Querying
MIDI Devices
Before
playing or recording MIDI data, you must determine the capabilities of the MIDI
hardware present in the system. MIDI capability can vary from one multimedia
computer to the next; applications should not make assumptions about the
hardware present in a given system.
Windows
provides the following functions to determine how many MIDI devices are
available for input or output in a given system:
|
midiInGetNumDevs |
Retrieves
the number of MIDI input devices present in the system. |
|
midiOutGetNumDevs |
Retrieves
the number of MIDI output devices present in the system. |
Like other
audio devices, MIDI devices are identified by a device identifier, which is
determined implicitly from the number of devices present in a given system.
Device identifiers range from zero to the number of devices present, minus one.
For example, if there are two MIDI output devices in a system, valid device
identifiers are 0 and 1.
After you
determine how many MIDI input or output devices are present in a system, you
can inquire about the capabilities of each device. Windows provides the
following functions to determine the capabilities of audio devices:
|
midiInGetDevCaps |
Retrieves
the capabilities of a given MIDI input device and places this information in
the MIDIINCAPS
structure. |
|
midiOutGetDevCaps |
Retrieves
the capabilities of a given MIDI output device and places this information in
the MIDIOUTCAPS
structure. |
Each of these
functions has a parameter specifying the address of a structure that the
function fills with information about the capabilities of a specified device.