KR0181080B1 - Apparatus coding escr information in mpeg - Google Patents

Abstract

The present invention relates to an apparatus for ESCR encoding in system encoding. The present invention relates to an elementary stream encoder for encoding an audio / video signal based on MPEG recommendation, and a PES packet tie for PES packetizing the encoded output. The PES packet is transport packetized, and the initial ESCR is divided by the amount of data accumulated by the transmission rate from the time when the transport packetized stream is first recorded in the transport buffer to the time when the first ESCR received in the transport buffer is recorded. In the apparatus for outputting the ESCR for meeting the decoding time criteria with the transport packet to the transport channel, to inform the start of the audio and video signal in the elementary stream, which is the output of the elementary stream encoder 510 ESCR for generating a flag or matching decoding time according to the start code detection result A packet generating means 530 for generating a flag based on a comparison between a count value counted from the time point at which the data is recorded and transmitted and a preset reference value, and packetizing the PES packet output from the PES packetizer 520, A transmission packetizer 540 for recording and outputting a flag from the flag generation means 530 in the transmission packetized transmission packet, and a PES packet stream to be received at a decoder based on the initial ESCR and a system clock. An encoder clock system 550 for generating an ESCR is recorded, and an ESCR that is an output of the encoder clock system 550 is recorded, and the recording is performed in response to a detection result of a flag in a transmission packet that is an output of the transport packetizer 540. The detection and recording means 560 which reads the outputted ESCR and outputs it to the transmission buffer 570 can shorten the decoding time while satisfying the maximum transmission time constraint of the ESCR. It has an effect.

Description

APPARATUS CODING ESCR INFORMATION IN MPEG

1 is a block diagram schematically illustrating an encoder of a transport stream in an MPEG-2 (ISO / IEC13818) system.

2 is a diagram illustrating a relationship between elementary streams, packetizers, and PES packets.

3 to 5 are diagrams showing a packet configuration and a configuration of a transport stream.

6 shows a program constituting an audio / video elementary stream.

7 is an ESCR encoding apparatus of an MPEG system according to the present invention.

* Explanation of symbols for main parts of the drawings

510: elementary stream encoder 520: PES packetizer

530: flag generation means 540: transmission packetizer

550: encoder clock system 560: detection and recording means

570: transmission buffer

The present invention provides a packetized elementary stream (hereinafter referred to as ESCR) data based on elementary stream clock reference (ESCR) data in a decoder in MPEG-2 system encoding. The present invention relates to an apparatus for efficiently encoding a value of an ESCR so as to decode a PES).

The MPEG-2 transport stream is a type of MPEG system stream. As the final technology for the MPEG system, the official name of MPEG-2 is known as ITU-T Rec. H.222. 0 | ISO / IEC 13818.

MPEG-2 is largely divided into a first part system, a second part video, and a third part audio. The first part is a recommendation for the overall field of system layer coding.

Here, system layer coding (hereinafter referred to as system coding) means not only an audio / video stream compressed by MPEG-1 or MPEG-2 data compression method, but also multiplexing user data, etc. as necessary to transmit or store work. It relates to a technique for formatting to suit.

The process of receiving multiple bit streams and formatting them into a series of streams is called a system encoder, and the process of unpacking the formatted stream into the original input stream is called a system decoder. .

The formatting rule is called syntax, and the semantics that define the meaning of each part in the process of creating this syntax are called semantics.

Since the MPEG system IS prescribes the formatting rules syntax and semantics, when encoding in the system encoder, a bit stream must be created according to such a rule, and the system decoder must be configured to decode a stream produced by this rule. .

The system encoding not only combines and combines each audio / video stream, but also includes a process of inserting some parameters for reproducing the buffer control and synchronizing each decoded stream in the system decoder in decoding the stream. Include.

In the system encoding method, there are two types of transport stream encoding and program stream encoding, and the program stream is mainly used for storage.

FIG. 1 is a block diagram schematically illustrating an encoder of a transport stream in an MPEG-2 system, and shows a process of creating a transport stream from an audio / video stream through a packetizer.

Referring to FIG. 1, audio and video encoders 11 and 12 may assume MPEG-1 or MPEG-2, but in general the MPEG-2 system encoding excludes streams encoded with encoders other than the MPEG family. It could be a H.261 video encoder, a CCITT G.721 audio encoder, or a unique audio / video encoder used only for specific limited users.

