CN100454889C

CN100454889C - Method for acquiring load-bearing data in packetized basic data stream and relevant apparatus

Info

Publication number: CN100454889C
Application number: CNB200410028714XA
Authority: CN
Inventors: 蔡锦煜
Original assignee: MediaTek Inc
Current assignee: MediaTek Inc
Priority date: 2004-03-10
Filing date: 2004-03-10
Publication date: 2009-01-21
Anticipated expiration: 2024-03-10
Also published as: CN1668027A

Abstract

The present invention provides a data retrieving system which is used for retrieving load bearing data packaged by a basic data flow from a transmission data flow or a program data flow. The data retrieving system contains a data source device providing a data packet, a packet processing device, a transmission interface and a control circuit for controlling the operation of the data retrieving system, wherein the packet processing device is electrically connected with the data source device and is used for computing the length of the data packet to generate a packet length value; the transmission interface is electrically connected with the packet processoing device and is used for outputting load bearing data in the packet stored in the packet processing device; the control circuit is used for controlling the operation of the data retrieving system; according to the packet length value, the control circuit system controls the transmission interface to output the load bearing data in the data packet.

Description

The method and the relevant apparatus of the carrying data in the elementary stream of acquisition packetized

Technical field

The present invention relates to the method and the relevant apparatus of the carrying data in a kind of acquisition data package, particularly a kind of method and relevant apparatus of the data packet acquisition carrying data from the elementary stream of a packetized.

Technical background

Be referred to as elementary stream (Elementary Stream is called for short ES) behind the video-audio data process coding, and just become the elementary stream (Packetized ElementaryStream, abbreviation PES) of packetized after the ES process enfeoffment processing.

At moving picture coding (the Moving Picture Coding Experts Group 2 of expert group 2, hereinafter to be referred as MPEG 2 specifications) in, two kinds of data stream formats have been defined in order to transmission PES, be respectively program data stream (Program Stream, be called for short PS) and transmitting data stream (Transport Stream is called for short TS).

Program data stream is fit to apply in the extremely low Storage Media of wrong incidence.Therefore and be not suitable for the system that needs error correction this is because package (PS Packet) size of program data stream is fixing.The packed data of program data stream mainly is to be stored on the disc, as the videodisc of DVD.Program data stream is similar to the system data flow (System Stream) in the moving picture coding expert group 1 (MPEG 1 specification) basically, but the inner grammer (Syntax) revised and the new letter formula of being to use is to provide some functions than the advanced person.

Transmitting data stream has then used the package of regular length, except hardware is better handled, also is more suitable for carrying out the calculation of error correction.Therefore, transmitting data stream mainly is to be applied in to be easier to produce among the wrong transmission environment, as IEEE 1394 host-host protocols or digital video broadcasting (Digital VideoBroadcasting, DVB).Each data packet in the transmitting data stream (TS Packet) size is fixed as 188 bytes, and wherein preceding 4 bytes are so-called title (Header), and the part of the carrying data (Payload) behind the title promptly is the packet data of PES.(Packet Identifier, PID), pid value is that to represent the content of this transmitting data stream package be to belong to video data, voice data or data data to have a field to deposit the package identification code on the title of each transmitting data stream package.

Generally speaking, known technology is with direct memory access mode (Direct Memory Access, DMA) during the carrying data of transmission in the one PES package, required parameter includes address (SourceAddress), source, destination address (Destination Address), transmission length (TransferringLength) or the like, the information that needs to rely on this PES package length that is write down in this PES package title.Yet, field in order to the record package length in the title of each PES package only has 2 bytes (16 positions), when the package length of a PES package surpasses the scope that can represent 16 positions, this field can be defined as 0 (seeing ISO/IEC 13818-1, Information Technology-Generic Coding ofMoving Pictures and Associated Audio Information:Systems).Thus, when known technology is defined as this PES package of 0 in transmission package length field, because can't learn the definite length of this PES package in the title by this PES package, thus can't adopt direct memory access mode to carry out transfer of data, and the efficient when having reduced transfer of data.

