JPH08154242A - Delivery method for video program and execution device therefor - Google Patents

Abstract

PURPOSE: To eliminate interruption of a video image in the case of random jump by dividing video information whose coding rate is adjusted into the unit of access and adding padding information to the information thereby forming a transport segment of a prescribed length. CONSTITUTION: A coding control section 5 of a server 1 references a conversion table 6 depending on a required input from a system operation data input path 4 to command a coding rate calculated based on an object bit rate at coding of video information to a line bit rate corresponding to a coded unit number in the access unit of the video information to be divided to a video information coding section 8. Then a transport segment generating section 9 adds transport segment P1, P2,... to divided coding video information AU1, AU2,... divided in the unit of access to generate transport segments TS1, TS2,... with a length in which a line bit rate is coincident with the coding bit rate and interruption of a video image is not generated even in the case of random jump.

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, and more particularly, it is encoded by a variable bit rate encoding system in which information for a fixed reproduction time is an encoding unit which is a unit for encoding / decoding. The present invention relates to a video program delivery method and an implementation device for delivering a stored video program through a transmission path of a fixed bit rate, and a movie on-demand or interactive mode in which a video program stored in a video server is randomly accessed from a terminal. The present invention relates to technology that is effective when applied to TV services and the like.

[0002]

2. Description of the Related Art There have been the following two methods of delivering a video program in a conventional video-on-demand system of this type. FIG. 4 shows an example of the delivery method 1 and FIG. 5 shows an example of the delivery method 2.

(Distribution Method 1) The distribution method 1 is a method of matching a target bit rate at the time of encoding a video program with a fixed bit rate of the line. In FIG. 4, F11, F
12, ..., F16 represent each coding unit of the video program,
Z1 represents the amount of information passing through the line in the reproduction time of the coding unit. 4A shows an example in which the terminal accesses the video program in order from the beginning, and FIG. 4B shows an example in which the random access is performed. As shown in FIG. 4 (1), although the size of each coding unit is different, for example, like coding units F11 to F16 of a video program, the average coding unit length is averaged over a long time. Matches Z1.

(Distribution method 2) In the distribution method 2, the target bit rate at the time of coding a video program is set to be smaller than the fixed bit rate of the line so that the bit rate of each coding unit becomes equal to or lower than the fixed bit rate of the line. Is the way to do it.

In the delivery system 2, by setting the target bit rate at the time of encoding to be smaller than the line bit rate, as shown in (1) and (2) of FIG.
Of F21, F22, ..., F26, the information amount of the coding unit F22 having the maximum coding unit length is set to be equal to or less than the information amount Z2 when transferred at the fixed bit rate of the line. In FIG. 5, (1) is an example in which the access is sequentially performed from the beginning, and (2) is an example in which the random access is performed. Each coding unit length of F21, F22, ..., F26 is Z
It is smaller than 2.

[0006]

The present inventor has found the following problems as a result of examining the above-mentioned prior art.

In the conventional delivery method 1, when delivering a video program in order from the beginning to the end, if the terminal has a receiving buffer of a certain capacity to absorb the bit rate fluctuation, there is no interruption of the video. The program can be played back. However, when random access of a video program is performed from the terminal to the video server, as shown in (2) of FIG. 4, when only the coding units F12, F13, and F15 that happen to have a large amount of information are read out. In that case, the effective coding bit rate of the video program exceeds the bit rate of the line, and the video image is interrupted.

On the other hand, in the conventional delivery system 2, even when the video program is randomly accessed from the terminal, as shown in (2) of FIG. It does not exceed the rate.
However, since the target bit rate must be reduced at a fixed rate in order to directly limit the coding unit length of the video program, there is a problem that the image quality of the video program is always degraded at a fixed rate.

Further, since the average coding bit rate of the video program and the fixed bit rate of the line are different, a transfer bit rate control mechanism such as flow control is required.

It is an object of the present invention to provide a video delivery technique in which the video is not interrupted even when the video program is randomly accessed.

Another object of the present invention is to provide a video delivery technique capable of adjusting a target bit rate reduction amount at the time of encoding a video program with respect to a line bit rate.

Another object of the present invention is to provide a video delivery technique which does not require a transfer bit rate control mechanism.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0014]

The outline of the representative one of the inventions disclosed in the present application will be briefly described as follows.

