KR100212548B1 - Method for deciding the stop/start position of bit stream transmission in a digital storage media command and control system - Google Patents

Abstract

The present invention provides a transport stream of a digital storage media command and control (DSM-CC) system comprising a server providing a transport stream of an image program and a client requesting a transport service command of the transport stream provided by the server. A method for determining a start / stop position, wherein according to the method, a transmission start position of a transport stream transmitted from a server to the client is determined by the size of the transmitted image program and a transmission service command from the client. The transmission start time of the port stream is multiplied by the total running time value of the transmission program, and the transmission stop position of the transport stream transmitted from the server to the client is equal to the size of the transmitted image program. The client It is calculated by multiplying the transmission stop time (rStop) of the transport stream by the total running time value of the transmission program in the transmission service command from the client. You can determine the stop position.

Description

How to determine start / stop position of bit stream in digital storage media command and control system

The present invention relates to a digital storage media command and control (DSM-CC) system, and more particularly, to a method of detecting a start / stop position of a transport stream during a transport stream transport service command in a DSM-CC system.

Since many digital storage media have differently defined control instructions, the user must know a differently defined set of digital storage media control commands to access MPEG bitstreams from different digital storage media.

The digital storage media command and control (DSM-CC) standard established by the ISO to address these shortcomings is based on ISO / IEC 11172 (MPEG-) stored in the media, regardless of what digital storage media is used in the near or remote areas. 1) Bit stream and ISO / IEC 13818 (MPEG-2) A set of protocols that define common operations and control functions for managing bit streams.

These bitstreams consist of a series of packets, each of which has a constant length of 188 bytes. Each constant length packet consists of a header and a payload. The transport header contains useful information, such as time information such as a program clock reference (PCR), which is a system clock transmitted from the encoder to meet the time base at the decoder. The payload contains a data stream whose video and audio streams are truncated to a constant length.

Digital storage media using the DSM-CC protocol have a Video On Demand (VOD) service that enables immediate viewing at the time the television viewer wants to view the video information required. A video on demand (VOD) service composed of a client / server environment consists of a server providing a service and a settop box on the client side. The user on the client side wants to receive the service in the same way as using an existing VCR while receiving the service. Therefore, the user side transmits the play start time and the stop time to the server by using the video playing time like the VCR. At this time, the server determines the screening start position and the stop position of the transport stream with the time information provided from the user side. The method of determining the start / stop position of the transport stream is based on the AppNPT transform algorithm in the DSM-CC system. The AppNPT transform algorithm (1) searches the DSM-CC transport stream to find a sync byte. , (2) find the adaption_field, (3) find the PCR, (4) convert the PCR to decimal time, (5) compare whether the converted time matches the time requested by the user, and (6) match the corresponding packet. (7) If the start position is the play / stop position, and if it does not match, the loop is repeated again from step (1) to check the next packet. This AppNPT conversion algorithm requires a considerable amount of search time and computation since the transport stream is searched from the beginning of every client's command request.

Therefore, an object of the present invention is to provide a method for detecting a transmission start / stop position without retrieving a transport stream when a client requests a transport stream transport service command in a DSM-CC system.

According to the transmission start / stop position determination method of the transport stream of the present invention for achieving the above object, the transmission start position of the transport stream transmitted from the server to the client and the transmitted image program size (size) and The transmission start time of the transport stream from the client is calculated by dividing the transmission start time multiplied by the total running time value of the transmission program, and the transmission stop position of the transport stream transmitted from the server to the client is It is calculated by dividing the value of the image program size (size) to be transmitted and the transmission stop time (rStop) of the transport stream in the transmission service command from the client divided by the total running time value of the transmission program.

1 is a block diagram of a typical VOD system consisting of a server, a network and a client

2 is a flowchart illustrating a method of extracting a transmission start / stop position of a stream when a transport stream transport service command is requested according to the present invention.

* Explanation of symbols for main parts of the drawings

100: server 200: network

300: client

The above and other objects and various advantages of the present invention will become more apparent from the preferred embodiments of the present invention described below with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic block diagram of a VOD system for detecting a transmission start / stop position of a typical transport stream used in the present invention.

