I noticed when I export my footage at low bitrates (eg. 10 Mbps, 1080p), my 1080p footage looks way blurrier than my downscaled 4K footage.
This is despite the fact that the original footage looks similar in terms of sharpness when viewed at 1080p. Anyone knows what is the problem? This issue disappears at higher bitrates.
Another weird thing is that 10 Mbps 4K downsampled is actually sharper than 50 Mbps native 1080p? I can't get my head around this. I always thought the benefits of downsampling is only visible at high bitrates. Something about the low bitrate seems to affect the 1080p footage but not the 4K footage.
Have a look at the images below - no sharpening applied - tried to get roughly the same framing. Ignore my color grading, I know it's not that great.
Also, I'm using the latest version of Adobe Media Encoder. The 1080p footage in question is 120p if that matters, and the original 1080p footage has quite a low bitrate. However, as seen in the image below, despite the low bitrate, the original still looks relatively sharp.