KR20030039595A - Method for reproducing digital broadcasting program data - Google Patents

Abstract

The present invention relates to a method for reproducing digital broadcast program data, and more particularly, to an MPEG transport stream (TS) recorded and stored on a recording medium such as a hard disk (HDD) included in a digital broadcast receiver such as a set-top box (STB). Create and record a search information file (Index File), search for a data recording position corresponding to an arbitrary playback request time selected by the user using the search information recorded in the search information file, and then record the data recording position. By performing the playback operation from, it is a very useful invention that can be a trick-based play (Time Based Trick Play) operation based on the time selected by the user, to maximize the convenience of use.

Description

How to play digital broadcast program data {Method for reproducing digital broadcasting program data}

The present invention provides a digital broadcast program in a digital broadcast receiver such as a set top box that receives and transmits a digital broadcast program to an external connected device and records and stores the same on a recording medium such as a hard disk (HDD). The present invention relates to a data reproduction method.

In conventional analog television broadcasting, a video signal is transmitted through radio wave and wired cable by AM modulation or FM modulation, but recently, digital television broadcasting has been developed according to the development of digital technologies such as digital image compression and digital modulation / demodulation. Standardization and commercialization are rapidly progressing, and conventional terrestrial, satellite, and cable broadcasting are also being digitized based on the Moving Picture Experts Group (MPEG).

On the other hand, the digital broadcast as described above, according to the development of digital video / audio compression technology and digital transmission technology can provide a higher quality broadcast service than the analog broadcast signal service, in particular multiplexing and transmitting a plurality of broadcast programs in the same bandwidth And it has an advantage that can greatly increase the interoperability with digital communication media and digital storage media.

In the digital broadcast, a plurality of broadcast programs encoded on the basis of MPEG are multiplexed and transmitted in a transport stream, and the transport stream is a digital receiver such as a set-top box (STB) installed at a receiving side. A plurality of broadcast programs received by the broadcast receiver and included in the transport stream are demultiplexed.

Therefore, only one broadcast program desired by the user can be selected, and in a digital broadcast receiver such as the set-top box, the selected broadcast program is restored to the original audio and video signal by using a decoder provided in the receiver. After that, the output is transmitted to an A / V output device such as a general television.

Recently, a large capacity hard disk (HDD) is additionally provided in a digital broadcast receiver such as the set-top box, and a program recorded on the hard disk is stored and stored on the hard disk. According to the user's request, it is expected that a digital broadcast receiver having a digital broadcast recording / reproducing function for reproducing and outputting a broadcast program recorded on the hard disk will be developed and released.

However, in the digital broadcast receiver equipped with the digital broadcast recording / playback function as described above, the digital broadcast program recorded and stored on the hard disk is corresponding to the playback request time according to an arbitrary playback request time that the user selects and designates. There is no efficient solution for trick play for searching and reproducing and outputting data recording positions, and thus, there is an urgent need for providing a solution.

Accordingly, the present invention was created in view of the above situation, and an MPEG transport stream (TS) recorded and stored on a recording medium such as a hard disk (HDD) included in a digital broadcast receiver such as a set top box (STB). For Time Based Trick Play, which generates and records an index file for a file and searches for and outputs a data recording position corresponding to an arbitrary playback request time selected by a user. It is an object of the present invention to provide a method for reproducing digital broadcast program data.

1 illustrates header information included in a general MPEG transport packet (TSP),

FIG. 2 illustrates a correlation between a typical PES packet and a transport packet TSP.

3 is a block diagram of a digital broadcast receiver to which a digital broadcast program data reproducing method according to the present invention is applied;

4 illustrates a configuration of an index file generating unit according to the present invention.

5 illustrates a process of generating a search information file according to the present invention;

6 and 7 are graphs showing a statistically calculated comparison of data separation distances between data recording positions corresponding to search information according to the present invention;

8 to 10 illustrate an embodiment of a digital broadcast program data reproduction process according to the present invention.

※ Explanation of code for main part of drawing

10: Demultiplexer 11: Parser

12: buffer memory 13: hard disk

14 descrambler 15 decoder

16: micom 17: index file generation unit

170: header information detector 171: index information recorder

172: clock generator 173: index file generator

In accordance with another aspect of the present invention, there is provided a method of reproducing digital broadcast program data, the recording position of corresponding transport packets according to payload unit start indication information included in header information of transport packets constituting a transport stream. Generating and storing the index information as index location information, respectively; Calculating display time between recording positions of the index position information; Searching for index position information corresponding to the requested time based on the calculated display time and the trick play time requested based on the time; And performing a data reproducing operation by jumping to the recording position of the transport packet corresponding to the index position information.

