Scope Filter Sample
|Microsoft DirectShow 9.0|
The Scope filter is a renderer filter that displays sound data as wave forms.
This sample is included with the Windows SDK. It is located under the following path: [SDK Root]\Samples\Multimedia\DirectShow\Filters\Scope.
To use this filter, open GraphEdit and render an audio file (or a video file with an audio stream). Disconnect the audio renderer temporarily and insert the Infinite-Pin Tee (InfTee Filter Sample) sample filter. Reconnect the audio renderer. Then connect the Infinite-Pin Tee filter's second output pin to the Scope filter. Now run the graph.
The Scope window is implemented as a dialog box, not as an actual window. Developers creating control panels to alter filter parameters in real time might want to use a technique like this rather than property pages.
The Scope filter demonstrates setting up a separate thread to process data. In this case, the data is just copied to a separate buffer on the IMemInputPin::Receive method, and is then drawn on the Scope window on the separate thread.
The Scope filter also enables you to monitor audio output to determine if you are clipping, so you can adjust the gain.
This filter appears in GraphEdit as "Oscilloscope."