[Ffmpeg-devel] FFmpeg Roadmap
Colin Ward
lists
Thu Feb 2 08:12:44 CET 2006
Tim Allen wrote:
>> So can someone say once and for all, why is it so difficult to get
>> correct pts values from .mov files when they work for all other formats?
>
> I'm not that familiar with the ffmpeg mov demuxer, but I can make a
> general comment, which is that the frame rate and pts in a mov file tend
> to be defined in at least two, sometimes three, different places (the
> wrapper header, the track headers, and sometimes embedded in the tracks
> themselves), and in practice they don't always agree. I've seen files
> which have one or the other correct, and the other incorrect, with no
> real consistency about which is definitive. I've also seen cases where
> both are approximately correct, but different from each other, and
> neither seems to be exactly correct. So I'm not in the least surprised
> that the ffmpeg demuxer has a hard job getting it right.
I am not surprised about that, as it is an old file format that has
been refined over the years. Having assisted in the development of a
couple of file formats myself I know what it is like to add changes
while retaining downward compatibility - what a pain!
But my point is that the algorithm that client code uses to convert
the information returned by decoding a packet, into a timestamp, works
for all file formats except .mov and that needs to be fixed, regardless
of the difficulties that the demuxer/parser has in obtaining that
information. Currently I can't get the correct timestamps for *any*
Quicktime movie!
--
/-------------------------------------------------------------------\
[Hitman/Code HQ - 6502/z80/68000/604e/80x86/ARM coder - Amiga rulez!]
[VZ-200/VIC-20/MZ-700/c16/c64*10/c128*8/Plus-4/CPC464/CD32/500*2 ]
[600/1000/1200*2/A4000/SNES/N64/Dreamcast/Athlon 1100/AmigaOne ]
[Assembly Language: The most fun you can have with your clothes on! ]
\-------------------------------------------------------------------/
More information about the ffmpeg-devel
mailing list