JP3731926B2 - MPEG2 data transfer method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an MPEG2 data transfer method for transferring MPEG2 data by a transport packet system to an ATM (asynchronous transfer mode) line.
[0002]
[Prior art]
It has an architecture that combines the advantages of both circuit switching and packet switching, and can flexibly handle transmission speeds from megabits to gigabits in a data unit of short packet length (fixed cell 53 bytes). ATM networks, which are low-latency and high-speed networks for multimedia communication performed by hardware, are attracting attention.
The packet length of this ATM network is 48 bytes of actual data, and an ATM cell fixed length (53 bytes) is formed by adding a header to this packet.
Therefore, in the transfer of MPEG2 data, the demultiplexing method using transport packets with a relatively short packet length of 188 to 376 bytes fixed length is adopted to achieve consistency with the ATM network.
[0003]
As a result, transport packets of MPEG2 data can be transmitted on a plurality of fixed ATM cell lengths (53 bytes).
Under such circumstances, there is a demand for a technique for transferring MPEG2 data, which compresses a large amount of moving images at a high compression rate, to an ATM line at high speed.
When MPEG2 data stored on, for example, a laser disk is transferred to the ATM line by a personal computer or the like, conventionally, the MPEG2 data is first transferred to the main memory via SCSI under the control of the CPU. It has been considered that the CPU performs data processing by software processing, and then performs an operation of reading from the main memory and transferring it to the ATM line.
[0004]
[Problems to be solved by the invention]
The above transfer method has a drawback that it takes a long time to transfer MPEG2 data to the ATM line, and therefore cannot meet the demand for high-speed transfer.
SUMMARY OF THE INVENTION An object of the present invention is to provide an MPEG2 data transfer method for significantly reducing the transfer processing time of MPEG2 data to an ATM line by the transport packet method and performing stream processing for accurately reproducing the time. It is in.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the MPEG2 data transfer method according to the present invention is a standard time reading board for synchronizing MPEG2 data from a storage medium storing MPEG2 data using a transport packet demultiplexing method via a PCI bus. Forward to
When MPEG2 data is stored in the temporary storage unit of the synchronization standard time reading board, the synchronization standard time data is extracted from the MPEG2 data, and the extracted synchronization standard time data and the synchronization standard time data are stored. Store the temporary storage address separately from the MPEG2 data,
A read time interval is calculated from the extracted standard time data for synchronization and the address, and MPEG2 data is read from the temporary storage unit according to the read time interval,
The data is transferred to the ATM line board via the PCI bus.
Further, according to the present invention, in the above transfer method, when MPEG2 data is read from the storage medium, it is read to a bus different from the PCI bus, and then converted by a bridge circuit to be connected to the PCI bus and connected to the synchronization standard time reading board. Is configured to forward to.
[0006]
According to the above method, compared to the conventional transfer method, the transfer processing time can be greatly shortened while the MPEG2 transfer data is stream-processed.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing an embodiment of an MPEG2 data transfer method according to the present invention, and is a system block diagram of a personal computer constructed based on this transfer method.
This figure shows only the part directly related to the present invention.
A CPU 1 that controls the entire system based on a program is connected to a system bus 2. A PCI bus 3 that is a high-speed bus is connected to the system bus 2 via a bridge circuit 5.
[0008]
The bridge circuit 5 is for converting the mutual data formats of the system bus 2 and the PCI bus 3.
A PCR (program clock reference, standard time for synchronization) leader board 4 and an ATM board 11 are connected to the PCI bus 3.
PCR is a standard time for synchronization in an MPEG system decoder including a video and audio decoder, for setting and configuring the value of STC (reference synchronization information) as a time reference to a value intended on the encoder side. Defined as information.
Further, an EISA (extended industry standard architecture) bus 7 is connected via a bridge circuit 6.
The bridge circuit 6 is for converting the mutual data format of the PCI bus 3 and the EISA 7.
A laser disk device 9 and a hard disk device 10 are daisy chained to the EISA 7 by a connection cable 12 via a SCSI interface circuit 8.
In this example, MPEG2 data is stored in a laser disk 9 a loaded in the laser disk device 9, and a transport packet of this MPEG2 data is transferred to the ATM board 11 via the PCR reader board 4.
[0010]
FIG. 2 is a block diagram showing details of the circuit configuration on the PCR leader board 4.
The PCI bus 3 and the internal bus 19 are connected via the PCI interface circuit 13.
The circuit on the PCR reader board includes an MPEG2 data storage processing unit 14, a PCR processing unit 15, a control unit 18, and software interface means 20 including a PCI interface circuit 13.
The software interface means 20 includes a register for exchanging instructions between the CPU 1 and the control unit 18.
The MPEG2 data storage processing unit 14 includes a temporary storage unit having a capacity for a plurality of pages, and stores MPEG2 data sent via the PCI interface circuit 13 in the temporary storage unit according to address control.
[0011]
When MPEG2 is stored in all the page storage units of the temporary storage unit, reading is performed according to the time interval calculated by PCR in units of pages. MPEG2 data is stored in an empty memory section.
The PCR processing unit 15 includes a PCR sampling unit 16 and a PCR storage unit 17. The PCR sampling unit 16 detects PCR data from the MPEG2 transport packet sent from the laser disk 9a, and performs a sampling operation. I do.
The PCR storage unit 17 stores the extracted PCR data and the address of the temporary storage unit that stores the extracted PCR data.
