[FFmpeg-devel] GSOC update on the CDXL demuxer

Michael Niedermayer michaelni
Tue Apr 14 20:42:53 CEST 2009

On Tue, Apr 14, 2009 at 08:19:21PM +0200, Reimar D?ffinger wrote:
> On Tue, Apr 14, 2009 at 02:09:36PM -0400, Ronald S. Bultje wrote:
> > On Tue, Apr 14, 2009 at 2:02 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> > > the format has chunk size and previous chunk size, it has width&height&sample
> > > rate per chunk, assuming these dont change you have a shitload of things you
> > > can check
> > 
> > It doesn't have sample rate. Palette size can change since it doesn't
> > have to be there.
> Hm, I just noticed the current demuxer doesn't handle that...
> It might complicate things a bit for the video support.
> Does anyone know if it's allowed to mix different encoding methods in a
> CDXL file?
> > All I can think of is matching w/h or prev size to
> > current size, but that requires two packets, which is much more than
> > the max probe size that we use right now. Chunks are >10kb. Probe size
> > is 4kb, IIRC.
> Probe size is whatever the application provides. 32kB for MPlayer,
> FFmpeg I think increases probe size if it does not get a match but I do
> not know the limit.

the probe buffer size increasing is done in av_open_input_file()
if mplayer limits that somehow, this is a bug in mplayer ...

the size is increased from 2k -> 1mb currently until a high enough
score is returned
Its perfectly fine thus if a demuxer needs 1mb for probing to be
successfull although of course a demuxer should try very hard to
do it with the smallest amount

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Breaking DRM is a little like attempting to break through a door even
though the window is wide open and the only thing in the house is a bunch
of things you dont want and which you would get tomorrow for free anyway
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