Systems, methods, apparatus, and computer-readable media for bit allocation for redundant transmission

1. A method of processing an audio signal, said method comprising:

calculating at least one value of a decision metric for a second frame of the audio signal that is subsequent in the audio signal to a first frame of the audio signal; and

based on said at least one calculated value of the decision metric, selecting one among a plurality of reallocation candidates,

wherein said calculated at least one value is based on a measure of compressibility of the second frame, and

wherein said selected reallocation candidate indicates a reallocation of an initial bit allocation for the second frame into a first portion and a second portion.

2. The method according to claim 1 , wherein said method includes determining that said first frame is a critical frame of the audio signal.

3. The method according to claim 2 , wherein said determining that said first frame is a critical frame is based on information from an encoded version of a frame of the audio signal that is subsequent in the audio signal to the first frame.

4. The method according to claim 3 , wherein said encoded version is an encoded version of the second frame.

5. The method according to claim 2 , wherein said determining includes comparing a criticality measure to a criticality threshold.

6. The method according to claim 5 , wherein said determining includes calculating the criticality threshold based on information relating to a state of a transmission channel.

7. The method according to claim 6 , wherein said calculating the criticality threshold includes:

comparing a calculated value that is based on the information relating to the state of the transmission channel to a boundary value; and

in response to a result of said comparing to the boundary value, selecting the boundary value as the criticality threshold.

8. The method according to claim 1 , wherein said measure of compressibility indicates a correlation among subframes of the second frame.

9. The method according to claim 1 , wherein said selecting one among the plurality of reallocation candidates includes comparing a calculated value of the decision metric to each of an ordered plurality of decision thresholds, and

wherein each of the ordered plurality of decision thresholds corresponds to a different one among the plurality of reallocation candidates.

10. The method according to claim 1 , wherein said method comprises calculating a plurality of values of the decision metric, each corresponding to a different frame of the audio signal that is subsequent in the audio signal to said first frame, and

wherein each of said plurality of values of the decision metric is based on a measure of compressibility of the corresponding frame, and

wherein said method comprises, based on at least some of said plurality of values of the decision metric, selecting said second frame from among said different frames.

11. The method according to claim 1 , wherein said calculated at least one value of the decision metric includes a set of calculated values of the decision metric, and wherein each of the set of calculated values corresponds to a different one of the plurality of reallocation candidates.

12. The method according to claim 11 , wherein each of the set of calculated values is based on a measure of perceptual quality associated with the corresponding one of the plurality of reallocation candidates.

13. The method according to claim 11 , wherein said measure of compressibility is based on information from an encoded version of the second frame.

14. The method according to claim 11 , wherein said at least one calculated value is based on a relation between measures of perceptual quality of the second frame for different encoding rates.

15. The method according to claim 11 , wherein said at least one calculated value is based on a relation between (A) a measure of compressibility of the second frame for the initial bit allocation and (B) a measure of compressibility of the second frame for the corresponding one of the plurality of reallocation candidates.

16. The method according to claim 1 , wherein said calculated at least one value of the decision metric includes a plurality of sets of calculated values of the decision metric, each of the plurality of sets corresponding to a different frame of the audio signal that is subsequent in the audio signal to said first frame, and wherein, within each set, each value corresponds to a different one of the plurality of reallocation candidates.

17. The method according to claim 16 , wherein, within each set, each value is based on a measure of perceptual quality associated with the corresponding one of the plurality of reallocation candidates.

18. The method according to claim 16 , wherein, within each set, each value is based on information from an encoded version of the corresponding frame.

19. The method according to claim 16 , wherein said method comprises, based on calculated values of at least some of said plurality of sets, selecting said second frame from among said different frames.

20. The method according to claim 1 , wherein said method comprises, in response to said selecting one among the plurality of reallocation candidates, producing a packet that includes a redundant copy of said first frame and a copy of said second frame,

wherein the copy of said second frame is encoded into said first portion, and

wherein said redundant copy is encoded into said second portion.

21. An apparatus for processing an audio signal, said apparatus comprising:

means for calculating at least one value of a decision metric for a second frame of the audio signal that is subsequent in the audio signal to a first frame of the audio signal; and

means for selecting one among a plurality of reallocation candidates, based on said at least one calculated value of the decision metric,

wherein said calculated at least one value is based on a measure of compressibility of the second frame, and

wherein said selected reallocation candidate indicates a reallocation of an initial bit allocation for the second frame into a first portion and a second portion.

22. The apparatus according to claim 21 , wherein said apparatus includes means for determining that said first frame is a critical frame of the audio signal.

23. The apparatus according to claim 22 , wherein said determining that said first frame is a critical frame is based on information from an encoded version of a frame of the audio signal that is subsequent in the audio signal to the first frame.

24. The apparatus according to claim 21 , wherein said measure of compressibility indicates a correlation among subframes of the second frame.

