If I want to export just the last minute of a feature-length DCP to ProRes, I set "Trim from start" to 1 minute before then end of the DCP, before using Job -> Export.

When making a DCP from a DCP source, DCP-o-matic knows to skip decoding of frames which won't be used in the output. But when using Job -> Export, it appears that DCP-o-matic does efficiently seek to the start position before starting decoding.

At least, that's my guess as to what's happening. Observed behaviour is that "Transcoding" sits on "Encoding 0%, 0/1500 frames" for a very long time. CPU usage is very low during this time, so maybe it's not actually decoding the frames - but it's doing something for a long time before it gets to the actually producing any output.

I can't confirm if it ever gets to point of producing output, as I gave up waiting. But if you set trim in point to 10 minutes, and duration to 1 minute, it sits apparently idle for about 5 minutes with "Encoding 0%" before it starts producing output and then advances quickly up to 100%.

If it's relevant, in this case the source DCP is 4K, and I'm exporting as 2K ProRes.