KR100248894B1 - Method for controlling fast reproducing mode in the icatv - Google Patents

Abstract

The present invention relates to a fast playback mode control method for controlling a fast playback mode by recording information of a bitstream corresponding to a high speed playback in a DTS region of an audio PES packet header in an interactive cable television system. To this end, the method includes a time including position information of a high speed playback bitstream corresponding to a time information region indicating a decoding start corresponding to a predetermined double speed in a time information (DTS) region indicating a decoding start of an audio bitstream in the bitstream. Recording information (FPTS); If fast playback is requested from the set-top unit during the normal playback mode, the server checks whether FPTS is detected in the bitstream transmitted from the time when fast playback is requested; if the FPTS is detected, the FPTS is detected. Changing a file pointer of a bitstream to be transmitted to a position of a fast playback bitstream corresponding to the bitstream; After the file pointer is changed, the server transmits the high speed playback bitstream after the file pointer changed to the set top unit to the set top unit, and performs the high speed playback mode. And setting the FPTS to perform the fast playback mode while decoding the fast playback bitstream transmitted from the server.

Description

High Speed Playback Mode Control Method for Interactive Cable Television System

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fast playback mode control method in an interactive cable television (hereinafter referred to as ICATV) system. A method for controlling a mode.

ICATV is a system that provides Video On Demand (VOD) service. Compression / Restore processing of audio and video transmitted through server, network and network providing VOD service required by subscriber (client). The set-top unit is configured as a basic configuration.

As described above, the ICATV configured as described above is used to service the fast forward (hereinafter abbreviated as FF) playback mode or the fast backward (REWind, abbreviated REW) playback mode as in a general VCR. The stream is created and provided to the server.

That is, if the server has a normal playback bitstream, an FF bitstream, and a REW bitstream for the same program, and the subscriber requests the normal playback service for the corresponding program, first, the normal playback bitstream is sequentially Will be provided. At this time, the server forms a Program Specific Infomation (PSI) table together with the playback position of the bitstream transmitted during normal playback of information on the playback position of the FF bitstream and the REW bitstream corresponding to the corresponding program. Save it.

When the FF playback is requested from the set-top unit while the normal playback bitstream is being transmitted, the FF bitstream is searched by referring to the stored PSI table information, and when the FF bitstream is searched, the transport ( TS) should be sent according to the packet.

For example, when the 40th bitstream is being transmitted as shown in FIG. 1 during normal playback, if FF playback is requested from the set-top unit, the PSI table stored in the server plays the 10th bitstream of the FF bitstream. Since the location information is stored, the server searches for the 10th bitstream on the FF bitstream, and when searched, the server sequentially transmits the bitstream.

The same applies to the playback for REW. Unlike in the case of FF playback, since reverse playback is performed, as shown in FIG. 1, since the structure of the bit stream is arranged in reverse with the FF bit stream, the corresponding bit stream is searched from the rear part.

In this way, the server provided in the existing ICATV for high-speed playback control should form a PSI table for each bitstream transmission, and in order to transmit the transmitted bitstream to the set-top unit 200, the transport packet information must be transmitted according to transport packet information. Therefore, the burden on the server is great at run-time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described drawbacks. In the interactive cable television system, the DTS region of the PES packet header of audio records information of a corresponding bit stream during high-speed playback to control the high-speed playback mode. It is an object of the present invention to provide a regeneration mode control method.

In order to achieve the above object, the high speed playback mode control method according to the present invention includes a predetermined set top unit and a normal playback bit stream and a high speed playback unit to provide a bit stream according to a service required by the set top unit through a network. In a system composed of servers each having a bitstream, high-speed playback corresponding to a time information region indicating a start of decoding corresponding to a predetermined double speed in a time information (DTS) region indicating the start of decoding of an audio bitstream in the bitstream. Recording time information (FPTS) including position information of the for-use bitstream; If fast playback is requested from the set-top unit during the normal playback mode, the server checks whether the FPTS is detected in the bitstream transmitted from the time when the fast playback is requested; as a result of performing the first check step, the FPTS is detected. Changing a file pointer of a bitstream to be transmitted to a position of a fast playback bitstream corresponding to the detected FPTS when the bitstream is transmitted; After the file pointer is changed, the server transmits the high speed playback bitstream after the file pointer changed to the set top unit to the set top unit, and performs the high speed playback mode. Performing a high speed playback mode while setting the FPTS and decoding the high speed playback bitstream transmitted from the server; if the normal playback is requested from the set-top unit during the high speed playback mode, the server is transmitted from the time at which normal playback is requested. A second checking step of checking whether output time information (PTS) of the stream is detected in the bitstream; If the output time information (PTS) of the stream is detected as a result of performing the second check step, changing the file pointer of the bitstream to be transmitted to the position of the FPTS on the normal playback bitstream corresponding to the detected PTS; After the file pointer change is made, the server performing a normal playback mode while transmitting the normal playback bitstream after the file pointer changed to the set top unit to the set top unit; When the normal playback bitstream is transmitted according to the normal playback mode, the set-top unit is characterized by including setting the program clock reference to PTS and decoding the normal playback bitstream transmitted from the server.

