Convert to ProRes or render on ProRes timeline

Sorry for a 'back to basics' question but I need some guidance.
I have a project with a whole lot of mixed format footage that I want to edit in FCP7.
Now on a smaller project the conventional wisdom is to use compressor to convert everything to 422 and then bring it into FCP7 and put on 422 timeline/sequence.

However, time and storage space is an issue for this project. So, do I have to use compressor for hours to change it all to Pro Res 422 or could I just drag the original clips (xdcam / H264 etc) from the browser on to a ProRes 422 timeline in FCP and render them? Would that now be a 422 quality sequence?

I can imagine that it would require quite a bit of re-rendering if I started overlaying clips, color tweaking etc but if the settings of the sequence are saying ProRes422 and all the clips are happily rendered and playing on that timeline.... is it, or is it not a PR422 sequence?

What are the implications?

Now I'm presuming that when you take the Compressor route, Compressor is actually un-compressing H264/xdcam footage and therefore increasing the quality of the image, whereas simply re-rendering it on a 422 timeline you are creating a playable but basically still 'compressed' version of the footage. ?


However, is there not times when a project might not need the higher quality (the original footage looks fab and it's only gonna be delivered online), but it's handy and problem-free to edit in PR422 ?

If it's H.264, edit on an H.264 timeline.

ProRes will not lose any image quality, but it will not "add" anything, either. Can't add what isn't originally there.

Thanks for your response. I've seen so many people saying that everything should be converted to ProRes but couldn't see if this was for quality or for a (potentially) smoother editing experience.

However, I'm still interested in this image quality question which I'm hoping you can expand on. Accepting that H264 is a compressed format for acquiring footage and will edit far better (less potential glitches - processing needed etc) when it's transcoded to PR422... is it actually the case though, that the transcoded image quality is no 'better' than the original?

Logic would say that another layer of processing seldom improves quality. OR does the transcoding through Compressor literally 'unpack' further picture information that is compressed within the file? Thereby improving image quality AS WELL as making it an easier format for FCP7 to handle ?

However, I'm still interested in this image quality question which I'm hoping you can expand on. Accepting that H264 is a compressed format for acquiring footage and will edit far better (less potential glitches - processing needed etc) when it's transcoded to PR422... is it actually the case though, that the transcoded image quality is no 'better' than the original?

Like Ben said, you can't put things that aren't there.
However, the difference may be in the end result. ProRes material is much better at handling compositing, and color correction. So if you just string out a few clips on the timeline and export, you get nothing from transcoding; but if do a complicated edit with a lot of CC, for example, how each codec withstands it may make or break your end result.

Ah ha. That's great. I get it now.
I feel a lot more confident about choosing different work flows for different projects now.

Thanks for that guidance - it's surprising just how difficult it's been looking round the inter web to get a straight answer, so many thanks.