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8.2
Audio support and equipment
Audio support can be more easily implemented in a network video system than in an analog
CCTV system. In an analog system, separate audio and video cables must be installed from end-
point to endpoint; that is, from the camera and microphone location to the viewing/recording
location. If the distance between the microphone and the station is too long, balanced audio
equipment must be used, which increases installation costs and difficulty. In a network video
system, a network camera with audio support processes the audio and sends both audio and
video over the same network cable for monitoring and/or recording. This eliminates the need for
extra cabling, and makes synchronizing the audio and video much easier.
Figure 8.2a A network video system with integrated audio support. Audio and video streams are sent over the same
network cable.
Figure 8.2b Some video encoders have built-in audio, making it possible to add audio even if analog cameras are
used in an installation.
A network camera or video encoder with an integrated audio functionality often provides a
built-in microphone, and/or mic-in/line-in jack. With mic-in/line-in support, users have the
option of using another type or quality of microphone than the one that is built into the camera
or video encoder. It also enables the network video product to connect to more than one micro-
phone, and the microphone can be located some distance away from the camera. The micro-
phone should always be placed as close as possible to the source of the sound to reduce noise.
In two-way, full-duplex mode, a microphone should face away and be placed some distance
from a speaker to reduce feedback from the speaker.
AUDIO Stream
VIDEO Stream
Recording/monitoring
IP NETWORK
AUDIO Stream
VIDEO Stream
Video encoder
Recording/monitoring
Analog
camera
IP NETWORK
AU
DIO
I/O
IN
OU
T
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2
3
4
5
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CHAPTER 8 - AUDIO
