Nortel 1110 User Guide
Operation
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The jitter buffer has a desired size and a maximum allowable size. If the jitter
buffer exceeds its maximum allowable size, sufficient frames are discarded
to reduce the contents of the jitter buffer to the desired setting. If the jitter
buffer underruns, frames are held in the jitter buffer until it fills to the desired
level. Both underrun and overrun result in a discontinuity in the audio.
buffer exceeds its maximum allowable size, sufficient frames are discarded
to reduce the contents of the jitter buffer to the desired setting. If the jitter
buffer underruns, frames are held in the jitter buffer until it fills to the desired
level. Both underrun and overrun result in a discontinuity in the audio.
For codecs that support silence suppression, the jitter buffer is
resynchronized at the beginning of each talk spurt.
resynchronized at the beginning of each talk spurt.
QoS
A combination of codec selection, jitter buffer and packet time, and the
use of the DiffServ Code Point (DSCP) of the network contributes to the
end-to-end Quality of Service (QoS).
use of the DiffServ Code Point (DSCP) of the network contributes to the
end-to-end Quality of Service (QoS).
However, the IP Softphone 2050 is an application within the context of
the PC operating system, so the operating system has an effect on
the end-to-end QoS for the IP Softphone 2050. Functionality, which is
commonly handled in DSP hardware (such as, the codec packetization
implementation from within the Voice Gateway Media Card) is implemented
in software for the IP Softphone 2050. It runs as part of the application
code on the PC CPU. If the CPU is busy with other tasks, voice quality
can be negatively affected.
the PC operating system, so the operating system has an effect on
the end-to-end QoS for the IP Softphone 2050. Functionality, which is
commonly handled in DSP hardware (such as, the codec packetization
implementation from within the Voice Gateway Media Card) is implemented
in software for the IP Softphone 2050. It runs as part of the application
code on the PC CPU. If the CPU is busy with other tasks, voice quality
can be negatively affected.
The number of buffers used to buffer audio data between the application
and PC audio hardware device driver is adjustable from the Settings >
Sound Devices window. Using fewer buffers reduces the audio path delay
but increases the chances of dropouts and choppy speech, depending on
the speed and utilization of the PC CPU.
and PC audio hardware device driver is adjustable from the Settings >
Sound Devices window. Using fewer buffers reduces the audio path delay
but increases the chances of dropouts and choppy speech, depending on
the speed and utilization of the PC CPU.
This system-wide registry key setting affects other applications and
operating system components but is only effective if Windows QoS Packet
Scheduler is installed. For more information about Windows QoS Packet
Scheduler, see
operating system components but is only effective if Windows QoS Packet
Scheduler is installed. For more information about Windows QoS Packet
Scheduler, see
For Windows 2000 the Windows QoS Packet Scheduler is not installed by
default and the EnablePriorityBoost registry setting is not created.
default and the EnablePriorityBoost registry setting is not created.
For Windows XP the Windows QoS Packet Scheduler is installed by default
and the EnablePriorityBoost registry setting is created. The default setting
is 1 (enable QoS).
and the EnablePriorityBoost registry setting is created. The default setting
is 1 (enable QoS).
Windows 2000 and Windows XP require a system-wide registry key to
enable QoS capabilities. You must have Administrator privileges to create or
modify the following value:
enable QoS capabilities. You must have Administrator privileges to create or
modify the following value:
Nortel Communication Server 1000
IP Phones Fundamentals
NN43001-368
01.02
Standard
Release 5.0
20 June 2007
Copyright © 2003–2007, Nortel Networks
.