KR100797474B1 - Record-Playback system of Digital Audio and Video Stream - Google Patents

Abstract

The present invention relates to a method and apparatus for storing / playing a digital stream without a time stamp inserted therein.

A storage unit for storing a stream to which a time stamp is not inserted and index information required for reproduction from the stream; Select a picture type to be played by referring to index information of a digital stream to be stored stored in the storage, set an initial value of a system time clock (STC) corresponding to the picture, and search for a start position of the video / audio packet data to be played. And a playback section for transmitting for decoding for reading; A decoder unit for storing the packet data transmitted through the reproduction unit in a buffer and decoding the stored packet data; And a control unit for outputting a signal for controlling a bit rate of the packet data transmitted from the reproduction unit according to the buffer state of the decoder unit. According to the present invention, there is an advantage of preventing errors and waste of storage space caused by inserting and storing time stamps in a digital stream.

Timestamp, buffer overflow, data packet, digital stream, broadcast receiver

Description

Method for storing / playing digital streams and apparatus therefor {Record-Playback system of Digital Audio and Video Stream}

1 is a schematic internal configuration diagram of a digital broadcast receiver according to the application of the present invention;

2 is a flow chart illustrating a digital stream storage / playback method in accordance with the application of the present invention.

Figure 3 is a state diagram showing the correlation between the index information and the position where the packet data is stored in the recording apparatus according to the application of the present invention.

4 is a state diagram showing a method of extracting a reference PCR (Program Clock Reference) according to the application of the present invention.

5 is a graph illustrating a state of a video buffer according to packet data transmission according to the present invention.

The present invention relates to an apparatus for storing / reproducing a digital transport stream, and in particular, an apparatus capable of storing the transport without inserting a time stamp in each transport packet and efficiently performing clock recovery and buffer state control of a decoder during reproduction. It's about how.

In general, the data format of the Moving Picture Expert Group (MPEG) system standard, which is widely used as a digital video compression and transmission system, is divided into a program stream and a transport stream.

The program stream is used for a storage medium having less error in transmission, and the transport stream is used for digital broadcasting. In this case, unlike the program stream having no fixed data packet length, the transport stream has a constant packet transmission unit having a size of 188 bytes.

That is, according to the MPEG system standard, a transport packet has a packet structure of a constant size of 188 bytes. In general digital broadcasting, digital broadcasting is serviced according to this standard.

Recently, a personal video recorder (PVR) device capable of storing and playing transport streams using a large storage medium such as a hard disk (HDD) has been in the spotlight. It is spreading regardless of a broadcasting system using a multiplexing system that is outside the MPEG standard.

The PVR can be used for simple video recording and playback, as well as for instant pause and slow forward, fast reverse, slow reverse play, nonlinear play, and the like. Provide the function.

Conventional digital stream storage / reproducing apparatus inserts a timestamp indicating an input time point into a transport stream packet, and is used for clock recovery and reproduction bit rate adjustment when reproducing the digital stream.

The digital stream storage / playback apparatus according to the prior art may cause an error in a timestamp recorded due to damage due to scratching or the like of a digital stream storage medium that may occur at the time of inserting a timestamp or an error during reading or writing of the storage medium. In this case, there is a problem that the screen or the voice of the program is not reproduced smoothly by causing an underflow or an overflow of the bitstream buffer.

In addition, the digital stream storage / playback apparatus according to the prior art has a problem of an increase in storage space due to the insertion of a timestamp and a poor playback due to an error of a timestamp that may occur during a writing or reading process.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to increase the storage space by inserting and storing a timestamp in a digital stream, and to play back poorly due to a timestamp error that may occur during a read / write process. The present invention provides a method of storing / playing a digital stream to prevent a problem.

One feature of the broadcast receiver according to the present invention for achieving the above object is,

A storage unit for storing a digital stream having no time stamp inserted therein and index information required for reproduction from the stream; Select a picture type to be played by referring to index information of a digital stream to be stored stored in the storage, set an initial value of a system time clock (STC) corresponding to the picture, and search for a start position of the video / audio packet data to be played. And a playback section for transmitting for decoding for reading; A decoder unit for storing the packet data transmitted through the reproduction unit in a buffer and decoding the stored packet data; And a controller for outputting a signal for controlling a bit rate of packet data transmitted from the reproduction unit according to the buffer state of the decoder unit.

