JPH11289531A - Mpeg2 moving image distribution system and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To utilize the convenience of two-channel simultaneous viewing also for communication service by providing a device for reducing the transmission rate of an MPEG2 moving image in real time inside of a fast network so as to reduce the transmitting rate of the MPEG2 moving image according to the request of an end user. SOLUTION: A transmission rate reducing device 102 receives an MPEG2 transport stream packet from each MPEG2 moving image server 101 connected to a fast network 105 and receives a control command 112 selecting a sub- picture channel from a client 103. According to the request of the command 112, when the pay load is an intra-encoding frame (I-frame), sound and overhead information, the device 102 sends them to a client 103 and when the pay load is a predictive encoding frame (B or P frame), the device 102 abolishes it to remarkably reduce a transmission rate. Thus, a picture for a sub-picture can be distributed to an end user of a small transmission band.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system and method for distributing MPEG2 video using a high-speed network such as an ATM network.

[0002]

2. Description of the Related Art MPEG2, which is a high-quality digital moving image format, is being widely used in broadcasting, communication, and storage media. Approximately 6 Mbps when delivering MPEG2 video in real time using communication (MP @ ML)
Conventionally, it has been impossible to provide an MPEG2 moving image distribution service to other than some high-end users by communication because it requires a transmission band of s.

[0003] MP @ ML stands for Main Profile at Ma
An abbreviation of "in Level", which is one of a standard subset that enables real hardware to be configured while ensuring interconnectivity. MP is a subset that is represented by a profile defined by a set of encoding tools and a level representing the screen size, and is intended to be used most widely.
Call it $ ML.

In the future, it is expected that a transmission band of about 10 Mbps will be provided to each end user by introduction of a high-speed network such as an ATM network, and this makes it possible to distribute one MPEG2 moving image. It is still difficult to distribute a plurality of MPEG2 moving images at the same time.

[0005]

In the current TV broadcasting, an existing technology using a television receiver having a plurality of tuners is used.
It offers the convenience of simultaneous viewing of channels,
There is a need for a mechanism that can provide similar services using services using communication.

An object of the present invention is to provide convenience such as simultaneous viewing of two channels even in a service using communication.

[0007]

According to the present invention, the AT
MPEG2 inside a high-speed network such as an M network
A device for reducing the transmission rate of a moving image in real time is provided, and the transmission rate of an MPEG2 moving image is reduced according to an end user's request. Or 1-channel M that does not reduce the transmission rate
It is possible to distribute an MPEG2 moving image of one or more channels whose transmission rate is reduced with the PEG2 moving image.

FIG. 1 shows a network 10 on the end user side.
6 for end users with insufficient transmission bandwidth
1 shows a system for delivering two moving images. In the figure, 101 is M
PEG2 moving image server, 102: MPEG2 moving image transmission rate reduction device, 103: MPEG2 moving image client, 104: network (access network on the information provider side), 105: network (backbone network), 106: network (end user side) Access network), 107 is M
MPEG received by PEG2 video transmission rate reduction device
2 channel, 108 is an MPEG2 channel transmitted by MPEG2 moving image transmission, 109 is an end user side MP
EG2 channel display device, 110 is a main screen moving image, 1
Reference numeral 11 denotes a sub-screen moving image, and 112 denotes a control command for the MPEG2 moving image transmission rate reduction device.

MP connected to high-speed network 105
The MPEG2-TS (MP
EG2 Transport Stream: Moving Picture Exp
ertsGroup2-Transport Stream) packet transmission rate reduction device 1 for MPEG2 video via network
02. In this transmission rate reduction device, M
A PEG2-TS packet is transmitted to the MPEG2 moving image client 103 if the payload is intra-coded frame (I frame), voice, or overhead information, and discarded if the payload is a predicted coded frame (B, P frame). Processed by

The I, P, and B pictures described above will be briefly described. (1) I-picture (Intra-coded picture) When encoded, only closed information is used in one picture. In other words, when decoding, an image can be reconstructed using only the information of the I picture itself. Actually, DCT (Discrete Cosine Transform) is used without any difference from other images
And encode. Although this encoding method is generally inefficient, random insertion and high-speed reproduction can be achieved by decoding the I picture only by putting it anywhere. Further, if the I picture is decoded, stored in the memory, and read out in the reverse direction, reverse reproduction can be performed. (2) P picture (Predictive-coded picture: forward predictive coded picture) A P picture is a predicted picture (a reference picture for taking a difference).
And the previously decoded I
Use a picture or P-picture. That is, a frame predicted from the past to the present one direction. In practice, it is possible to select, on a macroblock-by-macroblock basis, whether to encode the difference from the motion-compensated predicted image or to encode without taking the difference (intra encoding). (3) B picture (Bidirectionally predictive-coded
picture: a bidirectionally predicted coded image) A B picture is a previously decoded I picture or P picture temporally located before and a previously decoded I picture or P picture temporally located as a predicted image , And interpolated images made from both. Here, in the case of an interpolation frame, prediction is performed from both directions, but there are three types of motion compensation prediction modes which are roughly classified. These are forward motion compensation for predicting the present from the past, backward motion compensation for predicting the present from the future, and interpolation motion compensation for predicting the present from both the past and the future. The forward motion compensation and the backward motion compensation are the same processes as ordinary motion compensation in that matching is performed with a block read from one reference frame. In addition, the interpolation motion compensation is to obtain a prediction signal by combining blocks read from two reference frames with weighting in consideration of the time distance between the current frame and the reference frame.

