Saturday, September 17, 2011

Why People Choose Wireless Security Cameras (WCCTV)

With the increase in need for security, the demand for security cameras is also on the rise. There are a variety of cameras available in the market, each made for specific purposes and have their own advantages and disadvantages. One of the never-ending debates is the choice between wired and wireless security cameras. While both have their own pros and cons, wireless cameras have become increasingly popular. Few reasons are:

1.) Wireless cameras can be placed at any location. You do not need to worry about installing wires or electric sockets at difficult to reach locations. All you need is a camera that can function within the signal range of your security system.
2.) You do not need to spend money on installing the new wiring system. In case of wireless security cameras, the expenditure on creating a network of insulated wires to connect the entire system can be saved. This is especially true for building that did not install extra wires at the time of construction.
3.) Wires can also make the presence of a camera obvious. If you looking at installing cameras that should not be noticed by every trespasser, wireless security cameras are the right option for you.
4.) Flexibility and mobility comes with wireless cameras. If you are investing in a security system for a building which you might leave in the future, it is best to invest in wireless security devices. Home owners who have taken their house on rent or lease prefer wireless cameras as they can take the cameras along as and when they move to the nest house.
5.) Save you decor with wireless cameras. You might have spent a lot of time and money in selecting the right decor for your home or office. Installing wires might interfere with the overall theme of your decor. Hence, you can opt for wireless cameras that can be installed with minimal disturbance to the entire property.
6.) If you are an owner of an ancestral property, you would not like to damage the masonry by drilling extra holes and wires into the invaluable structure. Hence, wireless cameras are the best option for you.
7.) Hidden cameras are best in wireless versions. While you can use wired cameras and hide them behind furniture, you need to be very careful in covering them. A wireless camera saves you from this effort. You can hide them anywhere without worrying about their getting discovered. Small toys, cutlery, pens and many other things can be equipped with wireless cameras easily.
8.) If you want to use internet to transfer images to you computer, you can go for wireless cameras. The data transmitted through internet can be accessed from any internet enabled system outside your home or office as well.
9.) If are installing the security system yourself, if is always better to choose wireless cameras as they are the easiest to install.

Sunday, September 11, 2011

IP cameras with Audio Detection

What is the best IP cameras with audio you used?
What security audio and video applications have you had experience with and what is the best IP cameras with audio you used?
What is IP Camera Audio and Advanced Audio Detection?
-- Many More Question comeout in my mail/phones ...

If you’ve never considered having an audio component with your surveillance system that may be because analog CCTV systms require separate audio and video cables to be installed from end to end which becomes difficult and costly over long distances. IP cameras make the implementation of audio a lot simpler because the audio and video information are sent over the same network cable eliminating the need for extra cabling.

More and more IP camera audio is becoming a common feature not only because it’s easier to process over a network cable but also because the importance of this additional surveillance medium is now being recognized.

Importance of IP Camera Audio:

Detect emergency situations and make sense of other events.
Audio covers a 360° area - surveillance systems coverage is extended beyond the field of view.
Audio detection can trigger email or, other alerts and automatically direct where a camera should record.
Having audio integrated into your surveillance simply gives you more information about a situation. Many times something is brought to our attention first by what we hear, not what we see. Car alarms, gunshots, breaking glass, and screams will not be recognized by a surveillance camera without audio. With 360° coverage, an event happening behind a camera can still be detected.

Three Audio Modes
If you’re considering audio for your appliction your intended use should be clear because it can affect which IP cameras you can select as there are three audio modes available:
Simplex: Audio can be sent in one direction only. Either from the camera only (most likely) or, from the user only.
Half-Duplex: Audio can be sent and received in both directions (to/from camera and user), BUT only in one direction at a time.
Full-Duplex: Audio is sent and received at the same time - similar to a telephone conversation.
For example, Axis offers a camera, the Axis 207MW that offers one-way audio with a built in mic while the Axis M1054 offers two-way audio support with a built-in mic and speaker.
Features such as noise cancellation and echo cancellation are also available that reduce background noise or eliminate feedback.

