Milestone XProtect Professional 2014 - Manual (Page 58)

Milestone XProtect ® Professional
2014
Administrator's Manual
www.milestonesys.com 58 Advanced configuration
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Audio recording affects video storage capacity. The system records audio to the associated
camera’s database. Therefore, it is important to bear in mind that the database is likely to
become full earlier if you record audio and video than if you only record video. The fact that the
database becomes full is not in itself a problem since your system automatically archives data
if the database becomes full. However, you may need additional archiving space if you record
audio.
o Example: If you use MPEG4, each one-second video GOP (Group Of Pictures) are stored
in one record in the database. Each second of audio is stored in one record in the
database. This reduces the database’s video storage capacity to half its capacity, because
half of the database’s records is used for storing audio. Consequently, the database runs
full sooner, and automatic archiving takes place more often than if you were only recording
video.
o Example: If you use MJPEG, audio is stored in one record for every JPEG for as long as
the audio block size does not exceed the time between the JPEGs. In extreme cases, this
reduces the database’s video storage capacity to half its capacity, because half of the
database’s records is used for storing audio. If you use very high frame rates, which
means less time between each JPEG, a smaller portion of the database is used for storing
audio records, and consequently a larger portion is available for storing video. The result is
that the database runs full sooner, and automatic archiving takes place more often than if
you were only recording video.
The above examples are simplified. The exact available video storage capacity also depends on
GOP/JPEG and audio kilobyte size.
About dedicated input/output devices
You can add a number of dedicated input/output (I/O) hardware devices to your system. For
information about which I/O hardware devices your system supports, see the release notes.
When you add I/O hardware devices, input on them can be used for generating events in your system
and events in your system can be used for activating output on the I/O hardware devices. This means
that you can use I/O hardware devices in your events-based system setup in the same way as a
camera.
With certain I/O hardware devices, the surveillance system must regularly check the state of the
hardware devices' input ports to detect whether input has been received. Such state checking at
regular intervals is called polling. The interval between state checks, called a polling frequency, is
specified as part of the general ports and polling properties (see "Ports and polling" on page 116). For
such I/O hardware devices, the polling frequency should be set to the lowest possible value (one tenth
of a second between state checks). For information about which I/O hardware devices require polling,
see the release notes.
Show or hide microphones or speakers
If you have added more microphones or speakers to your system than you need, you can hide the
ones you do not need by right-clicking the relevant microphone or speaker and select Hide. If you
need the hidden microphone/speaker again, you can right-click the overall microphone or speaker icon
and select Show Hidden Items.