The server 100 stores a storage unit 102 for recording an image program, data information, and the like, an MPEG2 stream control unit 104 for standardizing and controlling data stored in the storage unit 102 in the form of an MPEG2 transport stream, and a DSM. A command control unit 106 for executing commands related to the CC protocol, and a network interface 108 for interfacing with the network 200.

The network 200 consists of a session controller 202 that controls the relationship between the network interface 108 of the server and the network interface 302 of the client.

The client 300 is connected to a network device, decodes the network interface 302 for data transmission and reception between the client side and the network 200 and the received data, and displays the decoded data on a display device (not shown). MPEG2 decoder 304 to output to the system, the system control unit 306 for providing the server 100 with the time information of the start (Start) and stop (Trans) of the transmission in the stream transmission service command input from the user of the client .

When a stream transfer service command is requested from the client 300 to the server 100, the server 100 designates a starting position at which to start the stream transmission using a file pointer to perform a client command. The position is represented by an application normal play time (AppNPT) in microseconds indicating a relative absolute position of the stream from the start of the stream. The stream transport service command provided from the client described above is used to transport a stream to play the stream from the start AppNPT position to the stop AppNPT position, and to start the transmission of the stream at the AppNPT position. ), A transport stream pause that stops the stream transmission when the AppNPT position is reached, and a jump instruction that starts at the start AppNPT when the stream reaches the stop AppNPT position.

Now, referring to FIG. 2, a transmission start / stop position detection method of a transmission data stream according to the present invention will be described.

First, the server 100 waits for a transport stream transmission service command such as start / stop / jump / play transport stream transmission from the client 300 (step 10). At this time, the format of the command requested by the client is as follows.

module DSM {

interface Stream {

void pause (in AppNPT rStop);

void resume (in AppNPT rStart, in Scale rScale);

void jump (in AppNPT rStart, in AppNPT rStop, in Scale rScale);

void play (in AppNPT rStart, in AppNPT rStop, in Scale rScale);

};

};

Thereafter, if a transport service command from the client 300 is requested, and the time information regarding the start / stop of the transport stream (rStart / rStop) is provided in the above-described form (step 20), the server 100 Determines the transmission start / stop position using the size and the duration of the information (step 30). At this time, the structure of the information and the size of the server is as follows.

module DSM {

interface Access {readonly attribute u_longlong Size; }

interface Stream: Access {

struct Info_T {

stringDescription;

AppNPT duration; // total running time

boolean audio;

boolean video;

boolean data; };

};

};

According to the present invention, the process of determining the transmission start / stop position by the server 100 is as follows.

Position (u_longlong) = (Size (u_longlong) * rStart (AppNPT)) / Info.duration (AppNPT)

In detail, the transmission start and stop positions of the stream transmitted by the server may include the transmission program size indicated by the (u_longlong) term in the server data format and the start time value (AppNPT) indicated by the rStart term in the client command format. ) Is calculated by dividing the product by the total running time value (AppNPT) indicated by the Info.duration term in the server's data format.

Accordingly, the server 100 performs a command request from the client in search of a transmission start or transmission stop position of the transport stream calculated in step 30 (step 40).

As described above, by calculating the transmission start time information (rStart) or the transmission stop time information (rStop) when the client requests the transmission service by using the transmission program size of the server and the total transmission period (Info.duration), The advantage is that you can find the start / stop position of the stream without having to search the entire stream.

Claims (1)

Start transmission of the transport stream in a digital storage media command and control (DSM-CC) system comprising a server providing a transport stream of an image program and a client requesting a transport service command of the transport stream provided by the server. In the method of determining the stop position, The transmission start position of the transport stream transmitted from the server to the client is calculated by multiplying the transmission start time of the transport stream by the video program size and the transmission service command from the client. By dividing by the running time value, The transmission stop position of the transport stream transmitted from the server to the client is a value obtained by multiplying a transmission stop time (rStop) of the transport stream by the size of the transmitted video program and the transmission service command from the client. A method of detecting the start / stop position of a transport stream in a digital storage media command and control system, characterized by dividing by the total running time value of the transmission program.