[FFmpeg-devel] [PATCH v3] avformat/movenc: split empty text sample when duration overflow

[Carl Eugen Hoyos]

Am Di., 10. Sept. 2019 um 21:12 Uhr schrieb Jun Li <junli1026 at gmail.com>:
>
> 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 ++++++++++++++-----
>  tests/fate/subtitles.mak                      |  6 +++++
>  tests/ref/fate/binsub-movtextenc-long-dur     |  1 +
>  .../fate/binsub-movtextenc-long-dur-timebase  |  1 +
>  4 files changed, 26 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 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;

Please add two CRLFs and I am threatening to push this.

Carl Eugen