JPH09292900A - Device for regenerating compressed data of audio information - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the output of voice from a voice output device without generating a break by changing the decode accuracy and decode speed so as to control the flow-out speed of the decode voice data to be output. SOLUTION: A MPEG voice decoder control part 5 obtains the information on use amount of the output data buffer from a buffer memory 3 for output voice with a constant interval during the time of regenerating voice. In the case where the decode processing is advanced more than a threshold value, the MPEG decoder control part 5 selects for setting a combination at an accuracy higher than the decode accuracy of a parameter, which is really set in the MPEG voice decoder 2. In the case where the decode processing is delayed less than the threshold value, the MPEG voice decoder control unit 5 selects for setting a combination at a highest accuracy, of which flow-out speed is higher than the flow-out speed of a parameter really set in the MPEG voice decoder 2. Voice can be output from a voice output device 4 without generating a break by controlling the output variable of data buffer inside of a buffer memory 3 for output voice.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing device for a recording medium such as an optical disk or a hard disk, or a reproducing device for compressed audio data obtained via a communication line or the like.

[0002]

2. Description of the Related Art Recently, audio data has been compressed and recorded on a recording medium such as an optical disk or a hard disk.
Devices for expanding and reproducing the data are becoming popular. A decoder L for audio processing is used for the decoding processing of such a device.
A device using SI (Large Scale Integrated circuit) and a general-purpose CPU (C
entral Processing Unit) and DSP (Digital Signal Pr)
There is a device that performs decryption processing in the ocessor).

In a device for performing decoding processing by a general-purpose CPU or the like, if system resources (processing capacity of CPU, amount of memory, etc.) are lower than the capacity required for speech decoding processing,
By setting the decoding accuracy based on the system resources and lowering the decoding accuracy, the outflow speed is increased and reproduction without interruption of sound (real-time reproduction) is performed.

Here, the outflow speed, the decoding speed and the decoding speed will be briefly described. The outflow rate is the D /
It is a supply speed of data supplied to an audio output device such as an A converter. In order to perform real-time reproduction, the above-mentioned audio output device is used for D / D at a fixed speed such as 44.1 kHz.
In order to carry out A conversion, the outflow rate must be the same as the fixed rate. When a buffer is provided between the decoder and the audio output device, the outflow rate should be above the fixed rate on average. The decoding speed is the speed at which the decoding process is performed, and is directly proportional to the outflow speed. The decoding accuracy is the accuracy of the decoded data and is inversely proportional to the outflow speed. It is directly proportional to the consumption of system resources required to decode one sample.

Further, in a device using a dedicated decoder LSI, reproduction can be performed without interruption based on system resources (power consumption, amount of memory, etc.).
I was designing an LSI.

[0006]

By the way, according to the apparatus for performing the decoding processing by the above-mentioned general-purpose CPU or the like, the method of setting the decoding accuracy in advance based on the system resource is adopted. There is. When the CPUs are performing other processing (video decoding, etc.) in parallel, the setting is performed in advance based on the system resources assigned to the audio decoding processing.

However, in this method and apparatus, since the setting of the decoding accuracy is fixed, if the system resources allocated to the speech decoding process are not constant, for example, the number of processes to be processed in parallel during reproduction and the number of exception processes increase. In that case, with that setting, sound processing cannot be performed in time, resulting in sound interruption. Further, since the decoding accuracy setting is fixed, the sound quality becomes constant.

Also, the dedicated decoder LSI as described above
In the device using, since the LSI is designed based on a predetermined constant system resource, when the system resource is insufficient, for example, when the battery is exhausted, the system stops. I will end up. Therefore,
The present invention has been made in view of the above points, and an object of the present invention is to provide a compressed data reproducing apparatus for audio information without sound interruption.

[0009]

As a means for achieving the above object, the invention of claim 1 is such that compressed audio data is supplied and decoding accuracy and decoding speed are improved. By making at least one of them variable, the compressed audio data decoder 2 for controlling the outflow speed of the decoded audio data to be output, and the output to which the decoded audio data output from the compressed audio data decoder 2 is supplied. The data buffer memory 3, a means 31 for outputting information on the amount of use of the output data buffer memory 3, and the information obtained by the means are referred to, and accordingly the decoded voice output by the compressed voice data decoder is output. A means 5 for controlling the data outflow rate and the reproduction quality is provided.