1 is a conceptual diagram illustrating a conventional fast playback mode control method;

2 is a schematic block diagram of a typical interactive cable television system;

3 is a flowchart illustrating a method for controlling a fast play mode according to the present invention when switching from the normal play mode to the fast play mode;

4 is a flowchart of a method for controlling a fast play mode according to the present invention when switching from the fast play mode to the normal play mode.

<Description of the code | symbol about the principal part of drawing>

200: set top box (STU) 201, 221: network interface unit

202, 222: control unit 203: decoding processor

204: bit stream buffer 205: instruction grant unit

210: network 220: server

223: storage unit

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

Hereinafter, an embodiment of the present invention for achieving the above object in detail.

FIG. 2 is a schematic block diagram of a typical interactive cable television system. The server providing the requested service from the set-top unit 200 and the set-top unit 200 capable of receiving a service request for a predetermined information and a requested service. 220, a network 210 for transmitting and receiving information between the set-top unit 200 and the server 220.

In particular, the set-top unit 200 includes a network interface unit 201, a bitstream buffer 204 for storing a bitstream transmitted through the network interface unit 201, and a decoding processor 203 for decoding the transmitted bitstream. ), A control unit 202 for controlling all functions of the set-top unit 200, and a command application unit 205 for applying a command of a subscriber, and the server 220 includes a network interface unit 221 and a bitstream ( A control unit for analyzing a request of a predetermined subscriber and a request of a predetermined subscriber and controlling bitstream transmission according to a corresponding service by referring to bitstream information stored in the storage unit 223 ( 222).

3 is a flowchart illustrating a method of controlling a fast play mode according to the present invention when switching from the normal play mode to the fast play mode.

The operation flowchart shown in FIG. 3 will be described in more detail with reference to FIG. 2 as follows.

First, when the server 220 is transmitting a bitstream according to a predetermined service requested by the set-top unit 200 in the normal playback mode, and the set-top unit 200 is decoding the normal playback mode for the received bitstream. When the fast forward direction (hereinafter referred to as FF) regeneration request command is applied through the command application unit 205, the control unit 202 in the set-top unit 200 proceeds from step 301 to step 302 to the server 220. Process to send FF request signal. Accordingly, the FF request signal is transmitted to the controller 222 through the network interface unit 220 on the server 220 side via the network interface unit 201 and the network 200.

When the control unit 222 of the server 220 receives the FF request signal in step 303 while the normal playback bitstream is being transmitted, the control unit 222 proceeds to step 304 and the bitstream in the normal playback mode to be transmitted is FPTS ( Fast Forward Presentation Time Stamp (hereafter abbreviated as FPTS) information. The FPTS is information contained in the DTS region of the normal playback audio bitstream, and stores the PTS of the high speed playback video stream corresponding to the same bitstream. For example, if the fast playback speed is n times the normal playback speed, the FPTS is stored once when the PTS appears n times.

The reason why the FPTS is loaded in the DTS region of the audio bitstream is that the DTS region of the audio exists as an empty region due to the structural characteristics of the MPEG2 stream. That is, there are three types of visual information of the MPEG2 stream. The first is the Decoding Time Stamp (DTS) that indicates the start of decoding the stream, the second is the Presentation Time Stamp (PTS) that indicates the output time of the stream, and the third is the Program Clock Reference (PCR) that serves as their reference. . DTS and PTS are present in the PES header, and PCR is present in the Adaptation Field of the Transport (TS) packet. All three types of visual information apply to both audio and video. In the case of video, the decoding order and output order of the pictures do not match, so all three types of information are used, but in the case of audio, the decoding order and output order are the same. Because it does not use, it exists as an empty area. Accordingly, the normal playback bitstream has a structure in which FPTS information corresponding to the DTS area, which is an empty area of audio, is loaded. At this time, the actual FPTS information is not loaded in the DTS area of all audio, but is loaded according to the corresponding double speed as described above.

As a result of the check in step 304, if the FPTS is not detected, the process proceeds to step 305 where the controller 222 continues to transmit the normal playback bitstream until the FPTS is detected. When the FPTS is detected in step 304, the flow proceeds to step 306 to change the file pointer to a corresponding position of the FF stream, and the flow proceeds to step 307, where the controller 222 proceeds to a routine for transmitting the FF stream to the FF stream. Do the sending process.

On the other hand, the set-top unit 100 transmits the FF request signal to the server and proceeds to step 308 to check whether the FPTS has been received. If the check result is not received, the process proceeds to step 309 and continues checking whether the FPTS is received while continuing decoding in the normal playback mode.

