JPH07175745A - Cd-rom data processing method - Google Patents

Abstract

PURPOSE:To transfer data at a speed higher than normal by outputting the data recorded in a complete form in an internal buffer of a CD of a CD-ROM device directly to each external device. CONSTITUTION:In a computer system where a CD-ROM device is connected to a host machine through an SCSI bus as an external storage, the image data stored in a buffer RAM of the CD-ROM device are directly transferred to an image processing part through an SCSI controller of the host side and without passing through the main memory of a CPU of a host computer. Therefore the data stored in an internal buffer RAM of a CD are directly sent to an image processing memory via a CD SCSI controller and a host SCSI controller and with no intervention of the main memory. In such a data control way, the internal buffer of the CD can be used in various forms.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a CD-ROM in which a CD-ROM and a host computer are connected via a SCSI bus.
The present invention relates to a data processing method for a ROM computer device.

[0002]

2. Description of the Related Art An optical compact disc (CD) was developed as a medium capable of digitally recording and reproducing voice, and has become popular as a CD audio disc capable of reproducing faithful sound and continuously reproducing for a long time. Furthermore, attention is paid to large capacity and high-speed access performance, and its use as a recording medium is advancing.

The data structure of a CD audio disc will be described. L / R audio signal is PCM modulated and 1
Obtain digital data of 6 bits × 2 channels. 24 bytes of digital data in 6 sample sections are in 1 frame units. For the purpose of suppressing errors, when data is converted in units of L / R 12 bytes, an error correction code is entered and interleaved, 8 bits × 12 data and 8 bits × 4 parity are respectively obtained. A 1-byte subcode is added to 1 frame, and a digital signal obtained by modulation is recorded on a CD.

98 frames form one subcode block. The first 2 bytes are the subcode header,
The remaining 96 bytes are the subcode 8 channels. Of the subcode, 24 bytes are used for read control,
Address information for searching, such as the type of user data, absolute time, and subcode frame number, is recorded. 1
The data attached to one subcode block is 2352.
Equivalent to the amount of information in bytes.

The CD audio disc reproducing apparatus is provided with a program function using sub-codes, such as a cue of a music piece and setting of a reproduction order, as means for performing digital signal processing. Using the index on the innermost circumference of the disc as a clue,
The sub-code is searched for and demodulated, and the target block is searched by the absolute time of the sub-code. The read digital signal is demodulated, error correction is performed by deinterleaving and error correction code, and digital signal processing is performed to obtain digital data. Digital data is processed by D / A converter,
It is output as an audio signal.

A typical example of using an optical compact disc as a computer recording medium is a CD-ROM whose physical format is a unified standard. CD-R
The OM physical format standard is shown in FIG. As the physical format, three kinds of modes of mode 0, mode 1 and mode 2 are defined. One sector of CD-ROM is C
2 equal to the subcode block of the D audio disc
Each block is composed of 352 bytes of data, and a 12-byte block synchronization signal (sync) is placed at the beginning of each block for separating the blocks.

After the block synchronization signal, 4 bytes of header are arranged, which consists of 3 bytes of block address and 1 byte indicating the data recording mode. In mode 0 and mode 2, the remaining 2336 bytes become the data area. In mode 0, this data is all 0s.

Mode 1 is used for computer data that requires more accurate error correction. Program data, image data having a high compression rate, and the like cannot operate normally even with a 1-bit error. Unlike such image data or acoustic data that can be interpolated, such data is not allowed to have errors.

In order to improve the reliability of the data of the CD-ROM, an auxiliary data area is set in the data structure of 2336 bytes, and 2048 bytes of user data and 28
Divided into 8 bytes. The setting of auxiliary data is defined by setting the data recording mode to mode 1. 288 bytes of auxiliary data are 4 bytes for error detection,
The error correction is 276 bytes including 8 bytes of space, 172 bytes of P parity and 104 bytes of Q parity.

