Directshow Preview Only and Capture & Preview with a single Graph

Question

I have a Directshow application that needs to preview a webcam video, and when user clicks \'Record\' it needs to start capturing the video to a file.

To that end I

Answer 1

Filter graph can change state as a whole, you cannot run its part individually and separately.

The easiest solution is to build preview graph separately, and when you need to start recording, stop/close preview graph and rebuild new capture graph. This certainly would involve a certain delay in response to "start recording" command.

Another option is to use multiple graphs, share data between the two, in code or using "bridging", and start/stop graphs separately.