diff options
authorMartin Koch <>2020-06-22 16:11:51 +0200
committerMartin Koch <>2020-07-01 14:37:32 +0200
commit6e8d0032441680b65804ef0643c15be5db8fd224 (patch)
parent066c3f7f16ef69e80376942e8d6b8c4944b8ed08 (diff)
Documentation: Include details of early-audio implementation
Signed-off-by: Martin Koch <>
-rw-r--r--docx/images/early_announcement.pngbin0 -> 43711 bytes
-rw-r--r--docx/images/early_transfer.pngbin0 -> 42024 bytes
4 files changed, 109 insertions, 15 deletions
diff --git a/docx/10_early_audio.dox b/docx/10_early_audio.dox
index bdd72f5..fc2cf0c 100644
--- a/docx/10_early_audio.dox
+++ b/docx/10_early_audio.dox
@@ -1,4 +1,4 @@
- /*
* Copyright (C) 2012, BMW AG
* This file is part of GENIVI Project AudioManager.
@@ -6,26 +6,116 @@
* Contributions are licensed to the GENIVI Alliance under one or more
* Contribution License Agreements.
- * \copyright
+ * @copyright
* This Source Code Form is subject to the terms of the
* Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with
* this file, You can obtain one at
- * \\author Christian Linke (
+ * @authors Christian Linke, 2012 <>,\n
+ * Martin Koch, 2020 <>
- /*!
-\page early Early Audio
-\section req The Requirement
-The requirement reviews showed that one very important aspect of managing audio within GENIVI is the early/late phase where the Linux part of the system is
-not available. This feature is addressed via special domains: EarlyDomains. These domains are acting "unmanaged" - meaning without the interaction with the
-AudioManager - providing a simpler set of features until the AudioManager is up and running. When the Linux system is then fully operable a handover is done
-from the EarlyDomains towards the AudioManager. In order to be able to operate without the Linux up and running, the EarlyDomains must be implemented on a
-second fast-boot or always-on controller, e.g. the so called vehicle processor.\n
-\section earlys Early Startup
+ /**************************************************************************//**
+@page early Early Audio
+@section req The Requirement
+The requirement reviews showed that one very important aspect of managing audio within GENIVI is the
+early/late phase where the AudioManager daemon (possibly along with the entire Linux part of the system)
+is not available. This feature is addressed via special domains: EarlyDomains.
+In normal operation these domains are slave to the routing side of the audio-manager
+daemon and optionally also interact with its command side. Here they are acting "unmanaged",
+that is without the control through the AudioManager, and usually provide only a limited set
+of features until the AudioManager is up and running. At minimum, they need to be capable of
+establishing the audio or video connection autonomously and start streaming their information.
+Scenarios requiring such capabilities comprise:
+ - System alerts
+ + Door open
+ + Seat belt missing
+ + Engine faults
+ - Parking assistant warnings
+ + Rear view camera screen
+ + Beeps if distance goes below limit
+In order to handle above situations, such applications at least need to be prioritized during startup.
+Furthermore, if they need to be operational before the entire Linux is available, the EarlyDomains can
+be implemented on a second fast-boot or always-on controller, e.g. the so called vehicle processor.
+Later, once the Linux system is fully operable and the audio-manager process is also started,
+a hand-over is done from the EarlyDomains towards the AudioManager so the latter can synchronize
+its internal state.
+Similarly, on system shutdown, the audiomanager process may already be stopped and unloaded
+while above information is still required to be presented to the user.
+@section earlys Early Startup
This picture shows the principle of the early startup:
-\image html early.png
-\section late Late Rundown
+@image html early.png
+Once a routing adapter is connected to the audio-manager and has received the setRoutingReady()
+signal, it registers (announces) the topology elements (sources, sinks and gateways) accessible
+through it to the daemon, which assigns numerical IDs to each of them. Details are given along
+with the registration, such as
+ - element name
+ - domain membership
+ - class (grouping category) membership
+ - supported connection formats
+ - availability
+ - streaming state (ON/OFF, sources only)
+ - audible volume
+ - additional element-specific properties
+For announcing a pre-established audio connection above information is not sufficient,
+as no connection information can be extracted from it. Here the function @ref am::IAmRoutingReceive::registerEarlyConnection
+"registerEarlyConnection()" is used from the routing side. The daemon shall then transparently
+forward this notification to the controller, which in turn registers the new connection to
+the daemons database.
