Merge libavcore into libavutil
Done to keep ABI compatible. Otherwise this is just silly
Use the new libavcore audio channel API.
This also allows to remove a linking dependency of libavfilter onlibavcodec.
Originally committed as revision 25789 to svn://svn.ffmpeg.org/ffmpeg/trunk
Add asrc_anullsrc - null audio source.
Based on a patch by "S.N. Hemanth Meenakshisundaram" smeenaks!ucsd!edu.
Originally committed as revision 25188 to svn://svn.ffmpeg.org/ffmpeg/trunk