Messaging in DirectShow Graph

Question

I parse some information in my own source filter. I need send this information to my transform filter. How can I do that? Thanks.

Answer 1

If you are the source, then why not just extend the CMediaSample class with an own interface?

Or a second approach would be to send the MediaType with each sample and then save the extra bytes in the pbFormat block.

If you need to send information on a sample basis, these two methods are the best and cleanest way.

Answer 2

There is no standard general messaging for a task defined that broad.

1. You can connect filters outside of pipeline and have them exchanged with messages of any kind
2. With direct connection between the two, receiver might implement a custom interface sender would discover and use
3. same as 2 above, but sender might walk around the graph to find the interface of interest (enumerating connected filters and pins)
4. Filters might take advantage of graph's IRegisterServiceProvider interface to expose and discover custom interfaces/services of interest

Answer 3

I choose to use Mailslot. It's work fine.