CN203327182U - Network set-top box pcr correction processing system - Google Patents

Abstract

The utility model discloses a network set-top box PCR correction processing system comprising an encoding PCR correction processing unit and a decoding PCR correction processing unit. The encoding PCR correction processing unit includes a video compression encoding module, a video PES packet module, an audio compression encoding module, an audio PES packet module, a clock pulse generation module and a program multiplexer; and the decoding PCR correction processing unit includes a de-multiplexer, an RID filtering module, a PCR calculation module, an LP gain control module, a video disk VCD, a video decoding module, an audio decoding module and a synchronous analog AV output module. The network set-top box PCR correction processing system is simple in structure and can effectively reduce the number of operations and reduce the complexity of PCR correction processing.

Description

Network machine top box PCR proofreaies and correct treatment system

Technical field

The utility model relates to a kind of network machine top box PCR and proofreaies and correct treatment system.

Background technology

Program clock reference is called for short PCR(Program Clock Reference), be a RTTS.In order to guarantee the normal operation of sending and receiving end, the frequency of receiving terminal and transmitting terminal is consistent with phase place, must set up the synchronised clock of sending and receiving end, the PCR code, utilize counter to be counted system at transmitting terminal, after forming the PCR value, send the PCR value to receiving terminal with data at set intervals, receiving terminal has a local clock of working, and its rated power is identical with the transmitting terminal clock, equally also there is a counter to count it, form a local reference clock.At this moment, transmitting terminal can extract PCR from TS stream, with the coded message of audio frame, frame of video, insert in the PES bag, receiving terminal is placed on the PCR value in audio frame, frame of video in buffer memory, etc. the value in the audio frequency and video of transmitting terminal to be compared, occur, then with output control voltage controlled oscillator relatively, make the frequency phase lock of sending and receiving end by adjustment, thereby realize the Complete Synchronization of sending and receiving end sound and image.

Existing network machine top box PCR proofreaies and correct and processes position and the PCR numerical value that need to wrap with the TS that comprises PCR of a large amount of memory stores a period of time, also needs to carry out with a plurality of multipliers the computing of least square method, and the complexity that PCR proofreaies and correct is higher.

The utility model content

The purpose of this utility model is to overcome the deficiencies in the prior art, provides a kind of network machine top box PCR that can effectively reduce operation times, reduction PCR correction processing complexity to proofread and correct treatment system.

The purpose of this utility model is achieved through the following technical solutions: network machine top box PCR proofreaies and correct treatment system, and it comprises coding PCR correction processing unit and decoding PCR correction processing unit:

Coding PCR correction processing unit comprises video compression coding module, video PES package module, audio compression coding module, audio frequency PES package module, clock pulse generation module and program multiplexing device, the output of video compression coding module is connected with the program multiplexing device by video PES package module, and the output of audio compression coding module is connected with the program multiplexing device by audio frequency PES package module; The first via output of clock pulse generation module is connected with counter A, and counter A is connected with the program multiplexing device; The second tunnel output of clock pulse generation module is connected with counter B by frequency divider a, and the road output of counter B is connected with video PES package module, and another road output of counter B is connected with audio frequency PES package module; The Third Road output of clock pulse generation module is connected with the video compression coding module, and clock pulse generation module De Di tetra-tunnel outputs are connected with the audio compression coding module;

Decoding PCR correction processing unit comprises demodulation multiplexer, RID filtering module, PCR computing module, LP gain control module, video and audio CD disc VCD, video decode module, audio decoder module and synchronously simulating AV output module, the output of demodulation multiplexer is connected with the PID filtering module, one tunnel output of PID filtering module is connected with the input of video and audio CD disc VCD with the LP gain control module by PCR computing module, comparator successively, and the output of PCR computing module also is connected with counter C by the initialization loading module; The video PES output of PID filtering module is successively by video cache and video decode module and synchronously simulating AV output, and the audio frequency PES output of PID filtering module is successively by audio frequency buffer memory and audio decoder module and synchronously simulating AV output;

The first via output of described video and audio CD disc VCD is connected with counter C, the second tunnel output of video and audio CD disc VCD is connected with counter D by frequency divider b, the output of counter D connects respectively video cache and audio frequency buffer memory, and the output of video and audio CD disc VCD also is connected with video decode module, audio decoder module respectively.