(1) Information for a fixed reproduction time is used as an encoding unit which is a unit for encoding / decoding, and encoding is performed based on a variable bit rate encoding system in which the length of the encoding unit changes. A method for delivering a video program on a transmission path in a video-on-demand system, which requires a terminal to randomly jump the video program on a transmission path having a fixed bit rate to a video server that provides the video program. An access unit (variable length) that is a unit of random jump from a terminal and a transmission line of the fixed bit rate at the time of reproducing a video program for the access unit, which is a set of consecutive constant number of coding units. The information transmitted by is used as the transport segment (fixed length), and the largest access unit length in the video program is the transport segment. The characteristics of the video program at the time of coding are adjusted so as to be equal to or less than the input length, the adjusted coded video program is divided for each access unit, and video information for each access unit is inserted into the transport segment. Then, a transport segment is generated by filling the remaining part of the transport segment with padding data, and the video server generates a transport segment in response to a video program random jump request from the terminal. The port segment is provided to the terminal through the transmission path.

(2) Information for a fixed reproduction time is used as an encoding unit which is a unit for encoding / decoding, and encoding is performed based on a variable bit rate encoding system in which the length of the encoding unit changes. A video server that provides the selected video program,
A video program on the transmission line in a video-on-demand system including a terminal requesting a random jump of a video program to the video server and a fixed bit rate transmission line connecting the video server and the terminal In the delivery device, an access unit (variable length) that is a unit of a random jump from a terminal, and a video program for the access unit is reproduced by a set of coding units for every fixed number of continuous video programs. The information transmitted by the fixed bit rate transmission path at the time of execution is defined as a transport segment (fixed length), and when the video program is encoded such that the largest access unit length in the video program is less than the transport segment length. Encoding bit rate adjusting means for adjusting characteristics, and the encoding bit rate adjusting means The encoded video program is divided for each access unit, video information for each access unit is inserted into the transport segment, and the transport segment is filled by padding the rest of the transport segment. Transport segment generating means for generating and, in the video server, the corresponding transport segment of the video program generated by the transport segment generating means in response to a video program random jump request from the terminal, to the terminal through the transmission path. And means for providing.

[0017]

According to the above-mentioned means, a set of coding units for every fixed number of consecutive video programs is an access unit (variable length) which is a unit of random jump from the terminal, and a video program for the access units. The information transmitted by the fixed bit rate transmission line at the time of reproduction is defined as a transport segment (fixed length), and the video program is encoded so that the largest access unit length in the video program is equal to or less than the transport segment length. A means of adjusting the characteristics of time,
For example, since the means for adjusting the target bit rate guarantees that the coding bit rate of the video program will be equal to or lower than the bit rate of the line in each access unit, the order in which the terminal accesses the video programs Even when the random jump is performed every time, the coding bit rate of the video program does not exceed the line bit rate, and the interruption of the video image as shown in (2) of FIG. 4 does not occur.

At this time, the means for adjusting the target bit rate at the time of encoding (means for adjusting the characteristics) lowers the target bit rate at the time of encoding the video program to be lower than the line bit rate. Will be invited.

However, the method of the present invention does not necessarily lower the target bit rate at a fixed rate in order to directly limit the maximum coding unit length of the video program as in the conventional delivery method 2. The maximum length of a collection of a certain number of coding units (access unit) is limited.

In general, in variable bit rate coding,
The longer the observation range, the smaller the bit rate fluctuation. Therefore, according to the method of the present invention, the larger the number of coding units included in the access unit, the smaller the fluctuation of each access unit length, and the decrease in the coding target bit rate of the video program with respect to the line bit rate. And the target bit rate at the time of encoding can be made close to the line bit rate.

In this way, by designating the number of coding units included in the access unit, it is possible to adjust the reduction range of the coding target bit rate of the video program with respect to the line bit rate.

Further, the video program whose coding rate is adjusted by the coding bit rate adjusting means is divided into each access unit, video information for each access unit is inserted into the transport segment, and the transport is performed. Since the coding bit rate of the video program matches the line bit rate by means of filling the rest of the segment with padding data, a transfer bit rate control mechanism such as flow control is unnecessary.

In the video server, in response to a video program random jump request from the terminal, random access of the video program is performed by the means for providing the transport segment of the video program generated by the means to the terminal through the transmission path. There is no break in the video even if you go. Further, there is no need to provide a mechanism for controlling the transfer bit rate. Further, it is possible to suppress deterioration of the image quality of the video program to some extent.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a video program delivery device on a transmission line according to an embodiment of the present invention. In FIG. 1, 1 is a video server, 2 is a terminal,
3 is a fixed bit rate line connecting the video server and the terminal, 4 is a system operation data input path from the outside, 5
Is an encoding control unit that calculates a target bit rate as a means for adjusting the characteristics at the time of encoding from the input operation data, 6 is a conversion table for calculating the target bit rate, and 7 is analog video information from the outside. Source input path, 8 video information encoding unit, 9 transport segment generation unit, 10 transport segment video information storage unit, 11 transport segment on line based on request from terminal A line control unit 12 for delivering is a transport segment of video information transferred on the line.

