JPH07153174A - Cd-rom reproducing system - Google Patents

Abstract

PURPOSE:To confirm the reproducing state of a CD-ROM driving only by checking the state of busses by adding a BUSY-mode to an audio playing command. CONSTITUTION:The BUSY-mode is provided in the audio playing command issued from a host. At the same time, when the playing command is issued at the time of being in this mode, a CD-ROM driving device performs the reproducing processing of an audio and also delivers always the state of whether the device is reproducing the audio tracks or not to a SCSI controller. This processing is performed by the CPU of the CD-ROM device. When the side of the host wants to know whether the driving device is reproducing the audio tracks of the CD-ROM device or completed, the side can confirm a reproducing status only by performing the BUSY-check of the SCSI bus. Thus, the generation of an over-head generated by the issuing of another SCSI command is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to audio reproduction in a computer device having a CD-ROM as a recording medium.

[0002]

2. Description of the Related Art CD has been developed as a medium capable of digitally recording and reproducing sound, and has become popular as an audio disc capable of reproducing faithful sound and continuously reproducing for a long time. Further, with a focus on large capacity and high-speed access performance, it is also used as a recording medium of a computer.

The data structure of a CD audio disc will be briefly described. L sampled at 44.1 kHz,
Data of 6 samples of R2 channel, 16 bits x 2
× 6 = 192 bits, digital data of 24 symbols are grouped together into a CIRC (Cross Interleave Reed-So
It is encoded collectively by the lomon Code).

CIRC encoding and EFM (Eight to Fourt)
een Modulation) Digital data consisting of 32 symbols to which an error correction code obtained by modulation is added is combined with a frame synchronization signal and a control signal called sub-coding and written on a CD. A collection of this series of data is called a CIRC frame, and has a format structure on a CD as shown in FIG.

Each symbol is separated by a 3-bit separation signal. The first 24 bits are a frame synchronization signal, and the subsequent 14 bits are a sub-coding, and are responsible for control such as the beginning of a movement. The other 32 symbols are digital audio data.

The sub-coding is recorded as 14 bits on a CD, but this contains redundant bits by encoding, and is data having 8-bit contents when decoded. Each bit has P, Q, R, S, T, U, V,
Called W, P and Q are related to control such as the beginning of a movement, and R to W are related to image data such as a display.

The data of one frame of the CIRC has a length of about 0.17 mm on the CD, and 98 frames form one block. The signal representing the first frame of the block is a frame in which the subcoding is signals S0 and S1 for synchronization. FIG. 2 shows one block of data.

FIG. 3 shows only the subcoding shown in FIG. The sub-coding forms a block in frames 3 to 98. The P channel represents 1 between music (pause) and is used for rough cueing. The Q channel is used for finer control.
FIG. 4 shows the frame structure of the Q channel.

Control bits Q1 to Q4 are used to distinguish the number of audio channels, emphasis, digital data (CD-ROM), and the like. Q5 to Q8 represent modes, and the (0001) mode is mainly used. At this time, the 72-bit data of Q9 to Q80 has a format as shown in FIG.

In TNO, 00 represents lead-in, 01 to 99 represent movement number, and AA represents lead-out. X is an index, where 00 represents a pose, and 01 to 99 represent positions where the movement is further subdivided. The subsequent MIN, SEC, and FRAME indicate the elapsed time in the movement.

MIN is minutes, and CD is a maximum of 74.7 from the linear velocity standard (1.2 to 1.4 m / sec) of the reproducing head.
Since it can be reproduced for a minute, a value of 00 to 74 is taken. SEC
Is from 00 to 59 in seconds, and CD reads 75 blocks of data per second and one block (98 frames of CIRC) forms one frame of sub-coding. The value of 00 to 74 is taken as the subdivision of the above.

The time represented by (MIN, SEC, FRAME) returns to 0 at the beginning of each movement. On the other hand, (A
MIN, ASEC, AFRAME) represents the absolute elapsed time from the pause of the movement at the beginning of the CD.

The CD is read from the innermost lead-in portion to the outermost lead-out portion. The rotation speed of the CD changes depending on the position of the head so that the reading speed is uniform on the inner and outer circumferences. C read first as a lead-in
At the innermost part of D, the TOC (Table of C
There is a part corresponding to the contents of the whole CD called ontents).

By reading this data, the pickup can be moved to the position of the specified movement. In the lead-in, TNO is 00 and POINT is the sequence number from the beginning of the movement. Elapsed time in movement (MIN, SEC, FR
(AME) is similar to the explanation of the elapsed time in the above movement,
(PMIN, PSEC, PFRAME) represents the absolute time when the movement indicated by POINT begins.

By reading this TOC, the absolute time at the beginning of each movement can be known. However, for more detailed information in the movement, the read head is moved and the subcoding of the movement in question is read.

The CD developed for audio is also used as a computer recording medium. CD-ROM that has become a unified standard as a physical format for that purpose
There is. FIG. 7 shows the standard of the format of the CD-ROM. Format is mode 0, mode 1, mode 2 3
Kinds of modes are defined.

One sector of the CD-ROM is composed of data of 2352 bytes which is equal to a subcode block of a CD audio disc, and a 12-byte block sync signal (sync) is provided at the beginning of each block for separating the blocks. Is placed.

Following the block sync signal, a header of 4 bytes is arranged, and is composed of a block address of 3 bytes and a data recording mode of 1 byte. In mode 0 and mode 2, the remaining 2336 bytes are data. In mode 0, this data is all 0s.

