Blurry Stream when downscaling from 1440p to 1080p

[HamsterBBQ]

Hello everyone,

I am trying to stream at 1080p 60fps with OBS and I want to get the best quality possible.
I have 2 monitors, both 1440p, and I play games in fullscreen 1440p.

When I try to record (using the streaming encoder settings) at 1440p 60fps I get crystal clear image, everything is perfect.
But when I change in Video settings the output resolution to 1080p and Lanczos (36 samples) I get a blurry image.
I also tried to have the canvas at 1080p and output 1080p so there is no downscale in the Video settings but it is still blurry.

What is the best practice when downscaling and how can I improve the quality to have a nice 1080p 60fps streaming downscaled from 1440p?

SOME INFO
1. I have RTX 3090 and Ryzen 5950x
2. The GPU Max FPS is set to 120 to prevent overloading
3. The image is blurry even if I just record the desktop, so I assume is a rescale thing since there is no action on the desktop, just a static image

Clear log following the OBS instructions: https://obsproject.com/logs/txf1Al884sH9cbdX

Thank you!

 

[koala]

Any downscaling will make your image slighly blurry. This is because the original pixels have to be reduced to less pixels, but there is an odd ratio: 2560 to 1920 is an 1.3333:1 ratio or 4:3. That means, 4 original pixels are reduced to 3 pixels. Every 4 pixels are distributed over 3 pixels. This makes the image slightly blurry. The downscaling algorithm tries to minimize the effects, but it cannot avoid the effect completely.

If you want a crystal clear recording, you need to record with the same resolution as the source image was created, i. e. 2560x1440.

With streaming, if you want a cystal clear stream and you want a 1920x1080 stream, you need to switch the desktop or game (if you're streaming a game) resolution to 1920x1080, so no downscaling will take place, and stream this way. The funny thing is, you will perceive this as slightly blurry on your local monitor, because the monitor will upscale this to its native resolution, and this will create blurriness as well. But anyone who watches your stream with a media player using exactly 1920x1080 as resolution will see a crystal clear video.

Given the fact that many people will consume streams in a windowed player, not fullscreen, so rescaling will take place on the client side anyway, so blurryness is intruduced within the player, you should't try too hard to get a crystal clear stream only a minority will see anyway.

You should only make sure you choose a UI/Text size large enough so your viewers can still read it even downscaled.

 

[HamsterBBQ]

Any downscaling will make your image slighly blurry. This is because the original pixels have to be reduced to less pixels, but there is an odd ratio: 2560 to 1920 is an 1.3333:1 ratio or 4:3. That means, 4 original pixels are reduced to 3 pixels. Every 4 pixels are distributed over 3 pixels. This makes the image slightly blurry. The downscaling algorithm tries to minimize the effects, but it cannot avoid the effect completely.

If you want a crystal clear recording, you need to record with the same resolution as the source image was created, i. e. 2560x1440.

With streaming, if you want a cystal clear stream and you want a 1920x1080 stream, you need to switch the desktop or game (if you're streaming a game) resolution to 1920x1080, so no downscaling will take place, and stream this way. The funny thing is, you will perceive this as slightly blurry on your local monitor, because the monitor will upscale this to its native resolution, and this will create blurriness as well. But anyone who watches your stream with a media player using exactly 1920x1080 as resolution will see a crystal clear video.

Given the fact that many people will consume streams in a windowed player, not fullscreen, so rescaling will take place on the client side anyway, so blurryness is intruduced within the player, you should't try too hard to get a crystal clear stream only a minority will see anyway.

You should only make sure you choose a UI/Text size large enough so your viewers can still read it even downscaled.

Thank you so much for answering. This made me understand more how it works.

Basically I will have to keep the game at 1080p and to prevent downscaling I have to set the canvas and output to 1080p.

I guess I will keep it 1440p -> 1080p for a while and see how it goes. It's good to hear that is not a GPU problem or something and it's just the downscaling effect.

Thank you!

 

[Karambol2K]

I have the same concern...

I have 1440p monitor and play high motion games and when there is no action and picture is steady, its crystal clear. Once i move it's soup of pixels on my screen...

I won't downscale my game to 1080p bcs my eyes hurt...

The only way is to either change base resolution in obs to 1080p and adjust the screen in obs to fit in. Or set it to 1440p and output resolution to 936p or even lower... But it will never be perfect as bitrate is limited to 6000 for casual streamers...

It's such a pain...