Summary of the invention

Therefore main purpose of the present invention is to provide a kind of by the physical length value of calculating a data packet, to capture the method and the relevant apparatus of the carrying data in this data packet, the method and the relevant apparatus of the data packet acquisition carrying data particularly a kind of elementary stream (PES) from a packetized.

Data acquisition system of the present invention is the carrying data in order to the elementary stream package of acquisition one packetized from a transmitting data stream or a program data stream.This data acquisition system includes a Data Source device, in order to a data packet (PES Packet) to be provided; One package processing unit is electrically connected in this Data Source device, in order to calculating the length of this data packet, and produces a package length value; One coffret is electrically connected in this package processing unit, is stored in the carrying data in this data packet of this package processing unit in order to output; And a control circuit, in order to control the running of this data acquisition system; Wherein, this control circuit is to export carrying data in the middle of this data packet according to this package length value to control this coffret.

The invention has the advantages that, even the package length field of a PES package is defined as 0 or when making that owing to various factors the package length that write down in this package length field and actual package length are not inconsistent, also can be in the process that receives this PES package, calculate the length of this PES package, and then can direct memory access mode (DMA) transmit carrying data in this PES package, and can not have influence on the efficiency of transmission of data.

The accompanying drawing summary

Fig. 1 is the schematic diagram of data acquisition system of the present invention.

Fig. 2 captures the flow chart of method of the carrying data of a PES package for the present invention.

Fig. 3 is the sequential chart of an embodiment of calculation element among Fig. 1.

Fig. 4 and Fig. 5 are the schematic diagram of other embodiment of calculation element among Fig. 1.

The reference numeral explanation

10 control circuits

20 package original devices

22 filters

30 package processing unit

32 calculation elements

The tediously long check code verifier of 34 circulations

40 storage devices

42,44,46 Storage Medias

50 coffrets

100 data acquisition systems

Embodiment

Figure 1 shows that the schematic diagram of data acquisition system 100 of the present invention.Data acquisition system 100 includes a control circuit 10; One package original device 20 is electrically connected in control circuit 10; One package processing unit 30 is electrically connected in control circuit 10 and package original device 20; And a coffret 50, be electrically connected in control circuit 10 and package processing unit 30.Wherein, control circuit 10 is the runnings in order to control data acquisition system 100; Package original device 20 is in order to receive and to filter a transmitting data stream or a program data stream, to export a PES package Px; Package processing unit 30 mainly is in order to receiving this package Px, and calculates the length value of this package Px, and it includes a calculation element 32, the tediously long check code of a circulation (Cyclic Redundancy Check, CRC) verifier 34 and a storage device 40; And coffret 50 is in order to export the carrying data Payload_x among this package Px.

In brief, data acquisition system 100 is to receive a transmitting data stream or a program data stream by package original device 20, and therefrom capture a PES package Px, then utilize package processing unit 30 to calculate the length value of this package Px, last control circuit 10 is controlled coffret 50 according to this length value, exports the carrying data of this package Px in direct memory access (DMA) (DMA) mode.The detailed operation situation of data acquisition system 100 below will be described.

Please refer to Fig. 2 (and in the lump with reference to figure 1).Fig. 2 be data acquisition system 100 of the present invention from a transmitting data stream or a program data stream, capture flow process Figure 200 of method of the carrying data of a PES package.Flow process Figure 200 includes following steps:

Step 202: beginning.

Step 204: utilize 20 receptions of package original device and filter a transmitting data stream or a program data stream, so that a PES package Px to be provided.

Step 206: utilize the calculation element 32 of package processing unit 30 to calculate the length of this package Px, and produce a corresponding length value L ength_x.

Step 208: utilize the tediously long check code of circulation (CRC) verifier 34 of package processing unit 30, check the correctness of the tediously long check code of circulation of this package Px, and produce a corresponding check the value CRC_x.

Step 210: utilize control circuit 10 according to this length value L ength_x and this check the value CRC_x, control the carrying data Payload_x of coffret 50 this package of output Px.

Step 212: finish.

Below from a transmitting data stream, capture the carrying data of a PES package with data acquisition system 100 process be example, the function mode of description of flow diagram 200.

