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November 2010 |
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There are 2 different interpretations of the term:
(a) 2 video streams of different frame rates. For example, one is 8fps for recording and one is 1fps for remote viewing over the Internet. The Internet connection has a limited bandwidth and requires the video stream to have a lower frame rate.
(b) 2 video streams produced by different compression techniques. For example, one is MPEG4 for recording and one is MJPEG for viewing on a mobile phone. There are compatibility issues in addition to the compression technique but dual streaming is needed if mobile viewing and local recording are needed in parallel.
Not all cameras have dual streaming. Most have type (a), and some have type (b) in addition to (a).
Update on 16 August 2011
We have tested CAK-7211 which is a new camera model with 4MP and supports Dual Streaming with NVR Enterprise version 2.3. We have observed a pixel resolution limit of 1280 x 720 under Dual Streaming. The 1280x720 limit applies automatically when changing to dual streams even if it is set to 4MP single stream. After changing back to single stream the resolution will not automatically go back to 4MP and will stay as 1280x720.
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November 2010 |
DIO refers to the capability of a camera to process input and output in digital format (+-5V). Such cameras would have a termination block on the rear side of the camera for DIO connection, and there is no standard or convention on how many DIO provisions a camera should have. Most have none, some have 1 DI and 1 DO and few have more than 1 each.
What is DIO for? In the context of surveillance cameras, DI is an event and DO is a response. For example, DI can be the state of a lock on the window and DO can be the light of the room. When some one has broken into the room through the window, the window lock (when opened) produces a DI signal to the camera. With pre-defined algorithm, the camera can trigger the DO to operate the light of the room. The room will suddenly become bright and the camera will record with higher clarity.
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November 2010 |
DIO refers to the capability of a camera to process input and output in digital format (+-5V). Such cameras would have a termination block on the rear side of the camera for DIO connection, and there is no standard or convention on how many DIO provisions a camera should have. Most have none, some have 1 DI and 1 DO and few have more than 1 each.
What is DIO for? In the context of surveillance cameras, DI is an event and DO is a response. For example, DI can be the state of a lock on the window and DO can be the light of the room. When some one has broken into the room through the window, the window lock (when opened) produces a DI signal to the camera. With pre-defined algorithm, the camera can trigger the DO to operate the light of the room. The room will suddenly become bright and the camera will record with higher clarity.
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November 2010 |
DIO refers to the capability of a camera to process input and output in digital format (+-5V). Such cameras would have a termination block on the rear side of the camera for DIO connection, and there is no standard or convention on how many DIO provisions a camera should have. Most have none, some have 1 DI and 1 DO and few have more than 1 each.
What is DIO for? In the context of surveillance cameras, DI is an event and DO is a response. For example, DI can be the state of a lock on the window and DO can be the light of the room. When some one has broken into the room through the window, the window lock (when opened) produces a DI signal to the camera. With pre-defined algorithm, the camera can trigger the DO to operate the light of the room. The room will suddenly become bright and the camera will record with higher clarity.
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November 2010 |
PIR is a common device deployed in intruder detection security systems. It senses human body temperature and can differentiate between motion of human body and movement of leaves outside the window.
Some cameras have incorporated PIR as a means of reducing the uncertainty for motion detection purposes. For example, the camera will not start motion detection when the leaves outside the window move and will start motion detection if the PIR confirms the intrusion of human into the area of monitoring.
Do not be confused between IR filtering, IR LED and Passive IR as far as camera motion detection techniques are concerned.
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