JP2001103116A - Stream generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a load on a CPU and to more efficiently generate PES packet data. SOLUTION: An input DMA controller 12 transfers an ES generated by a video audio coder to a right area of a shared memory 13. The input DMA controller 12 informs a CPU 14 of a presence area of the ES when the transfer of the ES is finished. The CPU 14 calculates contents of a PES header from the contents of the ES and writes the contents to an output buffer 15. The CPU 14 calculates contents of the PES header from the contents of the ES to write the contents to an output buffer 15. The CPU 14 designates a transfer start address of the shared memory 13 in which the corresponding ES is stored and the number of transferred bytes to an output DMA controller 16 for succeeding PES packet data. The output DMA controller 16 transfers the ES data stored in the common memory 13 to the PES packet data from the address designated by the CPU 14 and by the designated number of bytes to the output buffer 15 as the PES packet data. Thus, the PES packet data can be generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video or audio encoding apparatus using a digital compression processing technique, and for example, from an ES (Elementary Stream) to a PES (Packetize) by MPEG2 (Moving Picture Experts Group 2).
d Elementary Stream) or TS (Transport Strea)
m).

[0002]

2. Description of the Related Art As is well known, a PES of MPEG2 has a PES header section and a PES packet data section. PE
In the S header part, in addition to the start code of the PES packet,
TS (Presentation Time Stamp) and DTS (Decoding
(Time Stamp) and data calculated from the ES information. On the other hand, the ES itself exists in the PES packet data section.

Conventionally, in a PES generation apparatus that generates a PES from an ES, the CPU stores the ES in a memory,
A method is used in which the contents of S are analyzed, a PES header part is generated and stored in a memory, and an ES corresponding to a PES packet data part is transferred to a subsequent memory area.

[0004] The TS of MPEG2 has a TS header section, an adaptation field section, and a payload section. The TS header section includes a synchronization byte indicating the head of the TS, as well as the content of data following the TS header section. The adaptation field includes a PCR (Program Clock Reference) indicating time information of the system. The PES itself exists in the pay funnel.

Conventionally, in a TS generating apparatus for generating a TS from an ES, a CPU once generates a PES, analyzes the necessity of an adaptation field, and then generates a TS header portion and stores the TS header portion in a memory. A method is used in which an adaptation feed is generated as necessary, stored in a memory area following the TS header, and a PES corresponding to the payload portion is transferred to the subsequent memory area.

[0006]

As described above, in a conventional stream generation apparatus for generating a PES or TS, a lot of processing is performed by the CPU, and high performance is required of the CPU.

The present invention has been made in view of the above circumstances, and has as its object to provide a stream generation apparatus capable of reducing the load on a CPU and generating a PES or a TS more efficiently.

[0008]

To achieve the above object, a stream device according to the present invention has the following characteristic configuration.

(1) In a stream generation device for generating a standardized stream having at least a header area and an information area from a basic stream of encoded data, a shared memory for storing the basic stream and an area of the shared memory An input memory control unit that manages and writes an input basic stream to a predetermined area of the shared memory and generates the memory management information; and a basic stream from the shared memory based on the memory management information from the input memory control unit. An arithmetic processing unit that captures and analyzes data, generates data to the header area, and specifies an area in the shared memory in which a basic stream to be written to the information area is written, and the arithmetic processing unit from the shared memory. Output memory control for transferring basic stream data in the specified area When, characterized by comprising an output buffer for storing the data of the information area to be transferred by the data and the output memory control portion of the header region generated by the arithmetic processing unit outputs.

(2) In accordance with the rules of MPEG2, ES
And a shared memory for storing the ES, an input memory for managing an area of the shared memory, writing an input ES to a predetermined area of the shared memory, and generating the memory management information. A control unit and, based on the memory management information from the input memory control unit, fetch and analyze the ES from the shared memory,
An arithmetic processing unit that generates the data of the ES header part and specifies an area where the ES to be written in the PES packet data part in the shared memory is written; and an ES in the area specified by the arithmetic processing unit from the shared memory. An output memory control unit for transferring data, and a PES generated by the arithmetic processing unit.
An output buffer for generating and outputting a PES by storing the data of the header section and the data of the PES packet data section transferred by the output memory control section is provided.

