Technical Description of TANDBERG 8000 with software version E3/B8
D12008 Rev. 11
39
Automatic Duo Video set up
When DuoVideo mode is set to Auto and the remote control buttons; DocCam, Aux, VCR or PC
are selected, the system will use this video input as its Duo Video source. The call bandwidth
will be split between the main video (including audio etc.) and the Duo Video. Once the Main
camera is selected, the system will use all its bandwidth for this video source.
When network is H.323
:
The system will use approximately 1/2 of its original bandwidth for Duo Video (i.e. the system
decides the DuoVideo rate according to the available HSD
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data rates- the DuoVideo rate will
be less than the main video rate for higher call rates).
When network is ISDN:
The following table applies for Duo Video Bandwidths*:
Call rate (kbps)
Duo Video rate (kbps)
128 64
192 64
256 64
320 128
384 128
512 128
768 256
1152 384
1472 384
1536 384
1920 384
1719
* For restrict use 56k multiples: E.g. 112 -> 56, 168 -> 56 etc
When using the Duo Video feature the main video bandwidth can be calculated by using the
formula below:
Main video rate = Call rate – DuoVideo – Audio – Framing (1.6 kbps) – Encryption control
(0.8 kbps)
E.g. A 320kbps call using G.722 (56kbps) audio will use:
320kbps – 128 – 56 – 1.6 – 0.8 = 133.6 kbps for main video
When network is Leased Line E1/T1:
the maximum Duo Video bandwidth is 768 kbps.
It is possible to change the picture quality (e.g. Digital Clarity) even after a Duo Video signal is
set up (Presentations Menu – Duo Video Quality).
Note: In a MultiSite call, the MultiSite ‘host’ can transmit Duo Video to the other sites if these
sites have Duo Video support. If some of the connected sites are single monitor systems and
have software B5 or later the single monitor systems will see the Duo Video picture (e.g.
presentation) and the Duo Video sites will see both presenter and the presentation.
34 Only possible when both systems have software B3 or later. Description of HSD is found in ITU recommendations: H.221, H.242 and H.243