Hereinafter, exemplary embodiments of a method of reproducing digital broadcast program data according to the present invention will be described in detail with reference to the accompanying drawings.

First, in the discovery information recording operation according to the present invention, in order to identify discovery information generation and optimal random access unit for the MPEG transport stream (TS) recorded and stored on a hard disk (HDD) included in the digital broadcast receiver As shown in FIG. 1, 4 bytes of header information of a 188 byte transport packet (TSP) including 4 bytes of header information and 184 bytes of payload are included. The 1-bit Payload Unit Start Indicator (PUSI) information is read and confirmed.

As a result of the check, when the 1-bit PUSI information is set to '1', it indicates that the first byte of the packetized elementary stream (PES) packet starts at the payload of the corresponding transport packet (TSP), If the 1-bit PUSI information is set to '0', it indicates that there is no PES packet newly started at the payload of the transport packet TSP.

That is, when the PUSI information is set to '1', a GOP (Group Of Picture) unit including at least one or more I-pictures at the head is divided into one packet, or The first byte of a PES packet defined to partition an I-picture, a P-picture (Predictive Picture), or a B-picture (Bidirectionally Predictive coded Picture) into a single packet is the first byte of the corresponding transport packet. It can be seen that the starting compartment is located in the payload.

For example, as shown in FIG. 2, the PUSI information recorded in the header information of the first transport packet TSP1 is '1', and then recorded in the header information of the seventh transport packet TSP7. When the PUSI information is '1', one PES packet divided into geo-pi or picture units is separately recorded in the payloads of the first to sixth transport packets TSP1 to TSP6. You will know.

As described above, the data length between transport packets TSP1 and TSP7 having PUSI information set to '1', or a time interval for detecting PUSI information of '1', respectively. Is statistically different from each other depending on whether the PES packet is partitioned by a GOP unit or by a picture unit.

For example, when the PS packet is partitioned in units of geopis, the spacing data length or time interval has a relatively long data length or time interval as compared to the case where the PS packet is partitioned in picture units. Since the data lengths or time intervals are statistically compared, it is possible to confirm whether the PS packet is divided into a geopi or a picture unit.

Accordingly, the search information for random access to the recording position of the transport packet in which the PUSI information is set to '1' is generated and recorded as index information, and the index information is the first recording position in the unit of geopy. It is possible to additionally record additional identification information or to generate and record different file names of the index file so as to identify whether the index information indicates the index information or the index information indicating the head recording position of each picture unit.

For example, when the index information is search information indicating the head recording position in units of geopi, the file name of the index file is designated as 'G_Index.xx', and the index information indicates the head recording position in picture units. In the case of the search information, the file name of the index file is designated as 'P_Index.xx' and recorded and stored on the hard disk.

On the other hand, if the PS packet is divided into picture units, the data length or time interval is statistically different from each other depending on whether the PS packet corresponds to an I-picture, a P-picture, or a B-picture. Differently detected.

For example, when the PS packet corresponds to an I-picture in a picture unit, the spacing data length or time interval is a relatively longer data length than when the PS packet corresponds to a P-picture or If the PS packet corresponds to the P-picture, the PS packet has a relatively longer data length or time interval than that of the B-picture.

Therefore, after discriminating and checking the type of the PS packet partitioned by the picture unit, identification information for identifying the type of the packet can be recorded in association with the corresponding index information. In this case, the PS packet is fixed to one of a geopi unit and a picture unit to be transmitted.

On the other hand, after detecting the optimal random access unit for the MPEG transport stream (TS) recorded and stored on the hard disk (HDD) through the above process, the index file corresponding to the random access unit (Index File) The following describes the generation recording operation in detail.

