[FFmpeg-devel] [PATCH] simplify ipmovie.c pts calculation

[Michael Niedermayer]

On Thu, Feb 26, 2009 at 11:01:26PM +0100, Reimar D?ffinger wrote:
> On Thu, Feb 26, 2009 at 09:37:53PM +0100, Michael Niedermayer wrote:
> > it should at least realize that 8341/125000 can represent them exactly
> > a patch that runs gcd over them is welcome
> 
> Something like attached patch? It should work fine for all files that
> actually are constant-frame-rate and have an exact time-base.
> It works great for .mve files, but I haven't tested it well and I won't
> (I'm supposed to learn for exams :-) ).

> 
> > also a patch that lets the user app configure its threshold of acceptance
> > a little would be welcome, for example
> > transcoding a file with 1/10000000 timebase to avi reqiures a smaller
> > timebase and it should select the best it can.
> 
> Hm, I think it's actually large duration values, not large time bases
> that causes problems, isn't it?

of course


> diff --git a/libavformat/utils.c b/libavformat/utils.c
> index 073e6da..9960fcd 100644
> --- a/libavformat/utils.c
> +++ b/libavformat/utils.c
> @@ -2006,6 +2006,7 @@ int av_find_stream_info(AVFormatContext *ic)
>      AVStream *st;
>      AVPacket pkt1, *pkt;
>      int64_t last_dts[MAX_STREAMS];
> +    int64_t duration_gcd[MAX_STREAMS]={0};
>      int duration_count[MAX_STREAMS]={0};
>      double (*duration_error)[MAX_STD_TIMEBASES];
>      int64_t old_offset = url_ftell(ic->pb);
> @@ -2127,6 +2128,7 @@ int av_find_stream_info(AVFormatContext *ic)
>                      double error= dur - ticks*1001*12/(double)framerate;
>                      duration_error[index][i] += error*error;
>                  }
> +                duration_gcd[index] = av_gcd(duration_gcd[index], duration);
>                  duration_count[index]++;
>              }
>              if(last == AV_NOPTS_VALUE || duration_count[index]<=1)
> @@ -2181,6 +2183,8 @@ int av_find_stream_info(AVFormatContext *ic)
>              if(st->codec->codec_id == CODEC_ID_RAWVIDEO && !st->codec->codec_tag && !st->codec->bits_per_coded_sample)
>                  st->codec->codec_tag= avcodec_pix_fmt_to_codec_tag(st->codec->pix_fmt);
>  
> +            if (duration_count[i] > 5 && duration_gcd[i] > 1)
> +                av_reduce(&st->r_frame_rate.num, &st->r_frame_rate.den, st->time_base.den, st->time_base.num * duration_gcd[i], INT_MAX);

maybe this should be under tb_unreliable() and the number should be higher
than 5 (patch ok with  <- these)

also if you ignore the first 1-2 durations then this might fix the fps of
h264_acc_in_flv.flv i think

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

Thouse who are best at talking, realize last or never when they are wrong.
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