The data encoded by these video and audio encoders 11 and 12 are called elementary streams, which are primarily packetized through respective audio and video packetizers 13 and 14.

This processed data is called a packetized elementary stream (PES), and the packetizer for making this PES packet is called a PES packetizer.

That is, each of the audio PES packets and video PES packets that are made through the audio packetizer 13 and the video packetizer 14, the transport stream (or program stream) is input to the multiplexer 15, and this multiplexer ( 15) creates and outputs a program stream and a transport stream.

In the end, system encoding corresponds to a process of receiving an elementary stream and generating a PES packetizing and transport stream. In other words, the system coding process can be divided into two functions, namely, PES packet and TS / PS multiplexing.

The PES packetizer makes elementary streams into PES packets, and TS / PS multiplexing corresponds to a process of creating TS / PS packets from PES packets.

As such, the MPEG-2 System Recommendations do not specify separately the specifications implemented for decoding, and there are no separate provisions for applications that may occur from time to time.

Therefore, the encoding system only needs to provide an accurate stream that meets the decoder specification specified by the MPEG-2 stream IS. However, the method of constructing the encoder and the technique of making an efficient decoder are not standardized. .

2 illustrates a process of PES packetization of an input elementary stream with reference to a system coding recommendation, in which all information encoded in a system encoder is formatted in packet units. 3 shows the configuration of a PES packet, which is composed of a header and a payload.

The payload 32 cuts and inserts the elementary stream into a predetermined length, and other useful information (eg, time information, address tag, etc.) is inserted into the header 31. Here, a device for generating a PES packet is called a packetizer, and a device for receiving an elementary stream to generate a packet is called a PES packetizer (reference numeral 22 in FIG. 2).

The elementary stream in the system encoder refers to an input stream for performing packetizing (packet making process), and more broadly, a stream in which an encoded stream in any form is input to the system encoder. do.

In the system encoding process, the elementary stream is input to make a PES packet, and the PES packet is input again to understand the transport stream as a packet or program stream packet.

4 shows an example of transport streams based on audio PES streams, video PES streams, and transport header information. Since the length of a transport packet is always equally short as 188 bytes, multiplexing, re-multiplexing, demultiplexing, and receiver are shown. It is easy to manufacture and has the advantage of low loss in transmission error such as cell loss.

Overall, a transport stream composed of transport packets is suitable for broadcasting using a channel having a large transmission error.

As such, since the transport stream is composed of short packets of fixed length, it is easy to convert to another stream and minimize the effects of loss such as cellulose.

FIG. 5 schematically shows the relationship between the transport packet described above with reference to FIGS. 3 to 4 and the PES packet, the compressed video and the audio stream, and it is understood that the compressed video and audio signal includes the start code. Can be.

6 shows a concept of time in addition to the encoder shown in FIG. 1, and shows a program composed of an audio / video elementary stream. That is, each elementary stream in which audio signals and video signals are encoded by the encoders 61 and 62 is input to the PES packetizers 63 and 64.

Here, the system clock stage 65 generates a time information clock (ESCR / PTS / DTS) to provide the PES packetizers 63 and 64. In this case, the PES packetizers 63 and 64 The input time information clock (ESCR / PTS / DTS) is inserted into the header portion of the PES packet, and the elementary stream is packetized and input to the TS / PS packetizer (or multiplexer) 66. Therefore, the TS / PS packetizer 66 inserts another time information clock (PCR / SCR) from the system clock stage 65 into the header portion of the transmission packet and packetizes the PES packet to TS / PS. Will output to the stream.

Here, the system clock corresponds to a system clock provided to all blocks constituting the system encoder, and the frequency of the system clock satisfies the following constraints.

27 MHz-810 Hz ≤ system_clock_frequency ≤ 27 MHz + 810 Hz system_clock_frequency time variation rate ≤75 × 10 ^-3 Hz / sec-(A)

In the sense of Equation (A), the system clock frequency allows a +, -810 Hz error at 27 MHz, which corresponds to a range of-, -0.003% based on 27 MHz. In addition, even when operating in the range of this error, the clock change should not occur suddenly. In other words, if it operates at a clock frequency of 27 MHz per second, allowing a change of 0.075 Hz per second, it means that one clock shifts from the 360 M clock. In summary, the formula (A) defines the operating frequency range of the system clock and the rate of change of the operating frequency.