[0011] In this system, the MPEG2 moving image client 103 on the end user side transmits an M2 image to reduce the transmission rate from a plurality of moving images received.
The transmission rate reduction device 1 is provided with a function of transmitting a control command 112 for selecting and changing a PEG2 moving image.
02 has a function of receiving the command and reducing the transmission rate of the MPEG2 moving image according to the request of the control command.

The MPEG2 moving image transmission rate reduction device 102 enables the MPEG2 moving image to be composed of a moving image of only intra-coded frames (I frames) and complete audio, and the transmission rate to be reduced from 6 Mbps to about 1 Mbps. . Since such an image can be viewed as an "outline" of the MPEG2 channel, by distributing the image, an end user connected to a network with insufficient bandwidth can be used for a sub-screen (for confirming the content of the channel). Image distribution becomes possible.

Further, this system selects a channel whose transmission rate is desired to be reduced according to a request from an end user.
By providing the command 112 that can realize the change,
When the end user sends a command for changing the channel to be viewed as the main screen 110, the channel for which the transmission rate is reduced by the transmission rate reducing device can be dynamically changed. As a result, the channel newly selected by the user on the main screen can be viewed as a complete moving image, and the channel previously viewed on the main screen continues to be displayed on the sub-screen 11.
1 makes it possible to browse the outline.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) Delivery of MPEG2 Channel to Narrow Band Best Effort Network The MPEG2 channel is usually delivered using a broadband and bandwidth guaranteed communication network such as an ATM network. However, at present, a large number of end users are connected to a best-effort network with a narrow band such as an IP network, and it is difficult to distribute an MPEG2 channel to such end users with existing technology. Reference numeral 201 in FIG. 2 denotes an MPEG2 moving image server, 202 denotes an MPEG2 moving image transmission rate reduction device,
03 is a gateway device between a narrowband network and a wideband network, 204 is an MPEG2 video client, 205 is a broadband / bandwidth guaranteed communication network (eg, ATM network), 206 is a narrowband / best-effort network (eg, IP network) ,
207 is the MPEG received by the moving image transmission rate reduction device
Two channels, 208 denotes an MPEG2 channel transmitted by the moving image transmission rate reduction device, and 209 denotes an MPEG2 channel by which the gateway device converts various protocols and transmits to the best-effort network.

In FIG. 2A, an MPEG2 channel 207 from the information provider side is received by the MPEG2 moving image transmission rate low band device 202, and the MPEG2 channel 207 is received.
The MPEG2 channel 208 is transmitted from the moving image transmission rate reduction device 202. Illustrated gateway device 20
3 transmits the MPEG2 channel 209 whose protocol has been converted over the network 206 to the moving image client 20.
Send to 4.

At this time, as shown in FIG. 2 (A), the transmission rate of the MPEG2 channel is reduced by using a system which can deliver the "overview" of the MPEG2 channel proposed in the present invention, and a narrow band network / broad band network separately provided. The data is transmitted to the narrow-band best-effort network 206 via a device having the same function as the inter-gateway device 203 or the transmission rate reducing device 202.

The gateway device needs a function for converting various protocols shown in FIG. 2 (B). FIG.
In (B), for example, the bandwidth guarantee protocol is AT
In M, it is realized by the QoS guarantee mechanism of ATM.
In the RSVP protocol and others. Hereinafter, the delay suppression protocol and the physical layer protocol are respectively realized by the corresponding ones shown in FIG.

By using a system including such a gateway device in the system proposed in the present invention,
MPE for narrowband best effort network
It is possible to distribute the “summary” of the G2 channel.

(Embodiment 2) Realization of Multi-Channel Broadcast Search Screen When the number of MPEG2 channels that can be browsed on a high-speed network such as an ATM network increases, the end user receives a plurality of channels simultaneously, listens to them completely, and completes the listening process. It is conceivable to perform a channel search such as selecting a channel that the user wants to view as a moving image. However, a transmission bandwidth of 6 Mbps × N is required to realize a screen for simultaneously searching N channels.
It is impractical to realize the G2 moving image.

