CN1102312C - Method and device for transmission of data by packaging data-flow - Google Patents

Abstract

A scheme is provided for communicating high rate isochronous data in an MPEG-2 type transport stream in a robust manner. The syntax for the data bitstream also provides for the communication of a data clock increment value to a decoder. The increment value enables a simplified and cost effective approach to the direct digital synthesis of a clock frequency necessary to recover data from the packetized data stream at the decoder. The time resolution for presenting isochronous data presentation units at the decoder is increased by providing a presentation time stamp (PTS) extension to supplement a standard MPEG-2 PTS.

Description

Method and device by packet data flow transmission data

The present invention relates to a kind of method and device that is used for by packet data flow transmission data, particularly a kind of method and device that is used for dynamic image cellular organization-2 (MPEG-2) data flow high speed rate synchronous transmission.

Transmission such as the digital data of Digital Television has many different standards.The example of this class standard comprises the dynamic image cellular organization standard that is called as MPEG-2 and Digi Cipther II standard (by the general instrument Corp. in Illinoi State, The United States Chicago, also being that assignee of the present invention institute is proprietary).Digi Cipher II standard and Moving Picture Experts Group-2 (well-known and be regarded as the image and voice compression regulation approved in file ISO13818 by International Standards Organization (ISO)) are similar and comprise wherein each aspect.

Except the image and voice compression property, a system's " layer " that provides with the irrelevant coding techniques of transmission medium also is provided the MPEG-2 standard, comprises the bit element flow of one or more MPEG program with foundation.The mpeg encoded technology is used a formal grammar and one group of semantic rules, to set up the defeated bit element flow of tendency to develop.This grammer and semantic rules comprise about multiplex (MUX), clock recovery, the synchronous and wrong regulation of recovering.For the present invention is described, any data flow similar to MPEG-2 class transport stream encoder form all is called as " MPEG-2 class transport stream ".An example (but unique absolutely not) of MPEG-2 class transport stream is one to meet the data flow of Digi Cither II standard.Other these class standards will come forth in future.

Mpeg 2 transport stream designs at the transmission situation that may produce error in data.Each MPEG-2 transmission package is 188 bit group regular lengths.Many programs (respectively comprising different assemblies) may be integrated with in the transport stream.Use the example of mpeg format service to have: the TV service of the cable TV of land and satellite network broadcasting, and conversational phone infrastructure service.The grammer of mpeg 2 transport stream is defined by International Standards Organization with semantic, be ISO/IEC13818-1, international standard, on November 13rd, 1994, title is that " the general coding of dynamic image and relevant sound: system " (Generic Coding of Moving Picturesand Associated Audio:System) recommendation H.222.0, with ISO/IEC13818-2, international standard, nineteen ninety-five, title be " the general coding of dynamic image and related sound: image " (Generic Codingof Moving Pictures and Associated Audio:Video) recommendation H.262, the two all is contained in this for your guidance.According to the regulation of Moving Picture Experts Group-2, the multiplex (MUX) flows (packetizd elementary streamPES) letter bag substantially with original basic stream (such as image of having encoded and the voice signal) enfeoffment of packing into, and this letter bag is inserted in the transmission letter bag.As mentioned above, each MPEG transmission letter packet length is fixed as 188 bit groups.First bit group is one to possess the sync bit tuple of 8 unique bit forms (as: 01000111).This sync bit tuple is in order to find out the starting point of each transmission letter bag.

Being right after the sync bit tuple is 3 bit group headings afterwards, it comprises the transmission letter bag error indicator of 1 bit, the initial indicating device in payload (payload) unit of 1 bit, the transmission elder generation power indicating device of 1 bit, and adaptive field (adaptation field) control of control one 2 bits and the continuous counter of one 4 bits are encrypted in the letter bag distinguished symbol (PID) of one 13 bits, the transmission of 2 bits.Use sync bit tuple and 3 bit group headings, stay the nearly payload of 184 bit groups, it is used for the transport communication data.The one adaptive field that can select to use can be followed after title, with the relevant specific information of being correlated with certain transport stream or the basic stream in certain transmission letter bag with MPEG of carrying.The regulation that clock is replied (for example the program clock benchmark (program clock reference PCR) and (splicing) control of splicing) is the typical information of adaptive field institute carrying.This information is placed in the adaptive field, and is encapsulated in, so that carry out again multiplex (MUX) and the running of network route planning with its related data.When using adaptive field, it is shorter that payload becomes relatively.

PCR is a counter, and when PCR bit group was inserted into transport stream, it was used to react the value of the system clock (system time clock STC) of relative program.Decoder uses PCR to realize decoder clocks and encoder system clock synchronization.9 lower bits provide the counter of a modulus for (modulo) 300 among the 42 bit PCR, and its value increases with 27 megahertz clock frequencies (system clock frequency).When each modulo-300 upset, the counting of 33 higher bits increases, so the representative of higher bit is counted with 90 khz frequencies.So make and show that value that time mark (presentation time-stamps PTS) and decode time mark (decoding time-stamps DTS) can 9 kilo hertzs relatively.Because each has its oneself PCR by the program of data flow institute carrying or service item, so program can asynchronous mode multiplexization with service.