Next, the ESCR value defined in the MPEG system represents a time reference value for a program consisting of only one elementary stream in the transmission stream, and this reference value is calculated as in Equation (B).

A program consisting of only one stream is called a PES stream. In the process of decoding such a PES stream in a decoder, a virtual decoder model is an abbreviation of PES-STD (Packetized Elementary Stream-System Target Decoder). The value indicating the time input to the motel for decoding is ESCR.

In Equation (B), i means i th byte and t (i) is the time when i th byte is input to PES-STD. Make it by sampling. The PES-STD means a virtual decoder model in an MPEG system, which is described based on a conceptual model in the process of defining a system standard.

In this process, the ESCR consists of a 33-bit ESCR_base expressed in 90 KHz units (system clock frequency / 300) and 9-bit ESCR_ext expressed in 29 MHz units (system clock frequency).

I in the ESCR (i) indicates the last byte of data of the ESCR-base. After all, ESCR (i) represents the time when the last byte of ESCR-base data is input to the PES-STD as a system-clock_frequency.

ESCR-base (i) = ((system-clock_frequency * t (i)) DIV300)% 2 ³³

ESCR-ext (i) = ((System_Clock_Frequency ＊ t (i)) DIV1)% 300

ESCR (i) = ESCR_baxe (i) ＊ 300 + ESCR_ext (i) --- (B)

(DIV is a truncation operation that makes the remainder zero by an integer division operation, and% is an operation that takes the remainder by a Modlo operation.

The ESCR data format is as follows. The 48 bits of the ESCR data format specified by MPEG consist of the following filters.

reserved 2 bits

ESCR_base [32..30] 3 bits

marker_bit 1 bit

ESCR_base [29..15] 15 bits

marker_bit 1 bit

ESCR_base [14..0] 15 bits

marker_bit 1 bit

ESCR_extension [29..15] 9 bits

marker_bit 1 bit

As described above, the entire ESCR is composed of 6 bytes, and 2 bits of reserved data and 4 marker_bits are meaningless values, and the length of the ESCR having actual information is 42 bits.

On the basis of the above, the transmission timing of the ESCR will be described. As recommended by MPEG, the ESCR data described in the prior art section must be retransmitted within 0.7 seconds.

However, if the time point for retransmission is set at any time within 0.7 seconds, the decoding time becomes long in the overall stream configuration.

In the process of starting the decoding operation in the decoder, the decoder decodes the PES stream after stabilizing all the clocks of the decoder system using the PCR value received from the setting of the decoder system clock.

However, even if the stream is in the buffer, the PES system decoder cannot decode the PES stream if the ESCR value is not received, and the decoding time is increased when the elementary stream (audio / video) is received before the ESCR. There was a problem getting longer.

Accordingly, an object of the present invention is to decode and play data on the basis of ESCR, and the system decoder shortens the decoding time of the received elementary stream by encoding and recording the ESCR defined by the MPEG before the start information of the elementary stream. An object of the present invention is to provide an ESCR encoding apparatus of an MPEG system.

According to the present invention for achieving the above object, an elementary stream encoder for encoding an audio / video signal based on an MPEG recommendation, a PES packetizer for PES packetizing the encoded output, and transmitting the PES packet The initial ESCR is obtained by dividing the amount of data accumulated by the transmission rate from the time when the transport packetized stream is first recorded in the transport buffer to the time when the ESCR first received in the transport buffer is recorded. In the apparatus for outputting the ESCR for matching to the transmission channel together with the transmission packet, according to the detection result of the start code for notifying the start of the audio and video signal in the elementary stream, which is the output of the elementary stream encoder 510 From the time the ESCR is recorded and transmitted to generate the flag or to meet the decoding time criteria A flag generation arithmetic operation 530 for generating a flag based on a comparison between a count value that has been undone and a preset reference value; A transport packetizer 540 which converts a PES packet, which is an output of the PES packetizer 520, into a transport packet, and records and outputs a flag from the flag generating means 530 in the transport packetized transport packet. An encoder clock system 550 for generating an ESCR for a PES packet stream to be received at a decoder based on the initial ESCR and a system clock; Record the ESCR, which is the output of the encoder clock system 550, and read the recorded ESCR in response to the detection result of the flag in the transmission packet, which is the output of the transmission packetizer 540, to the transmission buffer 570. Detecting and recording means 560 for outputting.

