[Ffmpeg-devel] Re: [PATCH] mov muxer vfr

Erik Slagter erik
Wed Jul 5 14:00:04 CEST 2006

On wo, 2006-07-05 at 13:42 +0200, Michael Niedermayer wrote:
> > With lavf api, chunk will contain many raw samples, and so have a long
> > duration, I could store each chunk duration but, according to quicktime,
> > CBR audio must have a compressed "stts" of one element, since raw
> > samples have all a duration of 1. If you don't do that it simply does
> > not work in quicktime.
> iam not sure what you are saying here ...
> do you mean some encoders concatenate multiple packets into a single
> AVPacket or that
> Quicktime handles CBR as if each byte would be a packet? or something
> else?

Just my $0.02, maybe I'm completely off, but you never know...

The sample durations (afaik for either audio and video) are encoded
using some sort of run length encoding (at least with newer .mp4
versions, don't know for mov). For cbr this would mean the complete
sample durations list would collapse into a single entry. Apparently
quicktime doesn't like it when this run length encoding is not
performed. And from Baptiste's comment I understand this approach is not
easy to implement in lavf...

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