[opus] FEC and Stereo

[Jon Lederman]

HI All,

We are trying to use Opus in a VoIP environment for sending stereo audio.  We have noticed a phenomenon where when FEC is enabled and packet_loss_percentage>0, that there is a mixing of audio from the left channel into the right channel and vice versa.  That is, rather than hearing each channel in its pristine form as it was in the file, there is a combination of right and left channels that is heard on the left and right playback.

First, is this the correct behavior?  If so, why does this occur?  Finally, is there a way to prevent this other than disabling FEC (which we don’t want).  

I look forward to your suggestions and comments.

Thank you in advance.

-Jon