,
In the deleting step, when the flag is active, the inter-frame coded picture at the beginning of the transfer block including the flag is deleted using the offset information after the cut switching. How to delete. 4. A cut switch after interframe coded picture delete method according to claim 3, wherein the video encoder is M
An inter-frame coded picture deletion method after cut switching, characterized by being of a PEG system.