FIG. 3 schematically shows a configuration of a digital broadcast receiver to which the present invention is applied. The digital broadcast receiver includes a multi-program transport stream (MPTS: Multi-Program TS) multiplexed with a plurality of digital broadcast programs. A demultiplexer 10 for selectively outputting a transport stream (SPTS: Single Program TS) of any one of the following: A parser (11) for separately outputting 188-byte transport packets constituting the transport stream of any one single program and header information of the transport packet; A buffer memory 12 for temporarily storing a transport packet output through the parser and then storing the transport packet on a hard disk 13 in units of a predetermined recording size; A descrambler 14 for decrypting the encrypted data when the transport packets temporarily stored in the buffer memory are scrambled encrypted data; A decoder 15 for decoding unencrypted data and restoring and outputting the original video and audio signal; An index file generation unit (17) for generating an index file for randomly accessing a transport stream recorded and stored in the hard disk (13) based on the header information separately output through the parser; And, according to the user's request, it can be configured to include a microcomputer 16 for controlling the operation of each component means to perform the reproduction or shift reproduction operation for the transport stream recorded on the hard disk.

On the other hand, when the recording capacity of the hard disk 13 is 40 GBytes, theoretically, the MPEG transport stream transmitted and received at a maximum of 16 MBps can be recorded and stored for about 330 minutes, and the index file generator 17 The generated index file is recorded and stored in the hard disk in association with the MPEG transport stream.

In addition, the microcomputer 16 operates and controls the respective constituent means so that any one digital broadcast program selected by a user and an index file for randomly accessing a transport stream of the broadcast program are stored in the hard disk ( 13), and when the user selects and specifies an arbitrary playback request time, the playback for searching and outputting the data recording position corresponding to the playback request time on the basis of the index file and then outputting the data. Control operation, that is, time based trick play operation is controlled.

The index file generation unit 17 detects and confirms the header information of 4 bytes separately output through the parser 11 as shown in FIG. 4, and then, as described above with reference to FIGS. 1 and 2. As described above, when the PUSI information is set to '1', the header information detector 170 outputs a detection signal informing of this; According to the detection signal, the recording position at which the transport packet TSP is recorded is recorded as index position information (Index_Add), and time information (Index_Time) counted at that time is additionally recorded in the index file as management information. Index information recorder 171; A clock generator 172 for providing a clock required for generating and recording the index position information; The index file generator 173 may include an index file generator 173 that checks whether the index position information is search information for random access in units of a GOP or picture, and generates an index file of a file name for identifying the index information. Can be.

Accordingly, in the header information detector 170, when the PUSI information included in the header information of the transport packet (TSP) is set to '1', for example, as shown in FIG. When the PUSI information included in the header information of the transport packet TSP1 is set to '1', a detection signal for informing this is output to the index information recorder 171, and the index information recorder 171 The recording position of the first transport packet TSP1 recorded and stored in the hard disk 13 is recorded as first index position information Index 1_Add, which is then included in the header information of the seventh transport packet TSP7. When the configured PUSI information is set to '1', the header information detector 170 outputs a detection signal for informing this to the index information recorder 171, and the index information recorder 171, Above And performs a series of operations for the recording position of the disc record stored in the seventh transport packet (TSP7) to 13 which is recorded in the second index information (Index 2_Add) repeat,

Meanwhile, the index information recorder 171 counts a time interval in which the PUSI information is detected as '1', respectively, as described above, and allows the geo-program to randomly access the digital broadcast program received through the current broadcast channel. Index time information (Index_Time) required to reproduce picture units is generated and additionally recorded in the index file as management information together with information representing a current broadcast channel, that is, broadcast channel information BS_Channel.

For reference, the broadcast channel information and the index time information may be recorded and stored separately from the index file. In this case, link information for linkage with the corresponding index file may include the broadcast channel information and the index time. An additional record shall be recorded with the information.

In the index file generator 173, when a signal for requesting index file recording is received from the microcomputer 173, for example, when the user requests to play a broadcast program recorded and stored on the hard disk 13, A signal requesting generation and recording of the index file from the microcomputer 16 may be output to the index file generator 173, in which the index file generator may transmit the signal to the index information recorder 171. After calculating statistically the respective data lengths (Data Length) between the index position information generated and recorded, the average data length, as shown in Fig. 6, the preset reference data length, for example 150 KByte It is compared with the threshold of.

When the statistically calculated average data length exceeds the reference value, the index file generator determines that the index location information is index location information for random access in a GOP unit, and the statistical As shown in FIG. 7, when the calculated data length is less than the reference value, it is determined that the index position information is index information for random access on a picture basis.

