The MM_DRVM_DATA callback message notifies a client that a user-mode video capture driver has filled a buffer with capture data.
Parameters
dwMsg
MM_DRVM_DATA
dwParam1
Pointer to a VIDEOHDR structure describing the data buffer that has been filled.
dwParam2
Not used.
Comments
A user-mode video capture driver sends an MM_DRVM_DATA message to its client, by means of a callback, when the driver has filled a buffer with capture data. The driver uses the dwParam1 argument to indicate which buffer has been filled. The driver sends the message to the client by calling DriverCallback, passing the specified parameters.
The driver sends the MM_DRVM_DATA message only if the client has previously specified a notification target with a DVM_STREAM_INIT message. The VIDEOHDR structure was received along with a DVM_STREAM_ADDBUFFER message.
Drivers using VCUser.lib do not have to call DriverCallback to send callback messages. Code within VCUser.lib handles delivery of callback messages for the driver.
For more information about notifying clients, see Notifying Clients from Video Capture Drivers.