JP2002015519A - Digital audio data reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple and low-cost reproducing device, capable of reproducing CD-DA data and compressed audio data by only using a general low-cost DA converter mounted on a CD reproduction apparatus. SOLUTION: The reproducing device is mounted with a decoder which receives either of CD-DA data extracted by a CD processor and digital audio data (audio stream) decoded by a CD-ROM decoder from its different input terminals, generates PCM data by decoding compressed audio data according to the kind of data, and outputs the obtained PCM data at a sampling rate of 44.1 kHz, or outputs the inputted CD-DA data at an unprocessed rate. Thereby, despite of the kind of optical disk media to reproduce audio data, the audio digital data outputted to the decoder is made into analog audio signals by a normal and low-cost DA converter for CD reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital audio data reproducing apparatus for reproducing an audio CD and compressed audio data.

[0002]

2. Description of the Related Art Audio compressed data typified by MP3 and AAC are recorded on a semiconductor memory typified by smart media, and are also recorded on a CD-R using a personal computer.
It can be recorded on an optical disk medium such as a CD or a CD-RW.

Under such circumstances, a device for reproducing CD media needs a function of reproducing compressed audio data in addition to a conventional audio CD (CD-DA).

FIG. 5 is a block diagram showing a configuration example of a conventional digital audio data reproducing apparatus. The optical disk medium 100 is rotated by a driver 1, data on the disk is read by an optical pickup (not shown), and the read data is amplified by an RF amplifier 2 and then input to a CD processor 3. CD processor 3
When the optical disc medium 100 is an audio CD, the read data is analyzed to extract CD-DA data, and the CD-DA data is output to the switching circuit 7.

On the other hand, if the optical disk medium 100 is a CD-
In the case of a ROM or the like, the CD processor 3 converts the read data (MP3) into a CD-ROM decoder 4 as it is.
Output to The CD-ROM decoder 4 extracts a desired audio stream from the input compressed audio data by using reference data, and outputs the extracted audio stream to the MCU 5. The MCU 5 has an interface between the CD-ROM decoder 4 and the decoder 6 and a buffer function.
The audio stream is sent to the decoder 6 so that no load is applied to the audio stream.

[0006] The decoder 6 analyzes the input audio stream to generate PCM data, and outputs the PCM data to the switching circuit 7. The switching circuit 7 is switched by the system processor 11 which controls the entire apparatus, and when the optical disc medium 100 to be reproduced is an audio CD, the CD-DA data is multi-fs.
Switching circuit 7 to output to corresponding DA converter 8
And a multi-fs compatible DA converter 8
Is set to 44.1 kHz.

On the other hand, the optical disk medium 100 to be reproduced
Is a CD-ROM, the PCM data is
The switching circuit 7 is switched so as to output to the s compatible DA converter 8, and the corresponding sampling frequency of the multi-fs compatible DA converter 8 is switched for compression of the type of audio data being reproduced at that time. The multi-fs compatible DA converter 8 converts the input PCM data into an analog audio signal, and outputs the analog audio signal to the power amplifier 9. The power amplifier 9 amplifies the power of the analog audio signal and outputs the amplified signal to the headphones 10.

[0008]

As described above, in the conventional digital audio data reproducing apparatus, the CD-ROM decoder 4, M
The CU 5, the decoder 6, the switching circuit 7, and the multi-fs compatible DA converter 8 are newly added, and the number of components is increased. Further, the multi-fs compatible DA converter 8 requires, for example, a PLL built-in DA converter compatible with various sampling frequencies (fs) supported by the audio compressed data, and is generally mounted on a conventional CD reproducing device. Since a low-cost DA converter cannot be used, the total cost of the apparatus is greatly increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide an audio CD and audio compression using only a general low-cost DA converter mounted on a CD playback device. An object of the present invention is to provide a simple and inexpensive digital audio data reproducing apparatus capable of reproducing data.

[0010]

According to a first aspect of the present invention, there is provided a digital audio data reproducing apparatus for reproducing an optical disk medium, comprising:
A CD processor that extracts DA data, a CD-ROM decoder that decodes data read from the optical disk medium to extract a desired audio stream, and outputs CD-DA data input from the CD processor at the same rate The audio stream input from the CD-ROM decoder is
After decoding according to the type to make PCM data,
The sampling rate of the obtained PCM data is set to CD-D
A decoder that outputs the data at substantially the same rate as the A data,
CD-DA data or PC output from the decoder
A DA converter for converting M data into an analog signal.

According to a second aspect of the present invention, the DA converter is built in the CD processor.

