CSourceStream class

[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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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 CSourceStream class provides an output pin for the CSource filter class.

For information on using this class, see CSource. This class inherits the CAMThread class, which provides a worker thread for streaming data from the pin. The CSourceStream class implements the following helper methods to send requests to the thread:

• CSourceStream::Exit
• CSourceStream::Init
• CSourceStream::Pause
• CSourceStream::Run
• CSourceStream::Stop

The first request to the thread must be Init. The Exit request terminates the thread. In practice, it is not necessary to call any of these methods directly, because the pin's CSourceStream::Active and CSourceStream::Inactive methods call them as needed.

The class also provides several "handler" methods:

• CSourceStream::OnThreadCreate
• CSourceStream::OnThreadDestroy
• CSourceStream::OnThreadStartPlay

These do nothing in the base class, but the derived class can override them.

Protected Member Variables	Description
m_pFilter	Pointer to the filter that contains this pin.
Protected Methods	Description
OnThreadCreate	Called when the streaming thread is initialized. Virtual.
OnThreadDestroy	Called when the streaming thread is about to exit. Virtual.
OnThreadStartPlay	Called at the start of the CSourceStream::DoBufferProcessingLoop method. Virtual.
Active	Notifies the pin that the filter is now active.
Inactive	Notifies the pin that the filter is no longer active.
GetRequest	Waits for the next thread request.
CheckRequest	Checks if there is a thread request, without blocking.
ThreadProc	Thread procedure. Virtual.
DoBufferProcessingLoop	Generates media data and delivers it to the downstream input pin. Virtual.
CheckMediaType	Determines if the pin accepts a specific media type. Virtual.
GetMediaType	Retrieves a preferred media type. Virtual.
Public Methods	Description
CSourceStream	Constructor method.
~ CSourceStream	Destructor method. Virtual.
Init	Initializes the streaming thread.
Exit	Signals the streaming thread to exit.
Run	Signals the streaming thread to run.
Pause	Signals the streaming thread to become active.
Stop	Signals the streaming thread to stop.
Pure Virtual Methods	Description
FillBuffer	Fills a media sample with data.
IPin Methods	Description
QueryId	Retrieves an identifier for the pin.

Requirements

Requirement	Value
Header	Source.h (include Streams.h)
Library	Strmbase.lib (retail builds); Strmbasd.lib (debug builds)

See also

Writing Source Filters