Chapter 4: Capturing Audio with DirectShow

Part II

Capture and Editing

Chapter 4

Capturing Audio with DirectShow

The next four chapters of this book deal with Microsoft DirectShow applications that capture media streams for manipulation by DirectShow. In most of the examples to follow, the streams will simply be written to disk for later playback or manipulation by another DirectShow application. The filter graphs we ll build will be relatively simple, consisting of a capture source filter (a special class of source filter that talks directly to capture hardware on the computer), one or two transform filters, and a renderer filter, which will write the stream to a file.

Although building filter graphs to capture streams is a straightforward affair, at the code level a number of issues need to be addressed to successfully create a filter graph. Starting with a very simple filter graph, which captures an incoming audio source as an AVI file (containing sound but no video), we ll progress through all the programming tricks you ll need to employ to successfully build DirectShow applications capable of capturing any media stream coming into your computer.