Otherwise the codec context and codecpar might disagree on the codec id,
triggering asserts in av_parser_parse2.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
(cherry picked from commit 98b3a797)
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>