KR20030066126A - communication method used in MPEG-4 system - Google Patents

Abstract

PURPOSE: An MPEG-4 system-based communication method is provided to allow a server to know a client's processing environment with respect to streaming data transmitted from the server to the client. CONSTITUTION: A client receives down-streaming data from a server(S300). The client transmits up-streaming data including buffer control information that indicates buffer-related information in the event of processing the down-streaming data to the server(S310). The server transmits down-streaming data, which is reconstructed with reference to the buffer controller information, to the client(S320). The buffer control information includes at least one of buffer status information, status information of a decoding buffer and status information of a composition buffer.

Description

Communication method used in MPEG-4 system

The present invention relates to an MPEG-4 system-based communication method, and more particularly, to an MPEG-4 system-based communication method capable of changing streaming data transmitted by a server according to a client state.

MPEG-4 is a standard for next-generation multimedia proposed and standardized by SG29 WG11 under ISO / IEC. It is not only used for information and distribution of video and audio, but also features such as interactivity provided by MPEG-4. It is possible to apply to various fields by making use of. MPEG-4 is an object-oriented system that can view all the media used in the existing multimedia communication as one object and compose the whole, which has the advantage of being able to process objects independently.

1 is a block diagram illustrating a server and a client based on the MPEG-4 system.

In the block diagram, there is a server 10 and a client 20, and the server 10 and the client 20 exchange data with each other through a downstream channel and an upstream channel. Although only one client 20 is shown in the block diagram, more clients 20 may be connected to the server 10.

The MPEG-4 system defines an MPEG-4 client (or terminal) 20 that integrates audio and visual standards, and uses Real-Time to transmit data in real time between the server 10 and the client 20. Protocol) and the RTCP (RTP Control Protocol) protocol.

RTP is an Internet protocol for transmitting real-time data such as audio and video, and the server 10 transmits RTP packetized streaming data to the client 20 through a downstream channel.

Here, streaming refers to a technology that can process the transmitted data as if it is a continuous and continuous water flow. Streaming technology is gaining in importance with the growth of the Internet because most users do not have fast access lines to download large multimedia files immediately. Using streaming technology, a browser or the like in the client 20 can start expressing the data even before all the files are transmitted.

In order for the streaming to work, the client 20 receiving the streaming data must be able to collect the data and send it as an endless flow to an application that processes the data and converts it into a sound or a picture. This means that if the client 20 receives streaming data faster than necessary, it needs to store the extra data in a buffer. Thus, if the data does not come in fast enough, the representation of the data will not be smooth, and if the data comes in too fast, it will be in a buffer full.

RTP itself, on the other hand, does not support techniques that guarantee timely data delivery or other guarantees of quality of service. Moreover, it guarantees RTP packet delivery, but does not guarantee packet delivery order. However, there is provided an apparatus for transmitting and receiving applications to support streaming data.

In the block diagram, the server 10 receives the reception status of the client 20 side of the streaming data transmitted to the client 20 as an RTCP packet through an upstream channel. In this case, the RTCP packet does not encapsulate audio or video data units. Instead, RTCP packets are sent periodically and include sender reports and / or receiver reports that provide statistics that may be usefully used by the application. This statistic includes the number of packets sent, the number of packets lost, and interval jitter.

However, the MPEG-4 based communication method can process the reception state of the data on the client 20 side, but in the MPEG-4 system environment with many kinds of streaming data, the performance of the client 20 side and the stream for each The situation is not sufficiently transmitted to the server 10.

That is, in the MPEG-4 system environment, since the information transmitted from the client 20 to the server 10 is insufficient as an RTCP packet, the server 10 may change the streaming data transmitted according to the processing environment of the client 20. There is a problem that can not be.

The present invention has been made to solve the above problems, an object of the present invention, in the MPEG-4 system-based communication method consisting of a server and a client, the client processing environment for the streaming data transmitted from the server to the client To provide a communication method that the server can know.

1 is a block diagram of a server and a client based on the MPEG-4 system;

2 is a block diagram of a book and a client for explaining an MPEG-4 system-based communication method according to the present invention;

3 is a flowchart illustrating a method of communication based on an MPEG-4 system according to the present invention.

