midi - device-independent MIDI driver layer
midi* at autri?
midi* at mpu?
midi* at opl?
midi* at pcppi?
midi* at sb?
midi* at wss?
pseudo-device sequencer [count]
The midi driver provides support for various MIDI peripherals. It provides
a uniform programming interface layer above different
MIDI hardware drivers. The MIDI hardware can be of many
e.g., an external synthesizer on a MIDI port (or a serial
port), the PC
speaker, an internal FM synth, or a wavetable synth.
There are two device file types available for MIDI operation:
/dev/rmidiN, and /dev/music. The /dev/rmidiN devices provides raw access
to a MIDI device. Data written is sent to the physical device as fast as
possible and is uninterpreted. Reading from the device returns data as
soon as it becomes available. A moderate amount of buffering is available
both for reading and writing. The raw MIDI devices are
for non realtime operations, such as downloading patches
to a device,
since it is hard to get the accurate timing needed for quality music from
a user program. But the devices can act as a simple patchboard for MIDI
devices. For example, a MIDI keyboard could be connected to
by the command
$ cat -u /dev/rmidi1 >/dev/rmidi2
The /dev/music device is a MIDI sequencer device. Data sent
to and from
this device not only contains the information sent to the
but also timing information. The kernel will make sure that
data is sent
to the physical device at the indicated time. The sequencer
the /dev/midiN devices internally and they are unavailable
when used by
The API for the sequencer device is binary compatible with
the OSS sequencer
midiplay(1), ioctl(2), ossaudio(3), audio(4), autri(4),
pcppi(4), sb(4), wss(4), ym(4)
The midi driver first appeared in NetBSD 1.4.
OpenBSD 3.6 August 6, 1998
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