FIG. 2 shows the target bit rate at the time of video information coding with respect to the number of coding units included in the access unit and the line bit rate for calculating the target bit rate from the designated line bit rate in this embodiment. It is a conversion table of the ratio of.

FIG. 3 is an example of a delivery format of video information delivered on the line 3 connecting the video server 1 and the terminal 2 created in this embodiment. (1) of FIG.
An example in which the transport segments are accessed in order from the beginning, (2) in FIG. 3 is an example in which the transport segments are accessed in a random order.

In FIG. 3, TS1, TS2 and TS3 are transport segments, AU1, AU2 and AU3 are access units, F01 and F02 are AU1, and F03 and F3.
04 is a coding unit included in AU2, F05 and F06 are coding units included in AU3, and P1, P2, and P3 are transport segments TS1, TS2, and T, respectively.
In S3, access units AU1, AU2, from the beginning
The padding is inserted in the remaining area after inserting AU3.

Next, the operation of the video program delivery apparatus of this embodiment will be described with reference to FIGS. In FIG.
First, the system operator of the video server 1 inputs the system operation parameters such as the bit rate of the line, the number of coding units included in the access unit of video information, and the reproduction time of the coding unit from the system operation data input path 4. .

The coding control unit 5 uses the conversion table 6 shown in FIG. 2 for converting the number of coding units included in the access unit and the ratio of the target bit rate at the time of video information coding to the line bit rate, and The target bit rate is calculated from the specified line bit rate.

This conversion table 6 is obtained in advance from the characteristics of the observation time and the fluctuation of the coding unit length generated by the coding unit. For example, when the number of coding units included in the access unit is “2”, the target coding bit rate needs to be set to a value 0.9 times the line bit rate, and the specified line bit rate is 1,544M
In the case of bps, the target coding bit rate is 1.54
4 × 0.9 = 1.896 Mbps.

As another example, when the number of coding units included in the access unit is 4, the target coding bit rate is 1.544 × 0.95 = 1.468 Mbps, and as another example, When the number of coding units included in the access unit is “6”, the target coding bit rate is 1.
The reduction amount of the target bit rate at the time of encoding with respect to the line bit race is adjusted according to the number of encoding units included in the access unit designated by the system operator, such as 544 × 0.98 = 1.51312 Mbps. .

The target bit rate calculated by the encoding control unit is passed to the video information encoding unit 8. There, the video information input from the path 7 is encoded at the specified target bit rate. Then, the encoded video information is passed to the transport segment generation unit 9.

In the transport segment generator 9,
Information such as the number of coding units included in the access unit, the line bit rate, and the reproduction time in the coding unit is acquired from the coding control unit 5, and a transport segment as shown in (1) of FIG. 3 is generated from the information. To do.

As shown in FIG. 3, in each transport segment TS1, TS2, TS3, access units AU1, AU2, AU3 are inserted from the beginning, and the remaining areas are filled with paddings P1, P2, P3, respectively. Is generated.

Each transport segment TS1, TS
The length of 2, TS3 is the amount of information transmitted by the line during the reproduction time of the access unit (the product of the number of coding units in the access unit and the reproduction time of each coding unit). The number of coding units is "2", the reproduction time of each coding unit is 0.5 seconds, and the bit rate of the line is 1.544 Mbps.
If it is, (2 × 0.5) × 1.544 = 1.5
It can be calculated by calculating 44 Mbit.

Next, the transport segment of the generated video program is temporarily stored in the video information storage unit 10. Then, the line control unit 11 delivers the transport segment 12 of the corresponding video program to the line 3 in accordance with the request from the terminal 2. At this time, since the terminal 2 requests the video server 1 to make a random jump, the transport segment 12 transferred on the line 3 is transmitted.
Are transport segments TS1, TS2, TS
Every 3 is in a random order.

FIG. 3B shows an example of the video information when the transport segments TS1, TS2 and TS3 are arranged in a random order. The size of each transport segment TS1, TS2 and TS3 is shown. Since it is constant, it can be seen that the bit rate does not change even if the order is rearranged.

Therefore, in the present embodiment, even if the terminal 2 makes a random jump, the video is not interrupted and it is not necessary to provide a transfer bit rate control mechanism.

