[MEncoder-users] [BUG] non-deterministic PSNR calculation with -lavcopts threads=2

Michael Niedermayer michaelni at gmx.at
Wed Dec 7 19:22:24 CET 2005


On Tue, Dec 06, 2005 at 05:07:14PM -0800, Corey Hickey wrote:
> I'm currently in the final stage of preparing an lavc mpeg-4 mencoder
> command for Doom9: testing threads=2 and seeing how much quality is
> lost. I have a full encode going right now, but meanwhile I've been
> testing a short clip.
> Quality is visibly a bit lower on the clip I tested when two threads are
> used, but, oddly enough, the PSNR shown is not only about 4-5% higher,
> but varies somewhat each time I run mencoder. The output file is the
> same each time, however, so the encoding itself should be correct.
> I haven't used TOOLS/psnr-video.sh yet to see what the PSNR really is,
> but the variation didn't look right.

the variation should be fixed


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