An io channel is an unlock for Input Channel and Output Channel
You also need io channel to remove watermark and upgrade resolution for video export.
An io channel can be purchased directly on the website of Smode: https://smode.fr/shop/i-o-channels/

No IOChannel

Video export - Resolution: 2048x1200 px
Video export - Formats: .mov, .mp4
Video export - Video Codecs: H264, HAP, HAPQ
Video export - Audio Codecs: AAC

1 IOChannel

2048x1200 px on Video Input Device
+
2048x1200 px on Video Output Device
+
32 full Universes for ArtNet or sACN
+
Video export - Resolution: 4096x2400 px
Video export - Formats: all
Video export - Video Codecs: all
Video export - Audio Codecs: all

2 IOChannel

4096x2400 px or 2x 2048x1200 px on Video Input Device
+
4096x2400 px or 2x 2048x1200 px on Video Output Device
+
64 full Universes for ArtNet or sACN
+
Video export - Resolution: Unlimited
Video export - Formats: all
Video export - Video Codecs: all
Video export - Audio Codecs: all
Render multiple views of a same scene in parallel. Particularly useful for 3D mapping Projects.

4 IOChannel

2x 4096 x 2400 px or 4x 2048x1200 px on Video Input Device
+
2x 4096 x 2400 px or 4x 2048x1200 px on Video Output Device
+
256 full Universes for ArtNet or sACN
+
Video export - Resolution: Unlimited
Video export - Formats: all
Video export - Video Codecs: all
Video export - Audio Codecs: all
Render multiple views of a same scene in parallel. Particularly useful for 3D mapping Projects.