[FFmpeg-devel] [PATCH v4] avformat/movenc: split empty text sample when duration overflow

[Jun Li]

On Mon, Oct 7, 2019 at 6:36 PM Jun Li <junli1026 at gmail.com> wrote:

>
>
> On Mon, Oct 7, 2019 at 6:34 PM Jun Li <junli1026 at 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)
>>
>> Signed-off-by: Jun Li <junli1026 at gmail.com>
>> ---
>>  libavformat/movenc.c                          | 26 ++++++++++++++-----
>>  tests/fate/subtitles.mak                      |  6 +++++
>>  tests/ref/fate/binsub-movtextenc-long-dur     |  1 +
>>  .../fate/binsub-movtextenc-long-dur-timebase  |  1 +
>>  4 files changed, 28 insertions(+), 6 deletions(-)
>>  create mode 100644 tests/ref/fate/binsub-movtextenc-long-dur
>>  create mode 100644 tests/ref/fate/binsub-movtextenc-long-dur-timebase
>>
>> diff --git a/libavformat/movenc.c b/libavformat/movenc.c
>> index 715bec1c2f..5dc2a19c3c 100644
>> --- a/libavformat/movenc.c
>> +++ b/libavformat/movenc.c
>> @@ -5750,7 +5750,8 @@ 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
>> @@ -5764,11 +5765,24 @@ 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;
>> +                    }
>> +                }
>>              }
>>          }
>>
>> diff --git a/tests/fate/subtitles.mak b/tests/fate/subtitles.mak
>> index 0042902161..4c2b34c431 100644
>> --- a/tests/fate/subtitles.mak
>> +++ b/tests/fate/subtitles.mak
>> @@ -34,6 +34,12 @@ fate-sub-movtext: CMD = fmtstdout ass -i
>> $(TARGET_SAMPLES)/sub/MovText_capabilit
>>  FATE_SUBTITLES-$(call ENCDEC, MOVTEXT, MOV) += fate-binsub-movtextenc
>>  fate-binsub-movtextenc: CMD = md5 -i
>> $(TARGET_SAMPLES)/sub/MovText_capability_tester.mp4 -map 0 -scodec mov_text
>> -f mp4 -flags +bitexact -fflags +bitexact -movflags frag_keyframe+empty_moov
>>
>> +FATE_SUBTITLES-$(call ENCDEC, MOVTEXT, MOV) +=
>> fate-binsub-movtextenc-long-dur
>> +fate-binsub-movtextenc-long-dur: CMD = md5 -i
>> $(TARGET_SAMPLES)/sub/WebVTT_movtext_long_dur.vtt -map 0 -scodec mov_text
>> -f mp4 -flags +bitexact -fflags +bitexact -movflags frag_keyframe+empty_moov
>> +
>> +FATE_SUBTITLES-$(call ENCDEC, MOVTEXT, MOV) +=
>> fate-binsub-movtextenc-long-dur-timebase
>> +fate-binsub-movtextenc-long-dur-timebase: CMD = md5 -i
>> $(TARGET_SAMPLES)/sub/WebVTT_movtext_long_dur.vtt -map 0 -scodec mov_text
>> -time_base 1000 -f mp4 -flags +bitexact -fflags +bitexact -movflags
>> frag_keyframe+empty_moov
>> +
>>  FATE_SUBTITLES_ASS-$(call DEMDEC, MPL2, MPL2) += fate-sub-mpl2
>>  fate-sub-mpl2: CMD = fmtstdout ass -i
>> $(TARGET_SAMPLES)/sub/MPL2_capability_tester.txt
>>
>> diff --git a/tests/ref/fate/binsub-movtextenc-long-dur
>> b/tests/ref/fate/binsub-movtextenc-long-dur
>> new file mode 100644
>> index 0000000000..eb8a3f8fc7
>> --- /dev/null
>> +++ b/tests/ref/fate/binsub-movtextenc-long-dur
>> @@ -0,0 +1 @@
>> +7f78c11bb4a6b16335540ef31ba10219
>> diff --git a/tests/ref/fate/binsub-movtextenc-long-dur-timebase
>> b/tests/ref/fate/binsub-movtextenc-long-dur-timebase
>> new file mode 100644
>> index 0000000000..185dcc0aab
>> --- /dev/null
>> +++ b/tests/ref/fate/binsub-movtextenc-long-dur-timebase
>> @@ -0,0 +1 @@
>> +349d78698cc1226d33d4e6699dbf46d9
>> --
>> 2.17.1
>>
>>
> Test file attached.
>

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