Tue Nov 27, 2012 5:22 am
Canon 5D footage is encoded with H.264, a very CPU-intensive codec which cannot be passed onto the GPU. Alexa footage (assuming you mean Prores) is relatively easy to decode. LUTs, burn-in, and nodes are handled by the GPU, so those things probably make a minimal difference here. I'm guessing if you watch your CPU usage while transcoding the Prores, it will be low — a sign that something else is the bottleneck (probably the GPU).
While transcoding H.264, I'll bet your CPU usage is near 100%. If that's not the case, let us know, and there might actually be a problem.
Elliott C. Balsley
DIT, Colorist, Cinematographer
www.llamafilm.com