Explanation of symbols on the main parts of the drawings

100: server 110: transport layer

120: sync layer 130: transceiver

200: client 210: transport layer

220: sync layer 230a to 230n: decoding buffer

240a ~ 240n: Decoder 250a ~ 250n: Synthetic buffer

260: synthesizer

In accordance with an aspect of the present invention, there is provided an MPEG-4 system-based communication method comprising a server and a client having interactivity, wherein the client is downstreamed from the server. Receiving data, and transmitting, by the client, upstreaming data including buffer control information indicating buffer related information when processing the downstreaming data to the server.

In this case, the server may further include transmitting the reconstructed downstreaming data to the client by referring to the buffer related information among the received upstreaming data.

The buffer related information may include at least one of information indicating buffer control information, buffer status information, status information of a decoding buffer, and status information of a synthesis buffer.

In this case, the state information of the decoding buffer includes at least one of the total number of buffers that the stream has, the number of decoding buffers currently used, and the average buffer usage rate of the decoding buffer. In addition, the state information of the synthesis buffer includes at least one of the total number of buffers of the stream, the number of synthetic buffers currently used, and the average buffer utilization rate of the synthesis buffer. Accordingly, an MPEG-4 system-based communication method capable of efficiently controlling the processing performance of the cluster may be provided.

Hereinafter, with reference to the drawings will be described the present invention in more detail.

2 is a block diagram of a book and a client for explaining a communication method based on the MPEG-4 system according to the present invention.

In the block diagram, there is a server 100 and a client 200, a downstream channel is formed from the server 100 to the client 200, and an upstream channel is formed from the client 200 to the server 100. . The server 100 and the client 200 communicate with each other through the downstream channel and the upstream channel, respectively.

The server 100 is internally composed of a transport layer 110, a sync layer 120, and a transceiver 130.

The transceiver 130 configures and transmits data to be transmitted to the sync layer 120 or receives data from the sync layer 120.

The sync layer 120 packages the data received from the transceiver 130. That is, an access unit of a lower medium such as a video or audio frame or a screen description command is packaged, and timing information such as clock reference value and time display, serial number, and the like are added. An access unit refers to data that is displayed at some time. When receiving data from the transport layer 110, the original data is extracted from the packaged data and transmitted to the transceiver 130.

The transport layer 110 is used to mutually communicate data with the client 200. MPEG-4 does not limit the facilities of its own transport layer 110 to be transmitted for various communication environments.

The client 200 internally includes a transport layer 210, a synchronization layer 220, a plurality of decoding buffers (DB) 230a to 230n, decoders 240a to 240n corresponding to each of them, and synthesis. A composition buffer (CB) 250a to 250n and a synthesizer 260 are included.

The role of the delivery layer 210 and the synchronization layer 220 in the client 200 is the same as the role in the server 100.

In the case of the client 200 supporting the MPEG-4 system, the decoding buffers 230a to 230n and the synthesis buffers 250a to 250n corresponding to each object are used for stable operation. The received streaming data is stored in the decoding buffers 230a to 230n before the decoders 240a to 240n decode, and the decoded information is stored in the synthesis buffers 250a to 250n before the synthesizer 260 uses them.

The information stored in the synthesis buffers 250a to 250n is combined with the screen display information in the synthesizer 260 to undergo a rendering step. That is, the result is displayed on the user's monitor, or in the case of audio, the result received from the user's speaker is reproduced.

In such a configuration, management of the decoding buffers 230a to 230n or the synthesis buffers 250a to 250n is important in order to ensure stable operation and a certain level of performance of the client 200, and the decoding buffers 230a to 230n or synthesis are important. In designing the buffers 250a to 250n, an overflow or underflow should be considered.

The management of the decoding buffers 230a to 230n or the synthesis buffers 250a to 250n may also be utilized as a means for obtaining a better quality of service (QoS). For example, if there is sufficient space in the decoding buffers 230a to 230n or the synthesis buffers 250a to 250n, the enhanced stream may be requested to the elementary stream. Therefore, the processing performance of the client 200 can be predicted by the states of the decoding buffers 230a to 230n or the synthesis buffers 240a to 240n.

Therefore, QoS can be improved by including the information of the decoding buffers 230a to 230n or the synthesis buffers 240a to 240n in the upstreamed data transmitted from the client 200 to the server 100.

3 is a flowchart illustrating a data communication method according to the present invention.

First, the server 100 transmits downstreaming data through the downstream channel to the client 200 (S300).

