Inside Macintosh: Sound Manager

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Supporting Continuous Recording

If your sound input device driver supports continuous recording, it must do more than respond to Status, Control, and Read requests. It must also, if continuous recording is on, begin recording into an internal ring buffer as soon as a Read request completes. The buffer should be made large enough so that the sound input device driver can support successive requests to the SPBRecord function in most circumstances; however, if your driver exhausts the internal buffer, your driver should begin recording again at the start of the buffer.

When the sound input device driver receives a subsequent Read request, it should record to the application's buffer first all of the data in the internal ring buffer and then as much fresh data as it can record during one interrupt.

If a Read terminates due to a KillIO request, your sound input device driver does not need to continue recording samples to the internal ring buffer until after the next uninterrupted Read request.

Inside Macintosh: Sound Manager

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