Been playing with Canon's bitrates and I think I understand it better now.
"VBR (Qscale) mode" in 7D seems to be used kinda like constant bitrates or rather "limited range bitrates". For example, recording the same scene with the same exposure settings on Qscale(+16) recorded at 1-2Mbps, (+15) was 1-3Mbps, (+14) 2-3Mbps, (+13) 2-4Mbps and all the way up to 42-76Mbps for Qscale(+16). It's like limiting the entire VBR spectrum to a smaller range, then Qscale sets that range high, low or somewhere in between. The range gets wider with higher quality settings (lower number) but the important thing is that it brings the lowest possible bitrate up.
"CBR mode" I assumed takes the bitrate "range" that is set by Qscale then multiplies it by a number of your choice (2.0x, 3.0x, etc.). CBR mode also tries to automatically set the highest Qscale it can (which is -16) but if your card or buffer is too slow is starts to scale it back, I got Qscale(-16 to -10) in CBR mode with a FlushRate of 4 but a constant Qscale(-16) with a FlushRate of 2. But what I still didn't understand is why are my bitrates in "VBR mode" with Qscale(-16) the same as "CBR mode" with Qscale(-16) set to 20.0x?
I've recorded with this card at an avg 160Mbps so I know it's not a hardware limitation.
So does "CBR mode" not multiply Qscale, does it just increase the selected Qscale's range upward?
Is most of that right so far? Thanks for everyone's work and help here