Meanwhile, when it is determined that the index position information is index information for random access on a picture basis as described above, in the index file generator 173, as described above with reference to FIGS. 1 and 2, between the index position information After calculating each of the spaced apart data lengths and comparing them with each other, the head index position information having the relatively longest data length is determined as the recording position of the transport packet corresponding to the head of the I-picture. Recording position of the transport packet corresponding to the beginning of the P-picture with the head index position information having a long data length, and recording position of the transport packet corresponding to the beginning of the B-picture with the head index position information having the shortest data length. And the identification information to identify the type of the corresponding picture, and on the index of the picture unit Information, generates a 'P_Index.xx' file, is recorded and stored in the hard disk 13.

When the index file generator 173 determines that the index position information is index position information for accessing a transport stream in a GOP unit, a file name distinguished from the 'P_Index.xx' file For example, a 'G_Index.xx' file is generated and stored in the hard disk 13.

For reference, a file name of an index file recorded on the hard disk may be generated and recorded as another various file names, and in the index file generator 173, 'P_Index. xx 'and' G_Index.xx 'files are created and recorded with the same file name as' Index.xx', and a separate file can be used to identify whether the index file is search information for accessing the geopi unit or picture unit. The identification information may be additionally recorded in the file.

Hereinafter, a preferred embodiment of a data reproduction method in a digital broadcast receiver according to the present invention will be described in detail.

First, as illustrated in FIG. 8, for example, an index file having a file name of 'G_Index.xx' may be recorded in association with a transport stream of a broadcast program corresponding thereto. In addition, broadcast channel information (BS_Channel) and index time information (Index_Time) may be additionally recorded as management information in the index file. Index position information recorded in the index file includes the transport stream in units of geopees. It is recorded as index position information (GOP_Add) for random access. Since the index position information indicates the first transport packet of each geophysical unit, the first transport of the I-picture corresponding to the beginning of each geophysical unit is eventually obtained. The recording position of the packet is indicated.

On the other hand, in the microcomputer 16, when the user requests to play a time-based trick play (Time Based Trick Play), for example, to search and play the recording position of 'one minute before' from the data recording position currently being played. In the case of selection and designation, the presentation time stamp (PTS) recorded in the payload of the transport packet descrambled by the descrambler 14 is searched and read to confirm the PTS information. The PTS information is time information defined to reproduce and output the access unit when the MPEG system matches the STC (System Time Clock), which is a synchronous clock inside the reference decoder, and the microcomputer 16 confirms this. Thus, the data recording position corresponding to the reproduction request time requested by the user is searched.

That is, when the presentation time information has a time value corresponding to '50min', and the index time information additionally recorded as management information in the index file has a time value corresponding to '1 sec', the microcomputer 16 generates information. After jumping from the specific index position information (GOP 65_Add) corresponding to the current data recording position to the index position information (GOP 5_Add) before the 60th (60 X 1sec = 1 min), the jumped index position information is The data recording position to be indicated, that is, the first I-picture in the 60th-previously recorded Geophysical unit is searched and reproduced.

On the other hand, in the hard disk 13, as shown in FIG. 9, an index file having a file name of 'P_Index.xx' can be recorded in association with a transport stream of a broadcast program corresponding thereto. In the file, broadcast channel information BS_Channel and index time information Index_Time may be additionally recorded as management information.

The index position information included in the index file may be recorded as index position information Pic_Add for randomly accessing the transport stream on a picture basis, and the index position information may correspond to a head trans of each picture unit. Since the port packet is indicated, the recording position of the first transport packet corresponding to the head of each picture unit is eventually indicated.

Therefore, as described above, when the user requests playback of Time Based Trick Play, for example, selects to search and play the recording position of 'one minute before' from the data recording position currently being played. In this case, the PTS information included in the payload of the descrambled transport packet is read and checked through the descrambler 14 to search for a data recording position corresponding to the reproduction request time requested by the user. do.

That is, when the presentation time information has a time value corresponding to '50min' and the index time information additionally recorded as management information in the index file has a time value corresponding to '1/30 sec', the microcomputer ( In 16), jump from the specific index position information corresponding to the current data recording position to the index position information before the 1800th (1800 X 1/30 sec = 1 min).

