Hello LiyenWang,
You can connect this camcorder to a "computer" directly using a USB cable to use the camcorder as a webcam. In the [System Setup] > [USB mode] menu item, select [UVC Output (UVC)]. You do not have to connect the camcorder with the HDMI cable in a case such as this. The HDMI connection is really just plug and play for the most part. Does your camcorder communicate via HDMI to a typical TV or monitor? If the connected monitor is not compatible with the signal output from the camcorder, then HDMI output will stop. You can check the different HDMI output options from the camcorder HERE starting on page 105. Also, try a different HDMI cable if you have not already.
