interpolations, since they are always 16-bytes aligned in practice.
Add asserts to ease narrowing down potential image corructions on exotic plateforms

Based on a patch by Mauricio Alvarez % lokifo A gmail P com %
Original thread:
Date: Jun 26, 2007 1:07 PM
Subject: Re: [FFmpeg-devel] [PATCH] h264 luma interpolation 8x8 for altivec

Originally committed as revision 10238 to svn://svn.ffmpeg.org/ffmpeg/trunk