Mode 2 has a data structure in which 2336 bytes are all user data, and image / sound data and the like that can be error-corrected by interpolation processing can be recorded. However, in general, define the structure in the user data of mode 2,
The physical format is expanded and the data structure of mode 2 is used when performing time division processing of various data. The program data and the like have a large number of consecutive redundant codes having the same code, and read errors are likely to occur. Therefore, in the block of 2352 bytes in which the sync data, the header data, and the auxiliary data data are added to the user data, the scrambling process is performed while leaving the sync data to eliminate the redundant code.

After the scramble process, like the CD audio disc, an error correction code is inserted and interleaved, a subcode is added, and a modulated digital signal is recorded in a CD-ROM.

The subcode corresponds to the structure of the CD audio disc, and one subchannel having a size of 8 channels × 12 bytes is added to one block. Of these, two channels are used for read control, and address information for searching, such as the type of user data, absolute time, and subcode frame number, is recorded.

The CD-ROM reproducing device is a computer,
An image display means such as a CRT or a printer, a data input means such as a keyboard, and a CD-ROM reading means are combined. In response to the address designation by the computer, the CD-ROM reading means performs digital signal processing in exactly the same manner as the reproduction of a CD audio disc.

Since the obtained digital data is scrambled, the sync in the data block is detected to descramble it, the header address is detected, and then the target block is accessed. After the error detection and correction using the auxiliary data is performed according to the data structure mode in the header, the user data is read into the computer. The reliability of data is enhanced by such a two-step error correction function.

The CD-ROM is common with the CD audio disc in digital signal processing. Originally CD-
Since the ROM is derived from the CD audio disc, most CD-ROM reading means are
It also serves as a playback device for audio discs.

The CD-ROM reproducing device is utilized as a multimedia, and image data as well as program data,
We handle acoustic data. The data transfer rate of the CD-ROM reading means is based on 1/75 second per block. By matching the data transfer rate to that of a CD audio disk and setting 1/75 second as a reference, it is used as a shared machine.

As the image display means such as a CRT, the NTSC system in which the horizontal synchronization and the vertical synchronization are about 16 kHz and about 60 Hz, respectively, is widely used. When displaying a moving image using a multimedia composed of a CD-ROM and a computer, the CPU prepares each screen data by processing the image data in the vertical blanking period every 1/60 seconds. Since the CD-ROM reading means transfers data every 1/75 second, the image data is temporarily held in a dedicated secondary buffer and is read from the buffer at a rate equal to the vertical synchronizing signal to achieve synchronization. ing.

In both the CD audio disc and the CD-ROM, the subcode has a space of 6 channels × 12 bytes. By inserting character data or image data here, a screen display function is added or supplemented. Even a CD audio disc can be displayed on the screen by providing a circuit for converting data into characters and images, a CRT, etc. in the reproducing device.

[0019]

There are several interfaces for connecting a CD-ROM and a host computer. Among them, the SCSI bus has been widely used recently. SCSI is one of the interfaces for small computers, such as magnetic disk unit, floppy disk unit,
This is a general-purpose input / output interface that can be connected to various peripheral devices such as magnetic tape devices, printers, and displays. Recently, multimedia is being developed, and CD-R
OM and audio connections are increasing. Due to its high versatility, SCSI is predominant in small computers such as personal computers and game consoles.

On the other hand, the buffer is a memory for temporarily storing data when transferring data from one device to another device. This buffer serves as a buffer area for correcting the occurrence of a data event caused by a difference in transfer rate or for performing effective data transfer.

Since a CD-ROM can store a large amount of data, it often handles image data that requires a large amount of data. Computer game machines and the like handle a large amount of image data in particular, so that it is necessary to transfer the data as soon as possible. It is an object of the present invention to provide a method for speeding up data transfer.

[0022]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a C external storage device via a SCSI bus.
In a computer system in which a D-ROM device and a host machine are connected, image data stored in a buffer RAM in the CD-ROM device is sent to the host-side SCS.
It directly transfers to the image processing unit through the I controller without passing through the main memory of the CPU of the host computer.

