[XviD-devel] MPEG-4 Part 10

Char Acter charact3r at yahoo.com
Fri Mar 7 03:34:59 CET 2003


Dear xvid people,

You’ve probably all heard of H.264 (aka AVC, JVT,
MPEG-4 Part 10).  Basically it’s the new and better
video compression technology that outperforms MPEG-4
Part 2 currently used by xvid.

I am the creator of hdot264, a first attempt at an
open source VfW / DirectShow codec supporting H.264. 
I believe an open-source implementation like this
could be hugely successful, but it needs a lot of work
in order to get some decent performance from the
codec.  Right now hdot264 is 90% JVT reference code,
so it’s very slow.  (9% is reused xvid code). 
Recently I’ve been far too busy to do much work on
this project – hence this email appealing for help.

Since great things have happened with xvid over the
past months, and the xvid Part 2 codec is now quite
mature, I’m hoping that other developers with an
interest in video and optimization will be interested
in starting work on Part 10.

Xvid had the advantage of code from DivX Networks /
Project Mayo to give it a big kickstart.  The start of
any work on Part 10 will be much more painful.  I
believe we should start building an optimized decoder
first to give people some hope of playing content in
real time.  For now we can use other emerging codecs
(or hdot264) to make source for testing.

So, here’s what I propose:

Brief:  Implement a Part 10 decoder from the spec,
starting with the baseline and working up.  Reuse
xvid’s DS and VfW wrappers, colorspace conversions.

Home page:  It doesn't matter whether the codec lives
at ffmpeg, xvid or hdot264 so long as it's GPL and we
have developers :)

Language:  C 

Optimization:  Typically would have at least three
versions of every costly function...
* Slow C, very clear and readable and very close to
the spec.
* Optimized C, loops unrolled, C prefetches, other
clever tricks
* MMX/XMM/SSE/SSE2 - assembler in nasm format

License:  GPL + "defined API" clause and preferably
also MPL (to encourage companies who might help but
will not because GPL prevents them licensing the codec
legally) [btw, i don't want to get into a big
licensing discussion at this stage]

Documentation:  doxygen

Source control:  CVS (either based at xvid.org or
hdot264 on sourceforge)


Anyway, sorry for a long email, let me know what you
think :)

Char

[apologies for anonymity]


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