Sound, image and data synchronization are to use the time mark method to realize in the program.Show that time mark and decode time mark are by in the transport stream of slotting as indivedual images and sound letter bag.The decoded device of PTS and DTS information uses, and when decode and Show Picture with decision, and the part that when plays sound.As mentioned above, PTS is relevant with the clock of being set up by PCR with the DTS value, but is subject to Moving Picture Experts Group-2, and its time resolution is 11.1 microseconds.This resolution is subject to PTS90 khz clock frequency (33 higher bits are provided by PCR).This restriction can be got rid of following phenomenon, as: data transfer rate is non-to be the integral multiple of per second 90 kilobit units (kbps), increases the weight of the time error of general high data rate, use with the standard mpeg 2 transport stream in the identical method that image and acoustic information provided is transmitted.

MPEG-2 data (as compressed image and voice data) must formattedly flow (packetized elementarystream PES) for wrapping the enfeoffment that forms by a succession of PES letter substantially.Each PES letter comprises a PES title and payload thereafter.PES letter bag is divided into several continuous regular length transmission letters and is surrounded by effect load.

PES letter bag has the length that can change and quite grow.Selectable different field (as showing time mark and decode time mark) can be connected on after the title of PES.When transmission letter bag was formed by PES, PES title and transmission letter packet header were side by side.One independent PES letter bag may be crossed in the continuous transmission letter bag that time part that comprises many transmission letter bags and PES letter bag must appear at the identical pid value of tool.But note that these transmission letter bags also can be staggered arbitrarily with other transmission letter bags of the data with different pid values and the different basic streams of carrying.

The image service is to put into PES letter bag via the MPEG imaging data stream that will encode, PES letter bag is cut apart to insert transport stream carried out again.Each image PES letter comprises all or part of of the image picture (being called as the image access unit) of having encoded.PTS and DTS data are placed into PES letter packet header, with the relevant information unit of package.PTS be used to start decoder with represent (as, " demonstration ") relevant information unit.When DTS instruction decoding device answers decipher this element.

The voice service that is provided is according to mpeg standard, uses and the identical regulation of PES letter covering.The PTS data are attached to the letter bag that comprises the sound block border.This border is defined by sound synchronization character (word).Sound block is defined as the data between the two continuous sound synchronization characters.

For image and voice signal from MPEG-2 class (as MPEG-2 or Digi Cipher II) transport stream institute carrying are rebuild television signal, need a decoder handling image letter bag exporting image decompression processor (video decompression processor VDP) to, and handle sound letter bag to export sound decompression processor (audio decompression processor ADP) to.The data of other kinds of transmission also are possible in this type of transport stream.For example, provide as teletext, stock quotation and can come carrying as the transmission letter bag (producing) that separates from the enfeoffment base flow that separates with the exclusive data of the service of other information.The non-synchronous data pipeline also can be supported, and so can to represent from decoder be the equivalence input of an encoder with the output of RS-232 form to pipeline.This information service transmission letter bag will with MPEG image and sound letter wrap in such as in the final multichannel communication that transmits with cable via satellite by the multiplexization.

It is favourable using synchronous (isochronous) data of MPEGF-2 class form carrying.Synchrodata is that the high data rate and the meeting that transmit at general rule clock edge place are different with bursting property " synchronously " data that irregular clock together arrives at.So, the clock of synchrodata carrying one beat type, and clock can be replied by simple phase-locked loop (phase olock loop PLL).Generally speaking, synchrodata partly is a data bit element with the part of normal speed transmission roughly, and it is attended by a clock signal.The clock of beating that any situation that departs from normal (synchronously) speed will be allowed is hidden.These type of data can be used to the pipeline of data on a large scale of any number.(just: the phone data line) transmission of data flow promptly is an example to the T1 numeral.This streaming rate is 1.554 100 ten thousand tuples/per seconds.Other application comprise once be not limited to an enterprise network circuit-switched data, general high-speed data communications and almost any other need continue the delayed data transfer rate data, services of (surpass and use asynchronous mechanics of communication can reach or be unsuitable for the change delay).These application characteristics are not allow bit slippage (bit slip).That is to say that mistake tolerated, but can cause the serious interruption that final data is synchronous more synchronously about the bit element flow net transfer.

