Technical data

8
Systems
MAGIC AC1 XIP & XIP RM Audio Codecs
General
The MAGIC AC1 XIP systems incorporate an ISDN
BRI interface, a X.21 interface and a LAN interface. The
coding algorithms G.711 (3.1- kHz), G.722 (7-kHz), ISO/
MPEG Layer 2 & 3 (15-kHz), AAC-LD (15-kHz), standard
apt-X and enhanced apt-X as well as PCM are supported.
For the transmission of the high quality signals, the
ISDN
1
interface, the X.21
1
interface or the LAN interface
can be taken.
The compact MAGIC AC1 XIP Audio Codec (½ x 19“,
1 U) is a powerful product for mobile operations as well
as for space-saving studio applications. In comparison to
MAGIC AC1 XIP, MAGIC AC1 XIP RM has a 19" design
and provides an integrated power supply.
Functionality
ISDN operating mode
After an ISDN connection is established, the MAGIC
AC1 XIP Audio Codec automatically determines with the
ITU-T J.52 inband signalling, whether or not the called
party can operate in 7-kHz or ISO/MPEG Layer 2 mode.
If all modes are available, the dial-up side chooses the
right coding algorithm. Otherwise the unit operates in
the conventional 3.1-kHz mode. MAGIC AC1 XIP can
use up to 2 ISDN B channels with a maximum data rate
of 128-bit/s for the transmission of a high quality Audio
signal. The required inverse multiplexing procedure is
also defined in the ITU-T J.52 standard. The inverse mul-
tiplexing procedure guarantees a minimum transmission
delay. Should a B channel drop or the routing of the B
channels in the transmission network changes, the unit
still can operate without interruption by using the
remaining B channel.
A remarkable feature is the transfer of a command signal
with 3.1-kHz or 7-kHz bandwidth in parallel to the trans-
mission of the high quality Audio signal. Additionally,
two independent data channels can be used.
X.21 operating mode
In the X.21 operating mode the MAGIC AC1 XIP pro-
vides a coded Audio signal with data rates from 8-kbit/s
to 384-kbit/s. All ISO/MPEG Layer 2/3, AAC-LD and
apt-X data rates are provided.
After the Audio algorithm is selected, the unit measures
the X.21 clock and adapts the Audio Codec’s data rate to
the X.21 line clock. PAD data can be transmitted together
with Audio data.
IP operating mode
Two IP transmission modes are available:
• Leased Line Mode with RTP
• Dial-up Mode with SIP according to the new EBU
Audio over IP standard N/ACIP TECH3326
2
ISDN/LAN (SIP) Auto Mode
With the ISDN/LAN (SIP) Auto Mode the system
decides on the basis of the type of the incoming call
which network interface shall be active- ISDN or LAN
(SIP). The user in the control room can use the ISDN/
LAN (SIP) configuration for all incoming calls. The
MAGIC AC1 XIP switches automatically to the right net-
work interface.
Automatic ISDN Backup
Optionally, an ISDN Backup function is available. It
establishes a Backup connection via ISDN if the main
connection via X.21 or IP fails. For the Backup connection
another coding procedure can be defined as for the main
one.
Interworking with Audio Codecs
Due to the implemented ADS (AutoDynamicSync)
functionality, the MAGIC AC1 XIP systems detect the
parameters of the calling or the called codec for 1B and 2B
ISDN connections and adapt them automatically. There-
fore, previous manual adjustments are no longer
required. In the LAN (SIP) dial-up mode the compatibil-
ity between Audio Codecs from other manufacturers is
guaranteed due to the new EBU standard for Audio over
IP. So ADS supports codecs like from ORBAN
(Musictaxi), CCS, TELOS as well as all 7-kHz and J.52
Codecs.
In SIP mode full compatibility to VoIP
phones is provided. If the remote IP phone
also supports HD telephony with G.722, the
system will be switched automatically in 7-
kHz mode and offers as a result high quality
speech.
1
If the ISDN or the X.21 interface is selected, the PCM coding
procedure cannot be used due to the required bit rate.
2
Further details can be found under http://www.ebu-acip.org