[Ffmpeg-devel] Re: mpeg samples with first pkt dts -1 and motion estimation weirdness

Michael Niedermayer michaelni
Tue Aug 8 23:42:32 CEST 2006


On Tue, Aug 08, 2006 at 10:49:02PM +0200, Baptiste Coudurier wrote:
> >> Here is a sample with first pkt with dts as -1. That is problematic for
> >> other formats (mov, gxf)
> > 
> > the -1 is not a real bug, you can add some (scaled) constant to all
> > timestamps to avoid the problem if you like, if you have some other
> > suggestion on how to solve it dont hesitate to tell me ...
> > but strictly speaking it is correct, the thing is that if you want
> > some frame displayed at time= 0 then you must have a dts<0 if you
> > use b frames
> Can we have a flag or something that prevent those negative dts and
> and treat them in av_write_frame or something ? I already see that code
> needed for mov and gxf muxer.

ive no objections as long as iam not the one who will write it, one
problem with it though will be that a +1 in one stream timebase wont
be representable in another in general ...

> OK, I understand, however that stream only contains only contains P
> frames, and dts/pts are different, but parser should set has_b_frames so
> that will be fine.

the parser will set has_b_frames=1 if any pts differs from dts at least
if the file isnt broken, iam not sure if thats what you want ...

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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