Compressor 4.4.6 Exporting Final Cut timeline at wrong bitrate

Update: I can correctly export a ProRes 422 Master File from FCPX. Running this through compressor still produces a capped bitrate (this time slightly higher at 7mbs). I'm now wondering if it is because the majority of the image is the PiP presentation, which is from a screen capture, so not high quality. It seems as though the data rate you input in Compressor is a target rate, but that it will be ignored if it is deemed unnecessary. But rather than allocate extra data rates for the full screen bits of the talking head, it still caps those at 5-7mbps.

Running the ProRes 422 Master file through Adobe Media Encoder with a target of 20mbps provides me with a correctly compressed MP4 file, at the bitrate I actually asked for.

Hi Al,

Yes it is changeable and active. It just has no effect. Convinced it is just analysing the project and overruling me. If I remove the PiP presentation from the export, and just output the talking head footage at full screen it behaves correctly. The PiP image is a fairly low bitrate screen recording, so I wonder if Apple just thinks it can override the target bitrate based on what's "required".

If you could point me how to do so in compressor when exporting to MP4 that'd be great? Unfortunately, the compressor UI does not seem to show me whether the end video would be VBR or CBR (unless it is hidden somewhere I haven't found yet?)