However, the channel search screen does not need to be a complete moving image, and may be any screen that can grasp the contents of the channel to some extent. Therefore, as shown in FIG. By using a system that can distribute the “overview” of the MPEG2 channel, the transmission rate of all the channels is reduced and distributed to the end user, thereby realizing the distribution of the channel search screen.

In FIG. 3A, reference numeral 301 denotes an MPE.
G2 video server (9 units), 302 is an MPEG2 video transmission rate reduction device, 303 is an MPEG2 video client, 304 is an ATM network, 305 is an MPE
MPE received by the G2 moving image transmission rate reduction device 302
G2 channels (9), 306 denotes an MPEG2 channel transmitted by the MPEG2 moving image transmission rate reduction device 302 (transmission rate is reduced: 9), 307 denotes an end user side MPEG2 channel display device, and 308 denotes a channel search screen (9). Screen). FIG.
In (B), 351 indicates the sum of the transmission rates of the channel 305, 352 indicates the sum of the transmission rates of the channel 306, and 353 indicates the assumed bandwidth of the access network on the end user side.

For example, nine MPEG2 moving image servers 30
The information from 1 is transmitted to the channel 3 having the reduced transmission rate in the MPEG2 moving image transmission rate reduction device 302.
At 06, it is sent to the MPEG2 moving image client 303.

With this system, a search screen of N channels can be realized if there is a transmission bandwidth of about 1 Mbps × N. For example, as shown in FIG. 3B, an end user whose ATM network transmission bandwidth is about 10 Mbps is provided to the end user. On the other hand, the system of the present invention can provide search screens of up to about 9-10 screens.

(Embodiment 3) Realization of Multi-Angle Broadcasting When a moving image is distributed using communication, an information provider can broadcast using a plurality of videos with a relatively small investment compared to the current radio wave broadcasting. it is conceivable that. For example, one M
Multi-angle broadcasting, such as simultaneous distribution of a plurality of angles of video on the PEG2 channel, can be easily realized. However, for example, when an information provider distributes video images of three different angles at the same time, a transmission band of 6 Mbps × 3 = 18 Mbps is required, and it is difficult for an end user to receive such a multi-angle broadcast. Therefore, as shown in FIG.
A system that can deliver the "outline" of the PEG2 channel is used.

In FIGS. 4A and 4B, 4
01 is an MPEG2 moving image server, 402 is an MPEG2 moving image transmission rate reduction device, 403 is an MPEG2 moving image client, 404 is a multi-angle image photographing camera, 405 is an ATM network, 406 is MPEG2
MPEG2 received by the moving image transmission rate reduction device 402
The channel (3 angles), 407 is an MPEG2 channel transmitted by the MPEG2 moving image transmission rate reduction device 402 (no transmission rate reduction: 1 angle, transmission rate reduced: 2 angles), and 408 is an end user MPE
G2 channel display device, 409: main screen moving image (1 angle), 410: sub screen moving image (2 angle), 43
1 is the sum of the transmission rates of the channel 406, 432 is the sum of the transmission rates of the channel 407, and 433 is the bandwidth of the assumed end user access network.

The MPEG2 moving image server 401 sends, for example, three-angle images from three cameras 404,
The PEG2 moving image transmission rate reduction device 402 receives the three-angle channel 406 and then reduces the transmission rate of the video of an arbitrary predetermined angle on the channel 4
07 to the client 403 side.

By distributing only the video of the angle that the end user wants to view as the main screen at the regular transmission rate and distributing the video of the other angles at a reduced transmission rate, in the above example, FIG. As shown, 6 Mbps +
Multi-angle broadcasting can be distributed in a transmission band of about 1 Mbps × 2 = 8 Mbps.

FIG. 5 shows a flowchart for changing the transmission rate. (Step S1): It is assumed that the end user receives the angle A without transmission rate conversion and the angles B and C with transmission rate conversion.

(Step S2): In this state, the end user transmits a command to the MPEG-2 moving image transmission rate reduction device 402 to change the transmission rate of the angle A and the transmission rate of the angle B without reduction. Suppose you did.

(Step S3): Upon receiving the command shown in step S2, the MPEG2 moving image transmission rate reducing device 402 finds and changes the angle at which the transmission rate should be changed in view of the state of step S1.

(Step S4): As a result, the end user receives the angle A with the transmission rate conversion, the angle B without the transmission rate conversion, and the angle C with the transmission rate conversion. Become.