In the present embodiment, an example in which the information is stored in the video information storage unit 10 after the transport segment generation unit 9 has been shown, but the video information after being encoded by the video information encoding unit 8 is shown. Is also stored in the transport segment generation unit 9 before the generation processing is performed, or the analog video information before being encoded in the video information encoding unit 8 is stored as it is. Conceivable.

Further, in this embodiment, since the maximum access unit length in the video program is set to the transport segment length or less, the target bit rate is adjusted as a means for adjusting the characteristics at the time of encoding the video program. However, a method of performing precise feedback of the encoding bit rate at the time of encoding can be considered.

As described above, the invention made by the present inventor is
Although the present invention has been specifically described based on the above-mentioned embodiments, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the scope of the invention.

[0043]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

(1) Since it is guaranteed that the coding bit rate of the video program will be equal to or less than the bit rate of the line for each access unit, random jump is performed in the access unit of the video program in the terminal. Even in this case, the coding bit rate of the video program exceeds the bit rate of the line, and the video is not interrupted.

(2) By designating the number of coding units included in the access unit, the reduction range of the target bit rate at the time of coding the video program with respect to the line bit rate can be adjusted.

(3) Since the bit rate of the video program and the bit rate of the line match due to the padding, it is not necessary to provide a mechanism for controlling the transfer bit rate.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a video program delivery device on a transmission line according to an embodiment of the present invention.

FIG. 2 shows the number of coding units included in an access unit and the ratio of the target bit rate at the time of video information coding to the target bit rate for calculating the target bit rate from the designated line bit rate in the present embodiment. It is a conversion table.

FIG. 3 is a delivery format of video information delivered in a line connecting a video server and a terminal created in the present embodiment.

FIG. 4 is an example of a delivery format of video information delivered on a line connecting a video server and a terminal in the conventional video information delivery system 1.

FIG. 5 is an example of a delivery format of video information delivered on a line connecting a video server and a terminal in the conventional video information delivery system 2.

[Explanation of symbols]

1 ... Video server, 2 ... Terminal, 3 ... Fixed bit rate line, 4 ... System operation data input path, 5 ... Encoding control section, 6 ... Conversion table, 7 ... Video information source input path, 8 ... Video information Encoding unit, 9 ... Transport segment generation unit, 10 ... Video information storage unit, 11 ... Line control unit, 12 ... Transport segment.

Claims (2)

[Claims] 1. The information for a fixed reproduction time is used as an encoding unit which is a unit for encoding / decoding, and encoding is performed based on a variable bit rate encoding method in which the length of the encoding unit changes. A method for delivering a video program on a transmission line in a video-on-demand system, which requires a terminal to request a random jump of a video program on a transmission line having a fixed bit rate to a video server that provides the video program, and the method is a continuous video program. A set of coding units for every fixed number of access units (variable length), which is a unit of random jump from the terminal, and the transmission line of the fixed bit rate is set at the time of reproducing the video program for the access units. Transport segment for transmission information (fixed length)
And, adjusting the characteristics at the time of encoding of the video program so that the maximum access unit length in the video program is less than the transport segment length, the adjusted encoded video program is divided for each access unit, Video information for each access unit is inserted into the transport segment, the rest of the transport segment is filled with padding data to generate a transport segment, and the video server randomly jumps from the terminal in the video server. A method of delivering a video program, comprising providing a corresponding transport segment of the generated video program to a terminal through the transmission path in response to a request. 2. The information for a fixed reproduction time is used as an encoding unit which is a unit for encoding / decoding, and encoding is performed based on a variable bit rate encoding method in which the length of the encoding unit changes. Video on demand comprising a video server providing a video program, a terminal requesting the video server to make a random jump of the video program, and a fixed bit rate transmission line connecting the video server and the terminal A method of delivering a video program on the transmission path in a system, comprising: an access unit (variable length), which is a unit of random jump from a terminal, of a set of coding units for a constant number of consecutive video programs, and The information transmitted by the transmission path of the fixed bit rate at the time of reproducing the video program for the access unit is transferred to the transport segment (fixed length). ), The encoding bit rate adjusting means for adjusting the characteristics at the time of encoding the video program so that the maximum access unit length in the video program is not more than the transport segment length, and the encoding bit rate adjusting means The segmented video program is divided for each access unit, video information for each access unit is inserted into the transport segment, and the rest of the transport segment is filled with padding data to generate a transport segment. And a corresponding transport segment of the video program generated by the transport segment generation means in response to a video program random jump request from the terminal in the video server, to the terminal through the transmission path. Hand Delivery device of the video program, characterized in that it comprises and.