Birkley :
I'm having the exact same issue. I'm recording in 1080p in Shadowplay at 60fps and when i'm exporting with Premiere Pro using the h.264 codec i'm at minimum using 30mbps (max of 50mbps), but my videos still look grainy as shit at 1080p on Youtube. They look perfect locally, but after upload it looks awful.
My audio is at a 320kbps, so i'm going to try changing that to 128kbps and see if things improve. Have you had any more luck with different settings?
Yes. Actually found that there are a couple things going on:
1) Shadowplay records at a fixed bitrate of about 48k. If you re-encode the vid, try to do so using a complimentary multiple (like 24k) of this bitrate. Don't let your average bitrate fall below about 20k if you use a variable bitrate. Variable vs. fixed doesn't seem to make a big difference in size, but fixed still seems to end up looking a bit better in various areas on YT - the image seems to more randomly degrade if starting w/a VBR. I think the fact that YT's conversion uses a VBR algorithm results in to much random sampling and thus degrades quality. I suggest encoding no lower than a fixed 24k. The resulting YT video will not retain this, but it WILL look better than if you drop it to Google's suggested rate of 8200, even after upload to YT.
To summarize, I would avoid converting to a VBR, and avoid bitrates above 28,000 because it's not worth it; there is no apparent difference once it reaches YT.
2) YouTube will only run at 29.9 FPS, but you shouldn't change the frame rate from your original recorded during your encode process. Leave it at the EXACT FPS it was recorded at. Note that with Shadowplay, this does vary a bit; anywhere from 57-59.997 FPS so make sure you look at the file properties before encoding. If you re-encode to 30FPS you will end up creating visual distortion between frames as the resampling isn't smart enough (even in Vegas 12) to only pic frames with minimal motion blur.
3) There's no point to having the audio quality above 192k because YT will convert it anyway. Using 128 is probably fine. The other problem here is that Total Bitrate is affected by both video AND audio. The resulting Total Bitrate will be considered when YT downsamples. The higher your audio BR, the higher your TBR, the more YT will degrade video quality.
Also avoid surround; you should only bother uploading stereo audio as YT will convert it anyway and it will be much larger with 5.1 or 7.1.
4) Color quality should be set to Video, rather than expanded or similar settings. In Vegas it's just called "video levels".
5) Reference frames should be 2 or 4, not an uneven value and not less than 2. More than 4 is probably overkill.
6) For some reason, editing your video using YT's tools then re-saving on YT itself degrades the quality. Avoid using their tools. Also, they're buggy as shit.
7) There are various versions of the h.264 codec. Make sure the one you're using actually supports rendering for YouTube and streaming. There are settings in Vegas that actually allow the file to be encoded in such a way that it loads properly in YT.
An example of when this is done incorrectly is when you view a video on YT and see that it only buffers 5-10% past your viewing spot.
An example of when this is done CORRECTLY is when the video keeps loading (on the navigation bar) throughout play. This improves playback overall.
I have a video I recently uploaded following these guidelines. You'll see the quality is significantly better than the example I posted earlier in this thread:
http://www.youtube.com/watch?v=5P0Bkiu6ik4
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