2. WebCCTV 1 Contents Introduction Getting Started Connecting the WebCCTV NVR to a local network Connecting the WebCCTV NVR to the Internet Restoring the WebCCTV NVR Storage & Bandwidth considerations Security Policy Troubleshooting

3. WebCCTV 2 Storage & Bandwidth considerations Terminology & basic video technology Factors influencing bit rate & video quality

4. WebCCTV 3 Storage & Bandwidth considerations Digital video Massive amount of data versus limited storage Compression by ‘ codec ’ Trade off between quality / performance and data size / compression technique Extra Use our Online Storage Calculator at : http://www.webcctv.com Detailed explanations in the installation manual

5. WebCCTV 4 Storage & Bandwidth considerations Important concepts Digital Image Pixels = array of image dots Each pixel represents a colour Resolution = amount of pixels in Vertical and Horizontal directions More pixels = higher resolution, better detail Video Series of digital images/frames Speed of display/transfer = frame rate (fps) Smoother video = higher frame rate = space and/or bandwidth increase Terminology & basic video technology

6. WebCCTV 5 Storage & Bandwidth considerations Important concepts Video (continued) Amount of data per second = Bit Rate. Expressed in kilobits per second (kbps) Example bit rate Uncompressed Video (5 fps of full D1 PAL Video) Resolution x Frame Rate x colour depth (amount of bits per pixel) = amount of data 576 x 768 pixels/frame x 5 frames/second x 24 bits/pixel = 530841 bits/sec = 50.6 Mbps On a 80 GB harddisk we can only store 3.6 hours of this kind of video stream. COMPRESSION needed ! Terminology & basic video technology

7. WebCCTV 6 Storage & Bandwidth considerations Compression technique (codec) Intra-frame coding (MJPEG) Each frame compressed independently = bigger storage and bandwidth requirements Less complex calculations Less CPU intensive Inter-frame coding (Windows Media, MPEG2, MPEG4, … ) Using similarities between subsequent frames = smaller storage and bandwidth requirements More complex calculations More CPU intensive Factors influencing bit rate & video quality

8. WebCCTV 7 Storage & Bandwidth considerations Compression technique (codec) Intra-Frame : Changing the quality of JPEG compression, changes the size of the JPEG, so influences the bit rate Inter-Frame : The bit rate is the parameter, changing frame rate and/or resolution, influences the quality of the video but not the bit rate. Factors influencing bit rate & video quality Recommended : For Network camera’s and Network Video Servers (NVS), use the native format in which the device streams = no recompression

9. WebCCTV 8 Storage & Bandwidth considerations Resolution Postage Stamp (160 x 120 pixels in NTSC) Low quality, no detail at all VHS quality (320 x 240 pixels in NTSC) Widely used, higher frame rate Favorable for storage & transmission SVHS quality (640 x 240 pixels in NTSC) Decimated in vertical direction, no 4:3 proportion For analog camera ’ s max resolution without motion artifacts In some players seen as ‘ squished ’ image Factors influencing bit rate & video quality

10. WebCCTV 9 Storage & Bandwidth considerations Resolution SVHS+ quality (640 x 480 pixels in NTSC) Max. for all analog and most network cams today Disadvantage : interlacing produces horizontal lines around edges of moving objects Progressive technology solves this Megapixel quality (1280 x 1024 pixels) More than 1,000,000 pixels ! Preserves much more detail Considerable storage & network bandwidth cost Factors influencing bit rate & video quality

11. WebCCTV 10 Storage & Bandwidth considerations Framerate Range Important parameter : ranges from 30 images per second to 1 image per 3 seconds => factor 100 ! MJPEG : influences storage & transmission heavily MPEG, WMV : bit rate fixed, so influences quality Smooth Video Around 15 fps for human eye (10 – 12 agreeable) Higher almost never useful, just increases bandwidth and storage requirements Recording Even further reduced, 3 to 6 fps Not much happens in 1/15 th of a second Factors influencing bit rate & video quality

12. WebCCTV 11 Storage & Bandwidth considerations Activity detection Live streaming ‘ Differential ’ : only sending the differences in subsequent images. Reduces bandwidth substantially Only analog camera ’ s Recording Only meaningful activity is stored on disk Easy Configurable ‘ Masking areas of unimportant activity : e.g. trees, cars,.. Recommended : typically storage time x 4 Factors influencing bit rate & video quality Detailed explanations in the installation manual