[FFmpeg-devel] Patch: CrystalHD decoder support

Philip Langdale philipl
Tue Dec 28 23:36:02 CET 2010

On Tue, 28 Dec 2010 23:22:30 +0100
Aurelien Jacobs <aurel at gnuage.org> wrote:

> On Tue, Dec 28, 2010 at 09:46:17AM -0800, Philip Langdale wrote:
> the usleep man page don't even mention _GNU_SOURCE, so no, it is not
> needed. Here is what is used in other places in ffmpeg:
> #define _XOPEN_SOURCE 600
> In ffmpeg we try to stay POSIX compliant and we avoid all the
> non-standard GNU extensions.

Thanks for pointing that out. I'll switch it over.

> Is there any advantage at all ?
> fast_memcpy() might even be slower than memcpy() depending on the CPU
> and the libc you use. And if fast_memcpy() is faster than memcpy() in
> some situations, then the optimizations should be ported inside the
> libc instead of duplicating it in every single projects.
> In any cases, if you want to push such an "optimization", you surly
> need to show some timming comparison to advocate it.

My tests are hardly rigorous - but in the context of the original
native mplayer decoder it seemed that I should use it - it's used in
various other places in mplayer that need to copy uncompressed frames
around. But if this kind of dependency is frowned upon, I have no
problem leaving it out.



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