Hi all,

I'm working on 3D (stereo) movies. For this, I need to first combine left and right video streams (format: MP4 from GoPro) and render them to intermediate files, so I can apply (cross)fades and other effects properly. The question now is what file format to use for this. As all video formats are lossy, repeated re-coding degrades quality, isn't it? Is there a 'RAW' video format best used for this, or are the losses negligible?

As far as I remember, DNxHD http://en.wikipedia.org/wiki/DNxHD_codec comes to my mind. However, I never woked with it so far, but saw it mentioned several times. You may find some old postings in this forum.

Ah, thanks for the tip! I'll give it a try.
Looks like there is no defined render profile for it - just several for transcoding (single) input files. Seems the only way to add render profiles is to hand-edit the profiles.xml?

Nope. Enter Kdenlive settings, then default settings. You should see a wrench icon, click on it and it will transfer you to a dialog titled "Manage profiles". In this dialog you can easily create new profiles, not only for proxies but also for rendering. Otherwise, look at the render dialog, it also offers creating new profiles.

Oops - I really overlooked the icon in the render dialog
I did look in settings, though, and there I could only edit project profiles or transcode targets - that's why I started looking in the xml file
Thanks again for putting me on the right path!

viewtopic.php?f=272&t=117706&p=293991&hilit=DNxHD#p293991 this thread describes how to set up render profile, parameter-wise.