doc: Adapt streaming guide to IPv6

It is a bit more complex to stream via IPv6 link-local addresses. This
commit adapts the user guide to it.

1 files changed, 9 insertions, 6 deletions

diff --git a/doc/documentation.tex b/doc/documentation.tex
index 993448d..2375ee3 100644
--- a/doc/documentation.tex
+++ b/doc/documentation.tex
@@ -82,7 +82,7 @@ In addition to \autoref{chap:introduction} `\nameref{chap:introduction}` the
 following sections document everything required to use \texttt{soundbox}
 devices.
 
-\section{Getting the IP address}
+\section{Getting the IP address}\label{get-ip}
 
 Each soundbox device has a label with the MAC address of the device in a format
 like \texttt{xx:xx:xx:xx:xx:xx}.
@@ -95,15 +95,18 @@ is a convenient way to do that.
 \section{Playing audio} \label{playing-audio}
 
 Audio can be streamed to \texttt{soundbox} devices with the \texttt{ffmpeg}
-command. Audio files or internet stream addresses can be passed as input. Since
-\texttt{ffmpeg} supports multiple outputs, the part enclosed in square brackets
-can be repeated multiple times with different \texttt{soundbox} device IP
-addresses.
+command. Audio files or internet stream addresses can be passed as input. The
+IPv6 address retrieved in \autoref{get-ip} should be used as IP and the
+interface has to be the one showing up in \texttt{ip link show} which is
+connected to the same network as the \texttt{soundbox} device.
 
 \begin{verbatim}
-ffmpeg -re -i <input> [-acodec flac -f ogg tcp://<ip>:5316]...
+ffmpeg -re -i <input> -acodec flac -f ogg tcp://[<ip>%<interface>]:5316
 \end{verbatim}
 
+The part starting with \texttt{-acodec} can be repeated multiple times to
+stream to more than one soundbox devices for a multi-room audio setup.
+
 More details about FFmpeg streaming can be read from the FFmpeg streaming
 guide\footnote{\href{https://trac.ffmpeg.org/wiki/StreamingGuide}{https://trac.ffmpeg.org/wiki/StreamingGuide}}.