What is your target output format?
Some notes about Shotcut:
- Shotcut is not field aware - it only operates on whole frames
- Some effects in Shotcut require it to deinterlace the video
- Deinterlacing in Shotcut (either explicitly specified by the user or implicitly by using a filter that requires it) will lose half of the temporal resolution.
Shotcut handles interlaced sources “fine” as long as you output the same format (resolution and scan type) or if you don’t mind losing half the temporal information (e.g. output 30fps progressive).
As a result, I choose to never edit interlaced source files in Shotcut. The last time I had a need to edit 480i source files, my target output format was 720p60. So I used ffmpeg to perform a high-quality deinterlace/scale to lossless 720p60 intermediate files. I then did my editing on the intermediate files.