Decimator And Decimating Method For Multi-Channel Audio

Abstract

A decimator is used to process a multi-channel audio signal, and includes a memory, a controller and a processing unit. The processing unit is used to decimate each input audio component of a multi-channel audio signal to generate corresponding multi-channel operational data. The controller is used to control read and write actions for each audio component of the multi-channel audio signal and the multi-channel operational data into or from the memory. The memory provides a digital signal process for decimation together with the processing unit. The input of the multi-channel audio and the output of the multi-channel operational data are performed through time division. Compared with conventional decimator circuits, the decimator circuit of the present invention reduces the cost and the power consumption of the hardware circuitry.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described according to the appended drawings in which:

FIG. 1( a) is a spectrum distribution diagram of a BTSC television multi-track stereo audio;

FIG. 1( b) is a schematic block diagram of the BTSC television multi-track stereo audio for decimation;

FIG. 1( c) is a schematic circuit diagram of a second order FIR filter;

FIG. 1( d) is a spectrum distribution diagram of an EIA-J television multi-track stereo audio;

FIG. 1( e) is a schematic block diagram of the EIA-J television multi-track stereo audio for decimation;

FIG. 2 is a schematic circuit diagram of a decimator according to a first embodiment of the present invention;

FIG. 3 is a schematic block diagram of a decimating system according to a second embodiment of the present invention; and

FIG. 4 is a schematic block diagram of a decimating system according to a third embodiment of the present invention.

Claims

1. A decimator for a multi-channel audio, comprising: a processing unit for decimating each audio component of an inputted multi-channel audio and generating multi-channel operational data;a memory coupled to the processing unit for storing each audio component of the multi-channel audio and the multi-channel operational data; anda controller coupled to the memory for controlling the multi-channel audio and the multi-channel operational data to be written to and read from the memory, and for processing the input of the multi-channel audio and the output of the multi-channel operational data through time division.

2. The decimator of claim 1, wherein the memory is a random access memory (RAM).

3. The decimator of claim 1, wherein the controller outputs a read/write control signal to the memory to indicate whether the multi-channel audio is written or the multi-channel operational data are read by the memory.

4. The decimator of claim 3, wherein the controller outputs an address bus signal to the memory so as to determine the writing or reading address of the memory.

5. The decimator of claim 1, further comprising a multiplex connected to an input port of the memory for selecting one of the audio components of the multi-channel audio written into the memory.

6. The decimator of claim 5, wherein the controller outputs a multiplex control signal to the multiplex for controlling the multiplex to select one of the audio components of the multi-channel audio.

7. The decimator of claim 1, further comprising a demultiplex connected to an output port of the memory for selecting the multi-channel operational data read from the memory.

8. The decimator of claim 7, wherein the controller outputs a demultiplex control signal to the demultiplex for controlling the demultiplex to select the multi-channel operational data.

9. The decimator of claim 1, wherein the controller controls and performs the steps of: writing each audio component of the inputted multi-channel audio into the memory through time division;reading each audio component of the multi-channel audio to the processing unit;decimating and generating multi-channel operational data from the processing unit;writing the multi-channel operational data into the memory; andreading and outputting the multi-channel operational data through time division.

10. The decimator of claim 1, wherein the each component of the inputted multi-channel audio is low-pass filtered in a frequency domain for decimation, and then the sampling frequency of the each component is reduced in a time domain.

11. The decimator of claim 10, wherein the low pass filtering is achieved by a finite impulse response (FIR) filter.

12. The decimator of claim 11, wherein the FIR filter comprises a time delayer implemented as a memory cell of the memory.

13. The decimator of claim 1, wherein the inputted multi-channel audio is a television multi-track stereo audio (MTS).

14. The decimator of claim 13, wherein the television multi-track stereo audio comprises a single-track signal, a stereo difference signal, a second audio program in-phase (SAP_I) signal, and a second audio program quadrature phase (SAP_Q) signal.

15. The decimator of claim 13, wherein the television multi-track stereo audio comprises signals with baseband signals as a main portion after being mixed and decimated.

16. The decimator of claim 14, wherein at least one of the multi-channel operational data is output to a frequency discriminator for frequency modulation (FM) demodulation.

17. The decimator of claim 16, wherein the frequency discriminator comprises an FIR filter and an FM demodulator, and the FIR filter comprises a time delayer implemented by a memory cell of the memory.

18. The decimator of claim 17, wherein at least one of the multi-channel operational data is first low-pass filtered by the FIR filter and then FM demodulated by the FM demodulator.

19. The decimator of claim 16, wherein at least one of the multi-channel operational data comprises the second audio program in-phase (SAP_I) signal and the second audio program quadrature phase (SAP_Q) signal.

20. The decimator of claim 16, wherein at least one of the multi-channel operational data comprises a stereo difference in-phase (L−RI) signal and a stereo difference quadrature phase (L−R_Q) signal.

21. A decimating method for a multi-channel audio, comprising: writing each audio component of a multi-channel audio into a memory;reading each audio component of the multi-channel audio;performing decimation to generate corresponding multi-channel operational data;writing the multi-channel operational data into the memory; andreading and outputting the multi-channel operational data.

22. The decimating method of claim 21, wherein the multi-channel audio is inputted into the memory through time division.

23. The decimating method of claim 21, wherein the multi-channel operational data are outputted through time division.

24. The decimating method of claim 21, wherein the each component of the inputted multi-channel audio is low-pass filtered in a frequency domain for decimation, and then the sampling frequency of the each component is reduced in a time domain.

25. The decimating method of claim 21, wherein the multi-channel audio is a television multi-track stereo (MTS) audio comprising a single-track signal, a stereo difference signal, a second audio program in-phase (SAP_I) signal, and a second audio program quadrature phase (SAP_Q) signal.

26. The decimating method as claimed in claim 21, further comprising performing a time delay of at least one sampling unit on the single-track signal, wherein the time delay equals the time required for further FM demodulation of the stereo difference signal.

27. The decimating method of claim 26, wherein the time difference between the single-track signal and the stereo difference signal exists as a predetermined value when the both signals are received, and the time delay equals the time required for FM demodulation plus the time difference.

28. The decimating method of claim 27, wherein the predetermined value for the time difference is 20 microseconds.