Opus Pre Skip is exported in AVCodecContext->delay similar to how
it is done for matroska. Doing the same for ogg too.
Signed-off-by: Vignesh Venkatasubramanian <vigneshv@google.com>
Reviewed-by: Nicolas George <george@nsup.org>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>