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

Baptiste Coudurier baptiste.coudurier
Thu Jul 6 10:27:03 CEST 2006


Michael Niedermayer wrote:
> [...]
> so with "48000, 1" you mean QT handles 1 single packet which when decoded
> would produce 48000 samples as if the packet actually could be split into
> 48000 decodable pieces of duration 1?
> now iam curious what byte sizes QT wants for these non existant 48000
> samples?
> [...]

Well I have absolutely no clue how quicktime handles that. I can only
guess. Atm the mov demuxer reads fixed sample size (stsz) audio by
chunk, check how many samples the chunk contain and then compute
duration based on "stts" atom. I think quicktime does the same thing.
That make sense.

Why "non existant" ?

I know FCP stores space for 48048 samples in each chunk for uncompressed
audio. I think quicktime computes byte size using stsd audio v1 first
(qdm2, adpcm), else based on fourcc it assumes a sample size.

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