Hereinafter, the present invention will be described in detail with reference to the illustrated drawings.

7 is an ESCR encoding apparatus diagram of an MPEG system according to the present invention.

Referring to FIG. 7, the ESCR encoding apparatus of the MPEG system of the present invention includes an elementary stream encoder 510, a PES packetizer 520, a flag generating means 530, a transmission packetizer 540, The encoder clock system 550, the detection and recording means 560, and the transmission buffer 570.

The elementary stream encoder 510 is configured to encode video and audio signals and provide them to the PES packetizer 520 and the start code detector 531 which will be described later as elementary streams.

The PES packetizer 520 is configured to include variable information data in the elementary stream provided from the elementary stream encoder 510 to be provided to the transport packetizer 540 described later after PES packetization.

The flag generating means 530 is a flag generated by the ESCR for generating a flag or matching the decoding time according to a detection result of a start code indicating the start of an audio and video signal in the elementary stream, which is an output of the elementary stream encoder 510. And a flag is generated based on a comparison between the count value counted from the time point at which it is transmitted and the preset reference value, and is provided to the transmission packetizer 540 described later.

More specifically, the flag generating means 530 is composed of a start code detector 531, a time-lapse irradiation unit 532, and a flag processing unit 533.

When the start code is detected in the elementary stream output from the elementary stream encoder 510, the start code detector 531 is configured to be provided to the flag processor 533, which describes a flag request signal according to the detection result.

The time-lapse irradiation unit 532 is initialized at the time when the ESCR is recorded and transmitted in the transmission buffer 570 to be described later, and the value counted from the initializing time coincides with the preset reference value (count value corresponding to 0.7 second). It is configured to provide a flag request signal 533 to the flag processor 533 to be described later.

The flag processor 533 may provide a flag to the transport packetizer 540 in response to a flag request signal of the start code detector 531 or set a flag in response to a flag request signal from the time-lapse irradiation unit 532. Configured to provide to the transport packetizer 540.

The transmission packetizer 540 transfers the PES packet, which is the output of the PES packetizer 520, and writes a flag signal in the transmission packetized transmission packet to detect and record means 560 which will be described later. It is configured to provide to the transmission buffer 570.

The encoder clock system 550 is configured to generate an ESCR for the PES packet stream to be received by the decoder based on the initial ESCR and the system clock, and provide it to the detection and recording means 560 which will be described later. Generates and outputs the ESCR.

More specifically, the encoder clock system 550, the initial ESCR detector 551, the system clock 552, the first counter 553, the comparator 554, the second counter 555, and the combination processing unit ( 556).

The initial ESCR detection unit 551 detects the initial ESCR from the transmission buffer 570, and provides the reset signal or the preset reference value to the first counter 553 and the second counter 555 as a result of the detection. The initial ESCR detection unit 551 is configured to record the first ESCR received in the transmission buffer 570 from the time when the transport packet stream output from the transport packet TI 540 is first recorded in the transmission buffer 570. It means that the initial ESCR obtained by dividing the accumulated data amount by the transmission rate until the time point.

The system clock unit 552 is initialized in accordance with the ON operation of the system encoder, and "27 MHz-810 Hz ≤ system_clock_frequency ≤ 27HNz + 810Hz, and the time change rate of the system_clock_frequency ≤ 75 x 10 ^-3 Hz / sec] Generates a system clock that satisfies the condition.

The first counter 553 may be configured to reset the initial value to 0 based on the initial ESCR detected by the initial ESCR detection unit 551 and to receive a reference value other than 0. 553 is initialized based on the reset signal of the initial ESCR detection unit 551 or based on a reference value, and a 9-bit counter is incremented by one for each clock of the system clock unit 552, and this value is a comparator for every system clock. 554 and a combination processor 556, wherein the first counter 553 comprises a module 300 9-bit counter. Herein, when the module 300 9-bit counter reaches a value of 0 to 299, it means that the period is 300 by setting it back to 0 at the next clock.

