video quality

8/7/2019 Video Quality

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What Affects Video Quality?

Dr Bob Banerjee | 2/27/2009 | © 2007 Robert Bosch LLC and affiliates. All rights reserved.

Dr Bob BanerjeeProduct Marketing

[email protected]


ISC 2009 Educational Sessions



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Simple questions

Is this just an IP video thing, or also analog?

How come competitive quotes need very different amounts of storage?

What kind of lighting, if any, should I use?

How far can I see with the light I choose?

Which compression should I use – and are there pros and cons?



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Spatial vs. Temporal

Figure 1: A Five-picture JPEG video sequence .

Figure 2: A Five-picture MPEG video sequence.



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Video Compression

Low

(1 FPS)

Standard

(3.75 - 7.5 FPS)

Full Motion

(30 FPS)

Bandwidth /

Mbps

Framerate

M - J P E G

M P E G - 4

M P E G

- 2

W a v e l e t

0

4

8

2

6

10

High

(15 FPS)

Performance of Different Video Compression Algorithms at

Various Frame Rates. Spreads shown at 30 FPS.

Source: Dr Bob Banerjee and Justin Lott,

© Bosch Security Systems, 2008

H.264



6 Marketing | 2/27/2009 | © 2007 Robert Bosch LLC and affiliates. All rights reserved.

Comparisons

Image size 171 KBImage size 8KB

30Mbps, 1m, 10TB



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Lighting

"You can see without it but it gets a bit dark."



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Categories of Light

Visible (accurate color, deterrant)

Incandescent / fluorescent

LED Power (40W vs. 1kW)

Life

Focus

Invisible

Active IR illuminators Detail

Passive IR (thermal)

Distance Cost



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Eye response

Source: http://astro.swarthmore.edu/ir/ir_basics.htmlhttp://photo.net/photo/edscott/vis00010.htm

850nm 940nm 1,000nmVisible IR Invisible IR Far IR



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How far can I see with my illuminator?

"Yes, it's high-end stuff. Reaches about 900 feet"

Since when do photons suddenly drop dead at 901 feet?




IR affects bitrate

Reduces image noise in low-light

More image detail Lower bitrate

0.99lux ambient

7Mbps

0.99lux ambient

Infrared Illumination

1.2Mbps

0

1

2

3

4

56

7

Bit rate

Mbps

Lighting

Without IR

IR




Examples of IR Performance

Before IR Imaging After IR Imaging



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Video resolution – Image size



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The High Resolution Trap

Resolution: CIF (Common Intermediate Format)

Based on ITU H.261 videoconferencing

QCIF is one quarter of CIF

Misconception 1: 4CIF beats 2CIF

Misconception 2: My 4CIF = Your 4CIF

CIF

2 CIF

4 CIF

352

240(288 PAL)

704

704

240(288 PAL)

480

(576 PAL)

Full D1 is 720 x 480 (576 PAL)



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Cameras and TVL (Horizontal) Resolution

0 100 200 300 400 500 600

570 TVL

540 TVL

4CIF

2CIF

480 TVL

380 TVL

2/3 D1

330 TVL

1/2 D1

CIF

Value of 2/3 D1



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Bit rates

The rate at which water flows through the network hose

The rate at which the storage bucket fills up



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Configurable factors affecting bit rate

Resolution

CIF, 2CIF, 2/3 D1 or 4CIF

Frame rate

1 - 30 FPS

Scene activity

Quiet – a lobby with infrequent visitors

Medium – an average scene

Busy – continuous motion, e.g. PTZ



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Quote 1 Quote 2

Specification called for an apple to look this big



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Image Quality All 4 images are 300 x 419 pixels (equal resolution) Increasingly compressed Tip – different manufacturers have VERY SIMILAR bitrates for the same

video quality CIF can look better than 4CIF if you artificially cap bitrate

4CIF ≠ QUALITY

Bitrate = Quality0

10

20

30

40

50

1 2 3

1,100 TB 860 TB 760 TB

Storage estimates for

256 cameras, 365 days



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Original



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Version 12x compression



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PredictabilityCCTV Activity in a K-12 School

0

25

50

75

100

4 AM 8 AM Noon 4 PM 8 PM 12 AM

Time of day

R e l a t i v e A m o u n t o f a c t i v i t y

Bitrate Capped at 1,000 kbps

0

500

1000

1500

2000


Time of day

B i t - r a t e / k b p s

Bitrate Uncapped

0

500

1000

1500

2000


Time of day

B i t - r a t e / k b p s

By capping or ‘throttling’ the permitted bandwidthyou control the peak network bandwidth load



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How long will 16 cameras last?

Recording Duration on a 6TB iSCSI RAID for 16 Cameras

0

20

40

60

80

0 500 1000 1500 2000 2500

Bitrate / kbps

D

a y s



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Focus on what you are interested in…

Overview cameras

Fixed (analog with encoders or IP) Big picture

Behavioural sensors

Detail cameras

PTZ cameras

Automatic tracking



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IVA and Forensic Search




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Fixed cameras can focus attention

Video Mgt System

AutoDomeModular withAutoTracker

Encoder runningIVA

Analog cameras orIP cameras running

IVA



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Flow

1. Fixed cameras detect something suspicious

2. They send an alarm to the video mgt system

3. VMS is programed to take action

4. PTZ sent to a preset position

5. PTZ's AutoTracker functionality is activated

6. PTZ gives you clear detail with up to 36x zoom, fills the whole image with

the object of interest



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IVA and Forensic Search




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Summary

Compression technology

Lighting

Bitrate

Resolution

Dr Bob BanerjeeProduct [email protected]

video quality

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