The MIDI stream connector represents the flow of MIDI information from the sequencer device to its associated amplifier-mixer (ampmix) device. During playback, the sequencer device sends MIDI information from either application memory or files to the ampmix device for subsequent conversion into audio that can be heard through conventional speakers or headphones.
Control of the characteristics of the MIDI information is provided by the sequencer device. Volume control is provided as an additional service, although this feature is actually provided by the ampmix device in a way that is transparent to the calling application. If other advanced audio-shaping features are required, the application can retrieve the device ID of the ampmix device using the MCI_CONNECTION message. Once the device ID has been obtained, the application can send set commands directly to the ampmix device to manipulate audio attributes, such as treble, bass, balance, and so on.