audioencoder: timestamp headers same as first buffer and use duration 0
Submitted by Håvard Graff (hgr)
Created attachment 310164
It makes sense that the headers being pushed out just before the first buffer should be timestamped like the first buffer.
As for duration 0, I think this makes more sense then -1, and plays nicer with muxers etc.
Patch 310164, "patch":