Screen capture resolution and sound sync issues

[thecenz1]

Hi,

My set up:
Sound recording: Zoom H6 used as audio interface via usb
Video recording: Canon EOS R mini hdmi output in 1080p, going through a usb adapter outputing 1080p
Graphic card GTX1660Ti

Scene:
1080p output
1 png image overlay (21Mb)
1 video capture scaled down to fit in a small corner
1 audio capture from the h6
1 display fullscreen capture

The screen is in UHD (1440p) downsized to fit the 1080p output.

Log attached, screen capture of the output video attached too.

Problem 1: the screen capture is of very bad quality as you can see in the printscreen. I have looked in the settings but nothing I can really tweak to improve. Should I downgrade the screen res to 1080p (would like to avoid that if possible and use OBS scaling instead)

Problem 2: video is out of sync. I check and hardware timestamps are not checked. It seems to be the video which is a bit behind (0.2s). I tried changing the color settings but it still lags behind.

Any help appreciated.

 

[carlmmii]

You did not include a screenshot, so we have no idea what you're talking about for "screen capture is of very bad quality".

For audio/video sync, you can't make video sources show earlier from within OBS, but you can delay other sources to match the delay. Start with delaying your audio by 200ms. Click the gear in the OBS audio mixer, select Advanced Audio Options. Set the offset to 200ms for your microphone source.

If you need to delay other video sources to match, right-click on the source, click Filters, and add an Async Delay filter (set to 200ms in your case).

 

[thecenz1]

sorry previous attachment was too large, here it is. You can see especially the tabs titles are very blurry

 

[carlmmii]

That level of compression is expected for CQP 23. You'll need to use a much lower CQP value to preserve sharp text.

The resolution situation shouldn't be much of an issue -- you're dealing with smooth text instead of fully pixelized characters, so it's much less of a problem. However, if you do notice that you're having issues with sharp/smooth pixel mismatching, you can try a different downscaling algorithm (lanczos/trilinear)… but the true solution is to record in the actual resolution of your screen to avoid the issue altogether.

You may also want to consider I444 if chroma subsampling becomes an issue. You would change this in the Advanced settings, and also have to change to x264 encoding since Nvenc only supports NV12 (which is 4:2:0).

 

[thecenz1]

Thanks, indeed this is much better (not in preview though, but doesnt matter much). I was already using lanczos. But indeed switching res to 1440p in the output gives a much better result.

If I select x264 I cannot use CQP, what rate would be good to avoid this smooth text effect?

For the video delay I guess it is the video adapter which is causing some lag, so by adding a delay to all other inputs that works fine now. Thanks.

 

[carlmmii]

CRF is the equivalent method for x264, I would suggest around 16 as a starting point.

 

[thecenz1]

thanks a lot, very helpful!

 

[koala]

The downscaling from 2560x1440 to 1920x1080 is what the letters make slightly blurry. If you want crystal sharp letters and lines like the original, you have to record the original resolution. Rescaling always introduces some kind of blurriness, regardless of upscaling or downscaling.