Thu May 02, 2013 1:29 pm
It likely has to do with the hardware onboard the camera, and yes, the royalties (Though DNxHD is supposedly free).
ProRes and DNxHD are both extremely similar wavelet codecs, so creating an ASIC that can encode in both formats is not probably not too hard (ie, if you can do one, the other is very easily implemented).
Most cameras that can record internally, likely only have the hardware for the codec of their choice, and how it's implemented. For example, DSLRs use H.264, but with a very poor implementation that is incredibly inefficient (48Mbits looks like that?). Sony's implementation is about half that, while looking far superior. Fact of the matter is, the codec is built into the hardware and cannot really be changed. The throughput might be an issue, but fast enough media should do the job.
It's ultimately up to what he manufacturer wants to do, and where the camera is aimed in the market. For the C300, the camera encodes in 4:2:2 MPEG-2 50Mbit, which is broadcast spec, while providing ample recording time compared to ProRes. Different needs really. I guarantee you that a well-crafted H.264 codec at the same bitrate would wipe the floor with it, however.