+> A special case is given if the connection spans multiple domains. Although controlling the entire
+> route during startup and knowing that all involved elements do exist and are up and running,
+> the routing adapter cannot reliably assume that their registration to the audio-manager is
+> already completed. This can be overcome by using the existing functions @ref am::IAmRoutingReceive::peekSource "peekSource()"
+> and @ref am::IAmRoutingReceive::peekSink "peekSink()", which will return a valid numeric
+> identifier for the requested element specified with its unique name only. These functions
+> determine the IDs from either
+> - assigned IDs for actually registered elements
+> - or statically configured data
+> - or they reserve an ID which will be assigned to the element during later registration
+> So also in this case the proper hand-over of early connections should be possible.
+Below sequence chart illustrates the details:
+@image html early_announcement.png
+Once the connection is announced, the controller takes over full responsibility, including
+ - notifying the command side on its existence through function
+ @ref am::IAmCommandSend::cbNewMainConnection "cbNewMainConnection()"
+ - suspending or disconnecting it on command-side request according to business logic
+Thus a matching function __unregisterEarlyConnection()__ triggered by the routing adapter shall
+__not__ be necessary.
+@section late Late Rundown
+Connections which are still active (in state CS_CONNECTED or CS_SUSPENDED) and shall be kept
+alive beyond termination of the audio-manager process need to be handed over to the routing
+adapter before the daemon process terminates.
This picture shows the principle of the late rundown:
-\image html late.png
+@image html late.png
+Selectable for handover are all domains marked with status flag DS_INDEPENDENT_RUNDOWN indicating
+their capability of taking care of late connections autonomously. They shall be considered for the
+hand-over offering through asynchronous, non-blocking function @ref am::IAmControlReceive::transferConnection
+"transferConnection()". Below sequence chart shows the usage of this function and its forwarding
+and acknowledging siblings:
+@image html early_transfer.png
+After positive acknowledgment through the routing adapter the AM is no longer responsible
+for the connection and its elements, so the subsequent deregisterSource/Sink/Domain()
+requests do not harm.
+@note In case the audio-manager is restarted and said connection still exists under responsibility
+ of a routing adapter, above function registerEarlyConnection() can be invoked again.
*/ \ No newline at end of file
diff --git a/docx/images/early_announcement.png b/docx/images/early_announcement.png
new file mode 100644
index 0000000..b955f1f
--- /dev/null
+++ b/docx/images/early_announcement.png
Binary files differ
diff --git a/docx/images/early_transfer.png b/docx/images/early_transfer.png
new file mode 100644
index 0000000..f5ddb36
--- /dev/null
+++ b/docx/images/early_transfer.png
Binary files differ
diff --git a/include/IAmControl.h b/include/IAmControl.h
index e8545ad..d393b56 100644
--- a/include/IAmControl.h
+++ b/include/IAmControl.h
@@ -557,6 +557,7 @@ public:
* Hand-over to routing-side application any connection meant to survive AM shutdown
+ * (see page @ref early)
* @param handle: composite identifier used to map the response
* @param domainID: target domain which shall take over
@@ -564,6 +565,9 @@ public:
* @return E_OK if command was forwarded to routing adapter successfully,
* E_COMMUNICATION or other meaningful value otherwise
+ *
+ * @note Success of the responsibility transfer itself is acknowledged through corresponding
+ * function @ref am::IAmControlSend::cbAckTransferConnection "cbAckTransferConnection()".
virtual am_Error_e transferConnection(const am_Handle_s handle
, am_mainConnectionID_t mainConnectionID, am_domainID_t domainID) = 0;