The beneficial effects of the utility model are: circuit structure is simple, can effectively reduce operation times, reduce PCR correction processing complexity.

The accompanying drawing explanation

Fig. 1 is the position view of network machine top box PCR in the TS packet;

Fig. 2 is PCR correction processing unit structural representation block diagram in encoder;

Fig. 3 is that the TS that contains PCR flows the structural representation wrapped;

Fig. 4 is PCR correction processing unit structural representation block diagram in decoder.

Embodiment

Below in conjunction with accompanying drawing, the technical solution of the utility model is described in further detail, but protection range of the present utility model is not limited to the following stated.

PCR (Program Clock Reference) is Program Clock Reference, and Main Function is the benchmark parameter as video decode in when decoding, carries out synchronizeing of receiving terminal audio frequency and video and transmitting terminal audio frequency and video.

The position of PCR in the TS packet as shown in Figure 1, the coding that comprises 6 bytes in the self adaptation district in packet header, be used for producing the reference clock of decoder, utilize the reference clock of known program, can make the decoded video of digital TV set-top box export the signal end that is locked in the Video coding input, in multiplexer/encoder, program clock is locked in incoming video signal.Standard Definition Television SDTV(Standard Definition Television) transmission of video reference clock is 27MHz(50Hz, 625 row or 59.94Hz, 525 row), program clock is also just 27MHz.PCR inserts packet header with the frequency of fixing, and represents the clock of input source coding side, and the bit rate output of reflection coding, and receiving terminal is adjusted the clock frequency of decoding end according to PCR, to guarantee being correctly decoded video flowing.

Network machine top box PCR proofreaies and correct treatment system, comprises coding PCR correction processing unit and decoding PCR correction processing unit.

As shown in Figure 2, coding PCR correction processing unit comprises video compression coding module, video PES package module, audio compression coding module, audio frequency PES package module, clock pulse generation module and program multiplexing device, the output of video compression coding module is connected with the program multiplexing device by video PES package module, and the output of audio compression coding module is connected with the program multiplexing device by audio frequency PES package module; The first via output of clock pulse generation module is connected with counter A, and counter A is connected with the program multiplexing device; The second tunnel output of clock pulse generation module is connected with counter B by frequency divider a, and the road output of counter B is connected with video PES package module, and another road output of counter B is connected with audio frequency PES package module; The Third Road output of clock pulse generation module is connected with the video compression coding module, and clock pulse generation module De Di tetra-tunnel outputs are connected with the audio compression coding module;

Encoder PCR proofreaies and correct in processing procedure, in transport stream, the decoding of multi-channel program has oneself time origin independently, PCR also divides two-way to be encoded: the direct flip-flop number A of the 27MHz pulse that a route clock pulse generation module produces generates extension field PCR_ext, and length is 9bits; Produce the 90kHz pulse after another Lu Jingyi 300 frequency divider a, send into 33 digit counter B and generate the 90kHz base value, list PCR_base in, length 33bits, for comparing with PTS/DTS, produce the decoding of user's receiving terminal and the synchronizing signal of demonstration, form the PCR territory, jointly form the PCR of 42.

The numerical value be coded in PCR (i) has represented t (i), the byte of last that i refers to comprise the PCR_base field.Concrete regulation is as follows:

PCR_base (i)=((system clock frequency * t (i))) DIV300) %2

PCR_ext (i)=((system clock frequency * t (i)) DIV1) %300

PCR(i)=PCR_base(i)*300+PCR_ext(i)

The structure of the TS stream bag that contains PCR as shown in Figure 3.