The comparator 554 compares the value counted by the first counter 553 with a preset reference value (9-bit binary value of 299). The count value to be expressed as ESCR-ext in a 9-bit unit by the first counter 553 is configured to be provided to the combination processing unit 556 described later. The second counter 555 is initialized by the reset signal or the reference value of the initial ESCR detection unit 551, and counts the carry of the comparator 554, a combination that will be described later to the count value to be expressed in ESCR-base of 33 bits unit It is configured to be provided to the processing unit 556, the second counter 555 is composed of a 33-bit counter. Here, the 33 bit counter is calculated to increment once every 300 clocks of the system clock.

The combination processing unit 556 includes an additional bit of 6 bit units, and logically combines the count value of the comparator 554 with the additional bit of the 6 bit unit and the count value of the second counter 555 to form a 48 bit unit. Provide an ESCR of the ESCR memory 562.

The detection and recording means 560 records the ESCR which is the output of the encoder clock system 550, and reads the recorded ESCR in response to the detection result of the flag in the transmission packet which is the output of the transmission packetizer 540. It is configured to output to the transmission buffer 570.

More specifically, the flag detector 561 detects the presence of a flag in the header portion of the PES packet output from the transport packetizer 540, and provides the read signal to the ESCR memory 562 described later. Is configured to.

The ESCR memory 562 records the ESCR provided from the encoder clock system 550, and when a flag signal is detected by the flag detector 561, in response thereto, the ESCR memory 562 reads out the recorded ESCR and transfers a buffer to be described later. And output to 570.

The transport buffer 570 is configured to record the ESCR read out from the detection and recording means 560 into a transport packet stream which is the output of the transport packetizer 540 and output the ESCR to the transport channel.

In particular, the transport buffer 570 obtains an initial ESCR by dividing the accumulated amount of data by the transmission rate from the time when the transport packetized stream is first recorded in the transport buffer to the time when the first ESCR received in the transport buffer is recorded. An ESCR for meeting the time of decoding is output to the transport channel together with the transport packet.

The present invention configured as described above will be described in detail.

First, the flag generating means 530 performs the function of finding the start of the PES stream, and the detecting and recording means 560 performs the function of recording the ESCR before the start of the PES stream, and also the transmission timing of the ESCR. In order to prevent the maximum of 0.7 seconds from being recorded, the time point of the transmitted ESCR is recorded. If the PES stream does not restart within 0.7 seconds, the ESCR is transmitted regardless of the start of the PES stream.

Subsequent operations continue to examine the beginning of the PES stream and then record the ESCR in the transport packet and transmit it as described above.

The start (start) portion of the PES stream is generally composed of independent elementary stream units. Therefore, when the independent elementary stream is formatted and transmitted in units of frames, the beginning of the PES stream can be known by examining the timing of formatting such frames.

Looking at the configuration of the ESCR described above, it has a length of 42 bits, 33 bits of the ESCR-base portion and 9 bits of the ESCR-exe. The six bits in the middle consist of 48 bits (6 bytes) added as meaningless reserved bits.

In the process of creating an ESCR, since time is sampled at system_clock_frequency, the time between samplings is the inverse of sampling_frequency. Since the sampled time is expressed in 42 bits, it means an integer value of one unit expressed in 42 bits. .

This corresponds to the sampling interval, and since 42 bits determine the operating range, the range of time that can be expressed as an ESCR is from 0 seconds to the time interval x maximum value (the maximum integer that can be taken by the ESCR represented by 42 bits).

However, when the maximum value is reached from the value of the ESCR, a modular operation is made to be zero again, so the maximum value of this time does not need to be greatly conscious. That is, since the ESCR value is calculated as frequency × time, the result value is a constant without unit, frequency is system_clock_frequency, and time is time t (i) corresponding to the i th byte.

In equation (B), t (i), that is, the time corresponding to the i th byte, indicates the time corresponding to the i th byte when the time of the 0 th byte is 0 (that is, t (i) = 0). Transfer rate) corresponds to (i / transmission-rate) seconds if it is a value expressed in units of bytes / second.

In equation (B), the ESCR value is calculated separately by ESCR_base and ESCR-ext, where ESCR-ext is expressed as ESCR_base and the remaining time value is expressed in units of system_clock_frequency (27 MHz). Therefore, when ESCR is calculated in units of system clock frequency, it is ESCR_base × 300 + ESCR_ext.

