Encoding an audio signal

• US 20080059154A1
• Filed: 09/01/2006
• Published: 03/06/2008
• Est. Priority Date: 09/01/2006
• Status: Abandoned Application

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Laaksonen, Lasse, Ramo, Anssi
• Application Number:
  US11/515,499
• Publication Number:
  US 20080059154A1
• Time in Patent Office: Days
• US Class Current: 704/200.1
• CPC Class Codes: G10L 19/24 Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding
• CPC Class Codes: G10L 19/265 Pre-filtering, e.g. high frequency emphasis prior to encoding
• CPC Class Codes: G10L 21/02 Speech enhancement, e.g. noise reduction or echo cancellation reducing echo effects in line transmission systems H04B3/20; echo suppression in hands-free telephones H04M9/08

Abstract

For taking account of different requirements on encoded audio data having different bit rates, at least two different amounts of pre-processing are applied to an audio signal to obtain at least two different target signals. A first one of the target signals is then encoded to obtain primary coded data. At least a second one of the at least two different target signals is moreover used for generating enhancement data for the primary coded data.

Claims

1. A method comprising:

applying at least two different amounts of pre-processing to an audio signal to obtain at least two different target signals;

encoding a first one of said target signals to obtain primary coded data; and

using at least a second one of said at least two different target signals for generating enhancement data for said primary coded data.

2. The method according to claim 1, wherein said pre-processing comprises noise suppression.

3. The method according to claim 1, wherein said primary coded data and said enhancement data are provided in a single bit stream.

4. The method according to claim 3, wherein said bit stream is truncated, if needed, at least one of

at an encoding end generating said bit stream;

at a decoding end receiving at least a portion of said bit stream; and

on a transmission path employed for transmitting at least a portion of said bit stream from an encoding end to a decoding end.

5. The method according to claim 1, wherein said first one of said target signals is obtained by applying a highest amount of pre-processing of said at least two different amounts of pre-processing.

6. The method according to claim 1, wherein said using of at least a second one of said at least two different target signals for generating enhancement data for said primary coded data comprises using a plurality of target signals in sequence for generating enhancement data for the entirety of said primary coded data and any precedingly generated enhancement data.

7. The method according to claim 6, wherein at least four different target signals are used in sequence for generating enhancement data.

8. The method according to claim 6, wherein a last one of said target signals used in sequence for generating enhancement data is obtained by applying the lowest amount of pre-processing of said at least two different amounts of pre-processing to said audio signal.

9. The method according to claim 6, wherein each target signal used in sequence for generating enhancement data is obtained by applying a lower or equal amount of pre-processing compared to the amount of pre-processing that is applied for obtaining a target signal that is used for a preceding generation of enhancement data or for a preceding generation of primary coded data, respectively.

10. The method according to claim 1, wherein a lowest amount of pre-processing of said at least two different amounts of pre-processing is a pre-processing of zero.

11. An apparatus comprising:

a pre-processing component configured to apply at least one of at least two different amounts of pre-processing to an audio signal to obtain at least two different target signals;

a core encoder component configured to encode a first one of said at least two different target signals to obtain primary coded data;

at least one enhancement layer encoder component configured to use at least a second one of said at least two different target signals for generating enhancement data for primary coded data provided by said core encoder component.

12. The apparatus according to claim 11, wherein said pre-processing component is a noise suppression component.

13. The apparatus according to claim 11, wherein said apparatus is configured to provide said primary coded data and said enhancement data in a single bit stream.

14. The apparatus according to claim 11, wherein said pre-processing component is configured to apply a highest amount of pre-processing of said at least two different amounts of pre-processing for obtaining said first one of said target signals.

15. The apparatus according to claim 11, wherein said at least one enhancement layer encoder component comprises a plurality of enhancement layer encoder components arranged in sequence, said plurality of enhancement layer encoder components being configured to use respective target signals for generating enhancement data for the entirety of said primary coded data and any precedingly generated enhancement data.

16. The apparatus according to claim 15, wherein said plurality of enhancement layer encoder components comprise at least four enhancement layer encoder components.

17. The apparatus according to claim 15, wherein a last one of said plurality of said enhancement layer encoder components is arranged to receive a target signal for generating enhancement data, which target signal has been obtained by applying the lowest amount of pre-processing of said at least two different amounts of pre-processing to said audio signal.

18. The apparatus according to claim 15, wherein said plurality of said enhancement layer encoder components are arranged to receive a respective target signal which has been obtained by applying a respective lower or equal amount of pre-processing than used for the target signal provided to a respective preceding enhancement layer encoder component or to a preceding core encoding component, respectively.

19. The apparatus according to claim 11, wherein one of said at least two different amounts of pre-processing is zero, and wherein one of said at least one enhancement layer encoder components is arranged to receive said audio signal without an applied pre-processing as a target signal.

20. The apparatus according to claim 11, wherein said apparatus is an audio coder.

21. An electronic device comprising the apparatus according to claim 11 and a user interface.

22. A system comprising the apparatus according to claim 11 and an apparatus including a decoder configured to decode primary coded data and enhancement data generated by said apparatus according to claim 11.

23. A computer program product in which a program code is stored in a computer readable medium, said program code realizing the following when executed by a processor:

applying at least two different amounts of pre-processing to an audio signal to obtain at least two different target signals;

encoding a first one of said target signals to obtain primary coded data; and

using at least a second one of said at least two different target signals for generating enhancement data for said primary coded data.

24. The computer program product according to claim 23, wherein said first one of said target signals is obtained by applying the highest amount of pre-processing of said at least two different amounts of pre-processing to said audio signal.

25. The computer program product according to claim 23, wherein said using of at least a second one of said at least two different target signals for generating enhancement data for said primary coded data comprises using a plurality of target signals in sequence for generating enhancement data for the entirety of said primary coded data and any precedingly generated enhancement data.

26. The computer program product according to claim 25, wherein each target signal used in sequence for generating enhancement data is obtained by applying a lower or equal amount of pre-processing compared to the amount of pre-processing that is applied for obtaining a target signal that is used for a preceding generation of enhancement data or for a preceding generation of primary coded data, respectively.

27. An apparatus comprising:

means for applying at least one of at least two different amounts of pre-processing to an audio signal to obtain at least two different target signals;

means for encoding a first one of said at least two different target signals to obtain primary coded data;

means for using at least a second one of said at least two different target signals for generating enhancement data for primary coded data.

28. The apparatus according to claim 27, wherein said means for applying at least one of at least two different amounts of pre-processing are means for applying at least one of at least two different amounts of noise suppression.

29. The apparatus according to claim 27, wherein said means for applying at least one of at least two different amounts of pre-processing to an audio signal are configured to apply a highest amount of pre-processing of said at least two different amounts of pre-processing to said audio signal for obtaining said first one of said target signals.

30. The apparatus according to claim 27, wherein said means for using at least a second one of said at least two different target signals for generating enhancement data are configured to use a plurality of target signals in sequence for generating enhancement data for the entirety of said primary coded data and any precedingly generated enhancement data.

31. The apparatus according to claim 30, wherein said means for using at least a second one of said at least two different target signals for generating enhancement data are configured to use a respective target signal that has been obtained by applying a lower or equal amount of pre-processing compared to the amount of pre-processing that has been applied for obtaining a target signal that is used for a preceding generation of enhancement data or for a preceding generation of primary coded data, respectively.