Robust decoder

• US 7,590,531 B2
• Filed: 08/04/2005
• Issued: 09/15/2009
• Est. Priority Date: 05/31/2005
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Sun, Xiaoqin, Khalil, Hosam A., Chen, Wei-Ge, Koishida, Kazuhito, Wang, Tian
• Primary Examiner(s): Vo; Huyen X.
• Application Number:
  US11/197,792
• Publication Number:
  US 20060271359A1
• Time in Patent Office: 1,503 Days
• Field of Search: 704/267, 704/228, 704/229, 704/270, 704/201, 704/202, 704/206, 704/210, 704/219, 704/222, 704/223, 704/221, 704/226, 704/200, 704/500, 704/501, 704/503, 704/504, 704/207, 370/230.1
• US Class Current: 704/228
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm
• CPC Class Codes: G10L 21/045 using thinning out or insertion of a waveform

Abstract

Techniques and tools related to delayed or lost coded audio information are described. For example, a concealment technique for one or more missing frames is selected based on one or more factors that include a classification of each of one or more available frames near the one or more missing frames. As another example, information from a concealment signal is used to produce substitute information that is relied on in decoding a subsequent frame. As yet another example, a data structure having nodes corresponding to received packet delays is used to determine a desired decoder packet delay value.

Claims

1. A method comprising:

at an audio decoder, processing a bit stream for an audio signal, including, when encountering one or more missing frames from the bit stream, then;

identifying one of plural available segments from an available frame;

for the identified available segment of the plural available segments,

time-extending the identified available segment,

using one or more characteristics of the time-extended identified available segment to adapt a linear prediction coefficient filter in generating noise, and

superimposing the generated noise to onto the time-extended available segment to create a derived segment; and

forming a merged signal using the plural available segments and the derived segment.

2. The method of claim 1, wherein the one or more characteristics comprise energy of the identified available segment.

3. The method of claim 1, wherein the plural available segments comprise more than two available segments.

4. The method of claim 1, wherein the processing further comprises using the merged signal in place of the available frame and the one or more missing frames.

5. The method of claim 1, wherein the using one or more characteristics of the identified available segment to adapt a linear prediction coefficient filter in generating noise comprises:

passing random noise through the adapted linear prediction coefficient filter to produce the generated noise.

6. A method comprising:

at an audio decoder, processing a bit stream for an audio signal, including, when encountering one or more missing frames from the bit stream, then;

identifying plural available segments by breaking an available frame into the plural available segments;

for at least one of the plural available segments, using one or more characteristics of an available segment to adapt a linear prediction coefficient filter in generating a derived segment by analyzing the available segment to obtain linear prediction coefficients, passing random noise through a linear prediction coefficient filter which is configured according to the obtained coefficients to obtain generated noise, and generating the derived segment by superimposing the generated noise and the available segment; and

forming a merged signal by merging the plural derived segments between plural available segments.

7. The method of claim 6, wherein the available frame is an unvoiced frame.

8. The method of claim 7, wherein the one or more characteristics comprise energy of the available segment.

9. The method of claim 6, wherein the plural available segments include first and second available segments, wherein the plural derived segments include first and second derived segments, and wherein forming the merged signal comprises:

merging the first available segment with the first derived segment;

merging the first derived segment with the second derived segment; and

merging the second derived segment with the second available segment.

10. The method of claim 6, wherein the plural available segments comprise more than two available segments.

11. The method of claim 6, wherein the plural derived segments comprise more than two derived segments.

12. The method of claim 6, wherein the processing further comprises using the merged signal in place of the available frame and the one or more missing frames.

13. An audio decoder configured to process a bit stream for an audio signal and handle one or more missing frames from the bit stream, the decoder including:

means for identifying plural available segments from an available frame;

means for classifying one or more of the plural available segments as voiced or unvoiced;

means for, for each of the plural available segments, using one or more characteristics of the available segment to adapt a linear prediction coefficient filter in generating a derived segment, wherein the generating the derived segment changes depending on whether the classification of the one or more plural available segments is voiced or unvoiced, wherein the using one or more characteristics of the available segment to adapt a linear prediction coefficient filter in generating a derived segment comprises;

passing random noise through a linear prediction coefficient filter adapted to the available segment, and

superimposing the filtered noise onto an extension segment to generate the derived segment; and

means for forming a merged signal using the plural available segments and plural derived segments.

14. The decoder of claim 13, wherein the available frame is an unvoiced frame.

15. The decoder of claim 14, wherein the one or more characteristics comprise energy of the available segment.

16. The decoder of claim 13, wherein the plural available segments include first and second available segments, wherein the plural derived segments include first and second derived segments, and wherein forming the merged signal comprises:

merging the first available segment with the first derived segment;

merging the first derived segment with the second derived segment; and

merging the second derived segment with the second available segment.

17. The decoder of claim 13, wherein the plural available segments comprise more than two available segments.

18. The decoder of claim 13, wherein the plural derived segments comprise more than two derived segments.

19. The decoder of claim 13, further comprising means for using the merged signal in place of the available frame and the one or more missing frames.