Thomson announced last night that their Film Grain Technology for MPEG-4 has (finally) been approved for mandatory inclusion in HD DVD products. We say finally because they've been showing this off since 2004, and it was originally not approved by the DVD Forum
for mandatory inclusion back in February 2005. No word on what has changed between then and now, or exactly when the Steering Committee met and approved it, but it's in there now
). Currently this technology is only included for use with the h.264 codec, although they indicate it could be added to support other compression solutions, like VC-1 for example.They remove all trace of film grain before the movie is compressed, then the player recreates the effect during playback. Beyond just adding a different visual feel, they claim this will also enhance compression and lower necessary bitrates for high definition content further. This AVS Forum thread
provides much useful information on the effect of film grain and Thomson's technology.