John, heres a quote from Wil (a tech from Adobe) explaining why PrP doesn’t export in the same manner that FCP did…
What you’re looking for is what we commonly refer to as smart rendering, and it doesn’t exist in PPro. That’s a Final Cut ‘ism, where it splices rendered data from the preview QT files into the final render. Keep in mind that’s a QuickTime centric feature, & doesn’t translate automatically to all file formats.
The ‘Use preview files’ option in PPro is exactly that – if there’s a preview file, it decodes the frame out of it, & re-encodes it into the final file. So while it’ll help in (non-CUDA) effects heavy compositions, it also incurs a generation loss. Generally, we don’t recommend using it (hence the default to off) unless you really are sure that’s what you want.
Tom Daigon
Avid DS / PrP / After Effects Editor
http://www.hdshotsandcuts.com
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