Parse the ASMRuleBook SDP line to dynamically create one new AVStream for
each "rule" described in the ASMRuleBook. Each rule represents a stream
of identical content compared to other streams in the same rulebook, but
with a possibly different codec/bitrate/etc. See "[PATCH] rdt.c: ASM
rulebook parsing and AVStream creation" thread on mailinglist.
Originally committed as revision 16466 to svn://svn.ffmpeg.org/ffmpeg/trunk