In this way, the ESCR is calculated by dividing the SCR (System_Clock_Frequency), which functions as the MPEG-2 ESCR in the MPEG-1 (ISO / IEC 11172) system, at 90 KHz performed at 1/300 of the MPEG-2 system_clock_frequency. It is calculated to provide compatibility with this MPEG-1 system.

That is, when the MPEG-2 video elementary stream and the MPEG-2 audio elementary stream are transmitted as a transport stream of MPEG-2 and the program is decoded by the MPEG-1 video / audio decoder at the receiver (Disco), the MPEG- 1 The system decoder sees only the ESCR_base portion of the ESCR portion of the MPEG-2 transport stream and regards it as an SCR of MPEG-1.

The MPEG-2 video / audio elementary streams are compatible with each MPEG-1 audio / video stream so that the MPEG-2 stream can be decoded with an MPEG-1 decoder.

However, since the ESCR value representing the time input to the PES-STD for the PES stream targets a PES packet consisting of only one elementary stream, the PES stream can be simply decoded by an MPEG-1 system decoder.

In equation (B), the stream_clock_frequency × t (i) is divided by 300 to take only an integer value (DIV300 operation), and this is expressed as binary 33 bits by performing a modular operation of 2 ^33. ESCR_ext is a system_clock. After taking the value of frequency × t (i) (DIV 1 operation), the operation of modular 300 is performed and expressed as 9 bits. Eventually, the ESCR is calculated by the sum of these values, ESCR_base × 300 + ESCR_ext.

The transport packet structure for recording ESCR data is as follows.

Transpor_Packet {Transmit Packet Header () Transmit Packet Payload ()}

In the data of the transport packet header, transport packet sync data and other information required by the system are recorded. PES packet data is recorded in the transmission packet payload portion. Thus, the configuration of the transmission packet payload is as follows.

Transport Packet Payload () PES Packet Header () Packet Payload ()}

The PES packet is composed of a PES packet header and a PES packet payload portion, and the ESCR data is recorded in the PES packet header portion. This process is recorded as going through several more steps.

PES packet header () {... ESCR_flag 1 bit

... it (ESCR_flag = 1) {.. ESCR data 48 bits}}

If the value of the ESCR_flag in the PES packet header is 1, it means that there is ESCR in the current PES header. If the value of the ESCR_flag is 0, it means that there is no ESCR in the current PES header. do.

The ESCR data format at this time is 48 bits in length. As described above, assuming that the ESCR data is in the PES packet header, the transport packet is as follows.

Transmit_packet () {transmit packet header

Transmission packet payload () {... ESCR_ flag 1 bit ..

it (ESCR_flag = 1) {.. ESCR data 48 bits ..)

PES Packet Payload ()}}

As described above, the presence or absence of ESCR is reported in the current PES packet header according to the state of the ESCR_ flag in the PES packet header. Therefore, the decoder may use only this flag to indicate whether there is ESCR data in the data currently being received.

When the ESCR is recorded in the current PES packet header, the ESCR_ flag is set to '1'. Here, the ESCR is recorded after the data is created. In fact, since such data is recorded in the transmission buffer 570, the actual data is recorded in the transmission buffer 550 except for such a state.

When the present invention is explained by adding the ESCR generating means, first, the elementary stream encoder 510 provides the elementary stream encoding the video and audio signals to the start code detector 531 and the PES packetizer 520. The PES packetizer 520 converts the packet into a PES packet, and then outputs the PES packet to the transport packetizer 533.

When the start code is detected in the elementary stream which is the output of the elementary stream encoder 510, the start code detector 531 provides the flag request signal to the flag processor 533.

Here, the start code detection can be determined by the presence or absence of an audio frame start code or a video start code.

The flag processor 533 may provide a flag to the transport packetizer 540 in response to a flag request signal of the start code detector 531, or provide a flag in response to a flag request signal of the time-lapse irradiation unit 532. A transport packetizer 540 is provided.

The transport packetizer 530 records the flag from the flag processor 533 in the PES header and converts the PES packet into a transport packet and provides the flag to the flag detector 561 and the transport buffer 570. Additionally, PCR, which is time information related to the program, is recorded in the transfer header.

