The latest ffmpeg versions include a workaround to deal with a certain pecularity in Canon DSLR footage: instead of decoding pictures with the proper resolution of 1920x1080 they decode it with 1920x1088 and add a black bar at the bottom. Needless to say, that this screws up things in a lot of areas within blender (proxy indices, mask animations etc.) Since all blender versions besides Linux x86 32bit seem still to include older ffmpeg versions which still contain this bug, this patch adds a workaround for older versions until we have all versions on all platforms up to date. See also: http://git.libav.org/?p=libav.git;a=commit;h=30f515091c323da59c0f1b533703dedca2f4b95d