Update of post-processing states with variable sampling frequency according to the frame

Patent metadata

Field	Value
Publication number	US-10424313-B2
Application number	US-201515325643-A
Country	US
Kind code	B2
Filing date	Jul 6, 2015
Priority date	Jul 11, 2014
Publication date	Sep 24, 2019
Grant date	Sep 24, 2019

Abstract

A method and apparatus are provided for updating post-processing states applied to a decoded audio signal. The method is such that, for a current decoded signal frame, sampled at a different sampling frequency from the preceding frame, it includes the following acts: obtaining a past decoded signal, stored for the preceding frame; re-sampling by interpolation of the past decoded signal obtained; using the re-sampled past decoded signal as a memory for post-processing the current frame. A decoding method is also provided, which includes updating post-processing states.

First claim

The invention claimed is:

1. A method comprising the following acts performed by a decoding device for an audio frequency signal:
storing a past decoded signal frame in a memory, the past decoded signal frame being decoded from a preceding frame of the audio frequency signal at a first sampling frequency;
receiving a current decoded signal frame, the current decoded signal frame being decoded from a current frame of the audio frequency signal at a second sampling frequency, which is different from the first sampling frequency;
updating post-processing states applied to the current decoded signal frame, the updating comprising:
obtaining the past decoded signal frame, stored for the preceding frame;
resampling the past decoded signal frame obtained, at the second sampling frequency of the current decoded signal frame, by interpolation; and
using the resampled past decoded signal frame as a memory for post-processing the current decoded signal frame.

2. The method as claimed in claim 1 , wherein, in a case where the first sampling frequency of the preceding frame is higher than the second sampling frequency of the current frame, the interpolation is performed starting from a most recent sample of the past decoded signal frame and by interpolating in reverse chronological order and in a case where the first sampling frequency of the preceding frame is lower than the second sampling frequency of the current frame, the interpolation is performed starting from an oldest sample of the past decoded signal frame and by interpolating in chronological order.

3. The method as claimed in claim 1 , wherein the resampled past decoded signal frame is stored in a same buffer memory as the past decoded signal frame before resampling.

4. The method as claimed in claim 1 , wherein the interpolation is of a linear type.

5. The method as claimed in claim 1 , wherein the past decoded signal frame is of fixed length according to a maximum possible speech signal period.

6. The method as claimed in claim 1 , wherein the post-processing is applied to the current decoded signal frame on a low frequency band for reducing low-frequency noise.

7. The method as claimed in claim 1 , further comprising:
selecting the second sampling frequency for decoding the current frame;
decoding the current frame of the audio frequency signal at the second sampling frequency to obtain the current decoded signal frame; and
then performing the act of updating the post-processing.

8. A device for processing a decoded audio frequency signal, wherein the device comprises:
a non-transitory computer-readable medium comprising instructions stored thereon; and
a processor configured by the instructions to perform acts comprising:
storing a past decoded signal frame in a memory, the past decoded signal frame being decoded from a preceding frame of an audio frequency signal at a first sampling frequency;
receiving a current decoded signal frame, the current decoded signal frame being decoded from a current frame of the audio frequency signal at a second sampling frequency, which is different from the first sampling frequency;
updating post-processing states applied to the current decoded signal frame, the updating comprising:
obtaining the past decoded signal frame, stored for the preceding frame;
resampling the past decoded signal frame obtained, at the second sampling frequency of the current decoded signal frame, by interpolation; and
using the resampled past decoded signal frame as a memory for post-processing the current decoded signal frame.

9. The device as claimed in claim 8 , wherein the device is an audio frequency signal decoder and further comprises a module, which selects a decoding sampling frequency.

10. A non-transitory computer-readable storage medium on which a computer program is stored including code instructions for execution of a method when the instructions are executed by a processor of a decoding device, wherein the instructions configure the decoding device to perform acts comprising:
storing a past decoded signal frame in a memory, the past decoded signal frame being decoded from a preceding frame of an audio frequency signal at a first sampling frequency;
receiving a current decoded signal frame, the current decoded signal frame being decoded from a current frame of the audio frequency signal at a second sampling frequency, which is different from the first sampling frequency;
updating post-processing states applied to the current decoded signal frame, the updating comprising:
obtaining the past decoded signal frame, stored for the preceding frame;
resampling the past decoded signal frame obtained, at the second sampling frequency of the current decoded signal frame, by interpolation; and
using the resampled past decoded signal frame as a memory for post-processing the current decoded signal frame.

Assignees

• Orange

Inventors

• Daniel Jerome
• Kovesi Balazs

Classifications

• G10L19/18

  Vocoders using multiple modes · CPC title

• G10L19/26 Primary

  Pre-filtering or post-filtering · CPC title

• G10L19/12

  the excitation function being a code excitation, e.g. in code excited linear prediction [CELP] vocoders · CPC title

• G10L19/24 Primary

  Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding · CPC title