KR100568068B1 - PCR correction apparatus and method in transport stream transmission system - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a device and a method for calibrating a PC in a transport stream transmission system.

2. Technical problem to be solved by the invention

The present invention provides a device and a method for calibrating a PC in a transport stream transmission system, which can correct the PC through a simple operation without adding additional data to the PC in the transport stream transmission system. In this.

3. Summary of the Solution of the Invention

According to an aspect of the present invention, there is provided an apparatus for calibrating a PC in a transport stream transmission system, the apparatus comprising: temporary storage means for receiving the transport stream and temporarily storing and outputting the transport stream; First counting means for counting a time from the completion of storing the transport stream in the temporary storage means, using a clock received from an external source and a clock generated using the received clock; Multiplexing means for multiplexing the transport streams stored in a plurality of said temporary storage means; And correction means for correcting the plurality of PCs of the transport stream multiplexed by the multiplexing means by using the count value counted by the counting means.

4. Important uses of the invention

The present invention is used in a transport stream transmission system and the like.

MPEG-2, Transport Stream, Remultiplex, PDF Correction, PDF Jitter

Description

PCC correction apparatus and method in transport stream transmission system             

1 is a configuration diagram of an embodiment of a PCC correction apparatus in a transport stream transmission system according to the present invention.

Figure 2 is a detailed configuration diagram of an embodiment of the counting unit according to the present invention.

3 is an exemplary diagram showing a correlation between a 90 KHz count value and a 27 MHz count value according to the present invention;

4 is a flow diagram of one embodiment of a counting process in accordance with the present invention.

5 is a flow chart of one embodiment of a PCC correction process according to the present invention.

* Explanation of symbols for the main parts of the drawings

11: buffer part 12: counting part

13: multiplexer 14: PDF correction unit

The present invention relates to a device for calibrating a PC in a transport stream transmission system and a method for calibrating a program clock reference (PCR) in a transport stream (TS) transport system. In addition, the present invention relates to a device for correcting a plasma in a transport stream transmission system, and a method for correcting the plasma to remove the jitter generated in a process of remultiplexing the transport stream in the transport stream transmission system.

The transport stream transmission system according to the MPEG-2 (MPEG-2) standard ("ISO / IEC 13818-1") uses a time stamp to decode and output the transport stream at the correct time at the receiver.

The time stamp includes a decoding time stamp (DTS), which is information about a decoding time, and a presentation time stamp (PTS), which is time information for outputting a decoded signal, wherein the time stamp is a receiver. Use the 27 MHz System Time Clock (STC).

At this time, if the system clock of the receiver and the system clock of the transmitter are not correctly synchronized, the decoding and output cannot be performed normally. Therefore, the clock of the transmitter and the receiver are synchronized using the PC.

The PD exists in "adaptation_field" which is one of the fields constituting the transport stream header, and includes a "PCR_base" field and a "PCR_extention" field.

Here, "PCR_base", which is a configuration field of the PC, indicates time information with a count value synchronized with a 90 KHz clock, and "PCR_extention" shows time information with a count value synchronized with a 27 MHz clock.

In addition, the transport stream in which the PC exists is transmitted at least once every 100 ms.

Meanwhile, in digital broadcasting, a plurality of programs and data services may be provided in one transport channel. In order to accomplish this, various transport streams must be multiplexed into one channel. Here, this multiplexing process is called transport stream remultiplexing.

When the transport stream is remultiplexed, each input transport stream is temporarily stored in a buffer and then output as one bit stream. In this process, multiplexing delay occurs to generate PC jitter.

In addition, since the receiver does not accurately synchronize the clock with the transmitter due to the jitter, the transport stream cannot be decoded and output at the correct time.

Therefore, the PDF jitter must be removed through the correction of the PDF.

Looking at the prior art for removing the PDF jitter, the Republic of Korea Patent "PC jitter removal apparatus and method (Public Publication No. 2002-0074817)" is a time stamp value when the transport stream in which the PC is present 20 bytes are added to the transport stream (188 bytes), and the PCAL is corrected only by the time corresponding to the multiplexing delay compared to the time stamp value after multiplexing.

In other words, the total delay is obtained from the two time stamp values, and the value of the first transport stream without the buffer delay is subtracted and added to the existing PCL. However, this method has some problems.

First, since 20 bytes of time stamps are added to a 188-byte transport stream, the transport stream is processed in units of 208 bytes, so it is difficult to control the transmission rate of the finally output transport stream.

That is, the transmission rate of one transport stream finally output should be processed based on 188 bytes. Since the transport stream processed internally is 208 bytes, a complex algorithm considering the relationship between the two should be added.

Second, since the system time clock is 27 MHz, to get the PCL value, we need to multiply "PCR_base" by 300 and add "PCR_extention". In addition, when correcting a PCAL, it must be inserted after performing an inverse division operation.