(3) In a stream generation apparatus for generating a TS from a plurality of ESs based on the MPEG2 specification, a shared memory for storing the ESs, and an input ES managed by managing an area of the shared memory and storing the input ESs in the shared memory , An input memory control unit for generating the memory management information, and an ES that is fetched and analyzed from the shared memory based on the memory management information from the input memory control unit, and a PES header unit, a TS header , An arithmetic processing unit that generates each data of the adaptation field part, and specifies an area in which the ES to be put into the payload part in the shared memory is written, and an area that is specified by the arithmetic processing unit from the shared memory. An output memory control unit for transferring an ES, a PES header unit, a TS header unit, and an Characterized by comprising an output buffer for generating a TS output by storing the data in the payload portion to be transferred by the data and the output memory controller of flop station field unit.

(4) In the configuration of (3), when PCR is added to the adaptation field as information on the absolute time, the arithmetic processing unit sets a PCR flag when generating data of the adaptation field. And when the PCR flag is set in the output of the output buffer, the corresponding T
It is characterized by comprising a data replacement means for replacing S data with PCR data.

That is, in the stream generation apparatus according to the present invention, the data which must be simply transferred, except for the data which must be interposed by the arithmetic processing unit, is executed by the output memory control unit. The amount of arithmetic processing of the unit is reduced, and the stream can be generated even by an inexpensive CPU by reducing the burden. Furthermore, a stream with a higher bit rate can be generated as compared with a conventional device having the same CPU performance.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows the PES structure of MPEG2. The PES header is variable in length and has a packet start code prefix.
x) starts with a fixed pattern start code called
PTS, DTS, and the like are added as needed. PES
The packet data section is also of variable length, and the ES itself exists here.

FIG. 2 shows the structure of an MPEG2 TS. The TS header has a fixed length of 4 bytes, starts with a fixed pattern start code called a sync byte, and includes an adaptation field (Adaptation F).
There is adaptation field control information (adaptation field control) that indicates the presence or absence of an ield). The adaptation field is a variable length field that exists only when the adaptation field control value of the TS header is 2 or 3, and is a PCR that indicates system time information.
And so on. Since the number of bytes of the TS is a fixed length of 188 bytes, the value obtained by subtracting the header length (4 bytes) of the TS and the number of bytes of the adaptation field from 188 is the number of bytes of the payload. Although the PES packet itself exists in the payload, if all the PES cannot be transmitted by the payload of one TS, the remaining PES is carried on the payload of the subsequent TS packet and transmitted.

FIG. 3 shows the relationship among ES, PES, and TS. The ES itself exists in the PES packet data, and the PES divided into the required number of bytes exists in the payload of the TS. In the drawing, AF is an abbreviation for adaptation field.

FIG. 4 shows a PE according to a first embodiment of the present invention.
FIG. 3 is a block circuit diagram illustrating a configuration of an S generation device.

In FIG. 4, an input DMA (Dynamic Memory Access) controller 12 is provided on a data bus 11.
The shared memory 13, the CPU 14, the output buffer 15, and the output DMA controller 16 are connected.

The input DMA controller 12 fetches the ES generated by the video / audio encoding device, and
No. 3 is transferred to the appropriate area, and after the transfer is completed, the CPU 14 is notified of the existence area of the ES on the shared memory 13.

The CPU 14 controls the input DMA controller 12
In response to the notification, the ES fetches the ES from the shared memory 13, analyzes the ES, calculates the contents of the PES header, and writes the contents of the PES header to the output buffer 15. Further, the transfer start address and the number of transfer bytes of the shared memory 13 are specified to the output DMA controller 16 as ES information to be put in the PES packet data section.

The output DMA controller 16 is a CPU 14
From the address specified by the specified number of bytes,
The data in the shared memory 13 is transferred to the output buffer 15 as PES packet data. After the transfer, the shared memory 13
And releases the corresponding area to the input DMA controller 12 and the CPU 14.

The output buffer 15 receives the P
The PES is generated by storing the ES header and the PES packet data transferred from the shared memory 13 through the output DMA controller 16, and outputs the PES as appropriate.

That is, in the PES generation device having the above configuration, the ES generated by the video / audio encoding device is:
The input DMA controller 12 causes the shared memory 13
To the appropriate area. When the transfer of the ES is completed, the input DMA controller 12 sets the existence area of the ES to C
Notify PU14. The CPU 14 determines the PE from the ES contents.
The contents of the S header are calculated, and the contents are written to the output buffer 15.

