Overview

• What is latency, how to measure, why we need it ?

  Latency is a measure of how long it takes for a system to react without failure. 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.

• What we need a Discussion on numbers to this
• Terminology: System latency vs. achievable latency

Analysis:

Which hardware causes what, which driver causes what, overall performance tests of OS System

• PD structure causing latency causing latency
  • blocksizes and how it handles with latency
• OS structure causing latency for different OS systems which parts are responsible
• Limits of Hardware cards Which cards have limits to latency and why
• "synchronous vs. callback scheduler"

Measurements:

• How to Measure ?

  How to measure with pd

  How to measure system

• Results
• [Archive of low latency measurements]
• Guidelines for Patch-Programming for low latency patches
• Better PD Audio Support

References:

• Low Latency OS systems Links

  Paper MacMillan

  • linux
    • Linux Scheduler
    • Low Latency at lunuxdj
  • Windows

    Here a very good guide is RME's Tuning Tips for Low Latency Operation

  • Mac OS-X

    unkown, but OS-X seems to work quite fine.

Timeline:

• Projectend: Februar 2004
  • linux analysed, measured and solutions prepared. dez.2003
  • linux solution for ALSA direct end of january
  • windows part january
  • writing dokumentation februar