ENCODER FOR AUDIO SIGNAL INCLUDING GENERIC AUDIO AND SPEECH FRAMES

• US 20110218797A1
• Filed: 07/27/2010
• Published: 09/08/2011
• Est. Priority Date: 03/05/2010
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Ashley, James P., Mittal, Udar, Gibbs, Jonathan A.
• Granted Patent: US 8,423,355 B2
• Time in Patent Office: Days
• US Class Current: 704/200
• CPC Class Codes: G10L 19/0212 using orthogonal transformation
• CPC Class Codes: G10L 19/12 the excitation function being a code excitation, e.g. in code excited linear prediction [CELP] vocoders
• CPC Class Codes: G10L 19/18 Vocoders using multiple modes
• CPC Class Codes: G10L 19/20 using sound class specific coding, hybrid encoders or object based coding

Abstract

A method for encoding audio frames by producing a first frame of coded audio samples by coding a first audio frame in a sequence of frames, producing at least a portion of a second frame of coded audio samples by coding at least a portion of a second audio frame in the sequence of frames, and producing parameters for generating audio gap filler samples, wherein the parameters are representative of either a weighted segment of the first frame of coded audio samples or a weighted segment of the portion of the second frame of coded audio samples.

Claims

1. A method for encoding audio frames, the method comprising:

producing, using a first coding method, a first frame of coded audio samples by coding a first audio frame in a sequence of frames;

producing, using a second coding method, at least a portion of a second frame of coded audio samples by coding at least a portion of a second audio frame in the sequence of frames; and

producing parameters for generating audio gap filler samples, wherein the parameters are representative of either a weighted segment of the first frame of coded audio samples or a weighted segment of the portion of the second frame of coded audio samples.

2. The method of claim 1, producing the parameters by selecting parameters that reduce distortion between the audio gap filler samples generated and a set of reference audio gap samples in the sequence of frames.

3. The method of claim 1, wherein an audio gap would be formed between the first frame of coded audio samples and the portion of the second frame of coded audio samples if the first frame of coded audio samples and the portion of the second frame of coded audio samples were combined,

the method further comprising

generating the audio gap filler samples based on the parameters,

forming a sequence including the audio gap filler samples and the portion of the second frame of coded audio samples,

wherein the audio gap filler samples fill the audio gap.

4. The method of claim 1, wherein

the weighted segment of the first frame of coded audio samples includes a first weighting parameter and a first index for the weighted segment of the first frame of coded audio samples, and

the weighted segment of the portion of the second frame of coded audio samples includes a second weighting parameter and a second index for the weighted segment of the portion of the second frame of coded audio samples.

5. The method of claim 4,

the first index specifying a first time offset from a reference audio gap sample in the sequence of frames to a corresponding sample in the first frame of coded audio samples, and

the second index specifying a second time offset from the reference audio gap sample to a corresponding sample in the portion of the second frame of coded audio samples.

6. The method of claim 4,

determining the first index based on a correlation between a segment of the first frame of coded audio samples and a segment of reference audio gap samples in the sequence of frames, and

determining the second index based on a correlation between a segment of the portion of the second frame of coded audio samples and the segment of reference audio gap samples.

7. The method of claim 1, producing the parameters for generating the audio gap filler samples, wherein the parameters are representative of both the weighted segment of the first frame of coded audio samples and the weighted segment of the portion of the second frame of coded audio samples.

8. The method of claim 7, wherein the parameters are based on an expression:

ŝ

_g=α

·

ŝ

_s(−

T₁)+β

·

ŝ

_a(T₂)

wherein α

is a first weighting factor of a segment of the first frame of coded audio samples ŝ

_s(−

T₁), β

is a second weighting factor for a segment of the portion of the second frame of coded audio samples ŝ

_a(T₂), and ŝ

_g is representative of the audio gap filler samples.

9. The method of claim 8, producing the parameters based on a distortion metric that is a function of a set of reference audio gap samples in the sequence of frames, wherein the distortion metric is a squared error distortion metric.

10. The method of claim 8, producing the parameters based on a distortion metric that is a function of a set of reference audio gap samples, wherein the distortion metric is based on an expression:

D=|s_g−

ŝ

_g|^T·

|s_g−

ŝ

_g|

where s_g is representative of the set of reference audio gap samples.

11. The method of claim 8 further comprising receiving the sequence of frames wherein the first frame is adjacent the second frame and the first frame precedes the second frame, and wherein the portion of the second frame of coded audio samples is produced using a generic audio coding method and the first frame of coded audio samples is produced using a speech coding method.

12. The method of claim 1, producing the parameters based on a distortion metric that is a function of a set of reference audio gap samples.

13. The method of claim 1, producing the portion of the second frame of coded audio samples using a generic audio coding method.

14. The method of claim 13, producing the first frame of coded audio samples using a speech coding method.

15. The method of claim 1 further comprising receiving the sequence of frames wherein the first frame is adjacent the second frame and the first frame precedes the second frame.