Question

I’ve created a topology for a video file which contains just one stream (no audio).

It contains three nodes which are connected in order:

• a source stream node
• an Mpeg4Part2VideoDecoder as transform node
• an activate object for the EVR as output node

Calling SetTopology(), allowing for a partial topology results in working playback. However, I am trying to resolve the full topology myself.

Therefore, I first need to bind my output node to a media sink. I followed the guidelines specified in the manual, and all the required calls seem to succeed. When setting the full topology, I receive the MESessionTopologySet event.

Unfortunately, playback doesn’t work, but I don’t get any errors.

• Is there anything else required when creating a full topology?
• I recall reading somewhere in the msdn docs that the topology loader which is used when setting a partial topology also sets media types. Is this required, and if so where can I find more information on this?

Answer 1

Matt Andrews answered this one for me on the msdn forums.

You definitely need to negotiate your own media types if you are
bypassing the topology loader. This means obtaining the source’s
media type from IMFMediaTypeHandler, setting it on the downstream
transform, and then for each node down the chain, querying the
available input and output types to find a compatible media type. It
is much easier to use the topoloader unless you have a specific need
to avoid it.