Method for independent dynamic range control

• US 6,782,366 B1
• Filed: 05/15/2000
• Issued: 08/24/2004
• Est. Priority Date: 05/15/2000
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: LSI Logic Corporation (Broadcom, Inc.)
• Inventors: Huang, Wen, Lau, Winnie K. W., Mullane, Brendan J.
• Primary Examiner(s): Harvey, Minsun Oh
• Assistant Examiner(s): Faulk, Devona E
• Application Number:
  US09/571,691
• Time in Patent Office: 1,562 Days
• Field of Search: 704/230, 704/500, 704/224, 704/200.1, 704/501
• US Class Current: 704/500
• CPC Class Codes: G10L 19/008 Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing
• CPC Class Codes: H03G 7/007 of digital or coded signals

Abstract

Different dynamic range control values are applied to the 2-channel and m-channel outputs without repeating the inverse transform of the audio samples. First, m-channel dynamic range control values are applied to audio samples in the frequency domain (“frequency samples” or “frequency coefficients”). The frequency samples are then inverse transformed to generate audio samples in the time domain (“time samples”). The time samples are duplicated to two sets where the 2-channel dynamic range control values are applied to one set of time samples. 2-channel dynamic range control values include 2-channel final scales that, when multiplied with the first set of time samples, at least partially remove the effects of the m-channel dynamic range control and readjust the dynamic range for 2-channel output. The first set and the second set are then windowed. Thus, independent dynamic range control for the m-channel output and the 2-channel output are achieved without repeating the inverse transform, which is computational and/or memory intensive.

Claims

1. A method for controlling the dynamic range of audio samples, comprising:

determining a first or dynamic range final scale;

determining a second dynamic range final scale;

multiplying frequency samples with first second dynamic range final scale;

inverse transforming the multiplied frequency samples to time samples;

windowing the time samples to form windowed samples, said windowing comprising;

2. The method of claim 1, wherein the determining the second dynamic range final scale comprises:

determining a third dynamic range final scale;

inverting the first dynamic range final scale; and

multiplying the third dynamic range final scale with the inverted first dynamic range final scale to form the second dynamic range final scale.

3. The method of claim 1, further comprising outputting the downmixed samples.

4. A method for controlling the dynamic range of audio samples, comprising:

applying a first dynamic range control to a frequency sample to form a m-channel frequency sample;

inverse transforming the m-channel frequency sample to a m-channel time sample;

applying a second dynamic range control to the m-channel time sample to form a 2-channel time sample; and

windowing the 2-channel time sample to form a 2-channel windowed sample.

5. The method of claim 4, wherein the applying the first dynamic range control comprises:

determining a first dynamic range final scale; and

multiplying the frequency sample with the first dynamic range final scale.

6. The method of claim 5, wherein the applying the second dynamic range comprises:

determining a second dynamic range final scale;

inverting the first dynamic range final scale;

multiplying the second dynamic range final scale with the inverted first dynamic range final scale to form a third dynamic range final scale; and

multiplying the third dynamic range final scale with the m-channel time sample.

7. The method of claim 4, wherein the applying the second dynamic range control and windowing are combined as follows:

8. The method of claim 4, further comprising downmixing the 2-channel windowed samples to form 2-channel downmixed samples.

9. The method of claim 8, further comprising outputting the 2-channel downmixed samples.

10. The method of claim 4, further comprising windowing the m-channel time sample to form a m-channel windowed sample.

11. The method of claim 10, further comprising outputting the m-channel windowed sample.

12. A computer-readable medium carrying a program for controlling the dynamic range of audio samples comprising:

a first instruction to determine a first dynamic range final scale;

a second instruction to determine a second dynamic range final scale;

a third instruction to multiply frequency samples with first or second dynamic range final scale;

a fourth instruction to inverse transform the multiplied frequency samples to time samples;

a fifth instruction to window the time samples to form windowed samples, said windowing comprising;

 

window_time_sample=(time_sample_preblk*2ch_final_scale_preblk*window_coeff1+time_sample_currblk*2ch_final_scale_currblk*window_coeff2)*2; and

wherein window_time_sample is the windowed samples, time_sample_currblk is the time samples of the current block, parameter 2ch_final_scale_currblk is the second dynamic range final scale of the current block, time_sample_preblk is the windowed time samples from the previously block and 2ch_final_scale_preblk is the second dynamic range final scale from the previously block; and

a sixth instruction to downmix the windowed samples from the channels of input to the channels of output to form downmixed samples.

13. The medium of claim 12, wherein said second instruction further comprises:

a seventh instruction to determine a third dynamic range final scale;

an eighth instruction to invert the first dynamic range final scale; and

a ninth instruction to multiply the third dynamic range final scale with the inverted first dynamic range compression control to form the second dynamic range final scale.

14. The medium of claim 12, further comprising a seventh instruction to output the downmixed samples.

15. A computer-readable medium carrying a program for controlling the dynamic range of audio samples comprising:

a first instruction to apply a first dynamic range control to a frequency sample to form a m-channel frequency sample;

a second instruction to inverse transform the m-channel frequency sample to a m-channel time sample; and

a third instruction to apply a second dynamic range control to the m-channel time sample to forma 2-channel time sample; and

a fourth instruction to window the 2-channel time sample to form a 2-channel windowed sample.

16. The medium of claim 15, wherein the first instruction comprises:

a fifth instruction to determine a first dynamic range final scale; and

a sixth instruction to multiply the frequency sample with the first dynamic range final scale to form the m-channel frequency sample.

17. The medium of claim 16, wherein the third instruction comprises:

a seventh instruction to determine a second dynamic range final scale;

an eighth instruction to invert the first dynamic range final scale;

a ninth instruction to multiply the second dynamic range final scale with the inverted first dynamic range final scale to form a third dynamic range final scale; and

a tenth instruction to multiply the third dynamic range final scale with the m-channel time sample.

18. The medium of claim 15, wherein the third instruction and the fourth instruction are combined to comprises a fifth instruction of:

19. The medium of claim 15, further comprising a fifth instruction to downmix the 2-channel windowed samples to form 2-channel downmixed samples.

20. The medium of claim 19, further comprising a sixth instruction to output the 2-channel downmixed samples.

21. The medium of claim 15, further comprising a fifth instruction to window the m-channel time samples to form m-channel windowed samples.

22. The medium of claim 21, further comprising a sixth instruction to output the m-channel windowed samples.