Reusing first pass information in HD

[AlienTiger]

I have some HD video that im working on encoding, right now its about 8hr on my first pass and 14hr on the second pass

the first pass was run using the 1080 as 1080
ditto for the second pass

i would like to encode a smaller version as well, but avoid the 8hr first pass again

so i was curious if it was possible to reuse the first pass information that was ran in 1080 or if i would have to redo the first pass inputting my smaller size

[foxyshadis]

It's possible! Since first pass is mainly about the relative frame sizes rather than absolute sizes, it should work okay if you shrink a little. The rate distribution will probably be thrown off more the more you shrink it, and I'd assume that around DVD size it'd be much better to just rerun first pass. (It'll be quite a bit faster by then anyway.)

I have no data to back this supposition up, so it's possible than it'll be wildly incorrect even at 720p. Hard to say.