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ffmpeg: honor -ss and -t parameters with muxed subtitles. 

This patch fixes two things:

 - in case of subtitles, check_recording_time() is comparing the current
   PTS to the recording time (-t option, set to INT_MAX by default), so
   the -ss option needs to be taken into account. It is not required in
   do_{audio,video}_out() because this adjustment is set while polling
   the filtergraph (see poll_filters()).

 - It also adjusts the PTS sent to the encoder (and later transmitted to
   the muxer) so the TS in the output make sense and are not kept
   verbatim.

Note: this only works for muxers honoring the PTS, such as
lavf/matroskaenc. But for other such as the ASS muxer which just does a
verbatim copy, or the SubRip muxer which doesn't write the TS in some
cases, it will not work yet.
This commit is contained in:
Clément Bœsch 2012-08-01 18:39:46 +02:00
parent c99d3e2e6c
commit 53a3748ed2
1 changed files with 5 additions and 2 deletions
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ffmpeg.c
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@ -1683,12 +1683,15 @@ static void do_subtitle_out(AVFormatContext *s,
else
nb = 1;
/* shift timestamp to honor -ss and make check_recording_time() work with -t */
pts = av_rescale_q(pts, ist->st->time_base, AV_TIME_BASE_Q)
- output_files[ost->file_index]->start_time;
for (i = 0; i < nb; i++) {
ost->sync_opts = av_rescale_q(pts, ist->st->time_base, enc->time_base);
ost->sync_opts = av_rescale_q(pts, AV_TIME_BASE_Q, enc->time_base);
if (!check_recording_time(ost))
return;
sub->pts = av_rescale_q(pts, ist->st->time_base, AV_TIME_BASE_Q);
sub->pts = pts;
// start_display_time is required to be 0
sub->pts += av_rescale_q(sub->start_display_time, (AVRational){ 1, 1000 }, AV_TIME_BASE_Q);
sub->end_display_time -= sub->start_display_time;