I have a client who is giving me 1920x1080 footage converted from MTS files and also a DVD that's 720x480 letterboxed. I need to use all footage in a timeline and output a 720x 480 quicktime file.
I've converted everything to pro res 422. The majority of the footage is 1920x1080. Would you edit in a 720 x480 timeline? In doing so all the 19201080 footage is red lined and needs to render to play it.
I'd edit in a 720/480 sequence. That way you can re-position your HD footage knowing what it will ultimately look like in the frame. Plus you won't be stretching (and then down-scaling) your smaller footage.