In step 204, data acquisition system 100 of the present invention is to utilize package original device 20 to receive a transmitting data stream, and filters this received transmitting data stream with the filter 22 in the package original device 20.In a preferred embodiment of the present invention, the data flow that enters package original device 20 is a transmitting data stream, therefore filter 22 can be a package identification code filter (Packet IdentifierFilter, PID Filter), in order to from this received transmitting data stream, filter needed TS package, and the back output one PES package Px that recombinated.This package Px can be sent to package processing unit 30 and handle, and is temporarily stored in the storage device 40.

In step 206, package processing unit 30 can utilize calculation element 32 when receiving this package Px, counts the figure place of this package Px.Thus, calculation element 32 just can calculate the length value L ength_x of this package Px, and be stored in the storage device 40 in the process that receives this package Px.

Please note, a technical characterictic of the present invention is, when package original device 20 filters out this package Px from a transmitting data stream or a program data stream, and this package Px transferred in the process of package processing unit 30, package processing unit 30 can utilize calculation element 32 to calculate the length of this package Px simultaneously.In a preferred embodiment of the present invention, calculation element 32 is to filter the action that the coherent signal that is produced in the process of this package Px is done calculating according to filter 22, and its detailed mode will be in explanation after a while.

In step 208, package processing unit 30 can utilize the correctness of the tediously long check code of circulation that is write down in the title of tediously long check code verifier 34 this package of the check Px of circulation, producing corresponding this check the value CRC_x, and this check the value CRC_x is stored in the storage device 40.In a preferred embodiment of the present invention, if the tediously long check code assay of circulation of this package Px is correct, it is 1 that the tediously long check code verifier 34 that circulates can be set this check the value CRC_x.Otherwise if the tediously long check code assay of circulation of this package Px is wrong, it is 0 that the tediously long check code verifier 34 that then circulates can be set this check the value CRC_x.The meaning of the value representative of above-mentioned this check code CRC_x only is to be illustrational convenience, and in fact, this check the value CRC_x is not limited to only can be 0 or 1, also can be made as other predefined value.

Clearly, the step 206 of flow process Figure 200 can be put upside down with the order of step 208, and can not influence effect of the present invention.

In step 210, the control circuit 10 of data acquisition system 100 can read this length value L ength_x stored in the storage device 40 and this check the value CRC_x, and the title of this package Px, with the carrying data Payload_x of control transmission interface 50 this package of output Px.

If this check the value CRC_x that control circuit 10 is read is 0, represent that then mistake may take place this package Px in transmission course.Therefore, control circuit 10 just may command coffret 50 abandon transmitting the carrying data Payload_x of this package Px.Otherwise, if this check the value CRC_x is 1, represent that the content of this package Px is correct, then control circuit 10 just can calculate the length of the carrying data Payload_x of this package Px according to this length value L ength_x that is read.Because the data length of this length value L ength_x representative, be title (Header) part and both the length summations of carrying data Payload_x part of this package Px, and the length for heading of this package Px is in the PES title data length column that is recorded in the title of this package Px.After control circuit 10 has read the title of this package Px stored in the storage device 40, just can learn the length for heading of this package Px.Therefore, as long as control circuit 10 deducts the length for heading of this package Px with this length value L ength_x, just can obtain the physical length value Length_x_payload of the carrying data Payload_x of this package Px.

Thus, as long as control circuit 10 is arranged in this package Px in the address of storage device 40, the amount of the length for heading of this package of translation Px is just can obtain the initial address Address_x_payload of the carrying data Payload_x of this package Px.In step 210, control circuit 10 just can be with this initial address Address_x_payload, and the data length Length_x_payload of required transmission is sent to coffret 50, so that coffret 50 is according to this initial address Address_x_payload and data length Length_x_payload, in direct memory access (DMA) (DMA) mode, the carrying data Payload_x of this package Px in the storage device 40 is sent to a destination device (for example a memory or a video decoder).

