Re: [FFmpeg-devel] [PATCH v3 1/4] avformat/movenc: fix assert failure in get_cluster_duration()

["\"zhilizhao(赵志立)\"" <quinkblack@foxmail.com>]

Ping.

> On Dec 31, 2021, at 7:36 PM, Zhao Zhili <quinkblack@foxmail.com> wrote:
> 
> When editlist is disabled, the workaournd method of shift dts to
> zero and increase the first sample duration doesn't work if the
> timestamp is larger than mp4 spec restriction (e.g., sample_delta
> in stts entry). Further more, it triggers get_cluster_duration()
> assert failure. This patch will drop large offsets between
> multiple tracks.
> ---
> libavformat/movenc.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/libavformat/movenc.c b/libavformat/movenc.c
> index 0f912dd012..f5bb785b01 100644
> --- a/libavformat/movenc.c
> +++ b/libavformat/movenc.c
> @@ -5917,7 +5917,18 @@ int ff_mov_write_packet(AVFormatContext *s, AVPacket *pkt)
>          * to signal the difference in starting time without an edit list.
>          * Thus move the timestamp for this first sample to 0, increasing
>          * its duration instead. */
> -        trk->cluster[trk->entry].dts = trk->start_dts = 0;
> +        if (pkt->dts + pkt->duration <= INT32_MAX) {
> +            trk->cluster[trk->entry].dts = trk->start_dts = 0;
> +        } else {
> +            /* Impossible to write a sample duration >= UINT32_MAX.
> +             * Use INT32_MAX as a tight restriction.
> +             */
> +            trk->start_dts = pkt->dts;
> +            av_log(s, AV_LOG_WARNING,
> +                   "Track %d starts with a nonzero dts %" PRId64
> +                   " which will be shifted to zero\n",
> +                   pkt->stream_index, pkt->dts);
> +        }
>     }
>     if (trk->start_dts == AV_NOPTS_VALUE) {
>         trk->start_dts = pkt->dts;
> -- 
> 2.31.1
> 
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