Inter-channel phase difference parameter modification

1. A device comprising:

a receiver configured to receive an encoded bitstream that includes an encoded mid channel and stereo parameters, the stereo parameters including inter-channel phase difference (IPD) parameter values and a mismatch value indicative of an amount of temporal misalignment between an encoder-side reference channel and an encoder-side target channel;

a mid channel decoder configured to decode the encoded mid channel to generate a decoded mid channel;

a transform unit configured to perform a transform operation on the decoded mid channel to generate a decoded frequency-domain mid channel;

a stereo parameter adjustment unit configured to modify at least a portion of the IPD parameter values based on the mismatch value to generate modified IPD parameter values;

an up-mixer configured to perform an up-mix operation on the decoded frequency-domain mid channel to generate a frequency-domain left channel and a frequency-domain right channel, the modified IPD parameter values applied to the decoded frequency-domain mid channel during the up-mix operation;

a first inverse transform unit configured to perform a first inverse transform operation on the frequency-domain left channel to generate a time-domain left channel; and

a second inverse transform unit configured to perform a second inverse transform operation on the frequency-domain right channel to generate a time-domain right channel.

2. The device of claim 1 , wherein the stereo parameter adjuster unit is configured to:

compare an absolute value of the mismatch value to a threshold; and

modify at least the portion of the IPD parameter values in response to a determination that the absolute value of the mismatch value satisfies the threshold.

3. The device of claim 1 , further comprising:

one or more speakers configured to output at least one of a left channel or a right channel, the left channel associated with the time-domain left channel, and the right channel associated with the time-domain right channel.

4. The device of claim 3 , wherein the stereo parameters include an inter-channel time difference (ITD) parameter value as the mismatch value, and further comprising:

an inter-channel alignment unit configured to:

adjust the time-domain right channel based on the ITD parameter value to generate the right channel; or

adjust the time-domain left channel based on the ITD parameter value to generate the left channel.

5. The device of claim 4 , wherein the inter-channel alignment unit is included in the up-mixer.

6. The device of claim 1 , further comprising:

a side channel decoder configured to decode an encoded side channel to generate a decoded side channel, the encoded side channel included in the encoded bitstream; and

a second transform unit configured to perform a second transform operation on the decoded side channel to generate a decoded frequency-domain side channel.

7. The device of claim 6 , wherein the stereo parameter adjustment unit is further configured to modify the IPD parameter values based on an availability of the encoded side channel.

8. The device of claim 1 , wherein the stereo parameter adjustment unit is further configured to modify the IPD parameter values based on a bit rate associated with the encoded bitstream.

9. The device of claim 1 , wherein the stereo parameter adjustment unit is further configured to modify the IPD parameter values based on a voicing parameter, a packet loss determination associated with a previous frame, a speech/music classification, or another parameter.

10. The device of claim 1 , wherein the stereo parameter adjustment unit is configured to set one or more of the IPD parameter values to zero values.

11. The device of claim 1 , wherein the stereo parameter adjustment unit is configured to temporally smooth one or more of the IPD parameter values.

12. The device of claim 1 , wherein the mismatch value indicates the amount of temporal misalignment in a frequency domain.

13. The device of claim 1 , wherein the mismatch value indicates the amount of temporal misalignment in a time domain.

14. The device of claim 1 , wherein the stereo parameter adjustment unit is integrated into a mobile device.

15. The device of claim 1 , wherein the stereo parameter adjustment unit is integrated into a base station.

16. A method of decoding audio channels, the method comprising:

receiving, at a decoder, an encoded bitstream that includes an encoded mid channel and stereo parameters, the stereo parameters including inter-channel phase difference (IPD) parameter values and a mismatch value indicative of an amount of temporal misalignment between an encoder-side reference channel and an encoder-side target channel;

decoding the encoded mid channel to generate a decoded mid channel;

performing a transform operation on the decoded mid channel to generate a decoded frequency-domain mid channel;

modifying at least a portion of the IPD parameter values based on the mismatch value to generate modified IPD parameter values;

performing an up-mix operation on the decoded frequency-domain mid channel to generate a frequency-domain left channel and a frequency-domain right channel, the modified IPD parameter values applied to the decoded frequency-domain mid channel during the up-mix operation;

performing a first inverse transform operation on the frequency-domain left channel to generate a time-domain left channel; and

performing a second inverse transform operation on the frequency-domain right channel to generate a time-domain right channel.

