IAMWMBufferPassCallback interface

The IAMWMBufferPassCallback interface is a callback interface used with the WM ASF Reader and WM ASF Writer filters. Applications can use this interface to get or set properties on individual samples, before the samples are passed downstream for further processing.

Applications can use this interface to retrieve data unit extensions such as the SMPTE time code for each sample. Another common use for this interface is to force key-frame insertion in a variable bit rate video stream during file writing.

To use this interface, query the filter's pin for the IAMWMBufferPass interface and call IAMWMBufferPass::SetNotify with a pointer to your implementation of the callback interface.


The IAMWMBufferPassCallback interface inherits from the IUnknown interface. IAMWMBufferPassCallback also has these types of members:


The IAMWMBufferPassCallback interface has these methods.


Called by the filter for each buffer that is delivered during streaming.



Minimum supported client

Windows XP with SP2 [desktop apps only]

Minimum supported server

Windows Server 2003 R2 [desktop apps only]


Windows Media Format 9 Series or later



See also

IAMWMBufferPass Interface
Using Windows Media in DirectShow