25. The apparatus according to claim 21 , wherein said means for calculating at least one value of the decision metric is configured to calculate a plurality of values of the decision metric, each corresponding to a different frame of the audio signal that is subsequent in the audio signal to said first frame, and

wherein each of said plurality of values of the decision metric is based on a measure of compressibility of the corresponding frame, and

wherein said apparatus comprises means for selecting said second frame from among said different frames, based on at least some of said plurality of values of the decision metric.

26. The apparatus according to claim 21 , wherein said calculated at least one value of the decision metric includes a set of calculated values of the decision metric, and wherein each of the set of calculated values corresponds to a different one of the plurality of reallocation candidates, and

wherein each of the set of calculated values is based on a measure of perceptual quality associated with the corresponding one of the plurality of reallocation candidates.

27. The apparatus according to claim 21 , wherein said calculated at least one value of the decision metric includes a set of calculated values of the decision metric, and wherein each of the set of calculated values corresponds to a different one of the plurality of reallocation candidates, and

wherein said at least one calculated value is based on a relation between measures of perceptual quality of the second frame for different encoding rates.

28. The apparatus according to claim 21 , wherein said apparatus comprises means for producing, in response to said selecting one among the plurality of reallocation candidates, a packet that includes a redundant copy of said first frame and a copy of said second frame,

wherein the copy of said second frame is encoded into said first portion, and

wherein said redundant copy is encoded into said second portion.

29. An apparatus for processing an audio signal, said apparatus comprising:

a calculator configured to calculate at least one value of a decision metric for a second frame of the audio signal that is subsequent in the audio signal to a first frame of the audio signal; and

a selector configured to select one among a plurality of reallocation candidates, based on said at least one calculated value of the decision metric,

wherein said calculated at least one value is based on a measure of compressibility of the second frame, and

wherein said selected reallocation candidate indicates a reallocation of an initial bit allocation for the second frame into a first portion and a second portion.

30. The apparatus according to claim 29 , wherein said apparatus includes a critical frame indicator configured to determine that said first frame is a critical frame of the audio signal.

31. The apparatus according to claim 30 , wherein said determining that said first frame is a critical frame is based on information from an encoded version of a frame of the audio signal that is subsequent in the audio signal to the first frame.

32. The apparatus according to claim 29 , wherein said measure of compressibility indicates a correlation among subframes of the second frame.

33. The apparatus according to claim 29 , wherein said calculator is configured to calculate a plurality of values of the decision metric, each corresponding to a different frame of the audio signal that is subsequent in the audio signal to said first frame, and wherein each of said plurality of values of the decision metric is based on a measure of compressibility of the corresponding frame, and

wherein said selector is configured to select said second frame from among said different frames, based on at least some of said plurality of values of the decision metric.

34. The apparatus according to claim 29 , wherein said calculated at least one value of the decision metric includes a set of calculated values of the decision metric, and wherein each of the set of calculated values corresponds to a different one of the plurality of reallocation candidates, and

wherein each of the set of calculated values is based on a measure of perceptual quality associated with the corresponding one of the plurality of reallocation candidates.

35. The apparatus according to claim 29 , wherein said calculated at least one value of the decision metric includes a set of calculated values of the decision metric, and wherein each of the set of calculated values corresponds to a different one of the plurality of reallocation candidates, and

wherein said at least one calculated value is based on a relation between measures of perceptual quality of the second frame for different encoding rates.

36. The apparatus according to claim 29 , wherein said apparatus comprises a packet assembler configured to produce, in response to said selecting one among the plurality of reallocation candidates, a packet that includes a redundant copy of said first frame and a copy of said second frame,

wherein the copy of said second frame is encoded into said first portion, and

wherein said redundant copy is encoded into said second portion.

37. A non-transitory computer-readable data storage medium having tangible features that cause a machine reading the features to:

calculate at least one value of a decision metric for a second frame of the audio signal that is subsequent in the audio signal to a first frame of the audio signal; and

select one among a plurality of reallocation candidates, based on said at least one calculated value of the decision metric,

wherein said calculated at least one value is based on a measure of compressibility of the second frame, and

wherein said selected reallocation candidate indicates a reallocation of an initial bit allocation for the second frame into a first portion and a second portion.

38. The medium according to claim 37 , wherein said medium includes tangible features that cause a machine reading the features to determine that said first frame is a critical frame of the audio signal, and

wherein said determining that said first frame is a critical frame is based on information from an encoded version of a frame of the audio signal that is subsequent in the audio signal to the first frame.

39. The medium according to claim 37 , wherein said measure of compressibility indicates a correlation among subframes of the second frame.

40. The medium according to claim 37 , wherein said medium comprises tangible features that cause a machine reading the features to produce a packet, in response to said selecting one among the plurality of reallocation candidates, that includes a redundant copy of said first frame and a copy of said second frame,

wherein the copy of said second frame is encoded into said first portion, and

wherein said redundant copy is encoded into said second portion.