MPEG-4 ALS encoder

Last weekend, I started working on an mp4als encoder for FFmpeg. Here is a summary of what I have implemented so far.

• rice coding (slightly different from jpeg-ls)
• random access (progressive prediction order)
• lpc prediction with fixed order
• joint stereo
• entropy block partitioning
• constant and zero block modes

I have quite a bit left to do though for a complete encoder. What I have so far gets comparable compression to the RM20 reference encoder with default settings, and is 3x faster.

Here is a patch against FFmpeg SVN.