[Ffmpeg-devel] Re: [PATCH] PKT_FLAG_B

Michael Niedermayer michaelni
Mon Jul 31 20:04:33 CEST 2006


On Mon, Jul 31, 2006 at 07:42:40PM +0200, Baptiste Coudurier wrote:
> Hi
> Michael Niedermayer wrote:
> > [...]
> > 
> >> I also said I would be really OK for a better alternative and I asked
> >> you to propose one...
> > 
> > looking at the mov/qt specs i cant find any hits for ctts, do you have 
> > anything more recent which describes ctts?
> ISO media 14496-12 describes in details ctts and stts. Especially the
> fact that those can't be negative and that quicktime is creating non
> standard files with those negative 'ctts'.

of course cts must not be < dts  (which is the same as negative ctts)

> Stream copy workflow is not accurate, and sometimes pts/dts are wrong in
> the source or not set (AVI even with -genpts), and got wrongly written
> in output file.
> Basically what I would like to access the frame type explicitly for GXF
> muxer, and for MOV muxer, to write or not 'ctts' atom. Like I said,
> having access to AVCodecParser might be a good solution too.

hmm iam still not completely sure what you propose ...
but a muxer must use the timestamps given to it, if they are wrong than
they are, its not the muxers job to second guess them

if for example pts are wrong for x264 b pyramid and xvid then these
encoders / wrapers must be fixed, if they are wrong in the source
then the source should be fixed, maybe with some generic pts
recalculation like -genpts ...

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In the past you could go to a library and read, borrow or copy any book
Today you'd get arrested for mere telling someone where the library is

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