In Moving Picture Experts Group-2, show that time mark can only be with the resolution sensing display unit (just: the data of the bit group of 8 bits are shown in decoder) of 11.1 microseconds.This restriction comes to be used to produce 90 kilo hertzs of speed that higher bit is set up in the PCR counting that shows time mark.Owing to be high-speed synchronous data, may improve the resolution, particularly purpose of display unit in order to correct a mistake.In particular, must represent unambiguously in time that display unit continues to change speed to support.Therefore, help improving the temporal analytical density that shows time mark, and the resolution that MPEG-2 provided that is above standard.For example, provide a structure that improves the PTS temporal analytical density, to allow synchronously or similar data is formed or higher speed rates with per second 9.0 megabits unit.

One reduced data receiver need be provided, to provide suitable clock rate according to system clock frequency in case from data flow also the structure of source data be more favourable.Especially, need a structure, so as receiver wherein can with any desired information data rate (as from per second 19.2 megabit tuples to per second 9 megabit tuples) provide clock for being used for by DDS output synchronizing information data.

The object of the present invention is to provide a kind of method and apparatus, with transmission and the data that receive in the PMEG-2 class transport stream, it should have above-mentioned advantage.

For achieving the above object, the present invention adopts following measure:

The present invention is in order to the method to MPEG-2 class transport stream high speed rate synchronous data transmission: synchrodata is located at enfeoffment and flows substantially in (PES), also is provided with a PES title before enfeoffment is flowed payload substantially; The PES payload comprises a synchrodata title, and many synchrodata display units are right after thereafter.The synchrodata title comes with thereafter display unit among the PES, and put in order: first bit of synchrodata title is right after after last bit of PES title.One clock added value is inserted in the synchrodata title, specifies the difference between this synchronous data rate and reference clock speed.This clock added value can make synchronous data rate strengthen the reference clock speed generation of synchronous data rate by decoder.PES is packaged into many synchronous data transmission letter bags, make that each payload bit of each transmission letter bag is first bit of synchrodata display unit, and last payload bit of each letter bag is last bit of synchrodata display unit.

Time mark (PTS) extention exists in the synchrodata title, to supply a standard MPEG-2 PTS who exists in the PES title.The PTS extention makes the temporal analytical density of decoder synchrodata display unit improve with combining of standard P TS.

In illustrated specific embodiment, there is the beginning of synchrodata title in the PTS extention.The PTS extention can derive from the most effective 8 bits in the standard MPEG-29 bit PCR extention.8 bit PTS extentions can combine with the standard 33 bit PTS of MPEG, to improve the temporal analytical density that synchrodata shows time mark, be increased to 74 nanoseconds (13.5 megahertzs) from Moving Picture Experts Group-2 resolution 11.1 microseconds (90 kilo hertzs), clearly to determine display unit zero-time by synchronous PTS appointment.

In illustrated specific embodiment, each synchrodata display unit comprises the bit group of two 8 bits, so display unit comprises the word of 16 bits.

One added value is present in the synchronous title, specifies the difference of synchronous data rate for the reference clock speed in the decoder.

Method of the present invention is with the synchrodata of reduction according to any one method transmission mentioned above.An one PES title and a synchrodata title are placed in the received synchronous transmission letter packet data streams.Program clock benchmark (PCR) value is taken out from synchronous data transmission letter bag.The PCR value is used to reduce reference clock speed.The clock added value is taken out from the synchrodata title, is used for producing synchronous data rate according to reference clock speed.Synchrodata is reduced with synchronous data rate.

Standard P TS is taken out from the PES title.The PTS extention is taken out from the synchrodata title.The standard P TS that is removed and PTS extention are with deciding an orthochronous to be contained in the synchrodata display unit that is received data flow to begin to show.In this illustrated specific embodiment, the PTS extention is present in the beginning of synchrodata title, yet also may there be other places in it.The PTS extention may be from the most effective 8 bits in the standard MPEG-29 bit PCR extention.

The invention provides a kind of device, is the mode of a kind of utilization reduction synchrodata from MPEG-2 class transmission letter bag, to avoid in high rate data transmission because of the wrong device that loses transmission letter bag.The enfeoffment that device of the present invention can be found out received synchronous data transmission letter Bao Liuzhong fail to be sold at auction substantially topic and synchrodata title.Device of the present invention also can take out program clock benchmark (PCR) value from synchronous data transmission letter bag stream.This device is in response in this PCR value and the reference clock speed of reducing.Device of the present invention can take out a clock added value from the synchrodata title.The clock added value that is removed is processed with the recasting synchronous data rate with the reference clock speed that is reduced.This device is in response to reduce synchrodata in the synchronous data rate of being remake.

Device of the present invention can take out the demonstration time mark of synchrodata from the PES title, and takes out the PTS extention of synchrodata from the synchrodata title.A device of the present invention in response in PTS that is removed and PTS extention, begins to show the orthochronous that is contained in the synchrodata display unit in the received transfer of data letter bag stream with decision.

In an embodiment of the present invention, the PTS extention is taken out by the beginning from the synchrodata title, and the length of each synchrodata display unit is 16 bits.

