[FFmpeg-devel] [PATCH 07/10] avformat/mux: Remove pointless timestamp backups

[Marton Balint]

On Tue, 31 Mar 2020, Andreas Rheinhardt wrote:

> write_packet() currently saves the original timestamps of the packet it
> got and restores them in case writing fails. This is unnecessary as none
> of write_packet()'s callers make any use of these timestamps at all. So
> remove this and add a general comment to the function that timestamps
> may be modified; also remove a long outdated comment about side data.
>
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> ---
> Actually, doing the timestamp backups in write_packet() never made much
> sense: Timestamps may also be modified before the packet reaches
> write_packet(). Furthermore, backups for av_interleaved_write_frame()
> don't make sense at all, so these backups should have been performed in
> av_write_frame().
>
> libavformat/mux.c | 12 ++----------
> 1 file changed, 2 insertions(+), 10 deletions(-)
>
> diff --git a/libavformat/mux.c b/libavformat/mux.c
> index be7652c97b..acb71b30c9 100644
> --- a/libavformat/mux.c
> +++ b/libavformat/mux.c
> @@ -670,8 +670,7 @@ FF_ENABLE_DEPRECATION_WARNINGS
> #endif
> 
> /**
> - * Make timestamps non negative, move side data from payload to internal struct, call muxer, and restore
> - * sidedata.
> + * Make timestamps non negative and call muxer; the original pts/dts are not kept.
>  *
>  * FIXME: this function should NEVER get undefined pts/dts beside when the
>  * AVFMT_NOTIMESTAMPS is set.
> @@ -681,10 +680,6 @@ FF_ENABLE_DEPRECATION_WARNINGS
> static int write_packet(AVFormatContext *s, AVPacket *pkt)
> {
>     int ret;
> -    int64_t pts_backup, dts_backup;
> -
> -    pts_backup = pkt->pts;
> -    dts_backup = pkt->dts;
>
>     // If the timestamp offsetting below is adjusted, adjust
>     // ff_interleaved_peek similarly.
> @@ -760,10 +755,7 @@ static int write_packet(AVFormatContext *s, AVPacket *pkt)
>             ret = s->pb->error;
>     }
> 
> -    if (ret < 0) {
> -        pkt->pts = pts_backup;
> -        pkt->dts = dts_backup;
> -    } else
> +    if (ret >= 0)
>         s->streams[pkt->stream_index]->nb_frames++;
>
>     return ret;

LGTM, thanks.

Marton