On Fri, Sep 6, 2019 at 4:10 PM Jun Li <junli1...@gmail.com> wrote: > Fix #7637 > One empty/end sample is created and inserted between two caption lines > when there is a gap. > This patch is to split the sample into multiple ones when its duration is > too long (>= INT_MAX). > --- > libavformat/movenc.c | 24 ++++++++++++++++++------ > 1 file changed, 18 insertions(+), 6 deletions(-) > > diff --git a/libavformat/movenc.c b/libavformat/movenc.c > index edddfeeb00..aeb7de351f 100644 > --- a/libavformat/movenc.c > +++ b/libavformat/movenc.c > @@ -5746,7 +5746,8 @@ static int mov_write_packet(AVFormatContext *s, > AVPacket *pkt) > * > * 2) For each subtitle track, check if the current packet's > * dts is past the duration of the last subtitle sample. If > - * so, we now need to write an end sample for that subtitle. > + * so, we now need to write one or multiple end samples for > + * that subtitle. > * > * This must be done conditionally to allow for subtitles that > * immediately replace each other, in which case an end sample > @@ -5760,11 +5761,22 @@ static int mov_write_packet(AVFormatContext *s, > AVPacket *pkt) > int ret; > > if (trk->par->codec_id == AV_CODEC_ID_MOV_TEXT && > - trk->track_duration < pkt->dts && > - (trk->entry == 0 || !trk->last_sample_is_subtitle_end)) { > - ret = mov_write_subtitle_end_packet(s, i, > trk->track_duration); > - if (ret < 0) return ret; > - trk->last_sample_is_subtitle_end = 1; > + trk->track_duration < pkt->dts) { > + int max_duration = INT_MAX - 1; > + if (trk->entry == 0 || !trk->last_sample_is_subtitle_end) > { > + ret = mov_write_subtitle_end_packet(s, i, > trk->track_duration); > + if (ret < 0) return ret; > + trk->last_sample_is_subtitle_end = 1; > + } > + if (trk->last_sample_is_subtitle_end && > + pkt->dts - trk->track_duration > max_duration) { > + int64_t dts = trk->track_duration; > + while(pkt->dts - dts > max_duration) { > + dts += max_duration; > + ret = mov_write_subtitle_end_packet(s, i, dts); > + if (ret < 0) return ret; > + } > + } > } > } > > -- > 2.17.1 > > Some details: Current implementation will insert one empty sample whenever there is a gap between two captions lines. But when the gap's duration is way too big, the sample's duration will exceed MP4's limitation, thus mov muxer will fail on function check_pkt.
This patch is to guarantee that, every empty samples' duration not exceed INT_MAX-1, and insert multiple ones when the gap is bigger than INT_MAX-1. Test results: Fate test passed. Also tested with following SRT file with cmd: ffmpeg -i input.mp4 -i input.srt -c copy -c:s mov_text test.mp4 -y I used Apple's QuickTime player, confirmed that the caption shows up at the correct time. "input. srt" as follows 1 00:35:47.484 --> 00:35:50.000 Durations that exceed the signed int max value break the program 2 00:40:47.484 --> 00:40:50.000 Durations2 that exceed the signed int max value break the program 3 00:50:47.484 --> 00:50:50.000 Durations3 that exceed the signed int max value break the program 4 02:50:47.484 --> 02:50:50.000 Durations4 that exceed the signed int max value break the program 5 03:50:47.484 --> 03:50:50.000 Durations5 that exceed the signed int max value break the program _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".