7D H.264 bitrate tops out at ~55 Mbps regardless of CBR setting

[Thomas Worth]

I installed Alpha 2 on my 7D to see how far I could push the H.264 recording bitrate. However, ML refuses to shoot anything more than about 48-55mbps ("Q-16" in top right corner) at 1080p/24 no matter how high I jack up the CBR setting. It looks as though the camera tries to shoot at a high bitrate, but then "drops back" to the low bitrate after about 1 second. I don't get any warning or anything. The benchmark reports the card is capable of 56.8 MB/sec writes, which is of course well over 400 Mbit/sec. I even checked the files out of the camera and they are indeed no more than around 50 Mbit/sec.

Is this a limitation of the H.264 encoder in the 7D? Does it top out at ~50 Mbit/sec at 1080p/24?

[deletedAcc.0021]

try changing scene complexity.