path: root/interfaces.tex
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authorMatthias P. Braendli <matthias.braendli@mpb.li>2014-12-11 17:57:48 +0100
committerMatthias P. Braendli <matthias.braendli@mpb.li>2014-12-11 17:57:48 +0100
commit50cc2b0dcceff73b5f86690f0f442e75efaf3d21 (patch)
tree5bb5d4127b8150e4454fa2a66257dba41522a19a /interfaces.tex
parentbc563e8e332010768f89370f3c3b4cddffaa9d8a (diff)
Add interface and scenario text
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1 files changed, 17 insertions, 3 deletions
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@@ -1,5 +1,6 @@
\section{Interfacing the Tools}
The first versions of these tools used files and pipes to exchange data. For
offline generation of a multiplex or a modulated I/Q, it is possible to
generate all files separately, one after the other.
@@ -111,6 +112,10 @@ This network connection is based on ZeroMQ, a library that permits the creation
connection with automatic connection management (connection, disconnection, error handling).
ZeroMQ uses a TCP/IP connection, and can therefore be used over any kind of IP networks.
+This connection makes it possible to put the different tools on different computers, but it is not
+necessary. It is also possible, and even encouraged to use this interconnection locally on the same
\subsubsection{Between Encoder and Multiplexer}
Between fdk-aac-dabplus and ODR-DabMux, the ZeroMQ connection transmits AAC superframes, with
@@ -121,8 +126,6 @@ makes more sense to calculate this in the encoder.
The toolame-dab encoder also can send MPEG frames over ZeroMQ, but is not yet able to calculate and
transmit audio level metadata yet.
-\sidenote{Add configuration example for encoders}
On the multiplexer, the subchannel must be configured for ZeroMQ as follows:
sub-fb {
@@ -186,7 +189,7 @@ available in fdk-aac-dabplus, which insures that the encoder outputs the AAC bit
nominal rate, aligned to the NTP-synchronised system time, and not to the sound card clock. The
sound card clock error is compensated for inside the encoder.
+Complete examples of such a setup are given in the Scenarios.
\subsubsection{Authentication Support}
In order to be able to use the Internet as contribution network, some form of protection has to be
@@ -207,4 +210,15 @@ to set up keys and to distribute them to the encoder and the multiplexer.
\subsubsection{Between Multiplexer and Modulator}
+The ZeroMQ connection can also be used to connect ODR-DabMux to one or more instances of ODR-DabMod.
+One ZeroMQ frame contains four ETI frames, which guarantees that the modulator always assembles the
+transmission frame in a correct way, even in Transmission Mode I, where four ETI frames are used
+Pipes are an older real-time method to connect several encoders to one multiplexer on the same
+machine. It uses the same configuration as the file input but instead of using files, FIFOs, also
+called ``named pipes'' are created first using \texttt{mkfifo}.
+This setup is deprecated in favour of the ZeroMQ interface.