The client 200 which receives the downstreaming data processes this, and the buffer control information indicating the state of the decoding buffers 230a to 230n, the synthesis buffers 250a to 250n, and the like at the time of processing is added to the periodic upstreaming data. Included and sent back to the server 100 (S310).

In this case, the buffer control information included in the upstream data transmitted to the server 100 may be as follows.

Command ServerCommandType = Buffer_control_Command

Buffer Buffer_Status = OD_ID, ES_ID, DB_Status, CB_Status

DB_Status = totalBufferCount, currentUsedBuffer, averageBufferUsage

B CB_status = totalBufferCount, currentUsedBuffer, averageBufferUsage

The buffer related information is described in detail as follows.

Command ServerCommandType = Buffer_control_Command

In MPEG-4, the structure of the screen presented to the viewer is called a scene, and in the MPEG-4 system part, BIFS (Binary Format for Scenes) is standardized as a scene description language for specifying an object display method and characteristics.

The buffer control information is transmitted to the server 100 by using the SeverCommandType node defined in BIFS. To indicate that the buffer control information is defined, SeverCommandType is defined as Buffer_Control_Command.

Buffer Buffer_Status = OD_ID, ES_ID, DB_Status, CB_Status

Shows the buffer status information. Here, OD_ID represents an object descriptor ID (Object Descriptior ID). Nodes referring to video and audio streams in scene descriptions specify a 10-bit identifier called the object descriptor ID.

ES_ID represents an ES descriptor ID (Elementary Stream Descriptor ID). An ES descriptor is required for each stream when the video and audio streams are scalable encoded and divided into a plurality of streams. The ES descriptor of each stream is identified by the 16-bit ES_ID.

DB_Status indicates the states of the decoding buffers 230a to 230n, and CB_Status indicates the states of the synthesis buffers 250a to 250n.

DB_Status = totalBufferCount, currentUsedBuffer averageBufferUsage

Indicates state information of the decoding buffers 230a to 230n. Here, totalBufferCount represents the total number of buffers the stream has, currentUesdBuffer represents the number of decoding buffers 230a to 230n currently used, and averageBufferUsage represents the average buffer utilization of the decoding buffers 230a to 230n.

B CB_status = totalBuffer currentUsedBuffer avaeageBuffer

The state information of the synthesis buffers 250a to 250n is shown. Here, totalBufferCount represents the total number of buffers the stream has, currentUesdBuffer represents the number of synthetic buffers 250a to 250n currently used, and averageBufferUsage represents the average buffer utilization of the synthetic buffers 250a to 250n.

Receiving such buffer control information, the server 100 reconstructs and changes the downstreaming data with reference to this (S320).

By this communication method, the server 100 can know the performance of the client 200 in the decoding and synthesizing step of the streaming data, independently of the transmission situation of the streaming data, with reference to the buffer control information.

For example, if a delay occurs due to the performance of the client 100 in decoding and synthesizing streaming data, each frame sends only intraframe, which uses its own information without relying on information of another adjacent frame. In this case, transmission of enhanced stream information can be stopped.

On the contrary, when the streaming data transmission situation and the performance of the client 200 are sufficient, the server 100 may provide a higher quality service to the user of the client 200, and various other applications may be considered. .

As described above, according to the present invention, the buffer control related information can be provided to the server on the client side, thereby improving the QoS. In addition, the server can manage the quality of the streamed service in a better way using the buffer control information.

In addition, although the preferred embodiment of the present invention has been shown and described above, the present invention is not limited to the specific embodiments described above, but the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Of course, various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

Claims (5)

In the communication method based on MPEG-4 system having a server and a client having interactivity, The client receiving downstreaming data from the server; And transmitting, by the client, upstreaming data including buffer control information indicating buffer related information when processing the downstreaming data to the server. The method of claim 1, And transmitting, by the server, the downstreamed data reconstructed with reference to the buffer control information among the received upstreamed data to the client. The method according to claim 1 or 2, The buffer control information includes at least one of information indicating that the buffer control information, the buffer status information, the status information of the decoding buffer, and the status information of the synthesis buffer. The method of claim 3, wherein The state information of the decoding buffer includes at least one of the total number of buffers of the stream, the number of decoding buffers currently used, and the average buffer utilization rate of the decoding buffer. Way. The method of claim 3, wherein The state information of the synthesized buffer includes at least one of the total number of buffers of the stream, the number of synthesized buffers currently used, and the average buffer utilization rate of the synthesized buffer. Way.