[opus] Question about FEC and ogg/opus

[Boris Grozev]

Hello,

We have a use case where we want to record an opus RTP stream to a .opus
file. We want to fill in any gaps in the stream, and we also want to
take advantage of inband FEC whenever possible.

The ogg/opus draft describes[1] how to fill in gaps by generating
zero-byte frames, but I do not understand how (and if) FEC can be used.
Is this possible, and if so, what is the recommended way of doing it?
Which component(s) would be responsible for handling FEC: the muxer
(e.g. by extracting FEC data from a previous packet and inserting this
instead of a zero-byte frame), the ogg player (by calling the opus
decoder with decode_fec=1 whenever necessary), or the opus decoder itself?

I failed to find any information about this specific topic. Please point
me to relevant documentation if it exists.


Thanks,
Boris

[1] http://tools.ietf.org/html/draft-ietf-codec-oggopus-03#section-4.1