I have some video clips of skiing in flat light on a cloudy/foggy day recorder with GoPro2 under ProTune settings at 35 mbps (1920x1080 at 30fps)
The quality is amazing considering the light, and much better than my previous experience without ProTune.

But I struggle to render them after editing in Movie Studio v10.
I get some very subtle but annoying artifact of vertical bars in rendered video. I tried AVS mp4 (20 mbps is the highest available), m2ts (35mbps), and can't figure out what to do.

I realize this question also belongs to another sub-forum, but I want to figure out a workflow from Movie Studio, and ideally I want to avoid CineForm (too many steps ).

I'm asking for recommendations or workflow? (detailed please) .
Thanks.

. I tried AVS mp4 (20 mbps is the highest available), m2ts (35mbps), and can't figure out what to do.
Did you mean AVI?
Might be able to help a bit more Stanley if you mention where your video is ending up, DVD, Bluray, or just internet.
Are you down sizing?
Heres 2 options-
For web-
Render out a master from the Vegas timeline to DnxHD (free codec, Google it) in the same size as your project.
Drop into Handbrake (free program, again, Google is your friend). Let Handbrake do your down sizing and mp4 conversion.
For DVD-
Vegas does a pretty good job of resizing but if you want better, render out to Lagarith lossless codec and resize in Virtual dub then do your Mpg 2 conversion back in Vegas.
Handbrake and Virtual Dub can use the Lanczos scaling algorithm which is a little sharper than what Vegas uses. There is not much in it though, up to you if its worth the trouble.
Or,
spend some dollars and get TMPGenc, so you can render a visually lossless master from Vegas (DnxHD or Lagarith etc) and TMPGenc can make anything from DVD files to Bluray, to mp4 for web delivery, and again all scaled with the Lanczos algorithm. Great program.
Or,
theres lots of other ways as well..... :)

Although I'll be making 720p video for internet, I'm primarily after bluray-quality video.
I was hoping some settings in Sony Movie Studio could be adjusted, but you sound like third-part software is needed. That's not a great news because it makes the process more time consuming.

For now, I converted the original files into avi using CineForm. The files are huge, so I'll be trimming them in CineForm instead of in Movie Studio. I made some tests, and after importing the avi's into Movie Studio, and exporting as 20Mbps 1920x1080 mp4 (or 35Mbps mpg) the final video looks great.
At some point I should also try TMPGenc - sounds like it's a great program.
Thanks.