SYSTEMS AND METHODS FOR MODIFYING A WINDOW WITH A FRAME ASSOCIATED WITH AN AUDIO SIGNAL

• US 20080027719A1
• Filed: 02/14/2007
• Published: 01/31/2008
• Est. Priority Date: 07/31/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Kirshnan, Venkatesh, Kandhadai, Ananthapadmanabhan A.
• Granted Patent: US 7,987,089 B2
• Time in Patent Office: Days
• US Class Current: 704/214
• CPC Class Codes: G10L 19/0212 using orthogonal transformation
• CPC Class Codes: G10L 19/20 using sound class specific coding, hybrid encoders or object based coding

Abstract

A method for modifying a window with a frame associated with an audio signal is described. A signal is received. The signal is partitioned into a plurality of frames. A determination is made if a frame within the plurality of frames is associated with a non-speech signal. A modified discrete cosine transform (MDCT) window function is applied to the frame to generate a first zero pad region and a second zero pad region if it was determined that the frame is associated with a non-speech signal. The frame is encoded. The decoder window is the same as the encoder window.

Claims

1. A method for modifying a window with a frame associated with an audio signal, the method comprising:

receiving a signal;

partitioning the signal into a plurality of frames;

determining if a frame within the plurality of frames is associated with a non-speech signal;

applying a modified discrete cosine transform (MDCT) window function to the frame to generate a first zero pad region and a second zero pad region if it was determined that the frame is associated with a non-speech signal; and

encoding the frame.

2. The method of claim 1, wherein the frame is encoded using an MDCT coding based scheme.

3. The method of claim 1, wherein the frame comprises a length of 2M, wherein M represents a number of samples in the frame.

4. The method of claim 1, wherein the first zero pad region is located at the beginning of the frame.

5. The method of claim 1, wherein the second zero pad region is located at the end of the frame.

6. The method of claim 1, wherein the first zero pad region and the second region comprise a length of (M−

L)/2, wherein L is a value that is less than or equal to M, and wherein M is a number of samples in the frame.

9. The method of claim 1, further comprising providing a look-ahead region of length L, wherein L is less than or equal to M, and wherein M is a number of samples in the frame.

10. The method of claim 9, wherein the look-ahead region of length L overlaps a future overlap region associated with a future frame.

11. The method of claim 1, wherein the first zero pad region and the present overlap region overlap a previous frame by 50%.

12. The method of claim 1, wherein the second zero pad region and the look-ahead region overlap a future frame by 50%.

13. The method of claim 1, wherein a sum of each sample of the frame added with an associated sample from an overlapped frame equals unity.

7. The method of claim 7, further comprising providing a present overlap region of length L.

8. The method of claim 7, wherein the overlap region of length L overlaps and is added with look-ahead samples associated with a previous frame.

14. An apparatus for modifying a window with a frame associated with an audio signal comprising:

a processor;

memory in electronic communication with the processor;

instructions stored in the memory, the instructions being executable to;

receive a signal;

partition the signal into a plurality of frames;

determine if a frame within the plurality of frames is associated with a non-speech signal;

apply a modified discrete cosine transform (MDCT) window function to the frame to generate a first zero pad region and a second zero pad region if it was determined that the frame is associated with a non-speech signal; and

encode the frame.

15. The apparatus of claim 14, wherein the frame is encoded using an MDCT coding based scheme.

16. The apparatus of claim 14, wherein the frame comprises a length of samples equal to 2M, wherein M represents a number of samples in the frame.

17. The apparatus of claim 14, wherein the first zero pad region is located at the beginning of the frame.

18. The apparatus of claim 14, wherein the second zero pad region is located at the end of the frame.

19. A system that is configured to modify a window with a frame associated with an audio signal comprising:

means for processing;

means for receiving a signal;

means for partitioning the signal into a plurality of frames;

means for determining if a frame within the plurality of frames is associated with a non-speech signal;

means for applying a modified discrete cosine transform (MDCT) window function to the frame to generate a first zero pad region and a second zero pad region if it was determined that the frame is associated with a non-speech signal; and

means for encoding the frame.

20. A computer-readable medium configured to store a set of instructions executable to:

receive a signal;

partition the signal into a plurality of frames;

determine if a frame within the plurality of frames is associated with a non-speech signal;

apply a modified discrete cosine transform (MDCT) window function to the frame to generate a first zero pad region and a second zero pad region if it was determined that the frame is associated with a non-speech signal; and

encode the frame.

21. A method for selecting a window function to be used in calculating a modified discrete cosine transform (MDCT) of a frame, the method comprising:

providing an algorithm for selecting a window function to be used in calculating an MDCT of a frame;

applying the selected window function to the frame; and

encoding the frame with an MDCT coding mode based on constraints imposed on the MDCT coding mode by additional coding modes, wherein the constraints comprise a length of the frame, a look ahead length and a delay.

22. A method for reconstructing an encoded frame of an audio signal, the method comprising:

receiving a packet;

disassembling the packet to retrieve an encoded frame;

synthesizing samples of the frame that are located between a first zero pad region and a first region;

adding an overlap region of a first length with a look-ahead length of a previous frame;

storing a look-ahead of the first length of the frame; and

outputting a reconstructed frame.