Mode 1 is used for computer data which 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, the auxiliary data area is set in the data structure of 2336 bytes, and the user data 2048 bytes and the auxiliary data 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 all 2336 bytes are user data, and image / sound data and the like which 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 of the same code, and thus a read error is 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 digital signal obtained by modulation is recorded in a CD-ROM.

As shown in FIG. 8, the subcode has the same structure as that 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 system is composed of 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. Upon receiving the address designation by the computer, the CD-ROM reading means C
Digital signal processing is performed in exactly the same manner as the reproduction of the D audio disc.

Since the obtained digital data is scrambled, the sync in the data block is detected to descramble the data, 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.

[0027]

In order to operate the CD-ROM drive having the above functions, an instruction from the host computer is required. Host and CD-ROM
If you don't coordinate the communication between them well, you'll end up with a lot of overhead and an inefficient system.

For example, when an audio track of a CD-ROM drive is reproduced, there is only a command for inquiring the state to the CPU of the CD-ROM drive side when obtaining the state. Therefore, there is a defect that the processing tempo becomes slow.

This is because when the audio track of the CD-ROM drive is being reproduced, whether or not the reproducing process is completed is determined by a SCSI command (for example, READ).
This is because there was only a method of acquiring the status with the SUBCODE-Q command).

Therefore, the same command must be issued many times, and the CPU processing of the CD-ROM drive is repeated many times to set the status. It is an object of the present invention to develop a system for eliminating such overhead that arises there.

[0031]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an audio play command including a mode for keeping a bus busy state during audio reproduction of a CD-ROM drive. This is so that the playback status can be confirmed simply by checking.

Specifically, the BUSY mode is added to the audio play command prepared in the system. Issuing a command in this mode always sets the status of the CD-ROM from the CD-ROM drive to the SCSI controller.

As a result, the host computer can use the CD
-SC without having to directly inquire to the ROM drive
CD just by BUSY check for SI bus
-It becomes possible to know the state of the ROM drive.

[0034]

EXAMPLES The present invention will be described based on examples.
FIG. 9 shows the internal structure of the CD-ROM drive device and the connection state with the host computer in the device of the embodiment of the present invention. The host and the CD-ROM drive are SC
It is connected by SI bus, and commands from the host and CD-
The signals from the ROM drive are transmitted bidirectionally through this bus.

First, the flow of processing when the audio play command with the BUSY mode of the present invention is not used will be described. To play the audio of the CD-ROM, an audio play command is issued from the host.

The commands are CD-R over the SCSI bus.
It is transmitted to the SCSI controller on the OM side, and further CD
The audio data is read from the CD by operating the CD-ROM drive as analyzed by the CPU on the ROM side.

The read data is sent to a CD internal buffer and further sent to a CD-ROM D / A converter, where it is converted into analog audio data and reproduced as sound from a speaker. After the audio play command is passed from the host to the CD-ROM drive, all the internal processing is performed in the CD-ROM drive.
Therefore, the host is not involved during sound reproduction.

However, in order to know the audio state, a new SCSI command is issued from the host and the CD-RO is issued.
I have to ask M drive. For example, one of them is a command called READ SUBCODE-Q. When this command is issued, the performance status is playing, STILL is in operation, AUDIO TRACKS
During PAUSE after EARCH, a status code such as a performance end state is returned to this command. This status requires the same information flow as the audio play command to be set.

That is, the CPU of the CD-ROM drive must be fully utilized to process this command. In the meantime, of course, the host must wait until the status is set. Moreover, the same command had to be repeatedly issued to check the playback end.

Therefore, in the present invention, a BUSY mode is provided for the audio play command, and at the same time, when the play command is issued in this mode, the CD-RO
M drive is always SC at the same time as audio playback processing.
The status of whether the audio track is being reproduced is passed to the SI controller.

This processing is performed by the CPU of the CD-ROM drive.
The host side does not need to take any action for this process. When you want to know whether the audio track of the CD-ROM drive is playing or finished on the host side,
The playback status can be confirmed only by directly checking the BUSY (in use) of the SCSI bus instead of going to the CPU of the CD-ROM drive. That is, the overhead caused by issuing another SCSI command is gone.

Note that FIG. 10 shows an example of the audio reproduction end check when the audio play command is issued in the BUSY mode. This example represents the program logic on the host side, in which the processing A ends when a certain audio ends and the processing B moves to the processing B. "B on the SCSI bus
If "USY check" is set to "Issue of READ SUBCODE-Q", the same processing as in the conventional method is performed. However, as mentioned above, there seems to be no difference externally, but there is a big difference in internal processing.

[0043]

As described above, according to the present invention, the overhead caused by issuing a SCSI command is eliminated, so that the overall processing speed can be increased.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of a format of a sub-coding frame.

FIG. 3 is an explanatory diagram of details of a sub-coding format of one frame.

FIG. 4 is an explanatory diagram of a frame structure of a Q channel.

FIG. 5 is an explanatory diagram of a structure of a data part of a Q channel.

FIG. 6 is an explanatory diagram of a structure of a TOC unit of Q channel.

FIG. 7 is an explanatory diagram of a CD-ROM format standard.

FIG. 8 is an explanatory diagram of a block configuration of a CD-ROM.

FIG. 9 is a block diagram of a CD-ROM reproduction system according to an embodiment of the present invention.

FIG. 10: BUSY in the system of the embodiment of the present invention
6 is a flow chart in the case where an audio play command is issued in a mode and the reproduction of the audio is ended by a BUSY check of the SCSI bus.

Claims (1)

[Claims] 1. A computer device using a CD-ROM as a recording medium, comprising an audio play command including a mode for keeping a bus busy state during audio reproduction of a CD-ROM drive.
ROM playback system.