Jitter buffer control, audio decoder, method and computer program

Patent metadata

Field	Value
Publication number	US-11580997-B2
Application number	US-202016899382-A
Country	US
Kind code	B2
Filing date	Jun 11, 2020
Priority date	Jun 21, 2013
Publication date	Feb 14, 2023
Grant date	Feb 14, 2023

Abstract

A jitter buffer control for controlling a provision of a decoded audio content on the basis of an input audio content is configured to select a frame-based time scaling or a sample-based time scaling in a signal-adaptive manner. An audio decoder uses such a jitter buffer control.

First claim

The invention claimed is:

1. A jitter buffer control for controlling a provision of a decoded audio content on the basis of an input audio content,
wherein the jitter buffer control is configured to select a frame-based time scaling or a sample-based time scaling in a signal-adaptive manner; and
wherein the jitter buffer control is implemented using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

2. The jitter buffer control according to claim 1 , wherein audio frames are dropped or inserted to control a depth of a jitter buffer when the frame-based time scaling is used, and wherein a time-shifted overlap-and-add of audio signal portions is performed when the sample-based time-scaling is used.

3. The jitter buffer control according to claim 1 , wherein the jitter buffer control is configured to switch between a frame-based time scaling, a sample-based time scaling and a deactivation of a time scaling in a signal-adaptive manner.

4. The jitter buffer control according to claim 1 , wherein the jitter buffer control is configured to select the frame-based time scaling or the sample-based time scaling in order to control a depth of a de-jitter buffer.

5. The jitter buffer control according to claim 1 , wherein the jitter buffer control is configured to select a comfort noise insertion or a comfort noise deletion if a previous frame was inactive.

6. The jitter buffer control according to claim 5 , wherein a comfort noise insertion results in an insertion of a comfort noise frame into a de-jitter buffer, and wherein a comfort noise deletion results in a removal of a comfort noise frame from the de-jitter buffer.

7. The jitter buffer control according to claim 5 , wherein a respective frame is considered inactive when the respective frame carries a signaling information indicating a generation of comfort noise.

8. The jitter buffer control according to claim 1 , wherein the jitter buffer control is configured to select a time-shifted overlap-and-add of audio signal portions if a previous frame was active.

9. The jitter buffer control according to claim 8 , wherein the time-shifted overlap-and-add of audio signal portions is adapted to allow for an adjustment of a time shift between blocks of audio samples acquired on the basis of subsequent frames of the input audio content with a resolution which is smaller than a length of the blocks of audio samples, or which is smaller than a quarter of the length of the blocks of audio samples, or which is smaller than or equal to two audio samples.

10. The jitter buffer control according to claim 8 , wherein the jitter buffer control is configured to determine whether a block of audio samples represents an active but silent audio signal portion, and wherein the jitter buffer control is configured to select an overlap-and-add mode, in which a time shift between the block of audio samples representing a silent audio signal portion and a previous or subsequent block of audio samples is set to a predetermined maximum value, for a block of audio samples representing a silent audio signal portion.

11. The jitter buffer control according to claim 8 , wherein the jitter buffer control is configured to determine whether a block of audio samples represents an active and non-silent audio signal portion, and to select an overlap-and-add mode, in which the time shift between blocks of audio samples determined on the basis of subsequent frames of the input audio content is determined in a signal adaptive manner.

12. The jitter buffer control according to claim 1 , wherein the jitter buffer control is configured to select an insertion of a concealed frame in response to a determination that a time stretching may be used and that a jitter buffer is empty.

13. The jitter buffer control according to claim 1 , wherein the jitter buffer control is configured to select the frame-based time scaling or the sample-based time scaling in dependence on whether a discontinuous transmission in conjunction with comfort noise generation is currently used or was used for a previous frame.

14. The jitter buffer control according to claim 1 , wherein the jitter buffer control is configured to select a frame-based time scaling if a comfort noise generation is currently used or was used for a previous frame and to select a sample-based time scaling if a comfort noise generation is not currently used or was not used for a previous frame.

15. The jitter buffer control according to claim 1 ,
wherein the jitter buffer control is configured to select a comfort noise insertion or a comfort noise deletion for a time scaling if a discontinuous transmission in conjunction with comfort noise generation is currently used or was used for a previous frame,
wherein the jitter buffer control is configured to select an overlap-add-operation using a predetermined time shift for a time scaling if a current audio signal portion is active but comprises a signal energy which is smaller than or equal to an energy threshold value, and if a jitter buffer is not empty, or if a previous audio signal portion was active but comprises a signal energy which is smaller than or equal to the energy threshold value, and if the jitter buffer is not empty;
wherein the jitter buffer control is configured to select an overlap-add-operation using a signal-adaptive time shift for a time scaling if a current audio signal portion is active and comprises a signal energy which is larger than or equal to the energy threshold value and if the jitter buffer is not empty, or if a previous audio signal portion was active and comprises a signal energy which is larger than or equal to the energy threshold value and if the jitter buffer is not empty; and
wherein the jitter buffer control is configured to select an insertion of a concealed frame for a time scaling if a current audio signal portion is active and if the jitter buffer is empty, or if a previous audio signal portion was active and if the jitter buffer is empty.

16. The jitter buffer control according to claim 1 , wherein the jitter buffer control is configured to select an overlap-add-operation using a signal-adaptive time shift and a quality control mechanism for a time scaling if a current audio signal portion is active and comprises a signal energy which is larger than or equal to the energy threshold value and if the jitter buffer is not empty, or if a previous audio signal portion was active and comprises a signal energy which is larger than or equal to the energy threshold value and if the jitter buffer is not empty.

17. An audio decoder for providing a decoded audio content on the basis of an input audio content, the audio decoder comprising:
a jitter buffer configured to buffer a plurality of audio frames representing blocks of audio samples;
a decoder core configured to provide blocks of audio samples on the basis of audio frames received from the jitter buffer;
a sample-based time scaler, wherein the sample based time scaler is configured to provide time-scaled blocks of audio samples on the basis of blocks of audio samples provided by the decoder core; and
a jitter buffer control according to claim 1 ,
wherein the jitter buffer control is configured to select a frame-based time scaling, which is performed by the jitter buffer, or a sample-based time scaling, which is performed by the sample-based time scaler, in a signal-adaptive manner.

18. The audio decoder according to claim 17 , wherein the jitter buffer is configured to drop or insert audio frames in order to perform a frame-base

Assignees

• Fraunhofer Ges Forschung

Inventors

• Reuschl Stefan
• Doehla Stefan
• Lecomte Jérémie
• Jander Manuel

Classifications

• H04J3/06

  Synchronising arrangements {(for television systems H04N5/04; bit-synchronisation H04L7/00)} · CPC title

• G10L21/04

  Time compression or expansion · CPC title

• G10L19/022 Primary

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

• H04J3/0664

  unidirectional timestamps · CPC title

• G10L19/012 Primary

  Comfort noise or silence coding · CPC title