[FFmpeg-user] Avid DNxHD QTs dropped/doubled frame problem

[Michael Root]

> Thanks a lot, Mike.

Happy to be of service.

> I applied that patch to ffmpeg from git as of an hour ago, compiled,
> and it did indeed produce a DNxHD36 Quicktime that imported in to our
> Avid without the problems I was seeing before.
>
> So, is this an ffmpeg bug, or an Avid bug?

As far as I'm concerned, it's a Quicktime bug--meaning, the entire format itself 
is an unholy mess of things that are undocumented, half implemented, or wrongly 
implemented.  For what it's worth, I don't think it's an Avid problem--If I 
remember correctly, qtpro was doing the same thing.


> If the former, was this patch submitted to the ffmpeg-devel list?  Any
> idea why it hasn't yet been merged in, or an equivalent fix made since
> the problem has been identified?

It hasn't been submitted to ffmpeg-devel.  I only just got on the ffmpeg-user 
list the other day.  Don't usually have the bandwidth...  I'll add myself 
though.  Got some "fun" questions about DNxHD colorspace. :)

-miker

> Here is the patch again against current ffmpeg source.
>
>
> --- libavformat/movenc.c.orig   2011-08-25 15:19:22.000000000 -0400
> +++ libavformat/movenc.c        2011-08-25 15:24:42.000000000 -0400
> @@ -1392,7 +1392,10 @@
>       avio_wb32(pb, 0); /* size */
>       ffio_wfourcc(pb, "trak");
>       mov_write_tkhd_tag(pb, track, st);
> -    if (track->mode == MODE_PSP || track->flags&  MOV_TRACK_CTTS || track->cluster[0].dts)
> +    if (track->mode == MODE_PSP ||
> +        track->flags&  MOV_TRACK_CTTS ||
> +        track->cluster[0].dts ||
> +        track->enc->codec_id == CODEC_ID_DNXHD)
>           mov_write_edts_tag(pb, track);  // PSP Movies require edts box
>       if (track->tref_tag)
>           mov_write_tref_tag(pb, track);
>
>
> Thanks again.
>
> -J
>
>
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