For illustrating that aforementioned calculation element 32 calculates the mode of this package Px, please refer to Fig. 3.Fig. 3 is the sequential chart 500 of an embodiment of calculation element 32 among Fig. 1.Wherein clock signal clk is the work clock of calculation element 32.And signal PID_MATCH represents whether the TS package of filter 22 in handling is the package of forming this PES package Px, when signal PID_MATCH is logical one, expression filter 22 present handled TS packages are to be used for one of package that reassembles into this PES package Px, so calculation element 32 is understood package processing unit 30 received bit data are at that time counted; Otherwise then calculation element 32 is not counted bit data at that time.Signal P_OUT represents the state of filter 22 dateouts, and when P_OUT was logical one, expression filter 22 was transferring data to package processing unit 30, and therefore, signal P_OUT also can be considered the enable signal of calculation element 32.Signal P_START represents whether the bit data that filter 22 is exported is the starting point of this PES package Px, when P_START is logical one, the bit data of representing filter 22 to export at present is the starting point of this PES package Px, therefore, in one embodiment of this invention, calculation element 32 can make zero and begin counting when the positive edge of next work clock CLK triggers.

As shown in Figure 3,510 o'clock time, the P_OUT signal was a logical one, and expression filter 22 will transfer data to package processing unit 32.At this moment, the PID_MATCH signal is a logical one, and the P_START signal also is logical one, and the received data of expression package processing unit are starting points of this package Px, therefore calculation element 32 will make zero, and counts when the positive edge of next work clock CLK triggers.520 o'clock time, the count value of counting device 32 just increased progressively since 1, until 530 o'clock time, the count value of calculation element has increased to 3.Yet between time 530 to the time 540, because the PID_MATCH signal is logical zero, so calculation element 32 stops counting, rests on 3 always.

Next 540 o'clock time, because the PID_MATCH signal is upgraded to logical one, therefore, when calculation element 32 triggers in the next positive edge of work clock CLK, that is 550 o'clock time, can continue to increase progressively count value again.Until 560 o'clock time, the P_OUT signal is reduced to logical zero, and expression filter 22 stops to transfer data to package processing unit 32, and therefore, calculation element also suspends counting, and this moment, count value was accumulated to 6.Before the P_START signal was upgraded to logical one once more, count value all can up be accumulated successively, and the data that expression filter 22 is exported still belong to this PES package Px.Meaning promptly, in a preferred embodiment of the present invention, when package original device 20 was sent to package processing unit 30 fully with this package Px, calculation element 32 just can be finished the action of calculating this package Px length immediately, and produces corresponding this length value L ength_x.Therefore, calculation element 32 of the present invention when calculating this package Px length, the time that can't postpone to transmit this package Px.

Note that in the above description this PES package Px, this length value L ength_x and this check the value CRC_x all are stored in the storage device 40.In one embodiment of this invention, storage device 40 can be a volatile memory (similarly being DRAM, SRAM).This package Px and other relevant information (this length value L ength_x and this check the value CRC_x etc.), can by one be electrically connected in storage device 40 the multiplexer orderliness export storage device 40 to, so that this PES package Px, this length value L ength_x and this check the value CRC_x are stored on the continuation address of storage device 40, also can store the diverse location of these data respectively in storage device 40.

Yet in practical application of the present invention, storage device 40 also can be the combination of different Storage Medias.Please refer to Fig. 4 and Fig. 5.Fig. 4 and Fig. 5 are respectively the schematic diagram of different embodiment of the storage device 40 of Fig. 1.As shown in Figure 4, storage device 40 includes one first Storage Media 42, is electrically connected in package original device 20; And one second Storage Media 44, be electrically connected in calculation element 32 and the tediously long check code verifier 34 of circulation.First Storage Media 42 can be a volatile memory (similarly being DRAM, SRAM), in order to temporary this package Px.And second Storage Media 44 can be a volatile memory or a buffer etc., in order to temporary this length value L ength_x and this check the value CRC_x.Storage device 40 among Fig. 5 then includes first Storage Media 42, is electrically connected in package original device 20; Second Storage Media 44 is electrically connected in calculation element 32; And one the 3rd Storage Media 46, be electrically connected in the tediously long check code verifier 34 of circulation.As previously mentioned, first Storage Media 42 can be a volatile memory (similarly being DRAM, SRAM), in order to temporary this package Px.Second Storage Media 44 can be a volatile memory or a buffer etc., in order to temporary this length value L ength_x.And the 3rd Storage Media 46 also can be a volatile memory or a buffer etc., in order to temporary this check the value CRC_x.In fact, the Storage Media of any energy of all uses temporary this PES package Px, this length value L ength_x and this check the value CRC_x all belongs to scope of the present invention.

