FB now allows you to make a video for your Timeline Profile. The resolution is 820 x 312. I've created a project with those dimensions, but I'm experiencing a really weird problem.
I'm importing clips, bringing them into the project, hitting "Spacial Conform: Fill" - But the image is soft as hell. I'm bringing in nicely focussed 1080 and 4K footage, so I should have loads of resolution.
I'm transcoding all video to optimised, sharpening it up, it looks gross.
Resizing an image, still or video, pushes it closer to losing image quality. This happens faster in enlarging an image, and slower when shrinking an image, but still happens.
One of two things is happening. Either you are shrinking 4K image too small to maintain image quality. Or you are looking at during playback, and have your Quality setting in the View menu set to Better Performance. Or a little of both.
Or you judge your 820 x 312 image too much enlarged. Resolution is all about relative size. As Yedlin proved in his famous resolution myths debunked, there is also a threshold below which the human eye - from any reasonable viewing distance/fov - immediately realizes that there is too little texture detail. This is around 1080p. That means you can upscale full HD to, say, 5k (iMac display), and there will be no striking softness. Sharpening in post is good for very heavily downscaled images - when viewed in their native size - but counter productive when they are then upscaled by the player. The embossed edges then would be more than doubled in 1080, not to speak of UHD. You would sharpen downscaled images if you are positive about their absolute size, i.e. when you prepare them for print.
You wouldn't expect a FB profile to be watched much bigger than the pixel-accurate size. So you wouldn't need to sharpen it. That way, if someone zooms it up very much, it will become softer, but will have fewer artifacts.
Thanks to everyone for their input. I found the solution and thought I'd share it with you here.
I had 2 adjustment layers over the top of the images (copy pasted) from a previous project. When I disabled them, the image returned to normal sharpness. Not sure what the adjustment layers were doing, but they had the effect of making the pic extremely soft.