TEMA TELECOMUNICAZIONI SRL
IP Module AA-600
MAS-AA600-REV02EN
Page 33 of 56
9.15. Multicast audio streaming
In a LAN, the term Multicast indicates the possibility of distributing information to a group of terminals. Multicast
uses class D addresses ranging from 224.x.x.x to 239.x.x.x.
In our case, AA-600 is able to receive multicast audio and play it on your own speaker (see par. 9.14). Audio can
be generated from a PC software application (for example VLC), from an IP SIP phone or from another AA-600
Doorphone. In fact, it is possible to program each of the system keys for the immediate sending of the audio
captured by its microphone (see par. 9.13). The audio received in streaming is reproduced without the need for
intervention by any operator, this function is useful for reproducing voice announcements (also called "Paging").
Obviously the streaming is unidirectional, in the sense that the audio stream is sent from the source (for example a
telephone) to the destination (the Doorphone) but not vice versa. Streaming audio can be sent to multiple AA-600
terminals at the same time (terminals that all have the same Multicast address) or with separate terminals (each
therefore equipped with its own address).
It is possible to program up to 16 audio reception addresses, each with its own priority and its own playback
volume, so that the same terminal, if it is already playing audio (for example music) can be interrupted by a higher
priority stream (or example an announcement) and with a different volume (typically an announcement must be
reproduced at a higher volume than a background music). The audio supported by this mode is in the G.711 (aLaw
or µLaw), G722 or 16 bit high quality linear (proprietary format, broadcasted via the AD615 or another AA-600).
By enabling this feature, AA-600 will listen to the specified address/port, and can reproduce on its speaker any
received audio streaming. This function has a lower priority than the normal telephone operation of the system
(outgoing or incoming calls will block or prevent the reproduction of the audio stream).
It is possible to configure up to 16 multicast addresses, each one with an higher priority than the previous. In the
above example, there are two addresses. The first (..43) could be used to play music at low volume from a PC. The
second (..44) could be an announcement from a special programmed phone for Multicast with an higher volume.
