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Default Behavior of Drivers

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[The feature associated with this page, MCI, is a legacy feature. It has been superseded by MediaPlayer. MediaPlayer has been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer instead of MCI, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

In many situations, the MCI command specifications define the default values and behavior for drivers of a particular device type. Since multimedia devices can have a wide range of features (and limitations), there can be undefined areas of behavior. Also, drivers might handle exceptions differently, based on the capabilities of the device.

For example, consider the following commands sent to a waveform-audio driver using the mciSendString function:

mciSendString("open sound.wav alias sound", lpszReturnString,
    lstrlen(lpszReturnString), NULL);
mciSendString("play sound notify", lpszReturnString,
    lstrlen(lpszReturnString), NULL);
mciSendString("record sound from 0 notify", lpszReturnString,
    lstrlen(lpszReturnString), NULL);

The record command returns a "Parameter out of range" value and stops the playback started by the previous play command. One might expect the driver to validate the record command before stopping playback, but the driver stops the playback first.