Hi there. Working on a MacBook Pro 15 inch, 2016 v 12.2.1
iphone footage shot in filmic pro with no effects added.
Footage plays pretty smooth in the source monitor but when put into a new sequence it has the yellow unrendered line and stutters. I have to render each clip to get it to play smooth with a green line.
Transcode to ProRes and work in a Sequence with the Video Previews also set to ProRes and you'll see no color line above your footage - this is, you won't have to render footage that has no effects added. You'll also benefit from Smart Rendering (things will be faster).
So, if you transcode to ProRes 422 LT, make sure your Sequence is also set to ProRes 422 LT. If using a recent version of Premiere Pro, you'll get this automatically when you create a new SEquence from a ProRes source clip.
Depending on your iPhone model, you may be able to shoot ProRes directly.
Thank you. I really appreciate all this. I'm shooting 4K - 10 bit in the Filmic Pro app on a 13 pro max using the most up to date Premier Pro, would you still suggest trascoding to ProRes 422 LT (I'm assuming using The Adobe Media Encoder?) Everything I read suggests that I leave it be.