Use PHP or Flash to extract a frame from a video

The quick question: is there a pure PHP library that can extract开发者_运维技巧 a frame from the video to use as the thumbnail? I guess the answer is "no" but let me know if I am wrong :-) ffmpeg wrappers will not go, since I want this feature to work on most hostings without special PHP modules or binaries to launch.

There might also be some tool to do this on the client side with flash for example... This also acceptable. I'll just have to upload the flash-generated content to the server.

This script claims to be able to do it just by using GD