Notifying CBasePin of Filter State Changes

[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The CBasePin class is notified whenever the state of the owning filter changes. For each state transition, the filter calls a corresponding method on the pin, as shown in the following table.

The derived class should override these methods to respond to the state change. Depending on the filter, the pin might start a worker thread that delivers samples, commit or decommit its memory allocator, and so forth.