Backport of "avvidenc: Don't take ffmpeg timestamps verbatim but only use them to calculate DTS" into 1.22
requested to merge tpm/gstreamer:backport-mr-3780-into-1.22-avvidenc-dont-take-ffmpeg-timestamps-verbatim into 1.22
Backport of !3780 (merged) "avvidenc: Don't take ffmpeg timestamps verbatim but only use them to calculate DTS".
Commits: