Stereoscopy/deliver bug - extreme aliasing - and workaround
Posted: Thu Apr 25, 2024 8:20 amThis affects side-by-side (SBS) or over-under (OU / TB / top-bottom) stereoscopic movie exporting. Rather than resampling the images, Resolve is dropping lines.
Extreme example - Resolve viewer on left, exported SBS movie on right. Even without zooming into the screenshot here, you can see the "i" and "l" are missing from Title:
Or exported as Top/bottom - note the missing crossbar on the "e" in Title:
Both these stereoscopic formats anamorphically squash two images into a single frame by scaling either the width or the height of the footage by 50%. Resolve seems to be doing this by discarding every other line of the images, doing no filtering / averaging at all.
To reproduce:
No need for any example footage; you can see the problem by creating a stereo timeline and dropping in something finely detailed (like the ultrathin font in the example above). Then on the Delivery page, under Render Stereoscopic 3D, choose Both eyes as Top and bottom or Side by side. The rendered movie will be missing every other line of horizontal or vertical pixels.
Workaround:
Don't use Resolve's SBS / TB options for Stereoscopic 3D movie export; instead, export as separate files, then stack and squish them afterwards. This can be done with ffmpeg (which means it can be automated) - ping me if you need help.
tags: aliasing SBS stereoscopic detail fizzing 3D export deliver
Extreme example - Resolve viewer on left, exported SBS movie on right. Even without zooming into the screenshot here, you can see the "i" and "l" are missing from Title:
- Screenshot 2024-04-25 at 08.58.35.png (483.58 KiB) Viewed 624 times
Or exported as Top/bottom - note the missing crossbar on the "e" in Title:
- Screenshot 2024-04-25 at 09.06.56.png (143.19 KiB) Viewed 624 times
Both these stereoscopic formats anamorphically squash two images into a single frame by scaling either the width or the height of the footage by 50%. Resolve seems to be doing this by discarding every other line of the images, doing no filtering / averaging at all.
- This only affects the exported file; on the Deliver page, if you have the viewer window set to side-by-side monitoring, the image appears to be scaled/filtered properly.
- I'm guessing this hasn't been caught because it's most noticeable on fine detail like hair or CGI, not on general camera shots
- And when actually delivering a stereoscopic film, it'll almost always be done using separate per-eye files, not a composite like SBS. But SBS etc are incredibly useful for production previews - means you can check the depth/convergence etc in a VR headset
- What makes this worse is that each eye will often see different hot and cold pixels from the aliasing, creating a harsh fizz around detail
- This is unaffected by the "Force sizing to highest quality" switch
To reproduce:
No need for any example footage; you can see the problem by creating a stereo timeline and dropping in something finely detailed (like the ultrathin font in the example above). Then on the Delivery page, under Render Stereoscopic 3D, choose Both eyes as Top and bottom or Side by side. The rendered movie will be missing every other line of horizontal or vertical pixels.
Workaround:
Don't use Resolve's SBS / TB options for Stereoscopic 3D movie export; instead, export as separate files, then stack and squish them afterwards. This can be done with ffmpeg (which means it can be automated) - ping me if you need help.
tags: aliasing SBS stereoscopic detail fizzing 3D export deliver