As shown in Figure 4, decoding PCR correction processing unit comprises demodulation multiplexer, RID filtering module, PCR computing module, LP gain control module, video and audio CD disc VCD, video decode module, audio decoder module and synchronously simulating AV output module, the output of demodulation multiplexer is connected with the PID filtering module, one tunnel output of PID filtering module is connected with the input of video and audio CD disc VCD with the LP gain control module by PCR computing module, comparator successively, and the output of PCR computing module also is connected with counter C by the initialization loading module; The video PES output of PID filtering module is successively by video cache and video decode module and synchronously simulating AV output, and the audio frequency PES output of PID filtering module is successively by audio frequency buffer memory and audio decoder module and synchronously simulating AV output;

The first via output of described video and audio CD disc VCD is connected with counter C, the second tunnel output of video and audio CD disc VCD is connected with counter D by frequency divider b, the output of counter D connects respectively video cache and audio frequency buffer memory, and the output of video and audio CD disc VCD also is connected with video decode module, audio decoder module respectively.

Decoder PCR correction processing procedure is as follows:

S201: at first utilize PCR to recover the 27MHz system clock of synchronizeing with encoder;

S202: after the recovery system clock, the decoding that utilizes DTS, PTS in PES stream to carry out between audio frequency and video is synchronous, utilizes VBV_Delay that the buffering duration of decoder is set simultaneously;

S203: start decoder and initially decode.

Concrete, the synchronous step of the described decoding of step S202 comprises following sub-step:

S2021: decoder solves PCR from the packet header of input code flow, and it is sent into to the time restore circuit of system;

S2022: new PCR of the every reception of system time restore circuit, just carry out a local system time clock recovery and phase-locked;

S2023: after the demodulation multiplexer demultiplexing, solve Presentation Time Stamp PTS and Decoding Time Stamp DTS from PES packet header, and send in the Basic Flow decoder;

S2024: after the Basic Flow decoder receives PTS and DTS, deposit in corresponding FIFO and manage; For the display unit that there is no PTS and DTS, its time label is carried out to interpolation, and send in FIFO;

S2025: before each display unit starts decoding, PTS, the DTS corresponding with it compare with corresponding system clock STC, only when system clock STC equates with PTS, DTS, just start decoding.

The PCR tolerance is the limits of error that receive PCR, this error can by initial p CR value and in multiplexed process again the modification to PCR cause, do not comprise that the grouping that network jitter causes arrives time error, the tolerance of PCR has limited the PCR mistake of the storage copy of a transmission stream, in general, the tolerance of PCR is ± 500ns.

Claims (1)

1. network machine top box PCR proofreaies and correct treatment system, it is characterized in that: it comprises coding PCR correction processing unit and decoding PCR correction processing unit:

Coding PCR correction processing unit comprises video compression coding module, video PES package module, audio compression coding module, audio frequency PES package module, clock pulse generation module and program multiplexing device, the output of video compression coding module is connected with the program multiplexing device by video PES package module, and the output of audio compression coding module is connected with the program multiplexing device by audio frequency PES package module; The first via output of clock pulse generation module is connected with counter A, and counter A is connected with the program multiplexing device; The second tunnel output of clock pulse generation module is connected with counter B by frequency divider a, and the road output of counter B is connected with video PES package module, and another road output of counter B is connected with audio frequency PES package module; The Third Road output of clock pulse generation module is connected with the video compression coding module, and clock pulse generation module De Di tetra-tunnel outputs are connected with the audio compression coding module;

Decoding PCR correction processing unit comprises demodulation multiplexer, RID filtering module, PCR computing module, LP gain control module, video and audio CD disc VCD, video decode module, audio decoder module and synchronously simulating AV output module, the output of demodulation multiplexer is connected with the PID filtering module, one tunnel output of PID filtering module is connected with the input of video and audio CD disc VCD with the LP gain control module by PCR computing module, comparator successively, and the output of PCR computing module also is connected with counter C by the initialization loading module; The video PES output of PID filtering module is successively by video cache and video decode module and synchronously simulating AV output, and the audio frequency PES output of PID filtering module is successively by audio frequency buffer memory and audio decoder module and synchronously simulating AV output;

The first via output of described video and audio CD disc VCD is connected with counter C, the second tunnel output of video and audio CD disc VCD is connected with counter D by frequency divider b, the output of counter D connects respectively video cache and audio frequency buffer memory, and the output of video and audio CD disc VCD also is connected with video decode module, audio decoder module respectively.

Images