The invention provides an acceptor device, with from data flow restore information data.This information is transmitted in data flow with an information data rate.One directly digital synthetic clock provides a plurality of reference clock speed according to system-clock rate.Device provided by the invention is to find out the information data title in the received information data transmission letter bag.The present invention also provides a device to take out the clock added value from message header.Clock added value appointed information data rate becomes accurate ratio with the phase-locked system clock frequency.The DDS clock is in response to providing a clock signal in the clock added value with information data rate, in order to output information data.

Added value is provided with integer.Data flow can comprise, as MPEG-2 class transmission letter bag stream.In this embodiment, the item system clock frequency is 27 megahertzs.Added value is near the product of information data rate and the modulus value N integer divided by item system clock frequency (just 27,000,000).In a certain specific embodiments, modulus value N equals 536,868, and 000.The increment of integer (but in conjunction with the degree of variation from the 30ppm of 27 megahertz system clock frequencys of MPEG item that is allowed to) provides one to continue to change clock generator to support synchrodata.

Brief Description Of Drawings:

Fig. 1: basic flow data is encapsulated into the schematic diagram of transmission letter bag;

Fig. 2: alleged PES and synchrodata title schematic diagram among Fig. 1;

Fig. 3: the calcspar of the encoder apparatus of transmission letter bag in the constitutional diagram 1;

Fig. 4: be the calcspar that the decoder device of the synchrodata of wrapping carrying is believed in a reduction transmission.

Fig. 1 shows how the multiplex (MUX) turns to the diagram that a string transmission letter wraps to different digital service elements.Reaching of multiplex (MUX) is by being encapsulated as PES letter bag such as original basic streams such as the image of having encoded, sound and data, and then these PES letter bags being encapsulated as transmission letter bag.This figure only is an embodiment, because may transfer to greater or less than illustrated 7 transmission letter bag 22a-22g such as the PES letter bag of illustrated letter bag 12.

In the embodiment in figure 1, an integral body is denoted as the data bit flow filament that 10 basic stream comprises a tandem, for example the synchrodata shown in.The data that note that other kinds can be provided in the basic stream to be transmitted with the method according to this invention.Similar basic stream will be provided, and according to the MPEG-2 transmission standard, be the image and the voice data of compression.

First step that forms transmission letter bag stream is that the basic stream with Various types of data is packaged as a corresponding enfeoffment of being made up of continuous P ES letter bag and flows (PES) substantially, and letter wraps 12 as shown in Figure 1.Each PES letter comprises a PES title 14, and its heel has the PES payload of the display unit (presentation units PU) 18 that comprises a string regular length.Payload comprises data waiting for transmission.PES mark 14 comprises to handling the payload data Useful Information, as the demonstration time mark (PTS) according to the MPEG-2 system specification.

According to the present invention, synchrodata title (ISO title) 16 is surrounded by a part of imitating load immediately following after the PES mark 14 for the PES letter.The display unit 18 of payload is immediately following after the ISO title 16.The ISO mark will describe in detail hereinafter.

Title in each PES letter bag and payload data are divided into the independently transmission letter bag 22,24,26 of regular length, and each transmission letter comprises a transmission header 30 and payload data 36.The payload data of each transmission letter bag will comprise a part of payload data (just display unit 18) in the corresponding PES letter bag 12, and also can comprise PES title 14 and ISO title 16, shown in 22a.Transmission letter bag 22d is another synchronous data transmission letter bag among the transmission letter bag multiplex (MUX) 20.This transmission letter comprises a transmission header 30 and payload 36.Do not comprise PES title or ISO title in the payload, because this transmission letter bag is by being right after interior PES title or the ISO title of PES letter bag, because this transmission letter bag is to change by being right after PES letter bag interior PES title and the payload data after the ISO title.In other words, because in each PES letter bag, have only a PES title and an ISO title, so have only first transmission letter bag that derives from this PES letter bag can comprise PES title and ISO title.Payload portions by other transmission letter bags that obtain in the PES letter bag will only comprise actual information section data waiting for transmission.

According to the MPEG-2 system specification, the program that transmission letter packet header 30 will comprise each other letter bag stream of transmission letter Bao Liuyu such as difference such as synchrodata letter bag stream, image letter bag stream or sound letter Bao Liu does not accord with (PID).Fig. 1 only represents the origin of synchronous data transmission letter bag 22.In order to obtain image letter bag 24 and sound letter bag 26, corresponding basic stream (not shown) is provided, these flow substantially in the roughly the same mode among Fig. 1 (about the formation of synchrodata letter bag 22) and are encapsulated as PES letter bag and transmission letter bag, but the synchrodata title 16 among the present invention is not present in image or the transfer voice letter bag.

