TANDBERG Compliance Appliance, Deployment Manual

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5 Optimizing TCA performance
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5 Optimizing TCA performance
To avoid call latency or other quality issues you need to consider the network configuration, the
location of the endpoints and the physical placement of the TCAs.
5.1 Efficient media streaming
When it records a call, the TCA interposes itself between the endpoints, so it’s important that it be
physically as close to the endpoints as possible.
Avoid situations in which the media from endpoints that are close together is being routed
over a wide area network to a TCA located far away (e.g. in another country). That sort of
configuration may create latency and other issues.
Slower speed links such as wide area network links are the ones you need to use most efficiently. As
calls are being made in real-time, the links between endpoints and TCAs need to be efficient enough to
support the video stream.
5.2 Efficient transcoding
The link to the external storage can afford to be slower as it only affects transcoding, but efficient
transcoding is still important. Transcoding rate is a function of resolution and link speed. The higher the
resolution required and the slower the link, the longer it will take to transcode the video.
Wherever possible, connect the TCA to external storage over a low-latency link and
transcode to the lowest possible resolution.
If the TCA is copying high-definition files to external storage over a slow wide area network , you may
also experience drop-outs, in which case TCA will restart transcoding whatever file was interrupted.
In extreme cases you risk being in ‘transcode deficit’ where the volume of incoming video exceeds the
rate of transcoding to the point where the TCA runs out of disk space. TCA can support 100 streams at
1 megabit/second while transcoding to CIF at 192 kb/s at two hundred times that rate, so this situation
is unlikely to occur unless you have massive input volumes, but it’s important to be aware of it.
5.3 Taking local regulations into account
Another factor affecting the number of TCAs is variations between local compliance regulations. For
instance, some countries require recordings involving their citizens to be stored in that country only, so
this can also affect where you physically put the TCA, or which external storage you transcode to.