[FFmpeg-devel] [PATCH] Implemented arrange feature to convert from low timebase formats to high timebase

[Michael Niedermayer]

On Wed, Oct 17, 2012 at 11:34:58AM +0400, Roman Arutyunyan wrote:
[...]
>  AVRational av_codec_get_pkt_timebase         (const AVCodecContext *avctx);
> diff --git a/libavformat/utils.c b/libavformat/utils.c
> index 05c4b7f..0b59eeb 100644
> --- a/libavformat/utils.c
> +++ b/libavformat/utils.c
> @@ -3498,6 +3498,14 @@ static int compute_pkt_fields2(AVFormatContext *s, AVStream *st, AVPacket *pkt){
>      if(pkt->pts == AV_NOPTS_VALUE && pkt->dts != AV_NOPTS_VALUE && delay==0)
>          pkt->pts= pkt->dts;
>  
> +    if (st->codec->arrange_threshold && pkt->dts != AV_NOPTS_VALUE && st->pts.val != AV_NOPTS_VALUE){
> +        int64_t diff = pkt->dts - st->pts.val;
> +        int64_t maxdiff = av_rescale(st->codec->arrange_threshold, st->time_base.den, AV_TIME_BASE * (int64_t)st->time_base.num);
> +        av_dlog(s, "Arrange dts=%"PRId64" cur_dts=%"PRId64" diff=%"PRId64" maxdiff=%"PRId64"\n", pkt->dts, st->pts.val, diff, maxdiff);
> +        if (diff > -maxdiff && diff < maxdiff)
> +            pkt->dts = pkt->pts = AV_NOPTS_VALUE;
> +    }

this doesnt look correct. The correction should be done where the
problem is currently introduced. As done here , ffmpeg.c would send
some timestamps to the muxer but the muxer would use different
timestamps. its ffmpeg*.c or a common utility function used by
ffmpeg*.c where the correction should be done.

Currently timestamps are rounded toward "nearest", what should
instead be done, is to round toward the exact duration + last_time
see av_get_audio_frame_duration() to find the exact frame duration.

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The worst form of inequality is to try to make unequal things equal.
-- Aristotle
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