That is, when the video of the angle to be viewed as the main screen 409 is changed according to the request of the end user according to the flow shown in FIG.
In the second method, the angle video that reduces the transmission rate is changed, the video of the angle newly selected by the user on the main screen is delivered as a complete moving image, and the video of the angle that has been viewed on the main screen until then is It is possible to provide an MPEG2 channel viewing mode in which the “summary” is continuously distributed as a video for the sub-screen 410.

[0033]

As described above in detail, according to the present invention, when distributing an MPEG2 moving image via a high-speed network such as an ATM network, the transmission rate can be reduced to an end user having a small usable transmission band. 1 channel MPEG2 video or 1 channel M
It becomes possible to distribute the MPEG2 moving image and the MPEG2 moving image of one or more channels whose transmission rate is reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a connection relationship of an MPEG2 moving image distribution system.

FIG. 2 (A) shows an example of a best-effort network with M
FIG. 2B is a diagram illustrating the connection relationship of a system that distributes PEG2 channels, and FIG. 2B illustrates functions necessary for a gateway device 203 between a narrowband network and a wideband network in a system that distributes MPEG2 channels to a best-effort network. FIG.

FIG. 3A is a diagram illustrating a connection relationship in an example in which 9 channels are simultaneously distributed in a multi-channel broadcasting system, and FIG. 3B is a diagram illustrating an example in which 9 channels are simultaneously distributed in a multi-channel broadcasting system. It is a figure explaining the introduction effect of a system.

4A is a diagram illustrating a connection relationship in an example in which three angles are simultaneously distributed in a multi-angle broadcasting system, and FIG. 4B is a diagram illustrating a book in an example in which three angles are simultaneously distributed in a multi-angle broadcasting system. It is a figure explaining the introduction effect of a system.

FIG. 5 is a diagram illustrating a flow at the time of main screen switching in an example in which three angles are simultaneously distributed in a multi-angle broadcast system.

[Explanation of symbols]

101 MPEG2 Moving Image Server 102 MPEG2 Moving Image Transmission Rate Reduction Device 103 MPEG2 Moving Image Client 104 Network (Access Network on Information Provider Side) 105 Network (Backbone Network) 106 Network (Access Network on End User Side) 107 Received MPEG2 Channel 108 MPEG2 channel to be transmitted 109 End user side MPEG2 channel display device 110 Main screen moving image 111 Sub screen moving image 112 Control command 201 MPEG2 moving image server 202 MPEG2 moving image transmission rate reduction device 203 Gateway between narrow band network and wide band network Device 204 MPEG2 video client 205 Broadband / bandwidth guaranteed communication network 206 Narrowband / best-effort network H 207 MPEG2 channel to be received 208 MPEG2 channel to be transmitted 209 MPEG2 channel to convert various protocols and send to best-effort network 301 MPEG2 moving picture server 302 MPEG2 moving picture transmission rate reduction device 303 MPEG2 moving picture client 304 ATM network 305 MPEG2 channel to be received 306 MPEG2 channel to be transmitted 307 MPEG2 channel display device for end user 308 Channel search screen 351 Total sum of transmission rate of channel 305 352 Sum total of transmission rate of channel 306 353 Assumed access network of end user side Bandwidth 401 MPEG2 moving image server 402 MPEG2 moving image transmission rate reduction device 403 MPEG Moving image client 404 multi-angle image capturing camera 405 ATM network 406 received MPEG2 channel 407 transmitted MPEG2 channel 408 end user side MPEG2 channel display device 409 main screen moving image 410 sub-screen moving image 431 transmission rate of channel 406 Total 432 Total transmission rate of channel 407 433 Assumed end user access network bandwidth

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04N 7/081 H04N 7/08 Z H04Q 3/00

Claims (2)

[Claims] 1. A system for delivering an MPEG2 moving image via a high-speed network, comprising: a function of receiving an MPEG2 transport stream packet, a function of receiving a control command, and a transmission rate of the MPEG2 moving image, which are arranged in the high-speed network. M comprising: a first device having a function of reducing the power consumption; and a second device having a mechanism for transmitting the control command to the first device.
PEG2 video distribution system. 2. A system for delivering an MPEG2 moving image via a high-speed network, comprising: a function for receiving an MPEG2 transport stream packet, a function for receiving a control command, and a transmission rate for the MPEG2 moving image, which are arranged on the high-speed network. An MPEG2 video distribution system comprising a first device having a function of reducing the number of transmissions, and a second device having a mechanism for transmitting the control command to the first device, wherein an end-user network If the transmission band of the transmission is insufficient, the control command for selecting and controlling the MPEG2 moving image for reducing the transmission rate is transmitted from the second device, and the first device receives the control command and performs control. Characterized in that the transmission rate of MPEG2 video is reduced according to a command. Method.