On-Net Surveillance Systems, Inc.
NetDVR 6.5
Administration
63
Audio
Important Information about Using Audio
If you use audio sources (i.e. microphones and/or speakers) on your NetDVR system, note the following:
•
Only audio from microphones is recorded:
Only incoming audio, i.e. audio recorded by microphones
attached to cameras, is recorded. Outgoing audio, i.e. what
operators say when they talk
through speakers attached to cameras, is not recorded.
•
Audio from microphones is recorded even when video is not:
When a microphone is enabled (see
), audio from the microphone will be recorded whenever the associated camera is online (i.e.
transmitting data to NetDVR; see
), regardless whether video from the camera
is being recorded or not.
Depending on your cameras’ recording settings, this may mean that when you play back recordings, you
may find that there are periods for which you only have audio recordings. This will also be the case for
exported recordings if audio has been included in the export.
•
Audio recording affects video storage capacity:
When a microphone is enabled, audio is recorded to the
associated camera’s database. This will affect the database’s capacity for storing video. A camera’s
database can contain a maximum of 40 GB or 600,000 records. It is thus important to bear in mind that the
maximum limit of the database is likely to be reached earlier if recording audio
and
video than if only
recording video.
o
Example: If using MPEG4, each one-second video GOP (Group Of Pictures) will be stored in one
record in the database. Each second of audio will also be stored in one record in the database.
When this is the case, the database’s video storage capacity will be reduced to a maximum of
300,000 records, because half of the database’s total maximum of 600,000 records will be used for
storing audio.
o
Example: If using 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. The database’s video storage capacity
can thus in extreme cases be reduced to a maximum of 300,000 records, because half of the
database’s total maximum of 600,000 records will be used for storing audio. If using very high frame
rates, where there is less time between each JPEG, a smaller portion of the database will be used
for storing audio records, and consequently a larger portion will be available for storing video.
Thus, a camera database’s maximum video storage capacity may in some cases be halved when an
associated audio source is enabled.
Note:
Above examples are simplified. Since databases also have a maximum limit of 40 GB of data, the
exact available video storage capacity will also depend on GOP/JPEG and audio kilobyte size.
Tip:
The
feature enables you to store recordings beyond the capabilities of cameras’
databases. Even if already using archiving, you may want to archive more frequently if recording audio and
video than if only recording video.
