JP2002109828A - Device for reproducing compressed audio data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently decode the compressed audio data which are written in a data buffer memory as CDROM(compact disk read-only memory) data. SOLUTION: A CDROM decoder 22 decodes CDROM data and writes the obtained compressed audio data in a data buffer memory 30 successively. A data I/F 24 transfers the compressed audio data stored in the data buffer memory 30 successively to a compressed audio data decoder 26 according to a request from the compressed audio decoder 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing apparatus for reproducing compressed audio data stored as CD ROM data.

[0002]

2. Description of the Related Art Recording of audio data is generally based on wave signals such as PCM signals obtained by A / D conversion of analog signals. Here, compressed audio signals such as MP3 (MPEG Layer 3), in which audio signals are highly compressed, have become widespread. According to the MP3, a compression ratio of about 10 times that of a normal wave signal can be obtained, and a signal having a capacity of 10 times can be stored in a storage medium having a limited capacity.

The MP3 format data is stored in various types of storage media. When storing the data in a CD, the data is stored in a CDROM data format. That is, the MP3 data is handled as ordinary digital data, which is coded into CDROM data and stored on a CD.

Therefore, in reproducing compressed audio using a CD as a recording medium, CDROM data is decoded to obtain compressed audio data (MP3 data), which is further decoded to obtain audio data.

[0005]

Here, a decoder LSI for CDROM data has been known, and a decoder LSI for compressed audio has been developed. Therefore, in a normal case, data obtained by decoding by a CDROM decoder is passed to a compressed audio decoder, and the audio data is reproduced.
In particular, these whole operations were controlled by another microcomputer.

However, the format of CDROM data differs from that of MP3 data, and the size of a data block as a unit for decoding is different. Usually a CD
The block size of the ROM data is larger than the block size of the MP3 data.

Therefore, the data decoded by the CDROM decoder cannot be directly supplied to the compressed audio decoder. For this reason, in a microcomputer that controls the entire operation, the decoded data of the CDROM decoder LSI is temporarily stored and supplied to the compressed audio LSI in data units necessary for the compressed audio LSI.

Accordingly, the microcomputer must also perform processing of simultaneously receiving and buffering CD ROM data while controlling the two LSIs and supplying data of a size corresponding to the compressed audio format to the compressed audio coder. Did not. Therefore, a microcomputer having a high processing capability is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a compressed audio data reproducing apparatus capable of performing efficient processing while reducing the load on a microcomputer.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a reproducing apparatus for reproducing compressed audio data stored as CDROM data, and comprises a C / D decoder for decoding CDROM data.
DROM decoding means, storage means for sequentially storing compressed audio data obtained by decoding in units of data obtained by decoding CDROM data, and storage means for storing compressed audio data stored in the storage means in storage data units of compressed audio data And a compressed audio decoding means for decoding the compressed audio data read by the reading means.

As described above, the compressed audio data obtained by decoding by the CDROM decoding means is read out in units of compressed audio storage data. Therefore, writing and reading between different data formats can be performed by writing to and reading from one storage unit. Therefore, the processing procedure is simplified, and the overall control is facilitated.

Preferably, the CDROM decoding means, the reading means, and the compressed audio decoding means are formed on one semiconductor chip.

It is preferable that the storage unit stores the time-series compressed audio data in the order of addresses.

Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a compressed audio reproducing apparatus according to an embodiment.
Compressed audio data compressed as M data is stored. The pickup 12 has a light emitting unit and a light receiving unit, and outputs a signal according to the reflected light (or transmitted light) from the CD 10. The signal obtained by the pickup 12 is R
The signal is supplied to the F.CD DSP 14, where it is amplified at high frequency and demodulated into CDROM data.

The obtained CDROM data is supplied to a microcomputer 16 and a decoder LSI
20. The microcomputer 16 determines from the supplied CDROM data whether the CDROM data is for compressed audio data or normal data. Then, the operation of the decoder LSI 20 is controlled thereafter.

The decoder LSI 20 has a CDROM decoder 22, a data I / F 24 and a compressed audio decoder 26, and an external data buffer memory 30 is connected to the data I / F 24.

The CD ROM decoder 22 has an RF / CD
CDROM data is supplied from the DSP 14. CD
The ROM decoder 22 decodes the CDROM data. At this time, the CDROM decoder 22 uses the data buffer memory 30 via the data I / F 24 to read and write data to perform data decoding, and stores the decoding results in time series.

On the other hand, the compressed audio decoder 26 sequentially reads out the compressed audio data stored in the data buffer memory 30 via the data I / F 24, decodes this, and outputs it as audio data.
Here, the reading of this data is controlled by the timing of data decoding in the compressed audio decoder 26. That is, the compressed audio decoder 2
6 sends a data request to the microcomputer 16 in accordance with its decoding processing status, and the microcomputer 16 instructs the data I / F 24 to transfer data.
The compressed audio data stored in the data buffer memory 30 is supplied to the compressed audio decoder 26. Therefore, the audio data is sequentially output from the compressed audio decoder 26.

The audio data is stored in an A / D
It is converted and output from a speaker or the like, and audio output is performed.

In the present embodiment, the data I / F 24 responds to a transfer command from the microcomputer 16.
Performs compressed data transfer to the compressed audio decoder 26 by transferring data in the data buffer memory 30. This operation will be described next.

