System and method for low power stereo perceptual audio coding using adaptive masking threshold

• US 8,332,216 B2
• Filed: 08/22/2006
• Issued: 12/11/2012
• Est. Priority Date: 01/12/2006
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Asia Pacific Pte Limited (STMicroelectronics NV)
• Inventors: Kurniawati, Evelyn, George, Sapna
• Primary Examiner(s): Shah, Paras D
• Assistant Examiner(s): KOVACEK, DAVID M
• Application Number:
  US11/507,678
• Publication Number:
  US 20070162277A1
• Time in Patent Office: 2,303 Days
• Field of Search: 704200-201, 704205-211, 704226-230, 704500-504, 704E19001-E2102
• US Class Current: 704/229
• CPC Class Codes: G10L 19/02 using spectral analysis, e.g. transform vocoders or subband vocoders

Abstract

A method for stereo audio perceptual encoding of an input signal includes masking threshold estimation and bit allocation. The masking threshold estimation and bit allocation are performed once every two encoding processes. Another method for stereo audio perceptual encoding of an input signal includes performing a time-to-frequency transformation, performing a quantization, performing a bitstream formatting to produce an output stream, and performing a psychoacoustics analysis. The psychoacoustics analysis includes masking threshold estimation on a first of every two successive frames of the input signal.

Claims

1. A method for stereo audio perceptual encoding of an input signal, comprising:

performing a time-to-frequency transformation;

performing a quantization;

performing a bitstream formatting to produce an output stream;

performing a psychoacoustics analysis including masking threshold estimation for a first channel on a first of every two successive frames of the input signal; and

reusing the estimated masking threshold on each first frame for a second channel and, unless the input signal is a transient signal, for the first and second channels of the second of the respective two successive frames, wherein when the input signal is of a transient characteristics, the masking threshold is reused only across channels within each individual frame.

2. The method of claim 1, further comprising:

performing a bit allocation on the first of every two successive frames of the input signal; and

reusing the bit allocation either across channels or across frames.

3. The method of claim 2, wherein reusing the bit allocation either across channels or across frames is at least partially carried out with spectral hole patching.

4. The method of claim 1, further comprising:

performing a bit distribution between channels on the first of every two successive frames of the input signal; and

reusing the bit distribution across frames.

5. The method of claim 1, wherein, when the input signal is stationary, the masking threshold is reused both across channels within each frame and across frames within each two successive frames.

6. The method of claim 5, wherein a bit distribution across channels is reused when the masking threshold is reused across frames.

7. The method of claim 1, wherein a bit distribution across channels is set to an equal distribution when the masking threshold is reused across channels.

8. The method of claim 1, wherein the masking threshold is reused across channels or across frames according to one of seven possible pairs of window types used in a perceptual audio encoder, the seven possible pairs being:

long window;

long window,

long window;

start window,

start window;

short window,

short window;

short window,

short window;

stop window,

stop window;

start window, and

stop window;

long window.

9. The method of claim 1, wherein the estimated masking threshold is reused by copying distortion controlling quantization parameters.

10. The method of claim 1, further comprising spectral hole patching applied prior to copying the distortion controlling quantization parameters, the spectral hole, patching comprising linearly interpolating adjacent parameter values when an actual energy of a band is above the masking threshold.

11. The method of claim 1, wherein, when the input signal is stationary, the masking threshold is reused across both channels and frames of each two successive frames, and when the input signal is of a transient characteristic, the masking threshold is reused only across channels of each individual frame.

12. A method for stereo audio perceptual encoding of an input signal, comprising:

performing a time-to-frequency transformation;

performing a quantization;

performing a bitstream formatting to produce an output stream;

performing a psychoacoustics analysis including masking threshold estimation for a first channel on a first frame of the input signal;

when the input signal is stationary across the first frame and a second, next successive frame of the input signal, reusing the estimated masking threshold for a second channel of the first frame and for both first and second channels of the second frame; and

when the input signal is transient across the first and second frames,

reusing the estimated masking threshold for the second channel of the first frame, and

performing a psychoacoustics analysis including masking threshold estimation for the first channel on the second frame.

13. The method of claim 12, further comprising:

performing a bit allocation on the first frame of the input signal; and

when the input signal is stationary across the first and second frames, reusing the bit allocation across the first and second channels for both the first and second frames.

14. The method of claim 12, further comprising:

performing a bit distribution between channels on the first frame of the input signal; and

when the input signal is stationary across the first and second frames, reusing the bit distribution across the first and second frames.

15. The method of claim 14, wherein reusing the bit allocation is at least partially carried out with spectral hole patching.

16. The method of claim 12, wherein a bit distribution across the first and second channels is reused when the masking threshold is reused across the first and second frames.

17. The method of claim 12, wherein, when the input signal is transient across the first and second frames, the bit distribution across channels is set to an equal distribution.

18. The method of claim 12, wherein the masking threshold is reused according to one of seven possible pairs of window types used in a perceptual audio encoder, the seven possible pairs being:

long window;

long window,

long window;

start window,

start window;

short window,

short window;

short window,

short window;

stop window,

stop window;

start window, and

stop window;

long window.

19. The method of claim 12, wherein the estimated masking threshold is reused by copying distortion controlling quantization parameters.