Mobile DVR DMB-X Installation and Setup Manual v2.5 © Aventura Technologies 2009 Page
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of
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“
Fixed Bitrate
” versus “
Variable Bitrate
”. For mobile applications or camera views where
there will be large levels of motion it is generally better to select “
Fixed
”. For applications
where the camera is static (rather than Pan Tilt Zoom) and where there is generally not a
lot of motion or change in the camera view, the “
Variable
” setting will save significant
amounts of hard disk space with generally minimal impact on the image quality.
Note.
If you
use a “
Variable
” setting and there is suddenly a lot of motion in the camera view, you may
find some initial blockiness in the recorded images.
“
Audio
” can be selected to record audio synchronised with the camera. This will require a
separate microphone installation. Note an Audio on a specific channel input will be
recorded with a like numbered video channel (i.e. AUD3 will be recorded on VID3 only).
“
Picture Resolution
” provides a choice of four image sizes or “resolutions”:
QCIF (176 x 144 pixels)
CIF (352 x 288)
DCIF (528 x 384)
4CIF (704 x 576)
Please note that the higher resolution that you choose, the higher the bitrate you will
require. We suggest an initial default setting of CIF for most purposes.
IMPORTANT:-
Processing constraints on the video capture card means that you cannot
set all cameras to record at maximum resolution and maximum frame rate and maximum
Bitrate.
Recording at the highest image resolution settings (4CIF or DCIF) and at the highest frame
rate setting (real-time 25/30 frames per second) should only be set up on a maximum of
half the channels at the same time (i.e. 2 channels on a 4 channel Mobile DVR). The other
channels must be set at CIF where they can still be run at 25/30 fps.
For the vast majority of mobile applications this constraint is not a problem. CIF quality is
sufficient for most evidential requirements, and the smaller image sizes require less hard
drive space.
“
Video Standard
” provides a choice of PAL, NTSC and SECAM depending on the national
standard you use. Generally PAL is used in the UK and most of the rest of the world. North
America uses NTSC. SECAM is used in France and some other EU markets.
7B