Each MPEG-2 transmission letter comprises the data (transmission header 30 and the payload data 36 that may reach 184 bit groups by at least 4 bit groups form) of 188 bit groups.According to the MPEG-2 system specification, one for example is that the adaptive field of 8 bit groups can be provided between transmission header 30 and the payload 36.The adaptive field (adaptation field) that can change length can comprise as being used for the synchronized program clock benchmark (PCR) of decoder system time clock.

Many synchrodata letters wrap 22a, 22b, 22c ... 22g ..., with other letter bags 24a-f ... with 26a-f.... by multiplexization (as shown in fig. 1), to form transport stream 20, this transport stream sees through communication channel and transfers to decoder from encoder.The purpose of decoder is from transport stream different types of transmission letter bag to be separated the multiplex (MUX) according to the pid value of each letter bag, and optionally handles each synchrodata, sound and image part so that be used for rebuilding television signal and the represented data flow of reduction synchrodata.

Fig. 2 shows PES title 14 and ISO title 16 in greater detail.PES title 14 comprises different length and structural information 50 according to MPEG-2 system regulation.One optionally PTS field 52 may be immediately following after variable-length and structural information 50.If PTS is provided, then its corresponding PTS appendix branch is present in the ISO title 16.As shown in Figure 2, PTS extention 54 preferably is present in the beginning of ISO title 16, and it is closelyed follow after the PTS52 in the PES title.But, the invention is not restricted to the PTS extention is set in the beginning of ISO title.Also can there be other parts of ISO title in the PTS extention, as long as it can be detected at decoder, to be used for that it is attached to PTS, the output of decoder is improved the temporal analytical density of display synchronization data.By 8 for example extra bits being set in the PTS extention, be added to 33 bits among the specified PTS of mpeg system specification then, standard MPEG-2 resolution 11.1 microseconds can rise to 74 nanoseconds, clearly to determine the correct display unit zero-time by the additional synchronizing information PTS appointment of quilt.

The ISO title also comprises different rates, length and added value information 56.More particularly, speed, length and added value information will comprise data rate flag, synchrodata title, length field and added value field, with the ratio of appointed information data rate (as synchrodata speed) for system clock frequency.This clock added value makes in the decoder directly that the synthetic clock of numerical digit provides clock signal with information data rate, is used for the information data of the dateout transport stream carrying according to the present invention.

Preferably in the specific embodiment, each synchrodata display unit 18 (Fig. 1) length is 16 bits, that is to say a word that comprises two 8 bit bit groups in the present invention one.Synchrodata display unit and PES data are in line, and make first bit group of synchrodata title closely follow after last bit group of PES title.The synchrodata display unit is surrounded by effect load with the transmission letter and is in line, first bit group (what closely follow is any adaptive field, PES title and synchrodata title field) that first payload bit group that makes the synchronous data transmission letter wrap is the synchrodata display unit.Last bit group of synchronous data transmission letter bag is last bit group of synchrodata display unit.

Being described as follows of synchrodata grammer of the present invention (using the formal syntax of the MPEG-2 system specification).The MPEG syntax are the grammer of a similar C language and are a kind ofly to retouch art continuously and may change the method for the bit sequence of speed, and program and its function of appointment program mode in computer C language.First row of grammer comprises grammatical feature.The second row confession under directions grammatical feature is the length of unit with the bit, and the third line is indicated the grammer kind.Kind has bslbf, and (the bit order is preferential (with uimsbf (no sign integer highest significant position is first preferential) with the Far Left bit.Grammatical feature in symbol " isochronous_data_header () { ... } " the expression braces is a named set, and can be called in other places of grammer, as long as use title " isochonous_data_header () ".The conditional of bit structure can be general " if " test represent.Relational operation habitual in the C language also is effective.Can use the C loop grammar of the loop structure and the standard of use.Syntax table is followed a string semanteme, each is provided previous undefined grammer field and limits their use.Following synchrodata bit element flow grammer and bit element flow be semantic represent an embodiment preferably of the present invention's employing:

The synchrodata sequence:

Grammer: the bit number helps to be recalled

isochronous_data_sequence{

Isochronous_data_header(?){

for(i＝0；i＜N；i++){

Isochronous_data_presentation_unit 16 bslbf}} Dian synchrodata title: Guo

For limiting each synchrodata sequence is even number bit group, and last field that is retained is designated as even number bit group in the synchrodata title.The grammer of title topic is synchronously:

Grammer: the bit number helps to be recalled

isochronous_data_header{

pts_ext8 8 bslbf

data_rate_flag 1 bslbf

reserved 3 bslbf

isochronous_data_header_length 4 uimsbf

if(data_rate_flag){

reserved 4 bslbf

increment 28 bslbf

}

Reserved n bslbf } Dian sync bit flow filament semanteme: the Guo synchronizing sequence:

Isochronous_data_presentation_unit ... 16 bit display units of one synchrodata, wherein first bit shows that (output) is before second and other bits.Synchronous title:

Pts_ext8 ...-8 bit fields extend the PTS of the PES title institute carrying of these PES data.This field is the highest effective 8 bits that are defined in the 9 bit PCR extentions of the MPEG-2 system specification, and the temporal analytical density that shows time mark according to the present invention in order to the raising synchrodata, be increased to 74 nanoseconds (13.5 megahertzs) from Moving Picture Experts Group-2 resolution 11.1 microseconds (90 kilo hertzs), clearly to determine correct display unit zero-time by synchrodata PTS appointment.