[0012]
The control unit 18 waits for the MPEG2 data to be stored based on the instruction held in the software interface means 20 and reads the PCR data and address from the PCR storage unit 17, and the MPEG2 data read time interval based on the PCR data and address. Is calculated.
The control unit 18 reads the MPEG2 data between the PCRs from the MPEG2 data storage processing unit 14 at the calculated time interval, and transfers it to the ATM board 11 via the PCI interface circuit 13 and the PCI bus 3.
[0013]
FIG. 3 is a diagram for explaining the operation of the MPEG2 data transfer method according to the present invention. Hereinafter, description will be made with reference to FIGS.
The CPU 1 sends a data transfer instruction (1) to the SCSI interface circuit 8. Also, a data transfer execution request (2) is sent to the software interface means 20 of the PCR leader board 4.
The control unit 18 of the PCR leader board 4 sends a page transfer request (3) to the CPU 1 when the environment setting necessary for the transfer is performed and the preparation for writing the MPEG2 data is completed. The CPU 1 instructs the SCSI interface circuit 8 to transfer the page data. Based on the instruction (4), the MPEG2 data is read from the laser disk 9a and transferred to the PCR reader board 4 in page units (for example, 256 Kbytes) ( (5)).
[0014]
In the PCR leader board 4, the MPEG2 data is sent to the MPEG2 data storage processing unit 14, and the MPEG2 data is stored in the temporary storage unit. At the same time, the PCR processing unit 15 extracts the PCR data from the MPEG2 data, and stores the PCR data and the address of the temporary storage unit storing the PCR data in the PCR storage unit 17. The PCR data and its address stored in the PCR storage unit 17 are read out, and the control unit 18 calculates the time interval.
When the MPEG2 data storage processing unit 14 is full, reading is performed in page units and transferred to the ATM board 11 via the PCI bus 3.
The transfer to the ATM board 11 is performed when the PCR reader board 4 directly writes data into the buffer of the ATM board 11 as a master under the control of the control unit 18.
[0015]
Data is read from the MPEG2 data storage processing unit 14 in accordance with the calculated time interval.
When the data in page units is transferred, the MPEG2 data storage processing unit 14 has a free space, so a page transfer request (3) is again sent to the CPU 1, and the temporary storage unit is instructed by (4) (5). Write MPEG2 data in the free space.
By repeating this operation, when all the scheduled MPEG2 data (the total number of data is written in the software interface means 20) is transferred to the ATM board 11, the control unit 18 sends an end report (6) to the CPU 1. To do.
[0016]
Thereafter, the CPU 1 can read the status information sent from the PCR leader board 4 and know the state of the PCR leader board 4.
The ATM board 11 converts the MPEG2 data stored in the buffer into, for example, a 53-byte fixed-length cell, thereby converting it into ATM information and sending it to the ATM line.
In the above embodiment, when transferring from the PCR leader board 4 to the ATM board 11, the example in which the PCR leader board 4 is directly written in the buffer of the ATM board 11 as a master has been described. It is also possible to set the DMA function as a master and activate it, and then operate as a slave to read data in the temporary storage unit.
[0017]
【The invention's effect】
As described above, the present invention transfers MPEG2 data from a storage medium storing MPEG2 data adopting a demultiplexing method based on transport packets to a synchronization standard time reading board via a PCI bus, and performs synchronization. When storing MPEG2 data in the temporary storage unit of the standard time reading board, the standard time data for synchronization is extracted from the MPEG2 data, and the address of the temporary storage unit in which the extracted standard time data for synchronization and standard time data for synchronization are stored It is stored separately from the MPEG2 data, the read time is calculated from the extracted standard time data for synchronization and the address, and the MPEG2 data is read from the temporary storage unit according to this read time and transferred to the ATM line board via the PCI bus. It is a thing.
Therefore, compared to the conventional transfer method, the transfer time of MPEG2 data to the ATM line can be greatly shortened, and an MPEG2 data transfer method suitable for a high-speed ATM line can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of an MPEG2 data transfer method according to the present invention.
2 is a block diagram showing a circuit configuration of the PCR leader board of FIG. 1. FIG.
FIG. 3 is a diagram for explaining the operation of the MPEG2 data transfer method according to the present invention;
[Explanation of symbols]
1 ... CPU
2 ... System bus 3 ... PCI bus 4 ... PCR reader board 5, 6 ... Bridge circuit 7 ... EISA bus 8 ... SCSI interface circuit 9 ... Laser disk device 10 ... Hard disk device 11 ... ATM board 12 ... Daisy chain connection cable 13 ... PCI Interface circuit 14 MPEG2 data storage processing unit 15 PCR processing unit 16 PCR sampling unit 17 PCR storage unit 18 control unit 19 internal bus 20 software interface means

Claims (2)

MPEG2 data is transferred from the storage medium storing the transport packet of MPEG2 data to the standard time reading board for synchronization via the PCI bus,
When MPEG2 data is stored in the temporary storage unit of the synchronization standard time reading board, the synchronization standard time data is extracted from the MPEG2 data, and the extracted synchronization standard time data and the synchronization standard time data are stored. Store the temporary storage address separately from the MPEG2 data,
A read time interval is calculated from the extracted standard time data for synchronization and the address, and MPEG2 data is read from the temporary storage unit according to the read time interval,
An MPEG2 data transfer method configured to transfer to an ATM line board via a PCI bus. When MPEG2 data is read from the storage medium, it is read to a bus different from the PCI bus, and then converted by a bridge circuit to be connected to the PCI bus and transferred to the synchronization standard time reading board. The MPEG2 data transfer method according to claim 1.

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