In such a process, since both multiplication and division operations are required in addition to addition and subtraction operations, implementation of a complex hardware system is not easy.

Accordingly, the present invention has been proposed to solve the above problems, and in the transport stream transmission system, a transport stream transmission capable of correcting a PCAL by a simple operation without adding a separate time stamp to the PCL. It is an object of the present invention to provide a device and a method for calibrating a PC in a system.

In order to achieve the above object, the apparatus of the present invention comprises: a temporary calibration means for receiving and temporarily storing and outputting the transport stream; First counting means for counting a time from the completion of storing the transport stream in the temporary storage means, using a clock received from an external source and a clock generated using the received clock; Multiplexing means for multiplexing the transport streams stored in a plurality of said temporary storage means; And correction means for correcting the PCAL of the transport stream multiplexed by the multiplexing means by using the count value counted by the counting means.

On the other hand, the method of the present invention, in the transport correction method in the transport stream transmission system, the temporary storage step for receiving the transport stream for a while to store and output; A first counting step of counting a time from the completion of storing the transport stream in the temporary storage step by using a clock received from an external source and a clock generated using the received clock; A multiplexing step for multiplexing the transport streams stored in a plurality of said temporary storage steps; And a correction step for correcting the plurality of PCs of the transport stream multiplexed in the multiplexing step using the count value counted in the counting step.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily implement the technical idea of the present invention. In adding reference numerals to the components of the drawings, the same components are to have the same number as much as possible even if displayed on different drawings.

1 is a block diagram of an embodiment of a PCC correction apparatus in a transport stream transmission system according to the present invention.

As shown in FIG. 1, the PCC correcting apparatus in the transport stream transmission system according to the present invention includes a plurality of buffer units for receiving, temporarily storing, and outputting each transport stream including a PCL correspondingly. (11) a plurality of counts connected in correspondence with the respective buffer sections 11 for counting the time since the buffer section 11 completes storing the transport stream using a 27 MHz clock and a 90 KHz clock; The multiplexer 13 for multiplexing each of the transport streams stored in the plurality of buffers 11 and the plurality of PCs of the transport streams multiplexed by the multiplexer 13 may be used. A PC correction unit 14 for correcting using the count value counted by the count unit 12 is included.

A detailed description of the functions and interactions between the components of the above-described PCC correction apparatus will be given below.

Each of the buffer units 11 temporarily stores a transport stream correspondingly inputted from the outside, and outputs a signal (read flag signal) indicating that the transport stream is completed and output to the multiplexer 13. do.

At this time, when the transport of the transport stream in which the PC exists (hereinafter referred to as 'PC TS') is completed, the counting unit 12 outputs an end marker signal, which is a signal indicating that the PC storage is completed. .

The counting units 12 start counting in synchronization with the 90 KHz clock and the 27 MHz clock, respectively, when correspondingly receives the end marker signals from the respective buffer units 11.

The multiplexer 13 is connected to the plurality of buffers 11, receives the transport streams from the buffer 11 that outputs the ready flag signal, and multiplexes them into a single transport stream. The transport stream thus output is output to the PCC corrector 14.

The PDF corrector 14 receives the transport stream multiplexed by the multiplexer 13 and extracts the PCTS included in the multiplexed transport stream.

Then, the operation of the counting unit 12 corresponding to the extracted PCTS is stopped, and the stopped count value is input to correct the PC using Equation 1 below.

At this time, the input count value is a count value (hereinafter referred to as "90KHz count value") synchronized with a 90KHz clock and a count value (hereinafter referred to as "27MHz count value") synchronized with a clock of 27MHz. The count value is the multiplexing delay time from the time when the PTS is completely stored in the buffer unit 11 to the time of multiplexing.

New_PCR_base = Old_PCR_base + Cfv + Carry

New_PCR_extention = Old_PCR_extention + Csv

Here, New_PCR_base is the corrected "PCR_base" value, Old_PCR_base is the "PCR_base" value before correction, Cfv is a 90KHz count value, Carry is 1, the value is generated when an overflow occurs in the New_PCR_extention value.

In addition, New_PCR_extention is the "PCR_extention" value after correction, Old_PCR_extention is the "PCR_extention" value before correction, and Csv is a 27 MHz count value.

By correcting the PC by performing these operations, there is no need for complicated operations such as multiplication and division.

2 is a detailed configuration diagram of an embodiment of a counting unit according to the present invention.

As shown in FIG. 2, the divider 21 receives the 27 MHz clock from the outside and generates a 90 KHz clock synchronized with the 27 MHz clock.

When the counter 22 receives an end marker signal from the buffer unit 11, the counter 22 starts counting in synchronization with the 27 MHz clock and the 90 KHz clock received from the divider 21.

When the counter 22 receives the counter stop signal from the PC corrector 14, the counter 22 stops the counting operation and outputs the corresponding count value to the PC corrector 14.

