d58e7b8aad
* update README.OpenBSD * add patches to let it build on gcc2 archs (from Sebastian Reitenbach) * disable audio(4) driver
51 lines
2.6 KiB
Plaintext
51 lines
2.6 KiB
Plaintext
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
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and 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
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device, this is likely the problem. If the device only supports
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playback, then the driver needs to be configured to use 0 input
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channels. For example 'jackd -d sndio -i 0' starts jackd in
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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
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the period size with the driver's -p option. The period size should
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be a power of two. The number of periods can be increased with the
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-n 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
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devices may not support the default sample rate. Or it may be that
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most of the audio that will pass through jackd is based on a
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different sample rate. Avoiding sample rate conversion will use
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fewer CPU cycles and perserve audio quality. The -r option can be
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used to change the sampling rate as 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 aucat(1) with the 'sndio'
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driver. However, the aucat server must be running at a higher than
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default scheduling priority. The aucat(1) manual has an example for
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doing this with renice(8). Note that jackd will use aucat's block
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size as it's period size. The following command sequence could be
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used to run jackd over aucat.
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$ aucat -l -b 1024 -z 1024
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$ sudo renice -20 `pgrep -x aucat`
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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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