Notifies a Media Foundation transform (MFT) that streaming is about to begin.
To send this message, call IMFTransform::ProcessMessage.
The client is not required to send this message. If the client sends this message, it must do so after setting all of the media types on the MFT, and before calling ProcessInput. The MFT can respond by allocating buffers or other resources. If the client does not send this message, the MFT allocates resources on the first call to ProcessInput. Therefore, sending this message can reduce the initial latency when streaming begins.
An MFT is not required to respond to this message.
|Minimum supported client
||Windows Vista [desktop apps only]
|Minimum supported server
||Windows Server 2008 [desktop apps only]