I'm trying to remotely start movie shoot on Canon T3 which is connect to a PC via USB cable. The moment I connect the camera to the PC, the live view gets disabled and thus I'm not able to start recording (The EDSDK command fails).
What should I do to avoid this?
to start movie recording you have to make sure that the camera is in movie mode (usually there is a physical switch on the camera). You can check if the camera is in movie mode with the PropID_Record property. It should have value 3 when the camera is ready.
Then, when you have opened a session you can show the live view either on the computer or on the camera by setting the appropriate value. You can set the live view output by using the PropID_Evf_OutputDevice property.
Let me know if you need something more specific or have a look at this article (although for C#, it might still be useful)