add valid statistics for the RTCP receiver report.
Basically taken verbatim from RFC 1889.
Patch by Ryan Martell % rdm4 A martellventures P com %
Original thread:
Date: Oct 31, 2006 12:43 AM
Subject: [Ffmpeg-devel] [PATCH] RTCP valid receiver statistics....

Originally committed as revision 6879 to svn://svn.ffmpeg.org/ffmpeg/trunk