3 is an exemplary diagram illustrating a correlation between a 90 KHz count value and a 27 MHz count value according to the present invention.

As shown in FIG. 3, the 27 MHz count value is reset and counted from the beginning each time the 90 KHz count value increases.

4 is a flowchart of an embodiment of a counting process according to the present invention.

First, a 27 MHz clock is received from the outside, and a 90 KHz clock synchronized with the 27 MHz clock is generated (41).

Subsequently, when the end marker signal is input (42), counting starts in synchronization with the 27 MHz clock and the 90 KHz clock (43, 44).

Subsequently, if the count stop signal is input from the PC corrector (45), the count value stopped after the count operation is stopped is output to the PC corrector (46).

5 is a flow chart of an embodiment of a process for correcting a plasma according to the present invention.

First, the multiplexed transport stream is input (51), and PCS contained in the multiplexed transport stream is extracted (52).

Subsequently, a count stop signal is outputted to the count unit corresponding to the extracted PCS to stop the count operation (53), and the stopped count value is obtained (54).

Subsequently, the “PCR_base” and “PCR_extention” of the PCAL included in the PCS are obtained (55).

Subsequently, an operation of adding 27 MHz count values to the "PCR_extention" is performed (56), and it is determined whether an overflow occurs in the adding operation (57).

As a result of the determination 57, when overflow occurs, the operation adds 1 and adds a count value of 90 KHz and 90 KHz.

As a result of the determination (57), when no overflow occurs, an operation of adding the "PCR_base" and the 90 KHz count value is performed (59).

The "PCR_base" and the "PCR_extention" are corrected with operation result values of the "56" process, the "58" process, and the "59" process (60).

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

As described above, the present invention has the effect of correcting the PCAL by a simple operation without adding additional data to the PC in the transport stream transmission system.

In addition, the present invention has the effect that it is possible to easily implement a hardware cystel without complex algorithms and complex processing.

Claims (9)

A device for correcting a PCAL in a transport stream transmission system, A plurality of temporary storage means for receiving, temporarily storing, and outputting a transport stream including a PCAL correspondingly; The temporary storage is performed by using the first clock received from the outside and the second clock generated using the first clock received from the outside, after storing the transport stream in each of the temporary storage means. A plurality of first counting means for counting corresponding to the transport stream output from the means; Multiplexing means for multiplexing transport streams stored in said plurality of temporary storage means; And PC correction means for correcting a PC of a transport stream multiplexed by the multiplexing means by using count values counted by the plurality of counting means Apparatus for correcting a PC in a transport stream transmission system comprising a. The method of claim 1, The first counting means, And a count value using the first clock received from the outside is counted again from the beginning whenever the count value using the generated second clock increases. The method of claim 2, The first counting means, Dividing means for dividing the first clock input from the outside to generate the second clock having a different frequency; And Second counting means for counting in synchronization with the first clock received from the outside and the second clock generated by the dispensing means; Apparatus for correcting a PC in a transport stream transmission system comprising a. The method of claim 3, wherein The first clock received from the outside has a frequency of 27MHz, the generated second clock has a frequency correction device in the transport stream transmission system, characterized in that the frequency of 90KHz. The method according to any one of claims 1 to 4, The correction means, The counting operation of the first counting means is stopped by using the transport stream multiplexed by the multiplexing means, and the PC is corrected using the stopped count value accordingly. Al correction device. The method of claim 5, wherein The correction means, A device for calibrating a PC in a transport stream transmission system, characterized in that the PCC is corrected by modifying "PCR_base" and "PCR_extention" using the following Equation. [Equation] New_PCR_base = Old_PCR_base + Cfv + Carry New_PCR_extention = Old_PCR_extention + Csv (Where New_PCR_base is the corrected "PCR_base" value, Old_PCR_base is the "PCR_base" value before correction, Cfv is the count value synchronized to the generated second clock, Carry is 1, and if the overflow occurs to the New_PCR_extention value, The generated value, New_PCR_extention is a value of "PCR_extention" after correction, Old_PCR_extention is a value of "PCR_extention" before correction, and Csv is a count value synchronized to the first clock inputted from the outside.) In the transport correction method in the transport stream transmission system, A temporary storage step of temporarily storing transport streams including PCALs; A counting step of counting a time from the completion of storing each transport stream in the temporary storage step by using a first clock from the outside and a second clock generated using the first clock; A multiplexing step of multiplexing the transport streams stored in the temporary storage step; And A correction step of correcting the plurality of PDs of the transport stream multiplexed in the multiplexing step using the count value counted in the counting step PCC correction method in a transport stream transmission system comprising a. The method of claim 7, wherein The counting step, And counting the count value using the first clock again from the beginning whenever the count value using the second clock increases. The method according to claim 7 or 8, And said first clock has a frequency of 27 MHz and said second clock has a frequency of 90 kHz.

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