Coding with improved time resolution for selected segments via adaptive block transformation of a group of samples from a subband decomposition

• US 7,546,240 B2
• Filed: 07/15/2005
• Issued: 06/09/2009
• Est. Priority Date: 07/15/2005
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Chen, Wei-Ge, Mehrotra, Sanjeev, Malvar, Henrique Sarmento
• Primary Examiner(s): ABEBE, DANIEL DEMELASH
• Application Number:
  US11/183,271
• Publication Number:
  US 20070016405A1
• Time in Patent Office: 1,425 Days
• Field of Search: 704/203, 704/204, 704/205, 704/226, 704/230, 704/254, 704/258, 704/500, 704/501, 704/503, 704/E19.011, 704/E19.012, 704/E19.014, 704/E19.02
• US Class Current: 704/230
• CPC Class Codes: G10L 19/0212 using orthogonal transformation
• CPC Class Codes: G10L 19/025 Detection of transients or attacks for time/frequency resolution switching

Abstract

A transform coder is described that performs a time-split transform in addition to a discrete cosine type transform. A time-split transform is selectively performed based on characteristics of media data. Transient detection identifies a changing signal characteristic, such as a transient in media data. After encoding an input signal from a time domain to a transform domain, a time-splitting transformer selectively perform an orthogonal sum-difference transform on adjacent coefficients indicated by a changing signal characteristic location. The orthogonal sum-difference transform on adjacent coefficients results in transforming a vector of coefficients in the transform domain as if they were multiplied by an identity matrix including at least one 2×2 time-split block along a diagonal of the matrix. A decoder performs an inverse of the described transforms.

Claims

1. A computer-implemented method of decoding audio information, the method comprising:

receiving side information and frequency coefficient data in a transform domain;

performing an inverse time-split transform on adjacent frequency coefficients in the frequency coefficient data as indicated in the received side information, wherein the inverse time-split transform comprises an inverse of a selectively-applied sum and difference orthogonal transform performed on the adjacent frequency coefficients that changes time resolution for a portion of the frequency coefficient data; and

performing an inverse transform on the received frequency coefficient data comprising transforming the coefficient data from the transform domain to a time domain.

2. The method of claim 1 further comprising:

identifying sub-frame sizes in the received side information;

wherein the inverse transform is performed according to the identified sub-frame sizes.

3. The method of claim 1 further comprising:

determining from the received side information whether there is a time-split in a sub-band.

4. The method of claim 1 further comprising:

determining from the received side information whether or not there is a time-split in each sub-band in an extended band.

5. The method of claim 1 further comprising:

prior to the performing the inverse time-split transform, performing the selectively-applied sum and difference orthogonal transform.

6. The method of claim 1 wherein the selectively-applied sum and difference orthogonal transform is performed in response to a detected changing signal characteristic.

7. The method of claim 6 wherein the adjacent frequency coefficients correspond to a location of the detected changing signal characteristic.

8. The method of claim 1 further comprising:

transforming coefficient data according to window and sub-band size information in the received side information.

9. The method of claim 1 wherein the adjacent frequency coefficients comprise at least one pair of adjacent coefficients in a vector X in the transform domain, where there are M coefficients in vector X that are uniquely identified as X[k] with k an integer ranging from 0 to M−

1, so that the pair of adjacent coefficients is of the form {X[2r], X[2r+1]}, where r is an integer.

10. The method of claim 1 wherein the side information comprises information indicating whether or not there is a time-split in an extended band.

11. A computer-implemented method of processing audio information, the method comprising:

receiving an input audio information stream comprising audio coefficient data in a frequency domain and time-split information corresponding to at least a first portion of the audio coefficient data;

performing a time-split transform on adjacent frequency coefficients in the first portion of the audio coefficient data based at least in part on the time-split information, wherein the time-split transform comprises a selectively applied sum and difference orthogonal transform that changes time resolution for the first portion of the audio coefficient data; and

performing an inverse of the time-split transform on the first portion of the audio coefficient data.

12. The method of claim 11 further comprising:

transforming the audio coefficient data from the frequency domain to a time domain.

13. The method of claim 11 wherein the time-split information comprises a signal in the input audio information stream that instructs a decoder to perform time-split transform processing.

14. The method of claim 13 wherein the signal is a single bit.

15. A computer-implemented method of processing audio information, the method comprising:

receiving an input audio information stream comprising audio coefficient data in a frequency domain corresponding to at least a first portion of audio coefficient data comprising plural frequency bands;

performing a time-split transform on adjacent frequency coefficients in a first frequency band in the first portion of the audio coefficient data, wherein the time-split transform comprises a selectively-applied sum and difference orthogonal transform that changes time resolution for the first frequency band in the first portion of the audio coefficient data while leaving time resolution unchanged for one or more other frequency bands; and

performing an inverse of the time-split transform on the first portion of the audio coefficient data.

16. The method of claim 15 wherein the selectively-applied sum and difference orthogonal transform is performed in response to a detected changing signal characteristic.

17. The method of claim 15 wherein the adjacent frequency coefficients correspond to a location of a detected changing signal characteristic.

18. The method of claim 15 further comprising:

transforming the audio coefficient data from the frequency domain to a time domain.

19. The method of claim 15 wherein the performing the time-split transform on adjacent frequency coefficients is responsive to a signal in the input audio information stream that instructs a decoder to perform time-split transform processing.

20. The method of claim 19 wherein the signal is a single bit.