11
E:
VIDEO TESTS SUMMARY
High Definition Image Quality
Unfortunately, during testing the cameras at both sites appeared to have faults that
limited the image quality. In calls between HDX 4500 systems one camera
produced soft focus images with a very limited depth of field. The other camera
produced more acceptable results but the edges of objects in the image appeared
artificially sharp whereas areas of fine detail, for example hair and skin texture
appeared blurred and with too much contrast (Posterised).
When Content material from a PC was transmitted on either channel the results
were good, suggesting that the problems experienced were camera related as
opposed to CODEC or picture monitor issues.
The ability to send and receive two high resolution, high frame rate images was
seen as a very positive feature.
F:
AUDIO TESTS SUMMARY
Setup
The echo canceller is fully automatic in operation. The quality of echo cancellation
and doubletalk from the system was excellent.
Audio levels adequate? (Yes/No)
Yes
Audio quality acceptable? (Yes/No) Yes
Echo cancellation acceptable?
(Yes/No)
Yes
Quality of double talk
Excellent
When the frequency response was measured it was found to be quite uneven for all
audio protocols. The levels measured 0 dB at both 1KHz and 7 KHz but at mid-
band (i.e. 3.5 KHz) was -6dB indicating a notch in the frequency response between
these frequencies.
G:
DATA TESTS
A PC may be directly connected to the CODEC via the DVI interface and may be
transmitted on either the main channel or the H.239 channel. Audio from a PC may
only be transmitted when the PC is selected on the main channel. People +
Content™ IP software may also be used to connect a PC to the CODEC across the
data network but with picture only
H:
CONNECTIVITY
Connectivity between Like Machines
H.323
There were no problems in establishing connections between the HDX units over
IP.