Data_rate_flag ... one 1 bit flag is illustrated in existence one added value field in the synchrodata title when being set as " 1 ".

Isochronous_data_header_length ... one 4 bit field, expression is closelyed follow after this field and is comprised word (16 bit) number of the synchrodata title of reserved word, (with 16 bits is that unit forces the synchrodata title to become even number bit group, lumping together with synchrodata display unit, adaptive field and PES title also is even number bit group, this allows synchronous data transmission letter bag to be produced and does not need any character of filling up, and has therefore improved efficient.)

Increment ... one 28 bit field, expression synchrodata clock added value, and as the correct ratio of synchronous data rate for phase-locked reference clock (as the 27MH Football Z Li benchmark of MPEG-2).One preferably among the embodiment, added value is:

Added value=NINT (synchronous data rate * 536,86,000/nominal_system_clock_frequency): wherein:

Nominal_system_clock_frequency is appointed as 27 megahertzs and " NINT " representative " immediate integer " by MPEG.As mentioned above, MPEG allows to have with the item system clock frequency variation of 30 pulse-position modulations (ppm).

Reserved ... the not default any special value of the reserved word of a n bit field, decoder.

Expression one may be used for implementing encoder of the present invention in the calcspar of Fig. 3.Synchrodata (as, from the basic stream among Fig. 2) see through terminal 60 and be input to title and insert the stage 62 (insert and form the required data of ISO title 16).These data are come freely, system's microprocessor (not shown).The PES wrapper stage 66 receives the ISO data that are inserted into the ISO title, and inserts PES title 14 (from the PES title data composition via terminal 68 inputs).As the ISO title data, the PES title data is from a systematic microprocessor or other Data Sources that is widely known by the people in the art.

The synchrodata clock signal inputs to the phase-locked loop (PLL) 67 of encoder among Fig. 3 via terminal 65.PLL may comprise as, one 27 megahertz oscillators and the DDS circuit clock signal (using the nearest added value that calculates according to said method) to pin input.The PCR value is taken as the transmission adaptation data, inputs to transmission letter bag wrapper 70 (describing in detail hereinafter).

In case ISO title and PES title are inserted into synchrodata and flow substantially, the payload data via terminal 60 input thereafter promptly is separated and follows after the title with the form of regular length display unit 18.Its result is a succession of PES letter bag 12, exports the transmission letter bag wrapper stage 70 to by PES wrapper 66.At this moment, form the required data of transmission header and receive in a conventional manner, and formed a transmission header (corresponding payload data is added up) via terminal 72.Payload data comprises the next partial data (just, PES title data, ISO title data and display unit) from present PES letter bag.The output of wrapper 70 is a string synchronous data transmission letter bags 22, and each synchronous data transmission letter bag will comprise a transmission header and payload, and might or can not comprise PES title and synchrodata heading message, and become the part of payload.

Can wrap the multiplexization with believing via the compressed sound letter bag of terminal 76 and 78 input multiplexers 74 and image respectively from the synchronous data transmission of wrapper 70 letter bag.Sound and image letter bag are provided according to well-known in the art mode according to the MPEG-2 system specification.Multiplexer 74 will transmit believes that package synthesizes transmission letter bag and flowed for 20 (as shown in fig. 1).Transmission letter bag stream is modulation in a traditional modulator 80, and via satellite, the communication pipe of cable or other existence is with 82 transmission of traditional transmitter.

Fig. 4 represents a receiver (" decoder ") from the transmission multiplex (MUX) of encoder among Fig. 3 output.The transmission multiplex (MUX) inputs to a decoder 92 via terminal 90, and in a traditional demodulator 94 by demodulation.One de-multiplexer 96 is from being gone back original sound letter bag, image letter bag and synchrodata letter bag by the transmission of modulation letter bag stream.Synchrodata letter bag is input to title processor 98, and title processor 98 can comprise traditional being used for by rule from the microprocessor of synchrodata letter bag stream reduction PES title and ISO title.Take out in the stage 102 at PTS, PTS is taken out from the PES title.Take out in the stage 104 in the PTS extention, taken out from the ISO title according to PTS extention provided by the present invention.PTS and PTS extention are combined in a colligator 106, so that synchrodata PTS to be provided, high-speed synchronous data are correctly in time shown.One PTS decoder 108 is from by the additional synchrodata PTS take-off time information of being extended of colligator 106 outputs.This time information is input to synchrodata extractor 110, and this synchrodata extractor 110 also receives the synchrodata letter bag from de-multiplexer 96.System time information from title processor 98 makes the taking-up stage 102,104, and PTS decoder 108 comes into force with synchrodata extractor 110, suitably to find out and to handle the data that enter each stage.Synchrodata extractor 110 is responded all PTS from PTS decoder 108 to show each synchrodata display unit (the ISO data that are reduced) at reasonable time.The ISO data that are shown are from ISO synchrodata extractor 110 output, in order to according to existing the information in the data that desired service content is provided.

