Ever since the the switch to the external ffmpeg I have suffered from these weird image artifacts when importing any video to Blender in either VSE or the compositor. It seems as if the scaling of the color channels is done wrong or perhaps it has something to do with the yuv to rgb conversion.

Anyway, here are some test images:
- Original test image, used to produce a static h264 video (attached) for the results below: http://www.pasteall.org/pic/3597

- How Blender opens and exports it: http://www.pasteall.org/pic/3596

- How the same video opens up in Avidemux: http://www.pasteall.org/pic/3598

- 400% crops from the images above: http://www.pasteall.org/pic/3599

This happens with all the video files I've tested, with many different codecs and resolutions. Although I must admit I haven't tested any 4:4:4 material.

This also happens only in Linux (Ubuntu 10.4, 64bit) and not in Windows (Vista, 32bit). I've tried multiple builds from GraphicAll and compiled Blender myself and always got the same results. I've also tried both Ubuntu repository and up to date SVN versions of ffmpeg and never have I got rid of this problem. (Although I have had a lot of problems getting them both compiled, but that's another story.)

I've tried to search the web for answers and similar problems, but haven't really found anything. Right now all I can think of is that this is a bug in Blender and effectively prevents all use of imported video.

I also believe the same artifacts are visible in the recent VSE video tutorial here: http://www.youtube.com/watch?v=yRwrEU6KDYY (for example the tree at 4:45)