Then, it is checked whether the jumped index position information is index position information corresponding to the I-picture. If the result of the check is not an I-picture, for example, as shown in FIG. 9, when it corresponds to a B-picture, index position information indicating the nearest I-picture is searched for, and the The first transport packet of the I-picture indicated by the index position information is read and reproduced.

Therefore, while the user plays back and watches the broadcast program recorded on the hard disk 13, the user selects and designates a desired data recording position based on time, so that the playback operation can be performed from the recording position corresponding to the corresponding time. You can do it.

On the other hand, if the data recording position corresponding to the playback request time selected and selected by the user is different from the broadcast program at the data recording position currently being reproduced and output, as shown in FIG. The broadcast program 1 recorded and stored through the broadcast channel #N, wherein the random access unit is a picture unit, and the data at the recording position requested by the user is the broadcast program 2 recorded and stored through the broadcast channel #K, and the random access unit is the geopi unit. In this case, the index time information (Index_Time = S seconds), which is the playback time in units of the geophysical unit corresponding to the broadcast program 1, and the index time information (Index_Time = P seconds, which is the playback time in the unit of the picture corresponding to the broadcast program 2; , P <S) will have different time values.

Accordingly, the microcomputer 16 searches and compares broadcast channel (BS_Channel) information additionally recorded in the index file of each broadcast program, and then records data requested by the user as described above with reference to FIGS. 8 and 9. The index position information for searching the position is searched differently by dividing each broadcasting program, and then searching and playing the data recording position indicated by the index position information, that is, the head I-picture of a specific geopi unit of the broadcasting program 1 Will print.

On the other hand, when the index position information searched through the above process is information indicating the head of the B-picture unit, as described above with reference to FIG. 9, the nearest I-picture is indicated earlier. Index position information is retrieved, and the first transport packet of the I-picture indicated by the index position information is read and reproduced.

For reference, the index file may be generated and recorded without being distinguished in units of geopi or pictures, and the end position information may be alternatively recorded instead of the head start position information of a random access unit.

In addition, one geop may be typically composed of 12 pictures, and the playback time of each picture may be reproduced or outputted at 25 frames or 50 fields per second, or at 30 frames or 60 fields per second. Therefore, it is possible to calculate the reproduction time required for each picture based on this.

In addition, the number of pictures included in one GOP may detect and count information of recorded picture start code (Picture_start_Code) including payload of the transport packet to determine the number.

The above-described preferred embodiments of the present invention are disclosed for purposes of illustration, and within the technical spirit and scope of the present invention disclosed in the appended claims, various other embodiments are improved, changed, replaced Or addition may be possible.

The digital broadcast program data reproducing method according to the present invention constituted and constructed as described above includes an MPEG transport stream recorded on a recording medium such as a hard disk (HDD) included in a digital broadcast receiver such as a set-top box (STB). After generating and recording a search information file (TS) for TS) and searching for a data recording position corresponding to an arbitrary playback request time selected by the user using the search information recorded in the search information file, By allowing the playback operation to be performed from the data recording position, a time-based trick play operation can be performed on the basis of the time selected by the user, which is a very useful invention that can maximize the convenience of use.

Claims (4)

In the digital broadcast program data reproduction method, Generating and storing the recording positions of the corresponding transport packets as index position information according to the payload unit start indication information included in the header information of the transport packet constituting the transport stream; Calculating display time between recording positions of the index position information; Searching for index position information corresponding to the requested time based on the calculated display time and the trick play time requested based on the time; And And performing a data reproduction operation by jumping to a recording position of a transport packet corresponding to the index position information. The method of claim 1, In the step 1, the data separation distance or the generation time interval between the index position information is statistically calculated and checked to determine whether the index position information indicates a recording position in picture units or a recording position in geopi units. And additionally recording information for identifying the discrimination result after the discrimination. The method according to claim 1 or 3, In the second step, when the index position information indicates a recording position in picture units, a display time is calculated by distinguishing whether the picture unit is a frame or a field, and the index position information is a recording position in geopi units. In the case of indicating, the number of pictures per one geopie and the display time per one picture, characterized in that for calculating the digital broadcast program data. The method of claim 1, In the index location information file including the index location information, each of the generated index location information, digital broadcast channel information, number of pictures per geoppy, display time information per picture, and corresponding program time information are recorded. Digital broadcast program data reproduction method characterized in that.