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wiki:raspberrypi [2017/02/17 20:32]
cheekyisgreat [Disabling unneeded services] Updated jackstart script URL
wiki:raspberrypi [2020/03/15 17:50] (current)
autostatic [On-board audio]
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 ===== On-board audio ===== ===== On-board audio =====
  
-The on-board chipset of the RPi has quite some limitations unfortunately. It only does playback and because of it'​s ​design it is not really suited for real-time, low-latency audio processing. It does work with JACK now that it has MMAP support but don't expect it to run without glitches at lower latencies.+The on-board chipset of the RPi has quite some limitations unfortunately. It only does playback and because of its PWM (Pulse Wide Modulation) based design it is not really suited for real-time, low-latency audio processing. It does work with JACK now that it has MMAP support but don't expect it to run without glitches at lower latencies.
  
 Other drawbacks of the analog audio output: Other drawbacks of the analog audio output:
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 Another option is to comment or remove the kernel module for the onboard soundcard (snd-bcm2835) from ''/​etc/​modules''​. Keep in mind this will disable the onboard sound altogether. This might save you some precious CPU cycles too but don't expect too much of it. Another option is to comment or remove the kernel module for the onboard soundcard (snd-bcm2835) from ''/​etc/​modules''​. Keep in mind this will disable the onboard sound altogether. This might save you some precious CPU cycles too but don't expect too much of it.
  
-===== Audio software repository ===== 
  
-There'​s a [[http://​rpi.autostatic.com/​|repository]] available with packages of Jack1, Jack2 (both patched for use on ARM) and a small collection of software that is either not available or not up to date in the standard Raspbian repositories. 
- 
-==== Adding the repository ==== 
- 
-  wget -O - http://​rpi.autostatic.com/​autostatic.gpg.key| sudo apt-key add - 
-  sudo wget -O /​etc/​apt/​sources.list.d/​autostatic-audio-raspbian.list http://​rpi.autostatic.com/​autostatic-audio-raspbian.list 
-  sudo apt-get update 
  
 ===== Using JACK ===== ===== Using JACK =====
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   export DBUS_SESSION_BUS_ADDRESS=unix:​path=/​run/​dbus/​system_bus_socket   export DBUS_SESSION_BUS_ADDRESS=unix:​path=/​run/​dbus/​system_bus_socket
  
-And then add the following lines to ''/​etc/​dbus-1/​system.conf'':​+And then add the following lines to ''/​etc/​dbus-1/​system.conf'' ​before the closing ''</​busconfig>''​ tag:
     <policy user="​pi">​     <policy user="​pi">​
 +          <allow own="​org.freedesktop.ReserveDevice1.Audio0"/>​
           <allow own="​org.freedesktop.ReserveDevice1.Audio1"/>​           <allow own="​org.freedesktop.ReserveDevice1.Audio1"/>​
     </​policy>​     </​policy>​
 +    ​
 +WARNING: In Raspbian Stretch I had to do the following instead of modifying ''​system.conf'':​
 +
 +Create a new file ''/​etc/​dbus-1/​system-local.conf''​ with the following contents:
 +
 +    <?xml version="​1.0"?>​ <​!--*-nxml-*-->​
 +    <​!DOCTYPE busconfig PUBLIC "​-//​freedesktop//​DTD D-BUS Bus Configuration 1.0//​EN"​
 +            "​http://​www.freedesktop.org/​standards/​dbus/​1.0/​busconfig.dtd">​
 +    ​
 +    <​busconfig>​
 +    ​
 +            <policy context="​default">​
 +                    <allow own="​org.freedesktop.ReserveDevice1.Audio0"/>​
 +                    <allow own="​org.freedesktop.ReserveDevice1.Audio1"/>​
 +            </​policy>​
 +    ​
 +    </​busconfig>​
 +
 +
  
 === Using an external USB audio interface === === Using an external USB audio interface ===
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 [[http://​wiki.linuxaudio.org/​wiki/​system_configuration#​build_your_own_real-time_kernel|Building a real-time kernel]] [[http://​wiki.linuxaudio.org/​wiki/​system_configuration#​build_your_own_real-time_kernel|Building a real-time kernel]]
 +
 +[[https://​github.com/​dddomin3/​DSPi/​|Instructions for kernel compilation modernized for Pi 3]]
  
 {{tag>​hardware_linux usb_audio_midi raspberry_pi howtos_and_faqs}} {{tag>​hardware_linux usb_audio_midi raspberry_pi howtos_and_faqs}}
wiki/raspberrypi.1487359944.txt.gz ยท Last modified: 2017/02/17 20:32 by cheekyisgreat