For the subsequent PES packet data, necessary data in the shared memory 13 may be transferred. For this reason, the CPU 14 specifies the transfer start address and the transfer byte number of the shared memory 13 where the corresponding ES is stored, to the output DMA controller 16. Output DMA
The controller 16 transfers the ES data in the shared memory 13 to the output buffer 15 as PES packet data by the designated number of bytes from the designated address of the CPU 14. Thus, a PES is generated.

In this operation, the CPU 14 accesses the data bus 11 only when the input DMA controller 12
, The time of writing the PES header to the output buffer 15, and the time of notifying the output DMA controller 16 of the transfer start address and the number of transfer bytes of the shared memory 13. The rest of the time can be used for ES analysis processing, PES header generation processing, communication processing with external devices, and the like. Therefore, efficient PES generation processing becomes possible.

FIG. 5 shows a TS according to a second embodiment of the present invention.
FIG. 2 is a block circuit diagram illustrating a configuration of a generation device. Since the TS generator described here has the same basic configuration as the PES generator, in FIG. 5, the same parts as those in FIG. 4 are denoted by the same reference numerals, and different parts will be described in detail. .

In FIG. 5, the ES generated by the video / audio encoding device is transferred to an appropriate area of the shared memory 13 by the input DMA controller 12. When the transfer of the ES is completed, the input DMA controller 12
The CPU notifies the CPU of the existence area of the ES. CPU 14 is ES
, A PES header is generated, the contents of the TS header and the adaptation field are calculated, and the contents are written to the output buffer 15.

The subsequent portion of the payload has only to transfer necessary data in the shared memory 13, so that the CP
U 14 specifies the transfer start address and the number of transfer bytes of the shared memory 13 where the corresponding ES is stored to the output DMA controller 16. The output DMA controller 16 transfers the data of the shared memory 13 to the output buffer 15 by the specified number of bytes from the address specified by the CPU. Thus, a TS is generated.

However, in the generation of the TS, PCR is added to the adaptation field as information on the absolute time. However, when the TS is burst-generated on the output buffer 15 by the transfer of the output DMA controller 16, the CPU
At the time of adding a PCR in step 14, the error increases, and the quality of the TS deteriorates.

To avoid this problem, the present device
When the adaptation field is written to the output buffer 15, the PCR flag is written together, and the TS is read from the output buffer 15 and, if the PCR flag is set, a process of replacing the data in that portion with the PCR is performed. Thereby, an accurate PCR value can be added.

Specifically, first, the write format to the output buffer 15 is changed to Bit 0 to Bit 0 as shown in FIG.
The upper bit Bit8 is added to the TS data of Bit7, and this is used as a PCR flag. When Bit8 is 0, the TS data (Bit [7: 0]) is handled as TS data, and when Bit8 is 1, the TS data (Bit [7: 0]) is replaced with a PCR value.

As shown in FIG. 5, a PCR generator 17 is prepared, and the PCR value output from the PCR generator 17 and the output data of the output buffer 15 are input to a selector (SEL) 18 as shown in FIG. The selector 18 selectively outputs according to the PCR flag value. CPU14
Writes the PCR flag (Bit 8) = 1 when writing the adaptation field to the output buffer 15. The output DMA controller 16 adds a PCR flag (Bit 8) = 0 when transferring the payload data to the output buffer 15. In the selector 18, the PC
If the R flag (Bit 8) = 1, the corresponding TS data (Bit [7: 0]) portion is
Replace with CR value and output, PCR flag (Bit8)
If = 0, the output of the output buffer 15 is transferred as it is.

In the above operation, the CPU 14 accesses the data bus 11 only when the input DMA controller 12
When the notification of the ES area is received from the PES header,
Only when writing the TS header and the adaptation field to the output buffer, when notifying the output DMA controller 16 of the address and the number of bytes of the shared memory 13, and when setting the PCR flag. The rest of the time can be used for ES analysis processing, PES header, TS header and adaptation field generation processing, and communication processing with external devices. Therefore, efficient TS generation processing becomes possible.

