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| -rw-r--r-- | doc/documentation.tex | 70 |
1 files changed, 69 insertions, 1 deletions
diff --git a/doc/documentation.tex b/doc/documentation.tex index 53452ee..ddade37 100644 --- a/doc/documentation.tex +++ b/doc/documentation.tex @@ -54,7 +54,7 @@ devices.. %\section{Device setup} -\section{Playing audio} +\section{Playing audio} \label{playing-audio} For a simple audio streaming test the following commands from the FFmpeg streaming @@ -179,6 +179,74 @@ lbu commit -d With this setup the Alpine Linux installation is completed. +\section{Configure Alpine Linux for soundbox} + +soundbox requires packages from the Alpine Linux community package repository. +Since this is not enabled by default it has to be done manually. This can be +done by editing the \texttt{/etc/apk/repositories} file with an editor like +\texttt{vi}. The hash sign \texttt{\#} in front of the URL to the community +repository has to be removed. Instead also \texttt{sed} can remove this sign on +a fresh installation quite easily since the community repository is the only +one with such a sign in front of it. + +\begin{verbatim} +sed -i 's/^#//g' /etc/apk/repositories +\end{verbatim} + +With an enabled community repository all required packages for soundbox can be +installed. The list with required packages can be written to the +\texttt{/etc/apk/world} file with \texttt{echo}. Running \texttt{apk add} after +it will install all of these packages including their dependencies and removes +everything else. This makes sure that always exactly the same set of packages +is used for a soundbox device. + +\begin{verbatim} +echo 'alpine-base +alsa-utils +alsaconf +busybox-mdev-openrc +chrony +ffplay +iw +openssh +openssl +wpa_supplicant' > /etc/apk/world + +apk add +\end{verbatim} + +The only user on a soundbox device is \texttt{root}. Even that super user has +to be added to the \texttt{audio} group to be able to play sound via ALSA. This +can be achieved with \texttt{addgroup}. + +\begin{verbatim} +addgroup root audio +\end{verbatim} + +soundbox uses the HiFiBerry shield to output high-quality audio. This shield +needs to be enabled as an audio output by specifying a Devicetree overlay in +the Raspberry Pi configuration file with \texttt{echo}. Since this file is +stored on the SD card only which is mounted as read-only it has to be remounted +with the read-write option first. + +\begin{verbatim} +mount -o remount,rw /media/mmcblk0p1 +echo 'dtoverlay=hifiberry-dac' >> /media/mmcblk0p1/config.txt +\end{verbatim} + +Since a diskless Alpine Linux installation is preferred for soundbox the +changes have to be made persistent with \texttt{lbu}. Rebooting after it makes +sure the SD card is again mounted in read-only mode and all Kernel-affecting +changes can be applied. + +\begin{verbatim} +lbu commit -d +reboot +\end{verbatim} + +After this reboot the soundbox device should be able to play audio like +described in section~\ref{playing-audio}. + %\section{Final assembly} %\chapter{Device internals} |