Writing a flag in the PES header makes room for recording an ESCR having a length of substantially 42 bits, and the actual ESCR is recorded in subsequent processing.

For reference, the ESCR should retransmit within a maximum of 0.7 seconds. Since this is a condition for the decoder to stably decode the decoding point (MPEG recommendation), the time-lapse irradiation unit 532 checks the time from this point in time if there is an ESCR transmitted immediately before, and when the time is 0.7 seconds, the flag processing unit ( 533), the flag request signal is applied.

That is, the time-lapse irradiation unit 532 operates regardless of the start code. Therefore, if the start code of the PES packet is present 0.7 seconds after the current ESCR recording time, the time case and the irradiation unit 532 can generate a flag request signal according to the operation and record the flag within at least 0.7 seconds. Make sure

On the other hand, if a flag is detected in the transport packet output from the transport packetizer 540, the flag detector 561 provides a corresponding read signal to the ESCR memory 562. Therefore, the ESCR memory 562 reads out the recorded ESCR, provides it to the transfer buffer 570, and records the recorded ESCR.

When the flag detection unit 561 checks that the ESCR_flag is 1 in the PES packet header in the payload of the transmission packet, the flag detection unit 561 reads the ESCR recorded in the ESCR memory 562 and uses the value as the PES packet header. It means to write on.

That is, as shown in FIG. 7, it means that the ESCR is generated and recorded on the basis of the point in time recorded in the transmission buffer 570 after receiving the flag request signal.

Since the time is recorded based on the time point recorded in the transmission buffer 570, other time values are described accordingly, and thus the decoder can interpret other time values based on this reference value.

Accordingly, the transmission buffer 570 records the read ESCR in the PES packet output from the transport packetizer 540 at a time earlier than the PES stream start code, and then outputs it to the transport channel, which is received by the PES stream start code. If the ESCR is first received and decoded before it is decoded, decoding can be performed at an earlier time.

Thereafter, the ESCR value stored in the ESCR memory 562 is obtained as follows.

The initial ESCR detection unit 551 accumulates from the time when the transport packet stream output from the transport packetizer 540 is first recorded in the transport buffer 570 to the time when the ESCR first received in the transport buffer 570 is recorded. After the initial ESCR obtained by dividing the data amount by the transmission rate is loaded into the first and second counters 533 and 555, the value is increased according to the operation of the system encoder clock unit 552.

The system clock unit 552 is a clock that satisfies the above-described 27 MHz-810 Hz ≤ system_clock_frequency ≤ 27 MHz + 810 Hz, the time change rate of the system_clock_frequency ≤ 75 × 10 ^-3 Hz / sec Occurs.

Accordingly, the first counter 553 and the second counter 555 perform initial and operation, and the system clock unit 552 generates a stable clock (27 MHz) within the range of the above-described conditions, thereby generating the first counter. It provides a counter 553.

The first counter 553 is incremented by one 9-bit counter for each clock of the system clock unit 552, and this value is provided to the comparator 554 and the combination processor 556 for each system clock.

Accordingly, the comparator 554 compares the counter value provided from the first counter 553 with the reference value 299, and generates a carry at the matching time point to provide the second counter 555, and the first counter. The value countered by 553 is also provided to the combination processing unit 556.

In addition, the second counter 555 counts the carry from the comparator 554 and provides the counted value to the combination processing unit 556.

That is, the comparator 554 is incremented by 1 while generating a carry at the same time as compared with the output of the 100101011 and the 9-bit counter (9-bit binary value of 299). The reason for this configuration is to calculate the ESCR value in synchronization with the encoder system and the clock.

The combination processing unit 556 includes additional bits in 6-bit units, and logically combines the count value of the comparator 554 with the additional bits in 6-bit units and the count value of the second counter 555 in 48-bit units. Then, the ESCR which is the logical combination information is provided to the ESCR memory 562.

The ESCR recorded in the ESCR memory 562 is read out and supplied to the transfer buffer 570 by the flag detection signal of the flag detector 561.

As a result, the transmission buffer 570 records the ESCR in the header of the PES packet output from the transmission packetizer 540 and then outputs the transmission channel.

Therefore, the system decoder can decode the PES packet on the basis of the ESCR inputted before the elementary stream (audio / video signal) in the transport packet.