A feature of the invention of claim 3 is that the CD-RO
That is, the M decoder and the decoder are integrated into one chip.

According to a fourth aspect of the present invention, the decoder comprises the CD
It has an input terminal for inputting -DA, an input terminal for inputting the audio stream, and a common output terminal for outputting CD-DA and PCM data.

[0014] The one-chip CD according to claim 5 of the present invention.
-The ROM decoder and the decoder have a common input terminal for inputting the CD-DA or audio stream and a common output terminal for outputting CD-DA or PCM data.

The present invention is characterized in that the sampling frequency of the audio compression data is converted to 44.1 kHz, which is the same as the audio CD data, in the duder, and is output from a terminal common to the audio CD data. The same components as those of the CD player can be used for the DA converter.

Further, since a CD converter is often provided with a built-in DA converter and can be directly connected to the built-in DA converter, an external DA converter is not required, which contributes to a reduction in system cost. .

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a digital audio data reproducing apparatus according to a first embodiment of the present invention. However, the same parts as those in the conventional example will be described with the same reference numerals. The digital audio data reproducing apparatus of this embodiment includes a driver 1 for rotating the optical disk medium 100, an RF amplifier 2 for amplifying data read from the optical disk medium 100, and a CD for analyzing data read from a CD and extracting CD-DA data. Processor 3, CD-R for analyzing data read from CD-ROM and extracting a desired audio stream
OM decoder 4, CD-ROM decoder 4 and decoder 1
MCU5, which is an interface with PC2, decodes the audio stream into PCM data, and further
Decoder 12 and decoder 12 for making the sampling rate of CM data substantially equal to the rate of audio CD data
A digital-to-analog converter 13 that converts digital audio data input from an analog audio signal into an analog audio signal, a power amplifier 9 that amplifies the power of the analog audio signal, and a headphone 1 that outputs the analog audio signal as audio.
0 and a system controller 11 for controlling the entire apparatus
have.

FIG. 2 is a block diagram showing an example of the configuration of the decoder 12 described above. The decoder 12 uses MP3 or AAC
Interface 1 for inputting audio stream
21, decoders 122 (for MP3) and 123 (AAC
), A sampling rate converter 124 for converting a sampling rate of PCM data, and a selector 125 for selecting and outputting one of CD-DA data and PCM data, and having two input terminals (SDI0, SDI1).
And one output terminal (SDO0).

Next, the operation of this embodiment will be described.
The optical disc medium 100 is rotated by the driver 1,
Data on the disc is read by an optical pickup (not shown), and the read data is amplified by the RF amplifier 2 and then input to the CD processor 3. The CD processor 3 determines that the optical disc medium 100 is an audio CD.
, The read data is analyzed and CD-D
A data is extracted, and this CD-DA data is
Output to 2.

On the other hand, the optical disc medium 100 is
In the case of a ROM or the like, the CD processor 3 outputs the read data (eg, MP3) to the CD-ROM decoder 4 as it is. The CD-ROM decoder 4 extracts a desired audio stream (compressed audio data) from the input data by using the reference data.
Output to CU5. MCU 5 is a CD-ROM decoder 4
And an interface of the decoder 12 and a buffer function, and sends an audio stream to the decoder 12 so that a load is not applied to the decoder 12.

The decoder 12 inputs the input audio stream to the decoders 1 and 2 via the interface (I / F) 121 shown in FIG. Depending on the type of the audio stream, the audio stream is decoded by either the decoder 1 or the decoder 2 into PCM data.
The M data is output to the selector 125 by the sampling rate converter 124 by unifying the sampling frequency to 44.1 kHz which is the same as the CD-DA data.

The decoder 12 receives the input CD-DA
The data is directly input to the selector 125. The selector 125 is instructed by the system controller 11 as to whether the currently reproduced disk is an audio CD or a CD-ROM, and audio digital data (CD-DA or PCM) corresponding to the currently reproduced disk.
And outputs the result to the DA converter 13.

The DA converter 13 converts the input audio digital data having a sampling frequency of 44.1 kHz into an analog signal, and outputs the analog signal to the power amplifier 9. The power amplifier 9 amplifies the power of the analog audio signal and outputs the amplified signal to the headphones 10.

According to this embodiment, the decoder 12 outputs the compressed audio data to the DA converter 13 as audio digital data having the same sampling frequency of 44.1 kHz as the CD-DA data.
The A-converter 13 is a low-cost ordinary converter for CD reproduction, does not require a multi-fs compatible DA converter, and can reduce the total cost of the apparatus.