As described above, in the PES generation device, the CP
The CPU analyzes the ES that the U must intervene and generates the PES header, and the PE that needs only data transfer.
The generation of the S data packet part is performed by DMA.

In the TS generation device, the CPU performs processing of time information that must be interposed by the CPU, generation processing of the TS header, and generation processing of the adaptation field, and generation of the payload that requires only data transfer is performed by the D.
Performed by MA.

As a result, the load on the CPU in the apparatus is reduced, and it is possible to generate PES or TS more efficiently.

[0038]

As described above, according to the present invention, it is possible to provide a stream generation apparatus capable of reducing the load on the CPU and generating PES or TS more efficiently.

[Brief description of the drawings]

FIG. 1 is a diagram showing a PES structure of MPEG2.

FIG. 2 is a diagram showing the structure of an MPEG2 TS.

FIG. 3 is a diagram showing a relationship between ES, PES, and TS of MPEG2.

FIG. 4 is a block circuit diagram showing a configuration of a PES generation device according to the first embodiment of the present invention.

FIG. 5 is a block circuit diagram showing a configuration of a TS generation device according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a format for writing to an output buffer according to the second embodiment;

[Explanation of symbols]

 11 Data Bus 12 Input DMA Controller 13 Shared Memory 14 CPU 15 Output Buffer 16 Output DMA Controller 17 PCR Generator 18 Selector

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C059 KK15 MA00 RB02 RB09 RC03 RC04 RC32 SS26 SS30 UA01 UA38 UA39 5K034 AA01 AA07 BB06 CC02 CC05 FF01 FF02 GG02 GG03 HH01 HH02 HH25 HH27 HH47 MM11

Claims (4)

[Claims] 1. A stream generating apparatus for generating a standardized stream having at least a header area and an information area from a basic stream of encoded data, comprising: a shared memory for storing the basic stream; and an area for the shared memory. An input basic stream is written to a predetermined area of the shared memory, and an input memory control unit that generates the memory management information.Based on the memory management information from the input memory control unit, a basic stream is output from the shared memory. An arithmetic processing unit that captures and analyzes data, generates data to the header area, and specifies an area in the shared memory in which a basic stream to be written to the information area is written, and specifies the area from the shared memory by the arithmetic processing unit. Output memory control unit for transferring the basic stream data of the area to be An output buffer for storing and outputting data of a header area generated by the arithmetic processing unit and data of an information area transferred by the output memory control unit. 2. An MPEG2 (Moving Picture Experts Groove)
up ES (Elementary Stream) based on 2)
A stream generation device that generates a PES (Packetized Elementary Stream) from a shared memory that stores the ES, writes an input ES to a predetermined area of the shared memory by managing an area of the shared memory, and writes the memory management information. An input memory control unit that is generated; and an ES that is fetched and analyzed from the shared memory based on the memory management information from the input memory control unit to generate data of a PES header unit,
An arithmetic processing unit that specifies an area in which the ES to be put into the S packet data unit is written; an output memory control unit that transfers the ES in the area specified by the arithmetic processing unit from the shared memory; An output buffer for generating and outputting a PES by storing the data of the PES header portion generated in step (a) and the data of the PES packet data portion transferred by the output memory control portion. . 3. An MPEG2 (Moving Picture Experts Groove)
up 2), multiple ESs (Elementary Str
eam), a stream generating apparatus for generating a TS (Transport Stream) from the shared memory for storing the ES, and managing an area of the shared memory to write an input ES to a predetermined area of the shared memory; And an input memory control unit for generating ES from the shared memory based on the memory management information from the input memory control unit.
(Packetized Elementary Stream) Generates data of a header section, a TS header section, and an adaptation field section, and stores the ES in the payload section in the shared memory.
An operation processing unit that specifies an area in which is written, an output memory control unit that transfers an ES in an area specified by the operation processing unit from the shared memory, and a PES header unit generated by the operation processing unit , A TS buffer section, an output buffer for generating and outputting a TS by storing data of a adaptation field section and data of a payload section transferred by the output memory control section. . 4. The method according to claim 1, wherein PCR (Program Cl
When the data of the adaptation field is generated by the arithmetic processing unit, a PCR flag is set in the arithmetic processing unit. 4. The stream generation device according to claim 3, further comprising a data replacement unit that replaces the corresponding TS data with the PCR data when the PCR flag is set.