Eagle-DVR Digital Video Recording System for local and remote surveillance
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frequently asked questions

Frequently Asked Questions > Q-01
Frequently Asked Questions : Q-01

Q: Compression - in-depth details, - which method is used.

A: We use a proprietary method compression algorithm. The algorithm consists of two phases:

- First phase: calculation of inter-frame differences.
The algorithm divides each frame by 8x8 pixel blocks. The average brightness level is calculated in every such block. The algorithm takes each pair of frames within the incoming sequence. It then performs a comparison of the blocks in the same positions within these frames. If the differences in brightness level rise above the threshold.defined in configuration (Delta sensitivity) this block will be marked as changed and
consequentially will have to be recorded.

- Second phase: compression of changed blocks
Marked blocks form the sequence. The sequence is compressed by algorithm based on DCT (Discrete Cosines Transform). The quality of compression is adjustable in the configuration (Picture quality). The compressed section goes to the video database as a single record to be recorded on to the hard drive. A key frame (complete frame) is recorded additionally for every defined period of time to ensure accuracy of video information and to avoid accumulation errors. This proprietary method gives better picture quality/storage size ratio compared to the standard compression algorithms (i.e. MPEG, MJPEG, H.262, etc), especially when the recording of small details is required. This is an important factor for digital surveillance
systems.

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