FIG. 3 is a block diagram showing a configuration of a digital audio data reproducing apparatus according to a second embodiment of the present invention. The configuration of this example is almost the same as that of the first embodiment shown in FIG. 1 except that a low-cost ordinary DA converter 14 for reproducing a CD uses a built-in CD processor 3. By eliminating the need for an external DA converter, the number of components can be reduced, which contributes to the downsizing of the device. Moreover, since the cost of the CD processor with a built-in DA converter is lower than that of two separate processors, the total cost of the apparatus can be further reduced.

FIG. 4 is a block diagram showing a configuration of a digital audio data reproducing apparatus according to a third embodiment of the present invention. The configuration of this example is basically the same as that of the first embodiment shown in FIG. 1, but the CD-ROM used in FIG.
ROM-decoder and decoder are integrated into one chip, CD-R
The OM decoder & decoder 15 is used.

Therefore, the CD processor 3 of the present embodiment has a CD-
It has a common output terminal for outputting either DA data or PCM data, and outputs data to the CD-ROM decoder & decoder 15.

The CD-ROM decoder & decoder 15 detects whether the input data input from the common input terminal is CD-DA data or an audio stream (digitally compressed data), and determines that the data is digitally compressed data. In this case, this is decoded by a built-in CD-ROM decoder and then input to the decoder. On the other hand, if the data is CD-DA data, it is immediately input to the decoder.

Since the configuration of the decoder is the same as that of FIG.
From the CD-ROM decoder & decoder 15, audio digital data (CD-DA or PCM) having a sampling frequency of 44.1 kHz is output from a common output terminal. The output audio digital data is input to the DA converter 14 built in the CD processor 3, where it is converted into an analog signal, input to the power amplifier 9, power-amplified, and output to the headphones 10.

Note that the CD-ROM decoder and the decoder are 1
Since it is implemented as a chip, the MCU serving as an interface between the CD-ROM decoder and the decoder can be omitted.

According to the present embodiment, the number of parts is significantly reduced, so that the effect of reducing the size and weight of the device is remarkable, and the total cost of the device can be reduced.

[0032]

As described in detail above, according to the digital audio data reproducing apparatus of the present invention, a DA converter corresponding to an arbitrary sampling frequency is newly connected to a CD reproducing apparatus for reproducing compressed audio data. This eliminates the necessity and allows the use of a general and inexpensive DA converter for normal CD playback, so that the digital audio data playback device can be made simple and inexpensive, and furthermore, a DA processor with a built-in CD processor can be used. If a converter is used, the number of parts can be reduced and the device can be reduced in size.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a digital audio data reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration example of a decoder illustrated in FIG. 1;

FIG. 3 is a block diagram showing a configuration of a digital audio data reproducing apparatus according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a digital audio data reproducing apparatus according to a third embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration example of a conventional digital audio data reproducing device.

[Explanation of symbols]

 Reference Signs List 1 Driver 2 RF amplifier 3 CD processor 4 CD-ROM decoder 5 MCU 9 Power amplifier 10 Headphone 11 System controller 12, 122, 123 Decoder 13, 14 DA converter 15 CD-ROM decoder & decoder 100 Optical disk media 121 Interface 124 Sampling rate converter

Claims (5)

[Claims] 1. A digital audio data reproducing apparatus for reproducing an optical disk medium, comprising:
A CD processor for extracting DA data, and a CD-R for decoding data read from the optical disk medium to extract a desired audio stream
An OM decoder and CD-DA data input from the CD processor are output at the same rate, and an audio stream input from the CD-ROM decoder is decoded according to the type to obtain PCM data. A decoder that outputs a sampling rate of the obtained PCM data substantially equal to a rate of the CD-DA data, and outputs the CD-DA data or PC output from the decoder.
A digital audio data reproducing device, comprising: a DA converter that converts M data into an analog signal. 2. The digital audio data reproducing apparatus according to claim 1, wherein said DA converter is built in said CD processor. 3. The digital audio data reproducing apparatus according to claim 1, wherein said CD-ROM decoder and said decoder are integrated into one chip. 4. The decoder has an input terminal for inputting the CD-DA data, an input terminal for inputting the audio stream, and a common output terminal for outputting CD-DA data and PCM data. The digital audio data reproducing device according to claim 1 or 2, wherein: 5. The one-chip CD-ROM decoder and the decoder are provided with a common input terminal for inputting the CD-DA data or audio stream, and a CD-ROM decoder.
4. The digital audio data reproducing apparatus according to claim 3, further comprising a common output terminal for outputting DA data or PCM data.