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This code began as part of the ffmpeg package. I have left the
copyright notices and source file names unchanged, but they bear only
a limited resemblance to the original. Mostly, I have ripped out
coding that was intended to optimize the original for speed, and to
support anything other than encoding MPEG-1 format video, which is to
say almost all of ffmpeg is missing. My goals have been completely
orthogonal to those of the ffmpeg authors. I have to support yorick
on a wide variety of platforms, and I was unable to get ffmpeg to
build on many of them. I'm sure if I had been willing to do things
like build gcc in order to be able to build ffmpeg, I might have been
able to coax it to build on a few more systems. I only have a passing
interest in performance; anything within a factor of two of what
ffmpeg achieves is easily good enough. However, I need the code to be
absolutely portable and stable. The interface to ffmpeg was still
changing as of 0.4.9-pre1 enough to require rewriting any code which
called it in order to support newer versions (to allow for changes in
structs and so on). Eventually, I would like to move away from the
ffmpeg avcodec.h API to something much smaller, but I haven't
attempted that yet. Originally, I intended to make it so that the
caller (ympeg.c in this case) would have the option of linking against
the real ffmpeg shared library instead of this stripped version, but
even that limited portability is impossible when the avcodec.h API
changes incompatibly as new version are released.
In its current state, this library builds and works correctly on
pretty much the same paltforms where I can get ffmpeg to compile and
work, so I haven't really gained anything at all by the exercise,
except for independence from changes in ffmpeg on those platforms.
In short, this still doesn't work, and needs lots more work.
Dave Munro
27/Oct/2007
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