JP2003076395A - Audio signal processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an audio signal processor which reduces the capacity of a memory formed in an LSI. SOLUTION: An input I/F 12 outputs control data, which are used to detect the standard of a bit stream BS on the basis of data set to the header of each frame of the bit stream BS, to a processor 13. The processor 13 outputs the control data to a discrimination circuit 14. The discrimination circuit 14 discriminates the standard of the bit stream BS and outputs standard data representative of the discrimination result to the processor 13. A decoding program is stored in an incorporated memory 15. An external memory 17 is externally attached to an audio decoder 11 consisting of an LSI, and all programs used in the processor 13 are stored in the external memory 17. The processor 13 reads out a program corresponding to the standard of the bit stream BS from the external memory 17 and sets it to the incorporated memory 15 and uses this program to perform decoding.

Description

Detailed Description of the Invention

[0001]

This invention relates to Dolby Digita.
The present invention relates to an audio signal processing device that performs a process of decoding audio data encoded according to a standard such as l, DTS, or MPEG AAC and returning it to PCM data.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional LSI (large-scale integrated circuit).
3 is a block diagram showing a configuration example of an audio decoder 1 according to FIG. In this figure, the bit stream BS is, for example, a digital audio output of a DVD player,
The audio data is divided into a plurality of frames, a header is added to each frame, and the serial data is supplied to the audio decoder 1. Here, the frame is a unit of data processing. Reference numeral 2 is an input interface, which determines which standard (Dolby Digital, DTS, MPEG ACC) the bitstream is from the control signal added to the header of each frame of the bitstream BS, and the determination result Is output to the processor 3. Also, the audio data of each frame is sequentially output to the processor 3 at a timing. Further, error detection is performed for each frame and the result is output to the processor 3.

The memory 4 is a memory in which a decoding program used in the processor 3 is stored.
When M (Read Only Memory) is used and RAM
(Random access memory) may be used.
In the case of the ROM, a decoding program corresponding to all the standards of the digital audio data input to the audio decoder 1 is stored in advance. In the case of RAM, the decode program is downloaded from the host computer 5 when the power is turned on. Here, the host computer 5 is a microcomputer that performs various controls of an AV (audiovisual) amplifier on which the audio decoder 1 (LSI) is mounted.

The processor 3 includes an input interface 2
The decoding program is read from the memory 4 based on the standard data indicating the standard of the bit stream supplied from the memory 4, the audio data output from the input interface 2 is decoded based on the read program, and the decoded PCM data is returned to the output interface 6. Output via.

[0005]

As described above, the conventional L
The SI audio decoder 1 is designed to store all programs to be used in the memory 4 in advance. As a result, the memory capacity becomes large and the LSI configuration becomes complicated. Also, the memory 4 is a ROM
If it is composed of, there is a drawback that the program cannot be added easily. Further, even when the memory 4 is composed of a RAM, the capacity of the memory 4 cannot be increased, so that there is a drawback that the program cannot be easily added. The present invention has been made in consideration of such circumstances, and an object thereof is to provide an audio decoder which can reduce a memory capacity formed in an LSI and can easily add a program. To provide.

[0006]

The present invention has been made to solve the above problems, and the invention according to claim 1 is
In an audio signal processing device comprising a plurality of processing programs, which processes an audio signal using the processing program corresponding to an input audio signal,
Control means for processing an input audio signal based on the processing program; a built-in memory for storing a processing program used in the control means, the processing program corresponding to the input audio signal; An external memory in which all processing programs used in the control means are stored, and the control means reads out a processing program corresponding to a currently input audio signal from the external memory and sets it in the internal memory. Is an audio signal processing device.

The invention described in claim 2 is the same as claim 1
In the audio signal processing device described in the paragraph 1, the control means detects a processing program corresponding to the audio signal from the data added to the input audio signal, reads the program from the external memory, and sets the program in the built-in memory. It is characterized by doing. The invention according to claim 3 is the audio signal processing device according to claim 1 or 2, characterized in that rewriting means for rewriting the external memory is provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an audio decoder 11 according to the same embodiment. The audio decoder 11 is composed of an LSI and is used in an AV amplifier. In the figure,
Reference numeral 12 is an input interface, which outputs control data for detecting the standard of the bitstream BS to the processor 13 based on the data set in the header of each frame of the bitstream BS. In addition, the audio data of the bit stream BS is sequentially output to the processor 13 with timing. Further, the data error of the bit stream BS is detected.

