Impath Networks i-Volution iN7000 Pro, User Manual

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Figure 5-76: Same as Storage
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Use existing compressed stream:
Depending on your capture source, there may be already com-
pressed video/audio stream. For example, source from network camera typically has a compressed
MJPEG stream in which case you can save a compressor. Using existing compressed stream is not man-
datory. You can choose to recompress video/audio with software WVC1/WMA codec.
- VBR and CBR: We recommend you to use CBR (Variable Bit Rate) if you need to webcast the video.
The default
CBR
(Constant Bit Rate) rate is 512 Kbit/sec (524288 bit). This value is sufficient for D1
video. If your video source resolution is lower than or equal to 720*480, we recommend you to set this to
a lower value, such as 256 Kbit/sec (262144), to lower the data size.
- Prefer secondary compressed stream: Depending on your capture source, there may be 2 existing
compressed video/audio streams—the primary and secondary compressed stream. This setting allows
you to select which stream to be used. In hardware compression card, there is so-call “dual hardware
compression”, which offers 2 compressed streams.
Typically the quality of the primary stream is better than that of the secondary stream, while the data size
of the secondary is smaller. This type of capture source is appropriate in situation where you require high
quality video to be stored locally, while reduced bandwidth video can be broadcasted over Internet.
Checking this box enabled the secondary compressed stream to be used.
- Compressor Complexity: the compressor complexity of WVC1 codec. We highly recommend setting
this value to 0. Theoretically a higher complexity value would generate better quality and smaller-size
data at the cost of more CPU resources. High complexity value can require excessive CPU usage for
minor gains in video quality.
- Key Frame Interval: The maximum interval between key frames during compression. If the compressed
stream needs to be broadcasted over Internet, please set this value to around 2000 milliseconds. A larger
interval would produce smaller-size data. This could be good for local storage but may cause problem on
Internet broadcast due to insufficient network bandwidth, resulting in dropped frames. If a key frame is
dropped, all frames until the next key frame will become useless and be dropped too.
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Decode profile:
Select the decode profile value according to the video resolution of the capture source.
There is excellent reference information about the decode profile at wiki: http://en.wikipedia.org/wiki/VC-1 .
- Pre-event time: sets the start time of an event.
- Post-event time: sets the end time of an event.
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Compress on event
: compress video/audio data only when events in the Events of Interest list occur.
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iN7000 User Guide