alsa-midi-latency-test

alsa-midi-latency-test measures the roundtrip time of a MIDI message in the alsa subsystem of the linux kernel using a high precision timer. It calculates the worst case roundtrip time of all sent MIDI messages and displays a histogram of the rountrip time jitter:

Install from source code

git clone https://github.com/koppi/alsa-midi-latency-test.git
cd alsa-midi-latency-test/

The following packages are required to build alsa-midi-latency-test:

sudo apt-get install debhelper autotools-dev automake libasound2-dev

Compile alsa-midi-latency-test as follows:

sh autogen.sh
./configure
make

Install alsa-midi-latency-test as follows:

sudo make install

or build and install an Ubuntu / Debian package:

debuild
sudo dpkg -i ../alsa-midi-latency-test*.deb

Run alsa-midi-latency-test

• $ alsa-midi-latency-test -l

  Lists available MIDI input and output ports.

• $ alsa-midi-latency-test -i [input port] -o [output port]

  This runs the benchmark with the given input and output port. Note, that the input and output ports have to be connected using a MIDI cable in the real hardware to loop the MIDI message back.

• $ man alsa-midi-latency-test

  The man page contains documentation for all available command line switches.

Benchmark Results

Please share your results in the Wiki.

User Experiences - Archive

2015

• Elia - MIDI PCI card with Envy24 chip and M-Audio Audiophile 2496
• More to be written.

2014

• Elia - MIDI Through virtual device loopback test
• Elia - Precision Measuring Instruments : reference MIDI hardware
• Elia - Wireless MIDI performance : CME WIDI X8

2013

• Robin Gareus - Utility to measure jackaudio MIDI latency see http://rg42.org/wiki/midilatency for more details
• Andre Majorel - LAU: ESI Romio II and alsa-midi-latency-test failure

2012

• Silicon Stuff - Serial Port MIDI on the Raspberry Pi

• Clemens Ladisch - comp.audio.jackit: MIDI support for OpenBSD?

  (The primary purpose is not so much measuring the hardware but the kernel's maximum scheduling delay. The UM-2EX results were done on a very optimized kernel.)

2011

• Silicon Stuff - Raspberry Pi Synthesizer
• WARPWOOD Wiki
• Mentoj Dija - cheap usb-audio-interface

2010

• drummerforum.de
  • siktuned - Asio 4 all mit addictive drums problem mit latenz
• ffado.org
  • IRQ Priorities How-To
• 64studio-users
  • Ralf Mardorf - PCI MIDI jitter - comparison Ubuntu (bad) and Suse (might be ok)
  • Ralf Mardorf - 3.0b and 3.3a amd64 MIDI latency test for several kernels
  • Ralf Mardorf - USB Device 0x170b:0x11, TerraTec EWX24/96
  • Ralf Mardorf - Correlation of alsa -p value and hw MIDI jitter
  • Ralf Mardorf - MIDI jitter - Today for 4 of 4 tests my USB device did pass all tests
  • Ralf Mardorf - ALSA MIDI latency test results are far away from reality
• ubuntu-studio-users
  • Ralf Mardorf - Real time for Ubuntu Studio 10.04 amd64
• Blog Posts
  • Matt Wheeler's Blog - Putting -rt kernels first in grub2

2009

• rt.wiki.kernel.org
  • Geunsik Lim - Worstcase Latency Test Scenario
  • various - Systems based on Real time preempt Linux
• 64studio-users
  • geoff - MIDI timing

2000

• Benno Senoner - Linux v2.4 - scheduling latency tests / high performance low latency audio

Definitions

• Wikipedia EN - Latency in engineering
• Wikipedia EN - Latency with audio

See also

• http://lists.linuxaudio.org/listinfo/linux-audio-tuning

  The linux-audio tuning (LAT) mailing list is to help GNU/Linux distribution maintainers and other interested users to share information on system performance tuning matters, especially with regard to real-time Linux kernels.

• http://www.alsa-project.org/

  The Advanced Linux Sound Architecture.

• http://www.evc-soft.nl/evc/products/miditest/

  The MidiTest software for Microsoft Windows.

Thanks

• to Arnout Engelen for initial testing and giving feedback.
• to Clemens Ladisch for a number of fixes with the high precision timer and alsa midi event handling.

BUGS and AUTHORS

Please report bugs to the authors.

• Jakob Flierl jakob.flierl@gmail.com

-- November, 2009, last updated August 2015.