How to run pjsua with null-video and record the incoming video into a file without opening any camera and display device?

Question

I need to run the pjsua application for video call and which needs to do the following

1. Play video from a file for transmission.
2. Record the received video into a file.
3. It should not try to open any camera or display device.

The reason for the above constraints is because the pjsua application will be used in an automated testing environment.

I could find out how to Play video from a file. That is, to provide the command line option to pjsua as --play-avi=<avi_file>.

Can anyone provide any help regarding point 2 and point 3? Do I need to create a null-video functionality as there is an option for --null-audio? In that case is there any guide in creating such a device?