Audio Algorithm Support - Polycom realpresence 1800 Administrator's Manual

Audio Algorithm Support

The Collaboration Server supports the following audio algorithms in AVC conferences: G.711, G.722,
G.722.1, G.722.1C, G.729A, G.719, G. 728, G.723.1, siren 7, Siren14, Siren 22 (in mono or stereo) and
SirenLPR.
Polycom's proprietary Siren 22 and industry standard G.719 audio algorithms are is supported for
participants connecting with Polycom endpoints.
The Siren 22 audio algorithm provides CD-quality audio for better clarity and less listener fatigue with audio
and visual communication applications. Siren 22 requires less computing power and has much lower
latency than alternative wideband audio technologies.
The Siren 7 audio codec is the preferred codec for SIP/Lync calls, depending on the value of the system
flag ALLOW_SIREN7_CODEC. This preference is aimed at preventing disconnection of Lync clients using
audio rates smaller than 42Kbps, when the Lync server is configured to allow 33Kbps audio rate. For more
information see ALLOW_SIREN7_CODEC.
The SirenLPR audio algorithm provides CD-quality audio for better clarity and less listener fatigue with audio
and visual communication applications.
In SVC conferences, the system supports SAC (Scalable Audio Coding) audio algorithm.
Audio Algorithm Support Guidelines
● Siren 22 and G.719 are supported in both mono and stereo.
● Stereo is supported in H.323 calls only.
● Siren 22 is supported by Polycom HDX and Group series endpoints, version 2.0 and later.
● Siren 7 is the preferred audio codec for SIP/Lync clients, provided the system flag
ALLOW_SIREN7_CODEC is set to YES.
● Where low line rates affect audio quality, it is possible to disable G.729 codec in favor of G.711 by
modifying the ENABLE_G729 system flag value to NO.
● G.728 is supported in H.323, SIP and ISDN environments.
● SirenLPR is enabled by default and can be disabled by setting the system flag ENABLE_SIRENLPR,
to NO.
● SirenLPR is supported:
 In IP (H.323, SIP) calls only.
 In CP and VSW conferences.
 With Polycom CMAD and HDX 3.0.1 and later and Group series endpoints.
 For mono audio at audio line rates of 32Kbps, 48Kbps and 64Kbps.
 For stereo audio at audio line rates of 64Kbps, 96Kbps and 128Kbps.
SIP Encryption
The ENABLE_SIRENLPR_SIP_ENCRYPTION System Flag enables the SirenLPR audio algorithm when
using encryption with the SIP protocol.
The default value of this flag is NO meaning SirenLPR is disabled by default for SIP participants in an
encrypted conference. To enable SirenLPR the System Flag must be added to system.cfg and its value set
to YES.
Polycom®, Inc.
Additional Conferencing Information
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