[FFmpeg-devel] [PATCH v2] avformat/mov: fix timecode with counter mode flag set

[Mark Reid]

On Sat, Jan 16, 2021 at 5:48 PM <mindmark at gmail.com> wrote:

> From: Mark Reid <mindmark at gmail.com>
>
> The current behaviour ends up squaring the avg_frame_rate if the conter
> mode flag is set.
> This messes up the timecode calculation, and looks to me as a regression
> that
> seems to have been introduced 428b4aac.
>
> Upon further testing is seems that no special case is need for having the
> counter flag set.
> av_timecode_init appears to handles the timecode correctly, at least in
> the sample files
> I have.
>
> Here is a sample mov file with the counter flag set
> https://www.dropbox.com/s/5l4fucb9lhq523s/timecode_counter_mode.mov
>
> before the patch ffmpeg will report the timecode as:
> 00:37:11:97 and warns that the timecode framerate is 576000000/1002001
>
> after patch:
> 14:50:55:02
>
> ---
>  libavformat/mov.c | 13 -------------
>  1 file changed, 13 deletions(-)
>
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 3215b53636..f8856a43dd 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -2350,19 +2350,6 @@ FF_DISABLE_DEPRECATION_WARNINGS
>              st->codec->time_base = av_inv_q(st->avg_frame_rate);
>  FF_ENABLE_DEPRECATION_WARNINGS
>  #endif
> -            /* adjust for per frame dur in counter mode */
> -            if (tmcd_ctx->tmcd_flags & 0x0008) {
> -                int timescale = AV_RB32(st->codecpar->extradata + 8);
> -                int framedur = AV_RB32(st->codecpar->extradata + 12);
> -                st->avg_frame_rate.num *= timescale;
> -                st->avg_frame_rate.den *= framedur;
> -#if FF_API_LAVF_AVCTX
> -FF_DISABLE_DEPRECATION_WARNINGS
> -                st->codec->time_base.den *= timescale;
> -                st->codec->time_base.num *= framedur;
> -FF_ENABLE_DEPRECATION_WARNINGS
> -#endif
> -            }
>              if (size > 30) {
>                  uint32_t len = AV_RB32(st->codecpar->extradata + 18); /*
> name atom length */
>                  uint32_t format = AV_RB32(st->codecpar->extradata + 22);
> --
> 2.21.1 (Apple Git-122.3)
>
>
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