On the one hand, this seems like a pointless duplication to me, but it has a big effect:
My project setting is set to UHD, i.e. 4K. When I use Rotoscoping and Transform, this filter has no effect after rendering in FHD. The same goes for Spot Removal. But if I select Rescale: Enable before rendering, everything works as it should.
Why do you need Rescale when in the render dialog the resolution is already set to 1920x1080?
Is anyone familiar with Rescale? Can it always be used without hesitation?
Use Rescale only if you want to render a version of your project in a smaller resolution for testing or other interim purposes. This option was introduced to avoid having to change the project settings or create multiple copies of the same project for different dimensions.
So, not a permanent solution then?
Should the target resolution always be set in the project settings?
I’m only asking these questions because Rotoscope + Transform + Mask Apply don’t work if the resolution in the project settings is different from the one selected for rendering.
My recordings are in 4K, I only want to render in FHD, but I want to keep the option open to maybe render in 4K one day.
That said, if you want to keep your projects at 4K for future rendering in 4K, you can do so and use the Rescale function to create (Full) HD videos in the meantime. This is one of the interim purposes I mentioned.
Why shouldn’t you always use it for 4K projects if you only want to render in FHD for the time being?
Without Rotoscoping or Spot removal, I never had any problems if the project was 4K and I only rendered the video in FHD in the Render dialog, without using Rescale: Enable.
You set your project for the intended (target) resolution/dimension and fps. If you want your videos to be (Full) HD (1920 x 1080), select the appropriate project profile.
You can use sources of all sorts of dimensions, even 4K. Kdenlive adjusts the size automatically, or you can keep the original size and do all scaling manually.
When rendering your project using the project’s dimensions you do not need to use the Rescale option.
You can always change the project profile for an existing project but this may break effects or other things. Therefore, it is not recommended.
So, if you want to create (Full) HD videos for now but want to retain the possibility to render projects with 4K sources as a 4K video sometime in the future, I recommend to use a project profile for 4K video for editing. Then use the Rescale option in the render dialog to create (Full) HD videos.
Rescale ultimately determines the resolution during rendering, regardless of the resolution selected in “Render Preset.” Surprisingly, with “Rescale: Enabled,” the rendering time is 25% shorter than without it, with the same resolution in the render preset.
It seems that Rescale: Enabled only has advantages for me. Are there any disadvantages that I am not yet aware of?
Once enabled, you can specify the new (different) dimensions for the rendering. If you leave it at the same dimensions as your project file, it doesn’t make any difference.
But 25% faster rendering with “Rescale: Enabled” is a big difference.
And the effect of “Spot Removal” or “Rotoscope + Transform + Mask Apply” remains, which is not the case without Rescale if the project has a different dimension than the resolution in the render profile.
For me, Rescale is a wonderful discovery.
