On Sun, 12 Oct 2003 12:23:41 -0800 "Paul Berry" <pnberry@xxxxxxxxxxxxxx> wrote: > Greetings all: > > I am trying to learn about the LADSPA plugins. I have downloaded and > installed the ladspa_sdk, read the ladspa.h header file and read Dave > Phillips article on the O'Reilly network. I've also added the CMT > plugin library. > > Okay, so I've got my plugins but I need some helping making them go. I > don't really understand how they work. I am trying to learn about them > in a console environment, that is to say just by themselves (if that > is possible, maybe that is part of the difficulty). I understand the > basics of the C language and the Linux operating system but most of > the information I have found seems to cover developing plugins and > consequently goes right over my head. The plugins can't be used by themselves - they need a host application, that provides connections to sound devices, allows you to set control values etc. > Lets say I wanted to use the sine.so plugin from the sample library to > play a continuos pitch from my sound card, how would I do that? I'm > confused by the need of an input file for this as I see the sine.so > plugin as the source. Can the output file be a dev file? How about > using the ALSA hw plugin hw:0,0 as the output, how would I do that? > I've read the ALSA library documentation about plugins and LADSPA but > again it goes right over my head. 'applyplugin' which comes with the ladspa_sdk assumes you are processing .wav files, applying a plugin as an effect. Most LADSPA hosts are GUI driven, and the only commandline host I have found is ecasound (which does a whole lot more!) - from the ecasound web page: http://www.wakkanet.fi/~kaiv/ecasound/welcome.html example to play a sinewave (under 'effects processing'): ecasound -i null -o /dev/dsp -el:sine_fcac,440,1 (no input, output to /dev/dsp, use ladspa plugin sine_fcac with frequency 440, amplitude 1) Use analyseplugin from the ladspa_sdk to get details of the plugin label and ports. Ecasound also comes with a nice interactive cli, which allows you to build 'chains' of plugins amongst other things. The manpages will tell you all about it. - Myk