In addition, one feature of the digital stream storage / playback method according to the present invention for achieving the above object,

Storing a digital stream having no time stamp inserted therein and index information required for reproduction from the stream; Setting a playback mode to play the stored digital stream; Setting an initial value of a system time clock (STC) corresponding to a picture to be reproduced according to the set mode; Transmitting the decoded packet data for decoding; Temporarily storing the transmitted packet data in a buffer; And controlling the bit rate of the transmitted packet data according to the buffer state.

More preferably, the index information includes a type of each picture that is a program access unit from the stream, a picture index that is a start point of packet data of the picture, a reference program clock reference (PCR) value that is system clock information of the picture, and the like. do.

More preferably, the playback mode is simple video recording and playback (Record-Play), Pause-Resume, Time-shifting Play, Fast Forward, Slow Playback (Slow) Forward, Fast Reverse, Slow Reverse Play, Nonlinear Play.

More preferably, the STC initial value is set using a reference PCR value of a picture to be reproduced.

More preferably, the reference PCR index information is stored after initializing the PCR (ORG) value indicating the PCR value transmitted by the PCR packet before the input of the packet data to be stored and the STC counter of the download control unit. It is calculated as the sum of the D (PCR) values, which is the value incremented by the system clock until the point of time of packet data entry.

More preferably, the packet data transmission step refers to the input buffer state of the audio decoder and the video decoder until the buffer is in a full state, and transmits the packet data when the buffer is in the full state. Control to stop.

More preferably, after stopping the packet transmission, the method may further include checking the buffer status and releasing the interruption according to the buffer status.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of the accompanying drawings.

Hereinafter, with reference to the accompanying drawings illustrating the configuration and operation of the embodiment of the present invention, the configuration and operation of the present invention shown in the drawings and described by it will be described by at least one embodiment, By the technical spirit of the present invention described above and its core configuration and operation is not limited.

1 is a schematic internal configuration diagram of a digital broadcast receiver according to an application of the present invention, and FIG. 2 is a flow diagram illustrating a digital stream storage / reproduction method according to an application of the present invention.

Referring to FIG. 1, a broadcast receiver according to an embodiment of the present invention includes a key input unit 110, a program filter 120, a control unit 140, a storage unit 140, a playback unit 150, and a decoder unit 160. Include.

The key input unit 110 receives a program selection signal input by the user. The input signal is transmitted to the program filter 120 through the controller 130, and the program filter 120 receiving the signal filters the corresponding program according to the selection signal and stores the program in the storage 140. .

The storage unit 140 stores the packet data filtered by the program filter 120 at a designated position without inserting a time stamp. In addition, the storage unit 140 extracts the reference PCR and the picture index of the stored packet data and transfers the extracted picture indexes to the control unit to be used for reproduction. In addition, the storage unit 140 processes the digital stream in packet units that can be decoded by the decoder unit 160 during reproduction.

In general, a video stream transmitted by digital broadcasting among video data stored in the storage 140 has a system structure of a transport packet, and may be 188 bytes (ie, an MPEG standard transport packet) or 130 bytes (DSS standard). Transport packet), and has various packet sizes. In addition, a video stream obtained through a network such as the Internet has a system structure of a transport stream or a program stream. Video streams recorded on existing storage media of DVDs and VCDs have a system structure of program streams.

Other types of digital video streams other than the above-mentioned digital video streams can also be reproduced by the method proposed by the present invention if they have a packet structure and size of the MPEG standard or the like.

The controller 130 sets an operation mode of each device or controls an organic state between the devices.

In addition, the controller 130 starts playback, and when a program to be stored is selected by the user, the controller 130 sets the PCR PID, video PID, and audio PID corresponding to the program to be stored in the storage unit, and stores the program. Search for index information including the storage location of the control unit and set the location in the playback unit 150 to control playback.

The reproduction unit 150 uploads the data packet of the program using the related information set by the control unit 130, transmits the data packet to the decoder unit 150, and reproduces the digital stream.