According to a second aspect of the present invention, compressed audio data decoding is possible in which compressed audio data is supplied and at least one of the decoding accuracy and the decoding speed is made variable to control the outflow speed of the decoded audio data to be output. Unit 2, an output data buffer memory 3 to which the decoded audio data output from the compressed audio data decoder 2 is supplied, and means 31 for outputting information on the amount of use of the output data buffer memory 3.
And a means 1 for detecting the amount of system resources allocated to the compressed audio data decoder, and the information acquired by the means is referred to, and accordingly, the decoded audio data output from the compressed audio data decoder is output. It comprises means 5 for controlling the outflow rate and the regeneration quality.

According to a third aspect of the present invention, in the voice data compressed data reproducing apparatus according to the second aspect, the means 1 for detecting the amount of system resources assigned to the compressed voice data decoder 2 is the compressed voice data decoder. At least one of the system resource usage data used by the device 2 and the system resource usage data required by the compressed voice data decoder 2 is supplied, and the system allocates to the compressed data decoder 2 accordingly. Controlled the amount of system resources.

The invention of claim 4 is the compressed audio data reproducing apparatus for audio information according to any one of claims 1 to 3, wherein the compressed audio data is compressed data according to the MPEG standard. I will offer it.

As described above, by controlling the decoding accuracy and the decoding speed during reproduction so that the data can be output from the output data buffer memory 3 to the audio output device at a constant speed, audio information without sound interruption can be obtained. An object is to provide a compressed data reproducing device.

According to the present invention, since the apparatus itself variably controls the decoding accuracy and the decoding speed as described above, there is always no sound break and reproduction is possible. In addition, the present invention can reproduce with the highest decoding accuracy that can be reproduced with the system resource allocated at that time, that is, with the sound quality.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a compressed data reproducing apparatus for audio information according to the present invention will be described below with reference to the drawings.
In this embodiment, MPEG (Moving P
Compressed audio data based on the icture Expert Group) standard (ISO11172 compliant) is used.

FIG. 1 is a block configuration diagram of an MPEG decoding unit used in an embodiment of a compressed data reproducing apparatus for audio information of the present invention, and FIGS. 2 and 3 show an embodiment of the present invention. It is a flowchart of a decoding control process. Also,
Table 1 below shows an example of the setting of the decoding parameter in the embodiment of the present invention.

[0017]

[Table 1]

First, each block of an embodiment of the audio information compressed data reproducing apparatus of the present invention shown in FIG. 1 will be described below in sequence. The system resource amount detector 1 is MPEG
The system resource amount information supplied to the audio decoder 2 is output to the MPEG audio decoder control unit 5.

The MPEG audio decoder 2 is supplied with compressed audio data, can classify and set decoding accuracy and decoding speed in several stages, and can output the set audio decoding data. Is.

The output voice buffer memory 3 is an MPEG.
It is a buffer memory to which the audio data decoded by the audio decoder 2 is supplied. The output voice buffer memory 3 is a FIFO (Fast In Fast Out) type buffer and can output information on the amount of stored data.

The audio output device 4 is supplied with the audio decoded data which is the output of the output audio buffer memory 3,
The audio output device has a D / A converter, an analog circuit, a speaker, and the like.

The MPEG audio decoder control unit 5 is suitable for the MPEG audio decoder 2 at that time based on the information obtained from the output audio buffer memory 3 and the information obtained from the system resource amount detector 1. The decoding accuracy parameter and the decoding speed parameter are set. The system resource amount detector 1 shown in FIG. 1 is not used in the first embodiment.

Example 1 Next, referring to FIG. 2 and Table 1,
A decoding control process in the first embodiment of the audio information compressed data reproducing device of the present invention will be described. MPEG here
The decoding accuracy and the decoding speed of the audio decoder 2 are the decoding accuracy L
OW and decoding accuracy HIGH, decoding speed LOW and decoding speed H
Each of IGH has two stages, and a CD disk is used as a recording medium.

As shown in FIG. 1, the compressed audio data read from the CD disk as the recording medium is MP
It is supplied to the EG audio decoder 2. And this MPE
The G audio decoder 2 decodes the compressed audio data according to the set parameters supplied from the MPEG audio decoder control unit 5.

The audio data decoded by the MPEG audio decoder 2 is supplied to the output audio buffer memory 3,
The audio output device 4 reads data from the output audio buffer memory 3 and outputs audio.

As shown in the flow chart of the processing of FIG. 2, the MPEG audio decoder control unit 5 is
Information about the output data buffer usage is obtained from the output voice buffer memory 3 at regular intervals (step 201).

If it is larger than a certain threshold value, it is judged that the decoding process is ahead of the output, and if it is smaller than a certain threshold value, it is judged that the decoding process is behind the output (step 202).

