Coding and decoding scale factor information

• US 20070016427A1
• Filed: 07/15/2005
• Published: 01/18/2007
• Est. Priority Date: 07/15/2005
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Thumpudi, Naveen, Chen, Wei-Ge, He, Chao
• Granted Patent: US 7,539,612 B2
• Time in Patent Office: Days
• US Class Current: 704/500
• CPC Class Codes: G10L 19/035 Scalar quantisation
• CPC Class Codes: G10L 19/06 Determination or coding of the spectral characteristics, e.g. of the short-term prediction coefficients

Abstract

Techniques and tools for representing, coding, and decoding scale factor information are described herein. For example, during encoding of scale factors, an encoder uses one or more of flexible scale factor resolution selection, spatial prediction of scale factors, flexible prediction of scale factors, smoothing of noisy scale factor amplitudes, reordering of scale factor prediction residuals, and prediction of scale factor prediction residuals. Or, during decoding, a decoder uses one or more of flexible scale factor resolution selection, spatial prediction of scale factors, flexible prediction of scale factors, reordering of scale factor prediction residuals, and prediction of scale factor prediction residuals.

Claims

1. A method comprising:

selecting a scale factor prediction mode from plural scale factor prediction modes, wherein each of the plural scale factor prediction modes is available for processing a particular mask; and

performing scale factor prediction according to the selected scale factor prediction mode.

2. The method of claim 1 wherein the selecting occurs on a mask-by-mask basis.

3. The method of claim 1 wherein the plural scale factor prediction modes include two or more of a temporal scale factor prediction mode, a spectral scale factor prediction mode, a spatial or other cross-channel scale factor prediction mode, and a cross-layer scale factor prediction mode.

4. The method of claim 1 wherein each of the plural scale factor prediction modes predicts a current scale factor from a prediction, and wherein the prediction is a previous scale factor.

5. The method of claim 1 wherein the particular mask is for a sub-frame, and wherein an encoder performs the selecting based at least in part upon position of the sub-frame in a frame of multi-channel audio.

6. The method of claim 1 wherein an encoder performs the selecting and the scale factor prediction, the method further comprising:

signaling, in a bit stream, information indicating selected scale factor prediction mode;

computing difference values between scale factors for the particular mask and results of the scale factor prediction; and

entropy coding the difference values.

7. The method of claim 1 wherein a decoder performs the selecting and the scale factor prediction, the method further comprising:

parsing, from a bit stream, information indicating the selected scale factor prediction mode;

entropy decoding difference values; and

combining the difference values with results of the scale factor prediction.

8. The method of claim 1 wherein the selected scale factor prediction mode is a temporal scale factor prediction mode or a spatial scale factor prediction mode, the method further comprising performing second scale factor prediction according to a spectral scale factor prediction mode.

9. The method of claim 1 wherein the selected scale factor prediction mode is a spectral scale factor prediction mode, the method further comprising reordering difference values prior to entropy coding or after entropy decoding.

10. The method of claim 1 wherein the selected scale factor prediction mode is a cross-channel scale factor prediction mode, and wherein the scale factor prediction includes predicting a current scale factor from a previous scale factor from another channel.

11. A method comprising:

selecting a scale factor spectral resolution from plural scale factor spectral resolutions, wherein the plural scale factor spectral resolutions include plural sub-critical band resolutions; and

processing spectral coefficients with scale factors at the selected scale factor spectral resolution.

12. The method of claim 11 wherein the plural scale factor spectral resolutions further include a critical band resolution and a super-critical band resolution.

13. The method of claim 11 wherein an encoder performs the selecting and the processing, the method further comprising signaling, in a bit stream, information indicating the selected scale factor spectral resolution.

14. The method of claim 11 wherein a decoder performs the selecting and the processing, the method further comprising parsing, from a bit stream, information indicating the selected scale factor resolution, wherein the decoder performs the selecting based at least in part on the parsed information.

15. The method of claim 11 wherein the selecting occurs for a frame that includes the spectral coefficients.

16. A method comprising:

selecting a scale factor spectral resolution from plural scale factor spectral resolutions, wherein each of the plural scale factor spectral resolutions is available for processing a particular sub-frame of spectral coefficients; and

processing spectral coefficients including the particular sub-frame of spectral coefficients with scale factors at the selected scale factor spectral resolution.

17. The method of claim 16 wherein an encoder performs the selecting based at least in part on criteria including one or more of bit rate and quality, and wherein the processing includes weighting according to the scale factors.

18. The method of claim 16 further comprising signaling, in a bit stream, information indicating the selected scale factor resolution.

19. The method of claim 16 further comprising parsing, from a bit stream, information indicating the selected scale factor resolution, wherein a decoder performs the selecting based at least in part on the parsed information, and wherein the processing includes inverse weighting according to the scale factors.

20. The method of claim 16 wherein the selecting occurs on a frame-by-frame basis.