Using an HDMI encoder is a great way to add a DSLR camera, camcorder or action camera to your broadcast. Details on choosing an HDMI encoder can be found here.
If your HDMI encoder is showing up as camera choice in Ecamm Live, but no video is displayed from the camera:
For Blackmagic devices, refer to these troubleshooting steps.
Try connecting the camera's HDMI cable to a television or display to make sure it's providing an HDMI signal.
If the encoder requires USB 3.0, ensure that your Mac has USB 3.0. If you're using a USB hub or multi-port dock/adapter, ensure that it supports USB 3.0. (Note that some multi-port adapters may have both USB 2.0 ports and USB 3.0 ports.)
If you're using a USB hub or multi-port adapter, try disconnecting other devices from the hub to rule out a power level issue.
Ensure that the HDMI encoder supports your camera's resolution and frame rate. Each HDMI encoder supports a range of video resolutions and frame rates. For example some encoders may not support 1080p60, while others support up to 4K resolution. Ensure that your camera is providing an HDMI resolution and frame rate listed in the encoder's technical specifications.
Try a different camera if possible.
Try a different HDMI cable if possible.
Try a different USB cable, especially if it's a USB-C cable. Not all USB cables transfer data. For example, the USB-C cable that Apple provides with MacBooks is for charging only.
For connecting a 4K camera, check these steps.