I would like to connect my Canon EOS R5C to AVio 4K to capture.
The R5C’s HDMI output seems to automatically switch between UHD and DCI.
When I connect the camera to AVio 4K, I get black margins at the edges of the screen. This means that even if I could capture in 4K, the image would be degraded because it would need to be enlarged.
Typically when black bars are seen this means the AVio4K is attempting to maintain the aspect ratio of an image when Preserve aspect ratio (enabled by default) is enabled.
If enabled, your AV.io 4K preserves the aspect ratio of your input signal by adding black bars to the sides or top and bottom of the frame (only for cases when the application using the signal requests a frame size with a different aspect ratio). For example, with this option enabled, a 4:3 input signal gets black bars added to the sides of the image when viewed in an application that requests a 16:9 aspect ratio.
Is it possible the Magewell is stretching the image?
You could try disabling Preserve Aspect Ratio with the AVio Configuration Tool, following this guide:
if the input resolution is showing 1080p, that is indeed what the camera is outputting. The AVio4K is only compatible with 8bit sources, and the Canon camera video output is manipulated by various camera settings. If I am familiar and from what I can see in the Canon manual, you may need to check you main recording format to mp4 (h264) to output 8bit from the HDMI output port.
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Otherwise, I would suggest reaching out to Canon support to see if they have any other suggestions.