When playback starts, the controller 130 sets the playback mode according to the selection signal input through the key input unit 110 [S210, S220].

The playback mode is simple video recording and playback (Record-Play), Pause-Resume, Time-shifting Play, Fast Forward, Slow Forward, Slow Fast reverse, slow reverse play, and nonlinear play are included, and the type and number of pictures to be played are determined according to the set playback mode.

In response to the determination, the controller 130 sets the reference PCR of the picture to be reproduced in the decoder unit 160 to initialize the decoder STC counter [S230].

The controller 130 sets the packet data start position of the picture to be reproduced in the playback unit 140, and the playback unit 140 uploads a video packet and an audio packet corresponding thereto from the set packet start position, and then the decoder unit 160. Transmit to [S240].

When the data packet is transmitted to the decoder unit 160, an element stream (ES) buffer is filled for buffering.

In general, the audio decoder does not use a buffer but decodes using an internal first input first output (FIFO). However, the video decoder performs decoding after accumulating a certain amount of video element streams (VESs) in the video buffer. In order to prevent the overflow of the video buffer, a stream must be input while maintaining a constant bit rate according to the buffer state [S250].

If the buffer 161 is in a full state, the controller 130 issues a transmission stop command to the playback unit 150 [S260, S270]. The playback unit 150 transmits the audio and video packet data to be reproduced at the maximum speed when the transmission stop command is received by the controller 130.

On the other hand, if the buffer full state is resolved, the transfer stop request is canceled, and the next step is proceeded. Otherwise, the transfer stop is maintained [S280].

When the transmission stop is terminated, the playback is terminated by checking whether the playback is completed [S290].

The decoder 160 buffers the packet data transmitted through the playback unit 150 in a buffer and transmits the packet data to the audio decoder 162 and the video decoder 163 to decode the data.

The decoder 160 may be an MPEG or DSS transport demultiplexer or a DVD or VCD program stream decoder, depending on the type of the stream.

The present invention is limited to the above-described types of digital video streams, but the packet unit of the reproduction unit 150 may vary according to the request of the decoder 160.

3 is a state diagram showing the correlation between the index information and the position where the packet data is stored in the recording apparatus according to the application of the present invention,

(a) shows the picture index, and (b) shows the state of the storage medium storing the picture. The index information is composed of a picture type, a reference PCR, and an index indicating a storage location of video packet data of the picture. The picture type is expressed in the form of I (Intra), P (Predictive), B (Bidirectional), and the storage location of each picture is expressed in the form of a corresponding picture (ptr).

4 is a state diagram showing a reference PCR extraction method according to the application of the present invention.

Reference PCR is extracted and calculated as shown in FIG. 4. It is calculated as shown in Equation 1 by PCR (ORG), which is a PCR value before packet data corresponding to each picture is input, and D (PCR), which is the time from the PCR (ORG) to the input time of packet data of the picture. .

The D (PCR) sets PCR (ORG) as an initial value in the regeneration unit's own System Time Clock (STC) counter, and calculates the packet data to be stored by incrementing the STC counter by the STC clock until the input point. .

5 is a graph illustrating a state of a video buffer according to packet data transmission according to the present invention.

Referring to FIG. 5, B represents the total size of the buffer, and B1 represents the buffer state after removing d1, which is an amount of bits corresponding to the decoded picture, from the buffer.

When the buffer state becomes full, such as the intervals T01 and T23, the video decoder generates an interrupt to request the host processor to stop packet transmission to prevent overflow. Maintaining the buffer pool state in the periods T01 and T23 means that the transmission is stopped. In other sections, the playback unit has transmitted the packet data to be reproduced at the maximum transmission rate to the video buffer.

As described above, the digital video stream reproducible in the storage medium of the present invention includes a transport stream stored in units of 188 bytes by a conventional device, a transport stream in which the storage packet unit is not 188 bytes, and a time stamp input through a network. Transport streams that do not exist, and program streams of DVDs, VCDs, and the like stored in the storage medium.

That is, the present invention can reproduce without limiting the packet unit of the digital video stream, and can reproduce a video stream that does not include a time stamp used for bit rate control.

