tree 0de5d1b2888541ddc14edce039268d64481479bd
parent 75e50c3141c5e3f96110fcab5fb819736dcdc62e
author Andreas Rheinhardt <andreas.rheinhardt@gmail.com> 1579327520 +0100
committer Andreas Rheinhardt <andreas.rheinhardt@gmail.com> 1587450980 +0200

avformat/matroskaenc: Redo handling of FlagDefault

Up until now, the Matroska muxer would mark a track as default if it had
the disposition AV_DISPOSITION_DEFAULT or if there was no track with
AV_DISPOSITION_DEFAULT set; in the latter case even more than one track
of a kind (audio, video, subtitles) was marked as default which is not
sensible.

This commit changes the logic used to mark tracks as default. There are
now three modes for this:
a) In the "infer" mode the first track of every type (audio, video,
subtitles) with default disposition set will be marked as default; if
there is no such track (for a given type), then the first track of this
type (if existing) will be marked as default. This behaviour is inspired
by mkvmerge. It ensures that the default flags will be set in a sensible
way even if the input comes from containers that lack the concept of
default flags. This mode is the default mode.
b) The "infer_no_subs" mode is similar to the "infer" mode; the
difference is that if no subtitle track with default disposition exists,
no subtitle track will be marked as default at all.
c) The "passthrough" mode: Here the track will be marked as default if
and only the corresponding input stream had disposition default.

This fixes ticket #8173 (the passthrough mode is ideal for this) as
well as ticket #8416 (the "infer_no_subs" mode leads to the desired
output).

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>