In addition, when the function mode of above-mentioned key diagram 2 flow process Figure 200, be that the process that captures PES package carrying data with data acquisition system 100 from a transmitting data stream is an example.As previously mentioned, the present invention is data acquisition system 100 also can capture a PES package from a program data stream carrying data.Do not influencing under the situation that the technology of the present invention discloses, below its function mode of simple declaration only.

In step 204, when package original device 20 receives a program data stream, can use filter 22 to filter this received program data stream.In another embodiment of the present invention, filter 22 is PS to a PES filter (PS to PES Filter), in order to from this received program data stream, filters needed PS package, and the back output one PES package Py that recombinated.Then, this package Py can be sent to package processing unit 30 and handle, and is temporarily stored in the storage device 40.

In step 206, package processing unit 30 can utilize calculation element 32 in the process that receives this package Py, calculates the length value L ength_y of this package Py, and is stored in the storage device 40.Next in step 208, package processing unit 30 can utilize the correctness of the tediously long check code of circulation that is write down in the title of tediously long check code verifier 34 this package of the check Py of circulation, producing corresponding this check the value CRC_y, and this check the value CRC_y is stored in the storage device 40.

In like manner, in step 210, the control circuit 10 of data acquisition system 100 can read this length value L ength_y stored in the storage device 40 and this check the value CRC_y, and the title of this package Py, export carrying data Payload_y to a destination device of this package Py with direct memory access mode with control transmission interface 50.

From the above, the mode that data acquisition system 100 is handled a transmitting data stream or a program data stream is very similar, and unique difference only is the function difference of employed filter 22.In fact, package original device 20 of the present invention also can include a package identification code filter and PS to a PES filter simultaneously.When the package original device receives a data flow, only need judge in advance that this data flow is a transmitting data stream or a program data stream, select a corresponding filter that this data flow is handled again, a PES package just can be provided.Then again this PES package is carried out among flow process Figure 200 step 206 to the step of step 210, just can direct memory access mode export the carrying data of this PES package.

Please note, in a preferred embodiment of the invention described above, package processing unit 30 utilizes the tediously long check code verifier 34 of circulation in step 208, check the correctness of the tediously long check code of circulation of this package, and produce a corresponding check the value, in step 208, control the running of coffret 50 according to this for control circuit 10.This is the inspection for many one decks, and to reduce the mistake of packet data transmission process, the present invention is not limited to check the correctness of the tediously long check code of circulation of this package.In another embodiment of the present invention, the tediously long check code verifier 34 that can not need to circulate in the package processing unit 30 is anticipated promptly, and step 208 can be omitted.At this moment, in step 210, control circuit 10 is the carrying data Payload_x that control coffret 50 this package of output Px according to this length value L ength_x.

In addition, the form that data acquisition system 100 of the present invention can also software program code is realized.Each assembly of data acquisition system 100 all can be realized by program code among Fig. 1, thus, when a computer system is carried out these program codes, just can capture the carrying data of the PES package in a transmitting data stream or the program data stream according to notion of the present invention.

From the above, no matter whether the package length field in the title of a PES package is defined as 0, data acquisition system 100 of the present invention all can utilize calculation element 32 when filtering out this PES package, calculates the physical length of this package.Therefore, the present invention can obtain the information of this PES package length efficiently, and exports carrying data in this PES package in the direct memory access mode, can not be defined as 0 transmission that has influence on the carrying data because of the package length field of this PES package.

When known technology captures a package length field and is defined as the carrying data of 0 PES package, because can't grasp the definite length of this PES package, and must check the beginning that whether arrives next PES package while the carrying data of transmitting this PES package, and the efficient when having influenced transfer of data, the progressive on data acquisition system of the present invention and data picking method clearly possess skills.