Decoder among Fig. 4 also comprises a DDS clock 100, is used to provide many reference clock speed (other parts by title processor and decoder are used).Output is one or more in the reference clock speed that provides according to the DDS clock from the system time of title processor 98.These reference clock speed are according to a system clock frequency, as specified system clock frequency 27 megahertzs of the MPEG-2 system specification.In order to handle PCR to produce the employed system clock frequency of DDS, decoder comprises one and is used for taking out the PCR resolver 97 of PCR value from synchronous data transmission letter bag.The PCR value that is removed is used for pinning one and produces the system clock phase-locked loop 99 of (as, 27 megahertzs).Clock signal of system is input to DDS clock 100, is used for producing above-mentioned reference clock speed.

For decoder simplification, a clock " added value " is provided in the synchrodata title to specify the ratio of synchronous data rate for system clock frequency.This added value is inputed to DDS clock 100 then by title device 98 reduction, and DDS clock 100 uses these added values to think that synchronous data rate provides clock news signal number to come the display synchronization data.

In the synchrodata title, provide the clock added value to make that decoder does not need oneself to calculate this added value.In the legacy system that uses the synthetic clock of Direct Digital, decoder receives an essential clock frequency indicating device together with data to be restored together.The clock frequency indicating device is dragged surely the actual clock frequency that will be synthesized by the DDS clock.Because the present system clock of DDS clock calculation is producing various fixed clock frequency, thus traditional decoder earlier the desired clock frequency of decision for the ratio of system clock frequency (desired clock frequency is produced by it).Carrying out the necessary processing hardware of this function increases the cost and the complexity of decoder.

In a digital television decoder, cost must be kept floor level, because the millions of television sets in may using need a decoder that separates with each.Via providing an added value (directly being used to produce desired frequency by the DDS clock) to give decoder, the complexity of receiver and cost can be lowered.In system of the present invention, provide the calculating of the necessary added value of desired frequency mainly to locate to finish at encoder (millions of decoders in the service use).Therefore, decoder does not need to carry out this computing.

Method and apparatus provided by the present invention, with in traditional MPEG-2 class transport stream such as the information data of synchrodata.Synchrodata is positioned at the payload portions that enfeoffment is flowed substantially after the PES title.The PES payload is a starting point with synchrodata title (being thereafter the synchrodata display unit).One preferably in the specific embodiment, display unit length is 16 bits.Display unit and enfeoffment stream substantially are arranged into delegation, and first bit group of synchrodata title is right after after last bit group of PES title.The synchrodata display unit also is arranged into delegation with their transmission letter bag of carrying.In particular, first bit group that first payload bit group of bag is a display unit is believed in transmission.Last bit group of transmission letter bag is last bit group of display unit.The synchrodata bit element flow grammer of one uniqueness is provided to implement the present invention.This grammer provides a clock added value in the synchrodata title, to describe the ratio of synchronous data rate for system's benchmark, provide extra data to decoder by this, so can reduce the complexity and the cost of receiver.

Specific embodiment is relevant preferably with one though the present invention has been described, and please notes that the present invention can do various adjustment and correction, and can not depart from the application's scope of patent protection.

Claims (22)

1, a kind of method of transmitting MPEG-2 class transport stream high speed rate synchrodata, this method comprises following all steps:

Provide synchrodata in an enfeoffment is flowed substantially, this enfeoffment stream substantially has an enfeoffment to fail to be sold at auction topic substantially before an enfeoffment is flowed payload substantially, and this enfeoffment is flowed payload substantially and comprised a synchrodata title, follows a plurality of synchrodata display units thereafter:

This synchrodata title and the display unit in this enfeoffment is flowed substantially thereafter are arranged into delegation, first bit group of synchrodata title is right after after last bit group of PES title is flowed in enfeoffment substantially;

Insert a clock added value in this synchrodata title, specify the ratio of this synchronous data rate for reference clock speed, this clock added value makes this synchronous data rate this reference clock speed to obtain from decoder; Wrap with this PES being packaged into a plurality of synchronous data transmission letters, last payload bit group that first bit group that first payload bit group that makes each transmission letter wrap is a synchrodata display unit and each letter wrap is last bit group of synchrodata display unit.