First, as described above, the CDROM decoder 22 uses a part of the data buffer memory 30 as a work area, and sequentially stores the compressed audio data obtained by decoding in a predetermined area of the data buffer memory 30. Write in. Note that the write address is
The microcomputer 16 determines the data I / F 24
Write sequentially.

Accordingly, as shown in FIG. 2, the compressed audio data is stored in the buffer memory 30 in a time series from the address 0000h. Where previous
Is an area where extension reproduction has been completed, and next is an area where extension reproduction is to be performed. Further, the CDROM data buffering area is an area used for decoding by the CDROM decoder, and stores compressed audio data (in this case, data which becomes "next6") after decoding is completed. After writing a fixed amount of decoded data (compressed audio data), the oldest data is overwritten.

Next, based on FIG. 3, the data I / F 24
Will be described.

First, when the processing is started, the data I / F
24 issues a data transfer request to the microcomputer 16 (S11). The microcomputer 16 determines a memory read address in the data buffer memory 30 in response to the data transfer request. Then, this read address is set in the data I / F 24 (S
12).

Next, it is determined whether or not the read flag F is H (S13). The flag F is set to H when the decoding of the received compressed audio data is completed in the compressed audio decoder 26, and indicates a data request of the compressed audio decoder 26. If the flag F is not H at S13, the process waits until it becomes H. If the flag F becomes H, the compressed audio data is read from the data buffer memory 30 and transferred to the compressed audio decoder 26 (S14). Here, this reading is performed according to the compressed audio format. In this example, one block of the compressed audio data format is smaller than one block of the CDROM data format.

Therefore, it is determined whether or not the block is completed (S1).
5) If not completed, return to S13 and repeat the read transfer. On the other hand, if the block has ended, it is determined whether or not the processing has ended (S16).
Returning to 11, the read transfer process is performed for the next block. If YES in S16, the process ends.

Next, the operation of the compressed audio decoder 26 will be described with reference to FIG. As shown in FIG. 4, the compression audio decoder 26 first sets the flag F to H (S21). As a result, the read data is transferred from the data I / F 24, and this data is received (S22). After receiving the data, the flag F is returned to L (S23), and the received data is decoded (S23).
24). As a result, audio data is obtained and output.

Next, it is determined whether or not the block is completed (S2).
5) If not completed, return to S24 to perform decoding, and if completed, determine whether or not to end the processing (S26). If it is determined that the processing has not been completed, the process returns to S21, and if it has been completed, the processing ends.

As described above, in this embodiment, the CD
ROM decoder and compressed audio decoder data
Since it is implemented as a chip, the data decoded from the CDROM is stored in the data buffer memory, and the necessary data is transferred to the LSI only by a transfer command from the microcomputer.
Internally it can be automatically transferred to the audio processing block. Therefore, the microcomputer has an effect that the load on the microcomputer can be greatly reduced without concern for data transmission / reception and a difference in data size between the two different formats.

Further, in this embodiment, as shown in FIG. 2, the capacity of the data buffer memory 30 is relatively large, and the compressed audio data in the data buffer memory 30 can be read at any time.
Therefore, the compressed audio data stored in the data buffer memory 30 can be used as an anti-shock function. In other words, even when the pickup 12 cannot perform continuous reproduction, it is possible to prevent the reproduction sound from being interrupted if reproduction by the pickup is returned while the compressed audio data already stored is being reproduced. .

Further, within the range of the data stored in the data buffer memory, the forward search and the back search of the reproduced data can be performed only on the memory without moving the pick of the CD. That is, by moving the read address within the range of the data stored in the data buffer memory 30, the reproduction position can be moved.

[0032]

As described above, according to the present invention,
The compressed audio data obtained by decoding by the CDROM decoding means is read out in units of compressed audio storage data. Therefore, writing and reading between different data formats can be performed by writing to and reading from one storage unit. Therefore, the processing procedure is simplified,
Overall control becomes easier.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an overall configuration of an apparatus according to an embodiment.

FIG. 2 is a diagram illustrating a method of using a data buffer memory.

FIG. 3 is a flowchart illustrating an operation of a data I / F.

FIG. 4 is a flowchart illustrating the operation of a compressed audio decoder.

[Explanation of symbols]

10 CD, 12 pickup, 14 RF / CDD
SP, 16 microcomputer, 20 decoder L
SI, 22 CDROM decoder, 24 data I /
F, 26 compressed audio decoder, 30 data buffer memory.

Claims (3)

[Claims] 1. A reproducing apparatus for reproducing compressed audio data stored as CDROM data, comprising: CDROM decoding means for decoding CDROM data; and CDR for decoding the compressed audio data obtained by decoding.
Storage means for sequentially storing data in units of data obtained by decoding OM data; reading means for sequentially reading compressed audio data stored in the storage means in storage data units of compressed audio data; A compressed audio data reproducing device, comprising: compressed audio decoding means for decoding compressed audio data. 2. The compressed audio data reproducing apparatus according to claim 1, wherein said CDROM decoding means, reading means, and compressed audio decoding means are formed on one semiconductor chip. 3. The compressed audio data reproducing apparatus according to claim 1, wherein said storage means stores the time-series compressed audio data in address order.