Shotcut can not “pass through” or copy codecs without re-encoding. The closest thing available to that is Properties > menu > Extract sub-clip, which uses the in and out points of a trimmed clip.
Extract sub-clip will find the key frame closest to the in/out points and copy the codecs into a new container without re-encoding. Any filters applied to the clip will not be applied to the sub-clip because that would require re-encoding.
This feature has some limitations and may not always provide the expected result:
- The extraction will round to the nearest codec keyframe - which could be more than a second a way from the selected in/out points
- The extraction tries to pack the media into the same container format as the original. But it may not always be able to get the packing or timing to match the original