In addition, the video stream not including the time stamp controls the bit rate according to the buffer state of the decoder, so that the video data packet can be reproduced.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

As described above, according to the digital video stream storage / reproduction method according to the present invention, there is an effect of saving the storage space by storing the digital video stream obtained through various paths without inserting a time stamp.

In addition, the present invention has an effect of preventing a problem caused by an error in the time stamp by adjusting the transmission bit rate without using the time stamp.

That is, it is possible to prevent the decoder from overflowing due to the interruption of transmission of the stored packet data and the overflow of the decoder due to exceeding the transmission bit rate, thereby smoothly reproducing the video and audio of the playback program without interruption.

Claims (14)

A storage unit for storing a digital stream having no time stamp inserted therein and index information required for reproduction from the stream; Select a picture type to be played by referring to index information of a digital stream to be stored stored in the storage, set an initial value of a system time clock (STC) corresponding to the picture, and search for a start position of the video / audio packet data to be played. And a playback section for transmitting for decoding for reading; A decoder unit for storing the packet data transmitted through the reproduction unit in a buffer and decoding the stored packet data; And a control unit for outputting a signal for controlling a bit rate of packet data transmitted from the reproduction unit according to the buffer state of the decoder unit. The method of claim 1, wherein the index information includes a type of each picture that is a program access unit from the stream, a picture index that is a start point of packet data of the picture, and a reference clock value (PCR) that is system clock information of the picture. Digital broadcast receiver comprising a. The digital broadcast receiver as claimed in claim 2, wherein the STC counter is initialized by the reference PCR index information, and decoded by the system clock to decode the video / audio packet. 4. The method of claim 3, wherein the reference PCR index information includes a PCR (ORG) value indicating a PCR value transmitted by a PCR packet before a packet data input time to be stored, and a PCR (ORG) initialized to its own STC counter of a download control unit. And then calculating the sum of the D (PCR) values, which are values increased by the system clock until the input of the stored packet data. The digital broadcast receiver as claimed in claim 1, wherein the initial value of the system time clock (STC) is set using a reference PCR value of a picture to be reproduced. The digital broadcast receiver as claimed in claim 1, wherein the storage unit transmits index information necessary for playing the stream to a control unit. The method of claim 1, wherein the control unit refers to the input buffer state of the decoder unit, and transmits packet data to be reproduced to the decoder unit until the buffer is full, the buffer is in a full state And outputting a control signal to stop transmission of the packet data. Storing a digital stream having no time stamp inserted therein and index information required for reproduction from the stream; Setting a playback mode to play the stored digital stream; Setting an initial value of a system time clock (STC) corresponding to a picture to be reproduced according to the set mode; Transmitting the decoded packet data for decoding; Temporarily storing the transmitted packet data in a buffer; And controlling the bit rate of the transmitted packet data according to the buffer state. The method of claim 8, wherein the index information includes a type of each picture that is a program access unit, a picture index that is a start point of packet data of the picture, and a reference clock value (PCR) that is system clock information of the picture. Digital stream storage / playback method characterized in that. The method of claim 8, wherein the playback mode is a simple video recording and playback (Record-Play), Pause-Resume, Time-shifting Play, Fast Forward, Slow playback (Slow Forward), Fast Reverse, Slow Reverse Play, Nonlinear Play (Nonlinear Play). 10. The method of claim 8, wherein the initial STC (System Time Clock) value is set using a reference PCR value of a picture to be reproduced. The method of claim 11, wherein the reference PCR index information is a PCR (ORG) value indicating the PCR value transmitted by the PCR packet before the packet data input time to be stored, and the PCR (ORG) initialized to its own STC counter of the download control unit. And then calculating the sum of the D (PCR) values, which are values increased by the system clock until the input of the stored packet data. The method of claim 8, wherein the transmitting of the packet data refers to an input buffer state of an audio decoder and a video decoder until the buffer becomes full, and when the buffer becomes full, the packet is transmitted. Digital stream storage / playback method characterized in that the control to stop the data transmission.  15. The method of claim 13, further comprising, after stopping the packet transmission, checking the buffer status continuously and releasing the interruption according to the buffer status.

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