Hi Ryan,
Definitely don’t let the websites do the compression – we’ve had good results with this formula:
1. Render the material out as ProRes (DNX 175 should also work) and check that you are happy with that render by reviewing it in Resolve on your video display (we view in rec.709 gamma 2.2)
2. Get the maximum quality upload specs from the video site, I strongly recommend Vimeo Plus/Pro over youtube: https://vimeo.com/help/compression
3. Compress that ProRes using compressor or similar program (I’ve been satisfied with compressor, some use handbrake) into H264 using those specs, then bring the resulting h264 into Resolve and compare against the original.
4. If you’re happy with the h.264, upload it and it should not recompress (or at least, only to create different resolution and bandwidth versions).
Definitely consider the presentation on the website. There will be a difference in perception of the blacks viewing against a black, gray, or white background. Also, one thing I like about Vimeo is the ability to limit the interface and customize the colors on the embed.
A lot of people are viewing now on devices with adjustable brightness, so if you are worried about crushed blacks, you might want to have some color bars or other reference that you can check displays with.
Cheers,
KC
Prehistoric Digital