56 lines
2.6 KiB
Plaintext
56 lines
2.6 KiB
Plaintext
$OpenBSD: README,v 1.4 2012/01/24 08:03:52 ajacoutot Exp $
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+-----------------------------------------------------------------------
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| Running ${FULLPKGNAME} on OpenBSD
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+-----------------------------------------------------------------------
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In this package of jackd, the 'dummy' and 'sndio' drivers are supported.
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The 'dummy' driver is mostly useful for testing jackd itself. The
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'sndio' driver uses sndio(7). To start jackd with default driver
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parameters, use the command 'jackd -d <driver>'.
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By default, jackd runs in full-duplex mode with a relatively low
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latency. This may not be exactly what you want, and it may not be
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possible with all hardware. Therefore, some configuration options may
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be necessary to effectively use jackd. The 'sndio' driver options can
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be viewed with the command 'jackd -d sndio -h'. Below are some tips and
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caveats to consider when using jackd on OpenBSD.
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Some audio devices do not support full-duplex operation. If jackd
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errors out on startup with a message about opening a full-duplex device,
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this is likely the problem. If the device only supports playback, then
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the driver needs to be configured to use 0 input channels. For example
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'jackd -d sndio -i 0' starts jackd in half-duplex play-only mode.
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By default jackd uses 2 periods (blocks) of 1024 frames each. This
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means there will be at most 2048 frames in the playback buffer. Some
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slower or loaded machines may not be able to keep the playback buffer
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from underrunning with these conditions. Jackd is designed to use 2
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periods, so if underruns are observed, it is best to first increase the
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period size with the driver's -p option. The period size should be a
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power of two. The number of periods can be increased with the -n
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option. For example, 'jackd -d sndio -p 2048 -n 4'.
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The sndio driver uses 44100 Hz sampling rates by default. Some devices
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may not support the default sample rate. Or it may be that most of the
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audio that will pass through jackd is based on a different sample rate.
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Avoiding sample rate conversion will use fewer CPU cycles and perserve
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audio quality. The -r option can be used to change the sampling rate as
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in 'jackd -d sndio -r 48000'.
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The realtime option -R is commonly used on other operating systems.
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However, this option is inconsequential on OpenBSD.
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It is possible to run jackd on top of sndiod(1) with the 'sndio' driver.
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Note that jackd will use sndiod's block size as its period size. For
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instance:
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- stop sndiod(8) using rc.d(8)
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- set sndiod_flags="-b 1024 -z 512" in /etc/rc.conf.local(8)
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- start sndiod(8)
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- start jackd:
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$ jackd -d sndio -p 1024 -n 2
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There is currently no MIDI driver in jack that works on OpenBSD.
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