Jitter buffer control, audio decoder, method and computer program

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-based time scaling.

19. The audio decoder according to claim 17 , wherein the decoder core is configured to perform a comfort noise generation in response to a frame carrying a signaling information indicating a generation of comfort noise, and

wherein the decoder core is configured to perform a concealing in response to an empty jitter buffer.

20. The audio decoder according to claim 17 , wherein the sample-based time scaler is configured to perform the time scaling of the input audio signal in dependence on a computation or an estimation of the quality of the time scaled version of the input audio signal acquirable by the time scaling.

21. A method for controlling a provision of a decoded audio content on the basis of an input audio content,

wherein the method comprises selecting a frame-based time scaling or a sample-based time scaling in a signal-adaptive manner.

22. A non-transitory digital storage medium having a computer program stored thereon to perform the method for controlling a provision of a decoded audio content on the basis of an input audio content,

wherein the method comprises selecting a frame-based time scaling or a sample-based time scaling in a signal-adaptive manner,

when said computer program is run by a computer.

23. 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 between at least a frame-based time scaling and a sample-based time scaling in a signal-adaptive manner, and

wherein the jitter buffer control is implemented using hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.