Audio Detection Alarm
In the same way that an IP camera can analyze video, they can intelligently analyze audio as well. As noted above, audio can hear what the video cannot see. Audio detection complements video motion detection very well because it reacts to events in areas that are too dark for the video motion detector to pick up on.
Audio detection alarms can be programmed so that when any sound (glass breaking, voices in a room, etc.) is detected, they can trigger an IP camera to:
Send & record video and audio
Send email or other alerts
Active external devices - Alarms, floodlights
Trigger a PTZ IP camera to automatically pan to a preset location to begin recording.
Audio detection can be enabled all time, at specific times, or disabled. It can also be configured to trigger an event if a sound level rises above, falls below, or passes a certain level of sound intensity. Sony IP Cameras has a great video demonstration of this function here:
Some of the applicable Sony IP cameras and video servers that have this feature can be found here:
Sony SNC-CH140
Sony SNC-RS46N
Sony SNT-EX101

Audio Compression & Audio Bit Rates:
Audio compression and audio bit rates, just like video compression and video bit rates, are an important consideration when calculating total bandwidth and storage requirements.
Just like video, audio compression uses a codec to reduce the size for efficient transmission and storage. Some audio codecs support CBR (constant bit rate) mode only or both CBR and VBR (variable bit rate) - these factors affect quality and file size.
Bit rate is an important audio setting because it determines the level of compression or, quality of the audio. Generally speaking, the higher the compression level = the lower the bit rate = the lower the audio quality.

Audio/Video Synchronization
Audio and video are two separate packet (data) streams that are sent over a network. For audio and video to play back perfectly syncronized, the two packets must be time-stamped so that they match up.

Best Practices For Audio Implementation
Audio Equipment & Placement: Select a location that will minimize interferring noise and one that’s as close to the source of the sound as possible.
Amplify Audio Signal Early: This minimizes noise in the signal chain.
Acoustical Adjustments: Adjust input gain and use features such as echo cancellation to improve audio quality.
Codec & Bit Rate Selection: Codec and Bit Rate choice affect audio quality. High compression = low quality (but available bandwidth may be a deciding factor).
Shielded Cable: Shielded cable reduces disturbance and noise. Avoid running cable near power cables or high-frequency switching signals.
Legal Implications: What are you allowed to record? Some countries restrict the use of audio and video surveillance - be sure to check with your local authorities.


Thursday, September 1, 2011

RAW Formats

RAW Format implies that there is no compression done on the image. The major types of RAW format are RGB, YUV, YIQ. Our eye is more sensitive towards light intensity variation than color variation. So loss on color information will not affect the over all quality of the image. RGB is an end stream format. Information from the image sensor is in RGB format and we need the same format for displaying the image on an end
device. YUV & YIQ formats are developed for Analog TV transmission (NTSC & PAL respectively) and the digital version of YUV, YCbCr is the most common format used for image and video compressions.
Conversion from one format to another is described below:
RGB to YCbCr Conversion
Y = 0.299 R + 0.587 G + 0.11B
Cb = 0.564 (B - Y)
Cr = 0.713 (R - Y)
YCbCr to RGB
R = Y + 1.402 Cr
G = Y – 0.344 Cb – 0.714 C r
B = Y + 1.722 Cb
Y – Luminance Signal
Cb, Cr – Chrominance Signal, Color difference signal
R – Red
G – Green
B – Blue
Need for Compression
Consider an image of resolution 640 × 480. Let us calculate the size of the picture in RAW format. Each of the 10 Color is represented by 8 bits. Then for each pixel it needs 24 bits. Total no of pixels in the image is 640 × 480 = 307200 pixels. Therefore the size of the image turns to 307200 × 3 bytes = 921600 bytes. But an image in compressed format with the same resolution takes only 100 KB.
In the case of RAW video stream of length 1 sec its needs 640 × 480 × 3 × 25 = 23040000 bytes (23 MB) of storage if the frame rate is 25 frames/sec. But it’s known that the VCD format video having a size 700 MB plays for around 80 minutes. In the former case we need 110400 MBs (23 MB × 60 × 80) as storage space for 80 minutes video. Therefore we can achieve a high compression 150: 1 at the cost of computational complexities.