2, method according to claim 1 is characterized in that: comprise another step:

Be provided with one show time mark PTS extention in described synchrodata title supplying the standard MPES-2 PTS in the PES title, the temporal analytical density that combine these synchrodata display units of demonstration in the raising decoder of PTS extention and standard P TS.

3, method according to claim 2 is characterized in that also comprising another step: the beginning at described synchrodata title is provided with described PTS extention.

4, method according to claim 3 is characterized in that: described PTS extention is the extention of one 8 bits, and the PTS extention is derived from the highest effective 8 bits in the standard MPEG-29 bit PCR extention.

5, method according to claim 4 is characterized in that: described 8 bit PTS extentions combine with 33 bit PTS of a standard to improve temporal analytical density, bring up to 74 nanoseconds from 11.1 microseconds.

6, method according to claim 5 is characterized in that: described synchrodata display unit length respectively is 16 bits.

7, method according to claim 1 is characterized in that: described synchrodata display unit length respectively is 16 bits.

8, a kind of method of reducing the synchrodata in the described method of claim 1, it is characterized in that: this method comprises following all steps:

In the data flow of received this synchronous data transmission letter bag, find out a PES title and a synchrodata title:

From this synchronous data transmission letter bag, take out program clock benchmark PCR value;

Use the described reference clock speed of PCR value reduction;

State taking-up clock added value the synchrodata title from mistake;

Use this added value that is removed and obtain this synchronous data rate from this reference clock speed;

Reduce this synchrodata with this synchronous data rate.

9, method according to claim 8, it is characterized in that, before two-forty synchrodata described in the described MPEG-2 class transport stream of transmission, it is interior to supply the standard MPEG-2 PTS in this PES title that one demonstration time mark PTS extention is set at the synchrodata title, and this PTS extention improves the temporal analytical density that shows these synchrodata display units in the decoder with combining of standard P TS; This method that is used for reducing synchrodata also comprises the following step:

Take out standard P TS from described PES title:

Begin to show that with decision this is received the orthochronous of synchrodata display unit contained the data flow from described synchrodata title taking-up PTS and PTS extention.

10, method according to claim 9 is characterized in that also comprising another step: the beginning at described synchrodata title is provided with described this PTS extention.

11, method according to claim 10 is characterized in that, described PTS extention is the highest effective 8 bits that are derived from standard MPEG-29 bit PCR extention.

12, method according to claim 11 is characterized in that, described synchrodata display unit length respectively is 16 bits.

13, method according to claim 1 is characterized in that, comprises that also another one inserts described synchronous data transmission letter bag to be used for the step of in the decoder described reference clock speed of reduction with described PCR value.

14, a kind of by the packaging data-flow apparatus for transmitting data, it comprises:

In received synchronous data transmission letter bag, find out the device that (PES) title and a synchrodata title are flowed in an enfeoffment substantially;

Bao Liuzhong takes out the device of program clock benchmark PCR value from this synchronous data transmission letter;

Device according to described PCR value reduction one reference clock speed;

From described synchrodata title, take out the device of a clock added value;

Handle the reference clock speed of described clock added value that is removed and reduction, with the device of the described synchronous data rate of remaking; With

The device of the synchronous data rate reduction synchrodata that must make according to described processing means.

15, device according to claim 14 is characterized in that, also comprises:

Take out the device of the demonstration time mark PTS the described synchrodata from described PES title;

Take out the device of the PTS extention the synchrodata from described synchrodata title; With

According to described PTS that is removed and PTS extention, begin to show the device of the orthochronous that is contained in the synchrodata display unit that is received transfer of data letter Bao Liuzhong with decision.

16, device according to claim 15 is characterized in that, the described device that is used for taking out the PTS extention of described synchrodata takes out described PTS extention from the beginning of described synchrodata title.

17, device according to claim 15 is characterized in that, described synchrodata display unit length respectively is 16 bits.

18, a kind of decoder device from data flow restore information data is characterized in that, described information is transmitted in data flow with an information data rate, and decoder device comprises:

One directly digital synthetic DDS clock, so that a plurality of reference clock speed to be provided according to a system clock frequency:

Find out the device of an information data title at received information data transmission Bao Liuzhong; With

Take out the device of a clock added value from described information data title, clock added value appointed information data rate is in the ratio of described system clock frequency;

Wherein said DDS clock provides a clock signal according to the clock added value with described information data rate, is used for exporting described information data.

19, device according to claim 18 is characterized in that, described added value is an integer.

20, device according to claim 19 is characterized in that, described data flow is a MPEG-2 class transport stream;

Described system clock frequency is 27 megahertzs; And

Described added value be near the product of an information data rate and a modulus value N divided by 27,000,000 integer.

21, device according to claim 20 is characterized in that, described modulus value N equals 536,868,000.

22, device according to claim 18, it is characterized in that: described DDS clock based on the described system clock frequency that a permissible range is arranged, produce the reference clock speed of successive range roughly, with according to any information rate restore information in the described roughly successive range.

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