17. The method of claim 16 , wherein modifying at least the portion of the IPD parameter values comprises:

comparing an absolute value of the mismatch value to a threshold; and

modifying at least the portion of the IPD parameter values in response to a determination that the absolute value of the mismatch value satisfies the threshold.

18. The method of claim 16 , further comprising outputting at least one of a left channel or a right channel, the left channel associated with the time-domain left channel, and the right channel associated with the time-domain right channel.

19. The method of claim 18 , wherein the stereo parameters include an inter-channel time difference (ITD) parameter value as the mismatch value, and further comprising:

adjusting the time-domain right channel based on the ITD parameter value to generate the right channel; or

adjusting the time-domain left channel based on the ITD parameter value to generate the left channel.

20. The method of claim 16 , further comprising:

decoding an encoded side channel to generate a decoded side channel, the encoded side channel included in the encoded bitstream; and

performing a second transform operation on the decoded side channel to generate a decoded frequency-domain side channel.

21. The method of claim 20 , further comprising modifying the IPD parameter values based on an availability of the encoded side channel.

22. The method of claim 16 , further comprising modifying the IPD parameter values based on a bit rate associated with the encoded bitstream.

23. The method of claim 16 , further comprising setting one or more of the IPD parameter values to zero values.

24. The method of claim 16 , further comprising temporally smoothing one or more of the IPD parameter values.

25. The method of claim 16 , wherein the mismatch value indicates the amount of temporal misalignment in a frequency domain.

26. The method of claim 16 , wherein the mismatch value indicates the amount of temporal misalignment in a time domain.

27. The method of claim 16 , wherein modifying at least the portion of the IPD parameter values is performed at a mobile device.

28. The method of claim 16 , wherein modifying at least the portion of the IPD parameter values is performed at a base station.

29. A non-transitory computer-readable medium comprising instructions that, when executed by a processor within a decoder, cause the processor to perform operations comprising:

decoding an encoded mid channel to generate a decoded mid channel, the encoded mid channel included in an encoded bitstream received by the decoder, the encoded bitstream further comprising stereo parameters that include inter-channel phase difference (IPD) parameter values and a mismatch value indicative of an amount of temporal misalignment between an encoder-side reference channel and an encoder-side target channel;

performing a transform operation on the decoded mid channel to generate a decoded frequency-domain mid channel;

modifying at least a portion of the IPD parameter values based on the mismatch value to generate modified IPD parameter values;

performing an up-mix operation on the decoded frequency-domain mid channel to generate a frequency-domain left channel and a frequency-domain right channel, the modified IPD parameter values applied to the decoded frequency-domain mid channel during the up-mix operation;

performing a first inverse transform operation on the frequency-domain left channel to generate a time-domain left channel; and

performing a second inverse transform operation on the frequency-domain right channel to generate a time-domain right channel.

30. The non-transitory computer-readable medium of claim 29 , wherein modifying at least the portion of the IPD parameter values comprises:

comparing an absolute value of the mismatch value to a threshold; and

modifying at least the portion of the IPD parameter values in response to a determination that the absolute value of the mismatch value satisfies the threshold.

31. The non-transitory computer-readable medium of claim 29 , wherein the operations further comprise providing at least one of a left channel or a right channel to one or more speakers, the left channel associated with the time-domain left channel, and the right channel associated with the time-domain right channel.

32. An apparatus comprising:

means for receiving an encoded bitstream that includes an encoded mid channel and stereo parameters, the stereo parameters including inter-channel phase difference (IPD) parameter values and a mismatch value indicative of an amount of temporal misalignment between an encoder-side reference channel and an encoder-side target channel;

means for decoding the encoded mid channel to generate a decoded mid channel;

means for performing a transform operation on the decoded mid channel to generate a decoded frequency-domain mid channel;

means for modifying at least a portion of the IPD parameter values based on the mismatch value to generate modified IPD parameter values;

means for performing an up-mix operation on the decoded frequency-domain mid channel to generate a frequency-domain left channel and a frequency-domain right channel, the modified IPD parameter values applied to the decoded frequency-domain mid channel during the up-mix operation;

means for performing a first inverse transform operation on the frequency-domain left channel to generate a time-domain left channel; and

means for performing a second inverse transform operation on the frequency-domain right channel to generate a time-domain right channel.

33. The apparatus of claim 32 , further comprising means for outputting a left channel and a right channel, the left channel associated with the time-domain left channel, and the right channel associated with the time-domain right channel.

34. The apparatus of claim 32 , wherein the means for modifying is integrated into a base station.

35. The apparatus of claim 32 , wherein the means for modifying is integrated into a mobile device.