As described above, the present invention has the effect of reducing the decoding time while satisfying the maximum transmission time restriction condition of the ESCR data defined in the MPEG system.

Claims (5)

An elementary stream encoder that encodes an audio / video signal based on an MPEG recommendation, a PES packetizer that PES packetizes the encoded output, transport packetizes the PES packet, and the transport packetized stream first transmits The initial ESCR is obtained by dividing the accumulated amount of data from the time point written in the buffer to the time point in which the first ESCR received in the transmission buffer is recorded by the transmission rate, and the ESCR for meeting the standard of the decoding time together with the transmission packet. In the apparatus for outputting a signal, the ESCR for generating a flag or matching a decoding time standard according to a detection result of a start code indicating an start of an audio and video signal in an elementary stream which is an output of the stream encoder 510 of the element. Between the count value which counted from the time of recording and transmission and the preset reference value Flag generating means 530 for generating a flag based on the comparison; A transport packetizer 540 which converts a PES packet, which is an output of the PES packetizer 520, into a transport packet, and records and outputs a flag from the flag generation means 530 in the transport packetized transport packet. And an encoder clock system 550 for generating an ESCR for a PES packet stream to be received at a decoder based on the initial ESCR and a system clock, recording an ESCR that is an output of the encoder clock system 550, and transmitting the packetizer. MPEG (MPEG) characterized in that it comprises a detection and recording means 560 for reading out the recorded ESCR in response to the detection result of the flag in the transmission packet that is the output of the output to the transmission buffer 570 ESCR encoder of the system. The start code detection unit (531) of claim 1, wherein the flag generation unit (530) provides a flag request signal in response to a detection result of a start code in the elementary stream output from the elementary stream encoder (510). Wow ; A time-lapse irradiation unit 532 which is initialized at the time when the ESCR is recorded and transmitted in the transmission buffer 570, and provides a flag request signal at a time when the value counted from this initialization time coincides with a preset reference value; A flag is provided to the transport packetizer 540 in response to a flag request signal provided from the start code detector 531, or a flag is sent to the transport packetizer 540 in response to a flag request signal from the time-lapse search unit 532. An ESCR encoding apparatus of an MPEG system, comprising: a flag processing unit 533 provided to the riser 540. The flag detection unit 561 of claim 1, further comprising: a flag detection unit 561 which detects the presence or absence of a flag in the transport stream output from the detection and recording means 560 and the transport packetizer 540 and provides a read signal accordingly; ; ESCR memory 562 which records the ESCR provided from the encoder clock system 550 and reads out the recorded ESCR in response to the flag detection of the flag detector 561 and outputs the ESCR to the transfer buffer 570. ESCR encoding apparatus of the MPEG system, characterized in that consisting of. 4. The ESCR encoding apparatus of claim 3, wherein the flag is recorded in a header portion of a PES packet stream. The encoder clock system 550 of claim 1, wherein the encoder clock system 550 detects an initial ESCR from the transmission buffer 570, and outputs a reset signal or a predetermined reference value as a result of the detection. An initial ESCR detector 551; The system is initialized according to the ON operation of the system encoder, and satisfies the condition "27 MHz-810 Hz ≤ system_clock_frequency ≤ 27 MHz + 810 Hz, and the time-change rate of system_clock_frequency ≤ 75 x 10 ^-3 Hz / sec". A system clock unit 552 for generating and outputting a clock; A first counter 553 that is initialized based on a reset signal or a reference value of the initial ESCR detector 551, and outputs a counted value by incrementing the 9-bit counter by 1 for each clock of the system clock unit 552; ; As a result of the comparison between the value counted by the first counter 553 and a preset reference value (9-bit binary value of 299), a carry is generated and output at a matching time point, and is output by the first counter 553. A comparator 564 for outputting a count value to be expressed by ESCR_ext in units of 9 bits; A second counter 555 which is initialized by a reset signal or a reference value of the initial ESCR detector 551, counts a carry of the comparator 554, and outputs a count value to be expressed in ESCR_base of 33 bits; And an additional bit of the six-bit unit, and logically combine the count value of the comparator 554, the additional bit of the six-bit unit, and the count value of the second counter 555 to form an ESCR of 48 bit units. An ESCR encoding apparatus of an MPEG system, comprising: a combination processing unit 556 provided to a memory 562.