Javier Valcarce's Homepage


RTLADSPA is a small utility that executes [http://www.ladspa.org LADSPA] plugins in real-time using your computer's sound card, microphone and speaker/headphones.

It uses PortAudio v19 library to have access to the sound system of your computer. Main features:

  • Runs in a terminal, no fancy graphical interface
  • Runs LADPSA plugins in [http://en.wikipedia.org/wiki/Real_time real-time]. It lets you to adjust audio input/output buffer size to control the amount of latency. You can decrease it to the minimum that can be achieved by your sound card.
  • Let you to specify input control parameters to the plugin (I-CTL ports)


Plug your microphone and speaker into computer's sound card, adjust rec and play volume levels, open a command-line window and run the program. Command-line syntax is:

rtladspa --module your_plugin.dll --parameters param1 param2 param3 ...

The last parameters (floating point data) are for the plugin and their meaning depends on the concrete plugin you are using. For example:

$ rtladspa --module flanger_1191.dll --parameters 10 5 0.3 0.8

To show help:

$ rtladspa --help

During the plugin execution, if you see the message "Input buffer overflow!" this means that your plugin is not running in real-time, try to increase the size of buffers/latency (or buy a faster computer!).


  • Windows 2K/XP/Vista
  • Full-duplex sound card with drivers WMME (any sound card have a driver of this type). ASIO drivers is a plus, it offers the minimum latency and it's the one I recomend. With ASIO you can achieve a latency as low as 5 ms whereas with WWME don't expect less than 200 ms
  • Microphone and speaker/headphones

If Windows complains about msvcrt80.dll library then install [http://www.microsoft.com/downloads/details.aspx?FamilyID=32bc1bee-a3f9-4c13-9c99-220b62a191ee&DisplayLang=en vcredist_x86.exe] (2K/XP) or XP ServicePack 2.


2006-10-100.1rtladspa-src-0.1.zip rtladspa-bin-win32.zipX
ID Name File Comment
1188Ring Modulation X C
1440Hilbert TransformerX C
1191Flanger X C
1902Butterworth X C
1209Valve X C

At plugin.org.uk there is an interesting collection of plugins

This page forms part of website https://javiervalcarce.eu