I have a directshow filter that reads M2TS stream and demux it. I can render video and audio in GraphStudio and see it. My question is how can I use this filter as a live source
Expression Encoder would look for DirectShow video source devices, which are typically cameras. You might want to implement your won virtual camera so that EE4
would pick it up and start receiving video from it.
A popular sample on doing it is Vivek's virtual camera project available from http://tmhare.mvps.org/downloads.htm (4th link).