The above only is preferred embodiment of the present invention, and all equalizations of being done according to the present patent application claim change and modify, and all should belong to the covering scope of patent of the present invention.

Claims

1. the data packet from the elementary stream of a packetized captures the method for carrying data, and this method includes:

(a) use one package processing unit calculates the length of this data packet of being imported, to produce a corresponding package length value; And

(b) export carrying data in this data packet according to this package length value.

2. the method for claim 1, wherein in step (b), include the carrying data of using a coffret to export this data packet in addition.

3. method as claimed in claim 2, it includes in addition:

Use a control circuit, control the carrying data that this coffret is exported this data packet according to this package length value.

4. method as claimed in claim 3, it includes in addition:

According to a check the value that corresponds to the tediously long check code correctness of circulation of this data packet, control this coffret and export carrying data in this data packet.

5. method as claimed in claim 4, it includes in addition:

Use the tediously long check code verifier of a circulation, produce this check the value according to the correctness of the tediously long check code of circulation in the middle of this data packet.

6. method as claimed in claim 4, it includes this data packet of use one storing media stores, this package length value and this check the value in addition.

7. method as claimed in claim 4, it includes use one first this data packet of storing media stores in addition, and uses this package length value of one second storing media stores and this check the value.

8. method as claimed in claim 4, it includes use one the 3rd this data packet of storing media stores in addition, uses this package length value of one the 4th storing media stores, and uses one the 5th this check the value of storing media stores.

9. the method for claim 1, it includes in addition and uses this data packet of a storing media stores and this package length value.

10. the method for claim 1, it includes in addition and uses one first this data packet of storing media stores, and uses this package length value of one second storing media stores.

11. a data acquisition system, in order to the carrying data of the elementary stream package of acquisition one packetized from a transmitting data stream or a program data stream, this data acquisition system includes:

One Data Source device is in order to provide a data packet;

One package processing unit is electrically connected in this Data Source device, in order to calculating the length of this data packet, and produces a package length value;

One coffret is electrically connected in this package processing unit, receives this data packet in order to this package processing unit certainly, and exports the carrying data in this data packet; And

One control circuit is in order to control the running of this data acquisition system;

Wherein, this control circuit is to export carrying data in the middle of this data packet according to this package length value to control this coffret.

12. data acquisition system as claimed in claim 11, wherein, this Data Source device includes a package identification code filter, is used for filtering a transmitting data stream so that this data packet to be provided.

13. data acquisition system as claimed in claim 11, wherein, this Data Source device includes the elementary stream filter that a routine data flow to packetized, is used for filtering a program data stream so that this data packet to be provided.

14. data acquisition system as claimed in claim 11, wherein, this package processing unit includes:

One calculation element is electrically connected in this Data Source device, in order to the length of calculating this data packet and produce this package length value; And

One first Storage Media is electrically connected in this Data Source device and this coffret, is used for storing this data packet, and this data packet is sent to this coffret;

Wherein, this first Storage Media is as the buffer between this Data Source device and this coffret.

15. data acquisition system as claimed in claim 14, wherein, this package length value is to be stored in this first Storage Media.

16. data acquisition system as claimed in claim 14, wherein, this package processing unit includes one second Storage Media in addition, is electrically connected in this calculation element, in order to store this package length value.

17. data acquisition system as claimed in claim 14, wherein, this package processing unit includes the tediously long check code verifier of a circulation in addition, is electrically connected in this Data Source device, in order to the correctness of the tediously long check code of circulation of checking this data packet, and produce a check the value.

18. data acquisition system as claimed in claim 17, wherein, this control circuit is according to this package length value and this check the value, exports carrying data in the middle of this data packet to control this coffret.

19. data acquisition system as claimed in claim 17, wherein, this check the value is to be stored in this first Storage Media.

20. data acquisition system as claimed in claim 17, wherein, this package processing unit includes one second Storage Media in addition, is electrically connected in this calculation element, in order to store this check the value.

21. data acquisition system as claimed in claim 17, wherein, this package processing unit includes one the 3rd Storage Media in addition, is electrically connected in this tediously long check code verifier that circulates, in order to store this check the value.