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Thread: Alsa ladspa pcm plugin "Unknown PCM ladspa"

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  1. #1
    Join Date
    Jan 2009
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    Distro
    Ubuntu 9.10 Karmic Koala

    Alsa ladspa pcm plugin "Unknown PCM ladspa"

    I've been playing around with the /etc/asound.conf file for a couple of days now and I ran into a problem when I tried to use the ladspa plugins.

    I copied the example from http://alsa.opensrc.org/index.php/Ladspa_(plugin)

    Code:
    pcm.ladspa {
        type ladspa
        slave.pcm "plughw:0,0";
        path "/usr/lib/ladspa";
        plugins [
            {
                label delay_5s
                input {
                    controls [ 0.8 0.3 ]
                }
            }
        ]
    }
    after I put that in my /etc/asound.conf file I restarted Alsa
    Code:
    sudo /etc/init.d/alsa-utils restart
    and then I ran
    Code:
    aplay -Dplug:ladspa test.wav
    to test it and I recieved the following output
    Code:
    ALSA lib pcm.c:2205:(snd_pcm_open_noupdate) Unknown PCM ladspa
    aplay: main:590: audio open error: File exists
    Any help would be appreciated
    Last edited by samuelhug; August 26th, 2009 at 09:32 PM.

  2. #2
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    Sep 2009
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    Re: Alsa ladspa pcm plugin "Unknown PCM ladspa"

    I am facing exactly same problem.... Any updates?

  3. #3
    Join Date
    Jan 2009
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    Ubuntu 9.10 Karmic Koala

    Re: Alsa ladspa pcm plugin "Unknown PCM ladspa"

    nope. still havn't figured it out.

  4. #4
    Join Date
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    Re: Alsa ladspa pcm plugin "Unknown PCM ladspa"

    Ok I found the following article but I can make much scene out of it.
    As far as I can tell I need to recompile libasound2-plugins maybe?

    The Article

  5. #5
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    Re: Alsa ladspa pcm plugin "Unknown PCM ladspa"

    it worked for me after I upgraded to karmic beta

    also I should mention that pulseaudio is the default audio system for karmic but I didn't like it cause it was giving me problems so I switched it back to alsa.
    Last edited by samuelhug; October 2nd, 2009 at 03:42 AM.
    AMD Phenom X6 1055T 6-Core 2.8Ghz, 8GB RAM, 300GB HD, PNY Nvidea GeForce 9800GT 512MB

  6. #6
    Join Date
    Jun 2011
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    3

    Re: Alsa ladspa pcm plugin "Unknown PCM ladspa"

    Hello!
    Stopping the PulseAudio daemon helps in this case.
    Just type
    Code:
    pulseaudio --kill
    in the terminal of yor user and try playing the sound in a regular ALSA way. For example mplayer will determine the ALSA output device automatically.
    --------
    Update: One more problem may be that PulseAudio daemon will start itself automatically when you try to play something.
    A quick but dirty workaround may be making the PulseAudio configuration incorrect for PulseAudio could not start.
    I simply added a not existent device to the following string in the /etc/pulse/default.pa file:
    Code:
    load-module module-alsa-source device=hw:1,0
    There is no device "hw:1,0" in my system, so PulseAudio cannot start. And Mplayer will play everything directly through ALSA (as well as any other player, I believe).

    P.S. If you do so, just don't forget to correct the PulseAudio configuration back when you need it.
    P.P.S. Still it would be much better to figure out how to play the sound through the LADSPA plugins with PulseAudio running.
    Last edited by v_2e; January 7th, 2012 at 07:28 PM.

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