Audio Buffers

You can control the audio portion of a capture operation in three ways:

• Include or exclude audio from the capture operation.
• Request a specific number of audio buffers.
• Request that audio buffers be a specific size.

You can retrieve the settings for audio buffers by using the WM_CAP_GET_SEQUENCE_SETUP message (or the capCaptureGetSetup macro). The fCaptureAudio member of the CAPTUREPARMS structure specifies whether audio is included or excluded from the capture operation. The current requested number of audio buffers is stored in the wNumAudioRequested member, and the current audio buffer size is stored in the dwAudioBufferSize member. You can specify whether to include audio capture, specify the size and number of audio buffers by updating these members, and send the updated CAPTUREPARMS structure to the capture window by using the WM_CAP_SET_SEQUENCE_SETUP message (or the capCaptureSetSetup macro).

By default, audio is included in the capture operation, and four audio buffers are allocated. The default value of fCaptureAudio is TRUE. The default buffer size (the value of dwAudioBufferSize) can contain 0.5 seconds of audio data or 10K, whichever is greater.