[Cin] Problem rendering Ogg format

I have a problem achieving consistent results when rendering with ffmpeg/ogg format - the bitrate of resulting video is always unpredictable: Example, set bitrate to 9000000 and result is blotchy, from good 20mbps source; set q=8 resulting bitrate varies each time Cin is started, can be very high, set q=7 or q=6 bitrate very high, even down to q=1 still high, then set back to q=7 and bitrate is at 8.5Mbps. some results I've had q=9 11mbps q=10 79mpbs q=5 107mpbs q=2 28mpbs q=7 11.5mpbs With ogg vorbis I used to succeed better. Wild bitrates only create huge files that are difficult to store. Quinton