The determination circuit 14 is a circuit for determining the standard of the bit stream BS by hardware, determines the standard based on the data supplied from the processor 13, and outputs the standard data indicating the determination result to the processor 13. The output interface 16 outputs the PCM data output from the processor 13 to the outside. The built-in memory 15 is a memory (RA
M), and the capacity is the capacity for storing one decoding program. That is, this internal memory 15
Is a memory having a much smaller capacity than the conventional memory 4 (see FIG. 3).

The external memory 17 is a memory (RAM) externally attached to the audio decoder 11 of LSI, and the writing / reading can be performed by the processor 13. The memory 17 has a capacity capable of storing all programs used in the processor 13. The host computer 18 is a microcomputer that performs various controls of the AV amplifier. The processor 13 includes a CPU (central processing unit) and a DSP (Digi
TAL Signal Processor), the details of which will be described below.

Next, the operation of the above embodiment will be described. First, when the power is turned on, the host computer 1
Reference numeral 8 sequentially writes all the decoding programs used in the processor 13 into the internal memory 15. The processor 13 transfers the program to the external memory 17 each time a fixed amount of the program is written in the built-in memory 15. As a result, all the decoding programs are written in the external memory 17 in advance.

Next, the processing when the bit stream BS is applied will be described. In the bit stream BS, data is divided in units of frames. Then, the processor 13 performs the following processing for each frame of the bit stream BS.

First, the control data of the first frame output from the input interface 12 is read (step S1 in FIG. 2), and the read control data is judged by the judging circuit 14.
Output to. Then, the standard data output from the determination circuit 14 is read according to the control data. Next, it is determined whether the standard data is the same as the standard of the decoding program currently stored in the internal memory 15 (step S2). When the result of the determination is “NO”, that is, when the currently input bitstream BS cannot be decoded by the decoding program in the internal memory 15, the decoding corresponding to the bitstream BS from the external memory 17 is performed. Read the program and write it in the internal memory 15 (step S
3). In addition, when the determination result of step S2 is "YES", step S3 is skipped.

Next, the audio data output from the input interface 12 is decoded by using the decoding program in the built-in memory 15 and returned to PCM data (step S4). Then, the PCM data is output to the outside through the output interface 16 (step S5). Next, it is judged whether or not the processing for one frame is completed (step S6), and if not completed, the process returns to step S4 again to decode the next audio data.

When the decoding process for one frame is completed, the same process as described above is performed for the next frame.

As described above, in the above embodiment, the external memory 17 provided externally is provided outside the audio decoder 11 of LSI, and all programs are stored in the external memory 17. Then, only the program actually used by the processor 13 is set in the internal memory 15. As a result, the capacity of the built-in memory can be reduced. Also, when adding a program, it is sufficient to increase the capacity of the external memory 17, there is no need to replace the LSI, and therefore the program can be easily added. Further, in the case of changing the version of the program or the like, it is only necessary to rewrite the external memory 17, and the change can be easily performed. A FLASH ROM may be used as the external memory 17. In this case, each program is downloaded to the external memory 17 at the time of factory shipment, and unlike the case of the RAM, downloading at power-on is not necessary. Rewriting of the external memory 17 is necessary only when changing or adding a program.

[0017]

As described above, according to the present invention, the control means for processing the input audio signal based on the processing program, and the processing program used in the control means, Built-in memory that stores the processing program corresponding to the signal,
The LSI includes an external memory in which all the processing programs used in the control means are stored, and the control means reads the processing program corresponding to the currently input audio signal from the external memory and sets it in the internal memory.
It is possible to reduce the memory capacity formed inside and to easily add a program.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an audio decoder according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the audio decoder.

FIG. 3 is a block diagram showing a configuration example of a conventional audio decoder.

[Explanation of symbols]

11 ... Audio decoder, 12 ... Input interface, 13 ... Processor, 14 ... Judgment circuit, 15 ... Internal memory, 17 ... External memory, 18 ... Host computer.

Claims (3)

[Claims] 1. An audio signal processing apparatus, comprising a plurality of processing programs, for processing an audio signal using the processing program corresponding to an input audio signal, wherein the processing of the input audio signal is performed. A control unit that is based on a program; a built-in memory that is a processing program used by the control unit and that stores a processing program corresponding to an input audio signal; and all processing programs that are used by the control unit. An audio signal processing device comprising: a stored external memory; and the control means reads out a processing program corresponding to the currently input audio signal from the external memory and sets the processing program in the internal memory. 2. The control means detects a processing program corresponding to the audio signal from the data added to the input audio signal, reads the program from the external memory, and sets the program in the built-in memory. The audio signal processing device according to claim 1. 3. The audio signal processing device according to claim 1, further comprising rewriting means for rewriting the external memory.