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How can I lower latency?

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This FAQ applies to: Any version.

and what is this 'latency' everybody keeps talking about?

Latency is a measure of how long it takes for a system to react. In Pd, we are primarily concerned with the time it takes for audio, MIDI, or other input to cause audio output. This is "audio latency".

For reference, the audio latency between your speakers and your ears is approximately 1 ms per foot. (for people outside the UK and US, this is approximately 30cm per ms)

So how can you lower it?

  • Under Windows, use the ASIO driver. You're out of luck otherwise.
  • Under Linux, with a recent version of the stable kernel (2.4.x), special low latency patches, some hard drive tuning, and ALSA drivers, average audio latencies is 1.5 ms. If you really load your system, a maximum audio latency of 3 ms can be reached. Pathological bad cases have been known to cause 8 ms latencies this seems like the upper bound. More information on low latency under Linux can be found at Benno's site on the subject.

TODO (tell the people that Pd has 3 blocks buffer, which gives you 4.5ms at least on 44.1kHz)

by IOhannes m zmoelnig last modified 2008-05-04 09:29 PM

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