A method and apparatus for receiving video signals from a plurality of
video cameras, such as in a video surveillance system. The video cameras
are each coupled to provide a video signal to a respective input of a
multiplexer. The multiplexer routes a selected one of the video signals
to a video decoder. The video decoder receives the selected video signal
and is conditioned according to the video signal. This includes
synchronizing the video decoder to a frequency and phase of the video
signal, controlling a gain level for the video signal and adjusting a dc
clamping level for dc restoration of the video signal. Parameters
representative of each of these quantities are stored in association with
the identity of the corresponding video camera. The video decoder also
places each video signal into a format suitable for storage in a storage
device and for display by a display device. As the multiplexer is
utilized to cycle through the cameras according to a sequence, the
parameters for each camera are retrieved and utilized to initialize the
video decoder for decoding the video signal received from the
corresponding camera. As a result, the amount of time required to
condition the video decoder according to the video signal received from
each camera is significantly reduced. Accordingly, the present invention
allows a surveillance system to cycle through a plurality of cameras in
less time than prior systems having a single decoder, but without higher
costs associated with prior systems which employ multiple video decoders.