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Recorded Viewing Operation
When an operator requests a playback feature, the ISP detects the request and responds with the
proper playback feature. Figure 12 shows the interaction between the ISP, data converter, and
hybrid decoder when an operator who is using Monitor 1 requests to view recorded video from
Camera 5 by pressing the Instant Replay button.
Note:
Appendix A provides additional details about the network communication that takes place
during a video playback and describes the TCP/UDP port numbers that are used.
The hybrid decoder is connected to the matrix switch on input port 16 and video for Camera 5 is
recorded on the ISP named ISP_2.
Figure 12.
Example—Playing Recorded Video
In Figure 12, live viewing is taking place and no playback requests have been received. Keyboard
control commands are passed through the ISP to the matrix switch transparently until an operator
requests the playback of recorded video. Here is an example of the processes that occur when an
operator requests playback:
1.
While viewing video from Camera #5, an operator presses a key sequence requesting an
instant replay of Camera#5. ISP_1 receives this key sequence and detects that the user wants
to play recorded video. The default rewind time is 30 seconds, but this value may be changed
as shown on Page 5-12.
2.
Through the data converter, ISP_1 reads the currently selected camera from the matrix switch
and sends a device discovery request for an available hybrid decoder.
3.
If a hybrid decoder is available, ISP_1 sends the peripheral ID (Camera#5) and start date/time
to the hybrid decoder. If no hybrid decoders are available, the request terminates and no visual
changes take place on an operator's monitor.
4.
The hybrid decoder sends to all recorders, via multicast, a discovery request for the ISP that
has recorded peripheral ID 5 at the specified start date/time.
5.
ISP_2 responds to the hybrid decoder and a new TCP session is established between ISP_2
and the hybrid decoder.
Design Guide
2-7
Page-2-7
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