Resampling of an audio signal interrupted with a variable sampling frequency according to the frame

Patent metadata

Field	Value
Publication number	US-9940943-B2
Application number	US-201415106684-A
Country	US
Kind code	B2
Filing date	Dec 11, 2014
Priority date	Dec 20, 2013
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

A method for resampling an audio-frequency signal with an output sampling frequency, for a current signal frame. The method is used when the preceding frame is sampled at a first sampling frequency which is different from a second sampling frequency of the current frame. The method includes: determining a first and second segments of the signal by adding samples at zero at the end of stored samples of the preceding frame and at the start of samples of the current frame, respectively; obtaining the first resampled segment and the second resampled segment by applying at least one resampling filter respectively to the first segment resampling the first frequency at the output frequency, and to the second segment resampling the second frequency at the output frequency; and combining the overlapping portion of the first and second resampled segments to obtain at least one portion of the resampled current frame.

First claim

The invention claimed is:

1. A method for resampling of an audio frequency signal at an output sampling frequency, wherein the method comprises the following acts performed by a processing device of an audio coder or decoder:
receiving a current frame of an audio frequency signal sampled at a second sampling frequency and a stored part of a preceding frame sampled at a first sampling frequency different from the second sampling frequency, and wherein resampling comprises:
determining a first signal segment by addition of a first predetermined number of samples set at zero at the end of stored samples of the preceding frame;
obtaining a first resampled segment by application to the first segment of at least one resampling filter resampling from the first sampling frequency to the output sampling frequency;
determining a second signal segment by addition of a second predetermined number of samples set at zero at the start of samples of the current frame;
obtaining a second resampled segment by application to the second segment of at least one resampling filter resampling from the second sampling frequency to the output sampling frequency;
combining an overlapping part of the first and second resampled segments to obtain at least a part of the current resampled frame; and
transmitting the current resampled frame, which has been resampled at the output sampling frequency.

2. The method as claimed in claim 1 , wherein, in the case where the first sampling frequency is lower than the second sampling frequency, the obtaining of the second resampled segment comprises:
obtaining a transition segment by resampling from the second frequency to the output sampling frequency, of the second segment, over a limited frequency band;
obtaining a second intermediate resampled segment by resampling from the second sampling frequency to the output sampling frequency, of the second segment;
applying a cross-fading function to at least a part of the transition and intermediate segments.

3. The method as claimed in claim 1 , wherein, in the case where the first sampling frequency is lower than the second sampling frequency, the obtaining the second resampled segment comprises:
obtaining a sub-band division in at least the second segment;
applying a weighting function to at least one sub-band of the second segment;
obtaining the second resampled segment by recombination of the sub-bands comprising at least the one that is weighted.

4. The method as claimed in claim 1 , wherein, in the case where the first sampling frequency is higher than the second sampling frequency, the obtaining the first resampled segment comprises:
obtaining a transition segment by resampling from the first sampling frequency to the output sampling frequency, of the first segment, over a limited frequency band;
obtaining a first intermediate resampled segment by resampling from the first sampling frequency to the output sampling frequency, of the first segment;
applying a cross-fading function to at least a part of the transition and intermediate segments.

5. The method as claimed in claim 1 , wherein the method further comprises multiplying the current resampled frame resulting from the combination, by a weighting signal.

6. The method according to claim 1 , further comprising:
decoding the current signal frame of the audio frequency signal, comprising selecting a decoding sampling frequency, wherein, in the case where the preceding frame is sampled at the first sampling frequency different from the second sampling frequency of the current frame, the method comprises performing the resampling.

7. An audio coder or decoder device for resampling an audio frequency signal at an output sampling frequency, wherein the device comprises:
an input and an output;
a processor; and
a non-transitory computer-readable medium comprising instructions that, when executed by the processor configure the device to perform acts comprising:
receiving on the input a current frame of an audio frequency signal sampled at a second sampling frequency and a stored part of a preceding frame sampled at a first sampling frequency different from the second sampling frequency;
determining a first signal segment by addition of a first predetermined number of samples at zero at the end of stored samples of the preceding frame;
obtaining a first resampled segment by application to the first segment of at least one resampling filter resampling from the first sampling frequency to the output sampling frequency;
determining a second signal segment by addition of a second predetermined number of samples set at zero at the start of samples of the current frame;
obtaining a second resampled segment by application to the second segment of at least one resampling filter resampling from the second sampling frequency to the output sampling frequency;
combining the overlapping part of the first and second resampled segments to obtain at least a part of the current resampled frame
transmitting on the output the current resampled frame, which has been resampled at the output sampling frequency.

8. The device of claim 7 , further comprising an audio frequency signal decoder, which comprises a module that selects a decoding sampling frequency.

9. A non-transitory processor-readable storage medium, on which is stored a computer program comprising code instructions for executing a resampling method for resampling of an audio frequency signal at an output sampling frequency, when the instructions are executed by a processor of a processing device of an audio coder or decoder, the instructions comprises:
instructions that configure the processing device to receive a current frame of an audio frequency signal sampled at a second sampling frequency and a stored part of a preceding frame sampled at a first sampling frequency different from the second sampling frequency;
instructions that configure the processing device to determine a first signal segment by addition of a first predetermined number of samples set at zero at the end of stored samples of the preceding frame;
instructions that configure the processing device to obtain a first resampled segment by application to the first segment of at least one resampling filter resampling from the first sampling frequency to the output sampling frequency;
instructions that configure the processing device to determine a second signal segment by addition of a second predetermined number of samples set at zero at the start of samples of the current frame;
instructions that configure the processing device to obtain a second resampled segment by application to the second segment of at least one resampling filter resampling from the second sampling frequency to the output sampling frequency;
instructions that configure the processing device to combine an overlapping part of the first and second resampled segments to obtain at least a part of the current resampled frame; and
instructions that configure the processing device to transmit the current resampled frame which has been resampled at the output sampling frequency.

Assignees

• Orange

Inventors

• Ragot Stephane
• Daniel Jerome
• Kovesi Balazs

Classifications

• H03H2218/14

  Non-uniform sampling · CPC title

• G10L19/0204

  using subband decomposition · 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

• G10L19/022

  Blocking, i.e. grouping of samples in time; Choice of analysis windows; Overlap factoring · CPC title

• H03H17/0621 Primary

  with input-sampling frequency and output-delivery frequency which differ, e.g. extrapolation; Anti-aliasing · CPC title