TEMA TELECOMUNICAZIONI SRL
Doorphone AA-550
MAS-AA550-REV07EN
Page 18 of 67
6.7.
Multicast audio streaming
In a LAN network, the term Multicast indicates the possibility of distributing information to a group of terminals. For
Multicast, class D addresses are used and range is from 224.xxx to 239.xxx
In our case, AA-550 is able to receive Multicast audio and play it on its speaker (see par. 9.10). Audio can be
generated by a PC software application (eg VLC), an IP phone or another AA-550 Doorphone. Infact it is possible
to program each AA-550 button to immediately dispatch the audio captured by the microphone (see par. 9.9).
The received audio stream is played without requiring the intervention of any operator, this feature is useful for
playing back announcement voice messages (also called PA "paging").
Obviously the streaming is one-way, meaning that the audio stream is sent from the source (such as a phone) to
the destination (the Doorphone) but not vice-versa.
The audio stream can be sent to multiple terminals simultaneously (terminals that have the same Multicast
address) or to separate terminals (each with its own address).
It is possible to program up to 16 audio receive addresses, each with its own priority and its playback volume, so
that the same terminal, if it is already playing audio (eg music) can be interrupted by a higher priority stream (for
example an announcement) and with a different volume (typically an announcement must be played at a higher
volume than background music).
The audio supported by this mode is in the G.711 format (aLaw or
μ
Law), G722 or linear high quality 16 bit
(proprietary format, diffused through the AD615 device or another AA-540).
Example 1
In the installation there are 2 Doorphones, connected to the same network switch. From a telephone, I make a
voice announcement to the address 239.255.12.42:
Both Doorphones will reproduce the audio message announcement. It is possible to connecte more than the 2
devices as indicated in the example, since the only limit is the bandwidth of the network.
Example 2
In the installation there are 3 Doorphones. It is possible to use each system to play an announcement,
programming one of the four buttons to perform this function (for example the button 4):
Holding down the button 4 on Doorphone number 3, the audio captured by its microphone is sent simultaneously to
the Doorphones 1 and 2. Please note that it is possible to program each system so that it can send the audio
streaming to all the others and it is also possible to use all four keys only for the Multicast service.
Multicast
predisposed
telephone
AA-540 n. 1
Multicast address
239.255.12.42
AA-540 n. 2
Multicast address
239.255.12.42
LAN Switch
AA-540 n. 1
Multicast address
239.255.12.42
AA-540 n. 2
Multicast address
239.255.12.42
AA-550 n. 3 with button 4
programmed for sending
audio Multicast to
address 239.255.12.42
LAN Switch