Then, if the decoding process progresses more than a certain threshold value, a combination (step 203) having a higher decoding precision than the decoding precision of the parameter currently set in the MPEG voice decoder 2 is set to the MPEG voice decoder control unit 5.
Is selected and set in the MPEG audio decoder 2 (step 205).

On the other hand, if the decoding process is delayed by less than a certain threshold value, the outflow speed is faster than the outflow speed of the parameter currently set in the MPEG audio decoder 2, and the decoding accuracy of The MPEG audio decoder control unit 5 selects the highest combination (step 204) and sets it in the MPEG audio decoder 2 (step 20).
Five). By such control processing, the output data buffer amount in the output voice buffer memory 3 is controlled so that the voice output from the voice output device 4 is not interrupted.

Example 2 Next, referring to FIG. 3 and Table 1,
A decoding control process according to the second embodiment of the present invention will be described. C
The compressed audio data read from the D disc is MPE
It is input to the G audio decoder 2. Then, the MPEG audio decoder 2 decodes the compressed data according to the parameters set by the MPEG audio decoder control unit 5.

The decoded voice data is supplied to the next output voice buffer memory 3, and the voice output device 4 reads the data from the output voice buffer memory 3 and outputs voice.

The MPEG audio decoder control unit 5 acquires information from the system resource amount detector 1 at regular intervals during audio reproduction (step 301) and judges the currently allocated system resource amount.

Further, information on the amount of output data buffer used is obtained from the output voice buffer memory 3 (step 30
3) If it is larger than a certain threshold value, it is judged that the decoding process is ahead of the output, and if it is smaller than a certain threshold value, it is judged that the decoding process is behind the output (step 304).

Then, if the decoding process is advanced from among the combinations of parameters that can be processed with the current amount of system resources, a combination having a higher decoding precision than the decoding precision of the parameters currently set in the MPEG audio decoder 2 is obtained. If the decoding process is delayed, the MPEG audio decoder control unit 5 selects the combination whose outflow speed is faster than the outflow speed of the parameter currently set in the MPEG audio decoder 2 and which has the highest decoding accuracy. Is selected (steps 302, 305, 306) and set in the MPEG audio decoder 2 (step 307).

If the information acquired by the MPEG audio decoder control unit 5 is system resource amount = medium, output buffer amount> threshold, and the decoding accuracy of the parameter currently set in the MPEG audio decoder 2 is LOW, (Step
In 302), the combination of parameters that can be processed with the current system resource amount, the parameter set of Table 1 (2) (3) (4) is selected as a candidate, and in (Step 305), the decoding accuracy among them is selected. Table 1 (3), which is HIGH, is selected.

Next, when the information acquired by the MPEG audio decoder control unit 5 is system resource amount = large, output buffer amount <threshold value, and the outflow rate of the parameter currently set in the MPEG audio decoder 2 is slow. , (Step 20
The combination of parameters that can be processed with the current system resource amount is selected in 2), and the set of parameters in Table 1 (1) (2) (3) (4) is selected as a candidate. From Tables 1 (1) (2) (4) above, Table 1 (1) with the highest decoding accuracy is selected. By such control processing, the output data buffer amount in the output voice buffer memory 3 is controlled so that the voice from the voice output device 4 is not interrupted.

In the second embodiment, (step
305, 306) prioritized decoding accuracy, but prioritized saving of system resources and selected the combination of parameters with the smallest amount of system resource usage, priority and saving of other parallel processing. It can be applied to electric power.

(Embodiment 3) As Embodiment 3, Embodiment 2 is used.
1, the MPEG audio decoder control unit 5 outputs the system resource usage amount currently used by the MPEG audio decoder 2 to the system resource amount detector 1 as shown by the dotted line in FIG. As a result, it is possible to detect the amount of unused system resources among the system resources allocated to the MPEG audio decoder 2 by the system, and collect the unused system resources.

In addition, the MPEG audio decoder control unit 5 in the second embodiment outputs the required system resource amount for the MPEG audio decoder 2 to the system resource amount detector 1 as shown by the dotted line in FIG. To do. For example, the MPEG audio decoder control unit 5 outputs the required amount of system resources required for the decoding accuracy one step higher, and the system resource amount detector 1 detects it and outputs it to the system. As a result, the system allocates the system resource based on the information if the system resource has a margin based on the information.