The CD-ROM device includes a CPU, a buffer,
It is a so-called independent computer having a SCSI controller, a CD-ROM, and a CD-ROM drive. On the other hand, the host computer is an ordinary computer and also controls an external device.

The CD-ROM device and the host machine are SC
Connect with SI bus. The CD-ROM device operates by the SCSI command from the host machine, but once the command is received, the CD-ROM device side can operate independently.

Normally, READ from the CPU of the host machine
When the command is issued, the CD-ROM drive of the CD-ROM device reads the data from the CD-ROM,
Stored in the device buffer. When the CD-ROM device buffer (CD internal buffer) is full, it is automatically sent to the host machine through the SCSI bus.

In the WRITE command, the data flows in the opposite direction, and the data flows from the host machine to the CD internal buffer. Since the data flow at this time is processing via the main memory of the host machine, the data flow is put in one cushion. CD-R
Even if the data in the OM device can be directly output to the outside, the processing is delayed because the one cushion is provided.

Generally, when using SCSI, REA
It has D_BUFFER and WRITE_BUFFER commands. By using this command, the data on the CD-ROM is read into the CD internal buffer in advance, and conversely, the data processed by the host machine is stored on the CD.
Send to the internal buffer beforehand. Then, when the timing is checked, the data is directly sent from the CD internal buffer to each external device. By adopting such a method, the processing speed can be increased.

[0028]

EXAMPLE As an example of the present invention, the flow of image data will be described in comparison with a conventional (normal) method. Figure 2 is a CD-R
The internal structures of the OM device and the host machine are shown. The normal method and the processing method of the present invention will be described based on this figure.

<Normal image data flow> 1. The main CPU issues a READ command to the host SCSI controller. 2. The command is transmitted to the SCSI controller for CD through the SCSI bus, and the CPU for CD determines the command. 3. The CPU for CD operates the CD-ROM drive based on the judgment result, and stores the CD-ROM in the CD internal buffer RAM.
Save the data read from. 4. This data is read into the main memory in the order of the SCSI controller for CD and the SCSI controller for host on the host side. 5. The read data is processed, sent to the image processing memory by the main CPU, and displayed on the video display.

The above is the conventional processing that has been conventionally performed. However, since the image data is stored in a complete form, it is not necessary to process it when displaying it. In the conventional processing, it was possible to display only by the movement of the above data. As a result, the display speed is slowed down by one tempo, and a part of the main memory must be used. Therefore, in the present invention, the following processing is performed.

<Flow of Image Data of the Present Invention> Basically, it is the same as the above-mentioned <flow of normal image data>.
However, the difference of the present invention from the conventional flow is that the intervention of the main memory in the 4 and 5 processes is eliminated. Therefore, the data in the CD internal buffer RAM is the SCSI for CD.
It is sent directly to the image processing memory () via the controller and host SCSI controller.

By using the data control of the present invention, the CD internal buffer can be used in various ways. For example, by using the PRE-FETCH command, the CD-ROM data is read in advance in the CD internal buffer, the timing is checked and the READ_BUFF is read.
The data can be read by the FER command and directly sent to the video display.

By adopting such a method, the CD internal buffer can be divided into a number of parts for fine data handling.

[0034]

INDUSTRIAL APPLICABILITY By using the present invention, the CD-R
Since the data completely recorded in the CD internal buffer of the OM device can be directly output to each external device, the data transfer can be performed faster than usual.

If the CD internal buffer is made large enough and is divided according to the purpose, it is asynchronously
Data can be read from the D-ROM, which not only improves the processing speed, but also has the effect of enabling multipurpose buffer utilization.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a data format structure of a CD-ROM.

FIG. 2 is an explanatory diagram of internal structures of a CD-ROM device and a host machine.

Claims (1)

[Claims] 1. In a CD-ROM computer system in which a CD-ROM device and a host computer are connected via a SCSI bus, data stored in a buffer RAM in the CD-ROM device in complete form is stored in a host-side SCSI controller. A CD-ROM data processing method, characterized in that the data is directly transferred to the processing unit without passing through the main memory of the CPU of the host computer via the.