AI Developer wrote: > > Are you sure about that? Sounds like a bug in the renderer if it > expects a frame in paused state. I am absolutely positive. This is a well-known strangeness in DirectShow. You can check the DirectShow code in CBaseRenderer. It will not complete the transition to "paused" state until it either receives a frame, or gets an indication that the upstream filter cannot deliver one. For a KS source, that's done by setting KSPIN_FLAG_PROCESS_IN_RUN_STATE_ONLY in the the Flags member of KSPIN_DESCRIPTOR_EX: http://msdn.microsoft.com/en-us/library/aa509735.aspx For a user-mode filter, that's done by returning VFW_S_CANT_CUE from IMediaFilter::GetState: http://msdn.microsoft.com/en-us/library/ms783300.aspx As I said, the renderer relies on this behavior to put up a pretty "post" frame while the graph is still preparing. This was done because of network latency. When you are streaming a video from a network server somewhere, it makes a better user experience if you can display the first frame of the movie while you pre-fetch enough frames for smooth playback. > Seeing Neetu's later comment about Cancel request handling, could it > be that in your case also, a cancel request is not being handled > correctly? Perhaps the render is waiting for the request to be cancelled? Not in the video case. I guarantee it. > As for danger - yes there is a real danger. A lot of applications > submit buffers in pause state, so that the driver has a queue of > buffers ready when it switches to run state. Also, this way, the > client could ensure that there's going to be enough "backup" of > buffers during the time it takes to complete the request and to submit > a new one. Reduces chances of buffer underruns. Yes, but you're talking about "steady state" operation here. The operation at startup is kind of a corner case. On the other hand, you have convinced me that I could not possibly have been correct for the audio case. The video case is different. > And of course, the WHQL tests will fail your driver (I know this as a > fact for audio drivers) if you try to stream in paused state! Yes, it appears that I erred in attempting to extrapolate from the video case to his audio behavior... -- Tim Roberts, timr@xxxxxxxxx Providenza & Boekelheide, Inc.