Allocation of system resources will be described below with reference to Table 1 above. For example, it is assumed that the system resource usage amounts in Table 1 are large = 7, medium = 5, and small = 3, respectively. At present, the system resource amount detected by the system resource detector 1 is 4, and the system resource amount allocated to the MPEG audio decoder 2 is 4. From this value, the MPEG audio decoder control unit 5 informs the MPEG audio decoder 2 of (4).
Set the parameters of. The system resource detector 1 detects this information from the MPEG audio decoder control unit 5 and outputs it to the system. In this case, the number is 3. Further, the system resource detector 1 detects the amount of system resources required for the decoding accuracy one step higher from the MPEG audio decoder control unit 5 and outputs it to the system. In addition,
In this case, the number is 5.

From these information, if the system resource has a margin, the system sets 5 to MPEG audio decoder 2
Assign to When the system resources are not sufficient, the surplus system resources = 1 are collected.
Thus, by outputting at least one of the above information to the system, the system can always allocate the optimum amount of system resources to the MPEG audio decoder 2.

By thus outputting at least one of the above information to the system, the system can always allocate the optimum amount of system resources to the MPEG audio decoder 2.

Although the control in the above-described first, second, and third embodiments is carried out based on a certain threshold value, it is also possible to provide a plurality of threshold values and make it adaptive. Note that the following (1) and (2) are examples of methods for controlling the decoding accuracy and the outflow rate. (1) According to the MPEG standard, output data is calculated by combining frequency band data called 32 subbands.
The number of subbands to be combined is changed to control the amount of calculation. (2) Change the bit precision during operation.

Further, examples of the method of controlling the decoding speed and the outflow speed include the following (1) and (2). (1) Change the algorithm of memory usage (use of constant table, etc.). (2) Control the internal clock of the decoder.

In the above embodiment, the MPEG standard is adopted for the compressed audio data, but it can be applied to other audio compression systems.

[0046]

As described above, according to the compressed data reproducing apparatus for audio information of the present invention, during the audio reproduction, the amount of system resources allocated at that time and the progress of the decoding process,
The delay is judged, the decoding accuracy and the decoding speed are changed, and the outflow speed of the decoded audio data to be output is controlled to control the output data amount in the output audio buffer memory. The audio from will not be interrupted, and the highest decoding accuracy that can be reproduced with the system resources allocated at that time, that is, the highest sound quality can be reproduced.

Further, by changing the priority item at the time of parameter selection from decoding accuracy to saving of system resources, power saving (long time) reproduction and other parallel processing can be prioritized. Can be done.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a decoding unit of a compressed audio data reproducing apparatus according to the present invention.

FIG. 2 shows the operation of the first embodiment of the compressed data reproducing apparatus for audio information of the present invention, and is a flowchart of the processing of the audio decoder control unit 5 when controlling the decoding accuracy during reproduction.

FIG. 3 shows an operation of the second embodiment of the audio data compressed data reproducing apparatus of the present invention, and is a flowchart of a process of the audio decoder control unit 5 at the time of controlling the decoding accuracy during reproduction.

[Explanation of symbols]

1 system resource amount detector 2 MPEG audio decoder 3 output audio buffer memory 4 audio output device 5 MPEG audio decoder control unit 31 means for outputting information on the usage amount of output data buffer memory

Claims (4)

[Claims] 1. A compressed audio data decoder for controlling an outflow speed of decoded audio data to be output by supplying compressed audio data and making at least one of a decoding accuracy and a decoding speed variable. An output data buffer memory to which the decoded audio data output from the audio data decoder is supplied, a unit for outputting information on the amount of use of the output data buffer memory, and the information acquired by the unit is referred to and And a means for controlling the outflow speed and the reproduction quality of the decoded audio data output by the compressed audio data decoder. 2. A compressed audio data decoder which is supplied with compressed audio data and which makes variable at least one of decoding accuracy and decoding speed to control the outflow speed of decoded audio data to be output; An output data buffer memory to which the decoded audio data output from the audio data decoder is supplied, a means for outputting information on the usage amount of the output data buffer memory, and an amount of system resources allocated to the compressed audio data decoder. And a means for controlling the outflow speed and the reproduction quality of the decoded audio data output by the compressed audio data decoder according to the information obtained by the means. A device for reproducing compressed data of characteristic audio information. 3. The compressed audio data reproducing apparatus according to claim 2, wherein the means for detecting the amount of system resources assigned to the compressed audio data decoder is used by the compressed audio data decoder. At least one of system resource usage data and system resource requirement data required by the compressed audio data decoder, and the system controls the amount of system resource allocated to the compressed data decoder accordingly. A compressed data reproducing apparatus for audio information, characterized by the above. 4. The compressed audio data reproducing apparatus for audio information according to any one of claims 1 to 3, wherein the compressed audio data is compressed data according to the MPEG standard. Playback device.