experimental win pthreads that ffmpeg currently uses have a few problems we’re trying to fix: notably that they “hang” every so often when encoding using libx264:

possible work arounds for now until we get this cleared up:

use an ffmpeg compiled “without pthreads”

http://x32.elijst.nl/FFmpeg-20120622.7z

or my own builds (feature requests welcome!)

http://rogerdpack.t28.net/incoming/ffmpeg_distros/

or use an “older ffmpeg” like this one:

http://ffmpeg.zeranoe.com/builds/win64/static/ffmpeg-20120409-git-6bfb304-win64-static.7z

(oops, that one was bad, too–this one seems ok though: http://ffmpeg.zeranoe.com/builds/win32/static/ffmpeg-git-dd1fb65-win32-static.7z but only if you use -threads 1 — some later builds fail even with -threads 1)

or compile your own using this cross compiler script (which currently doesn’t use the pthreads libx264, so isn’t broken):

https://github.com/rdp/ffmpeg-windows-build-helpers

here is a compile from there:

http://rogerdpack.t28.net/incoming/ffmpeg_distros/ffmpeg-distro-static-3865ec2acea976da695b9d4c8375d1af1449a446.7z try it out, let me know!