Weird auto focus behaviour / focus issues

[olafvangerwen]

Dear people,
I stream using GoPro Hero4 cameras. When I do, the video feed seems soft or unsharp in some areas. The software seems to detect static areas and makes those out of focus, see attached screenshot: the left of frame is soft. When I put my hand in, the hand becomes sharp.

I can't find what it is! I know it's not the camera, because when I capture se same stream in Quicktime, it doesn't happen.
Hope someone can help?
Cheers,
Olaf

 

[olafvangerwen]

Annnnny one pls????

 

[AaronD]

It could actually be that the background is out of focus and the foreground is in focus. If the camera has a large aperture, to let in a lot of light, then the depth of field becomes shallow, so that only a thin plane is in focus. If that's where your hand is, then it'll be sharp while the doors in the distance are not.

Another possibility is that you have a lot of sensor noise because it's amplified a lot, to try and make better use of what little light gets in. Noise is effectively uncompressible, and so the encoder detects it and smooths it out first. The result of that smoothing looks a lot like soft focus.

If you really want to preserve sharp focus, then you'll have to allocate a lot of bits to describing the noise, which either adds to the data rate or takes away from everything else. If that's okay, then you can either:

• Increase the quality to just add those bits, or:
• If you have an option for "Grain", or "Animation", or "Film" presets, among others, then you might try the "Grain" one. That makes it less aggressive in detecting and smoothing noise, so that more of the available bits go towards that and less towards everything else.

Another option might be to use a physically larger camera, to let in more light in the first place. *That* is why professional fixed-mount cameras are so big. Their huge lenses capture a lot of light, which gives a lot more options. A small camera in the same environment might be doing all it can just to get a picture at all, nevermind a particular shot.

 

[olafvangerwen]

Thanks a lot. BUt,, it's a gopro. There is no focus whatsoever - everything is sharp, because of the tiny sensor. And as described, these artifacts do not happen when I open that exact same stream in QT.

 

[AaronD]

And as described, these artifacts do not happen when I open that exact same stream in QT.

Are you actually encoding in QT? Either streaming or recording to a file? If you're only showing it on the screen, then it's completely uncompressed, with no encoding artifacts except for what the camera itself or a capture card might do.

OBS should also show you in the moment, what it's actually getting. The preview window is similarly uncompressed, only scaled to fit its allotted space.
Where did your screenshot come from? The stream or recording? Or from OBS's window?