Workflow to fully preserve color quality in YV12?

[rebus_x]

Say I have some video file in a regular YV12 codec, like x264 , that I need to edit in NLE.

Right now I know that Premiere can read and output videos in YUV pixel formats, but looks like that's about it. Vegas is said to use RGB on output (render). Debugmode Frameserver page quickly states that all NLEs apart from Premiere do the same (use RGB).

My intention would be to shove my video into NLE directly as YUV and output as YUV, so that no RGB->YUV conversions take place.
Maybe i don't understand something? It seems strange that NLEs convert to RGB at all, i mean, their creators would surely know that most probably leads to quality loss, right?

If i'm correct to want to do that, then - is Premiere the only NLE that works in YUV?
If not - then where am i wrong and how do i go about this?

[poisondeathray]

Some open source NLE's such as kdenlive, shotcut can work in YUV too

YUV to RGB can be lossless if you work in float 32bit . This preserves negative RGB values and losslesss roundtrip back to YUV. BUT - the up/down chroma sampling from/to 4:2:0 must be done using nearest neighbor algorithm to be lossless, otherwise there will be sampling errors. It's complicated to get it working in RGB programs, and you often have to use other programs to do it properly , such as vapoursynth -because most NLE's do not give you the control required over the chroma sampling algorithm used, and some have issues with float support. You need to use EXR float or TIFF float sequences for the intermediates (large file sizes even with compression)

[rebus_x]

Some open source NLE's such as kdenlive, shotcut can work in YUV too

Thanks, I'll be trying kdenlive. And thanks for the conversion info