As a result of the check, if the FPTS is received, the process proceeds to step 310, the PCR is set to the FPTS, and the process proceeds to step 311. In operation 311, the audio decoding is stopped from being performed, and in operation 312, the processing proceeds to a decoding processing routine for the received FF stream and performs decoding processing on the FF stream.

On the other hand, Figure 4 is a flow chart of the high speed playback control method according to the present invention when switching from the fast playback mode to the normal playback mode. The operation of the flowchart shown in FIG. 4 with reference to FIG. 2 will now be described in detail.

That is, when the set top unit 200 decodes the FF stream and the server 220 transmits the FF stream, if the normal playback command is applied through the command applier 205 in step 401, the control unit ( 202 proceeds to step 402 to send a PLAY request signal to the server (220).

Accordingly, if the server 220 receives the PLAY request signal in step 403 while transmitting the FF stream, the server 220 proceeds to step 404 to check whether the current bitstream to be transmitted is a new PTS. As a result of the check, if it is not the PTS information, the FF stream is transmitted while iterating through steps 405 and 404 until a new PTS is detected.

When a new PTS is detected while transmitting the FF stream as described above, the controller 222 of the server 220 searches for a position where the PPTS corresponding to the value is stored on the normal playback stream, and moves the file pointer to the corresponding position. Change it. In step 407, the routine for transmitting the normal playback stream is performed. In this manner, the control unit 222 of the server side 220 sequentially transmits bitstream information starting with the FPTS stored in the normal playback bitstream.

On the other hand, the set-top unit 100 transmits a PLAY request signal in step 402, and then proceeds to step 408 to check whether the FPTS is received from the server 220. As a result of the check, if the FPTS has not been received, decoding processing for the transmitted FF stream is continued while iterating over steps 409 and 408 until reception.

As a result, if it is checked in step 408 that the FPTS has been received, the process proceeds to step 410 to set the PCR as a normal playback PTS, and the process proceeds to step 411 to control audio decoding. In step 412, the decoding processing routine for the normal playback stream is processed.

As described above, according to the present invention, in the interactive cable television system, the position information of the corresponding high speed playback bitstream is recorded in the DTS area corresponding to the high speed playback speed among the existing DTS areas on the audio PES, and the normal playback from the subscriber is performed. By changing the file pointer of the bitstream when switching from fast mode to fast playback mode or vice versa, the file stream of the bitstream is changed, thereby reducing the burden on the server side. It has the effect of fast and accurate stream switching.

Although the present invention has been described as the above-described embodiment, those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the fast forward playback mode FF is illustrated in the fast playback mode, but the same applies to the fast reverse playback mode REW. However, it does not implement both REW and FF modes. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (3)

In a system comprising a predetermined set-top unit and a server having a normal playback bitstream and a fast playback bitstream, respectively, to provide a bitstream according to a service required by the settop unit through a network. Time information (FPTS) including position information of a fast playback bitstream corresponding to the time information region indicating the decoding start corresponding to a predetermined double speed among the time information (DTS) regions indicating the decoding start of the audio bitstream in the bitstream. Recording); A first checking step of checking whether the FPTS is detected in the bitstream transmitted from the time point at which the high speed playback is requested, when the high speed playback is requested from the set top unit during the normal play mode; Changing a file pointer of a bitstream to be transmitted to a position of the fast playback bitstream corresponding to the detected FPTS when the FPTS is detected as a result of performing the first check step; After the file pointer change is made, the server performing a high speed playback mode by sending the fast playback bitstream after the file pointer changed to the set top unit to the set top unit; Setting the FPTS on the basis of a program clock and decoding the fast playback bitstream transmitted from the server when the fast playback bitstream is transmitted, and performing the fast playback mode; If normal playback is requested from the set-top unit while the fast playback mode is being performed, the server checks whether the output time information (PTS) of the stream is detected in the bitstream transmitted from the time point at which the normal playback is requested. ; Changing the file pointer of the bitstream to be transmitted to the position of the FPTS on the normal playback bitstream corresponding to the detected PTS when the output time information (PTS) of the stream is detected as a result of performing the second check step; After the file pointer change is made, the server performing a normal playback mode while transmitting the normal playback bitstream after the file pointer changed to the set top unit to the set top unit; When the normal playback bitstream is transmitted according to the normal playback mode, the set-top unit is configured to set a program clock reference to the PTS and to decode the normal playback bitstream transmitted from the server. High speed playback mode control method. The method of claim 1, wherein the fast playback mode control method comprises controlling to stop decoding of the audio in the set-top unit during the switching process from the normal playback mode to the fast playback mode, and from the fast playback mode to the normal playback mode. And controlling the decoding of the audio to be started in the set-top unit when the switching is performed. The method of claim 1, wherein the fast regeneration mode control method is configured to be operated in one of a fast forward regeneration mode and a fast reverse regeneration mode.

Images