Kdenlive currently only has “per Project” settings. This doesnt reflect well the reality of AV Production, where it has become standard to export derivates of one av “product” for other distribution channels with individual format & aspect ratio requirements. The variety of formats, however unfortunate, is a reality, especially in social media.
IRL you will encounter:
16:9
9:16
1:1
4:5
etc.
It is already possible to choose cropping and aspect ratio on export in kdenlive, but this is not enough: a program edited for 16:9 commonly needs to be reframed, clip by clip, to accomodate for the vastly different framing. Often clips need to be animated with “pan and scan” type of motion to fit a piece of content into the new format.
This also applies to Motion-Graphics, subtitles etc. If a text layout was positioned on a 16:9 screen, cropping it to 9:16 will make it illegible. Resizing the 16:9 sequence to 9:16 by accepting black bars on top and bottom will make the text too small to read.
The only “workaround” at the moment seems to be to create projects for each desired format and cut and paste the sequence content in the differently formatted projects. From a UX pov this is not great since it leads to inevitable organizational overhead and often chaos.
Kdenlive should support “per Sequence” settings in one Project to accomodate for the different format requirements of todays world.
There’s some simple things that would be relatively easy to improve, for things that are only “project settings” and not per-sequence because they predate sequences even Being A Thing - like the metadata used when rendering.
But having per-sequence profiles is going to need much more significant foundational work to really work as it should - it is however often raised and I believe somewhere on the One Day map. It’s not quite as simple as just moving that to per-sequence configuration, because a powerful feature of sequences is the ability to nest them, and until multiple profiles are supported together on the timeline, nesting sequences with different profiles is going to be A Problem.
For “one project, multiple aspect rendering” to really be able to work well, we probably want something like an “intermediate format” timeline profile, that gives a workspace which is the superset of all the desired output profiles, and possibly considerably larger (think working with 8k raw clips for an intended final render to 4k or 1080p scale sizes) - but then lets you select an animatable viewport of that working space to render rather than just simply rescaling and cropping the whole frame to the selected final aspect and size.
It should be possible to crudely “sort of” do that now as another “workaround” - but until some of the issues with working with a profile that doesn’t match your source clips are sorted out, that’s probably not going to be a whole lotta fun.
What you want is coming, but it’s not an “it will be here tomorrow” amount of work to get it here.