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System > Surveillance Index > Why we offer Dual Video Streaming

Why we offer the Dual-Video Streaming


   In the DVR card market, there are 2 kinds of the hardware compression cards.

     - One is Single-Video Streaming card.

     - The other is Dual-Video Streaming card.

   The Single-Video Streaming card is cheaper than the Dual-Video Streaming card, but Dual-Video Streaming card can make the remote video monitoring to be possible.

   The reason why we use the hardware compression card in PC-Base DVR machine is that we want to get the higher recording speed or the bigger image resolution. But the video film will become big. Due to the network bandwidth issue, when we try to send the image to the remote site from the DVR machine, we need to consider whether we have enough bandwidth to transfer the huge data of the video streaming by through the network. The difference of these 2 cards to perform the remote video monitoring is described below.

1. Single-Video Streaming card

   The incoming video is captured and processed the video compression at this H/W DVR card. Then, this compressed video data flows to the PC and stores it into HDD. If the remote site wants to view the image of this DVR machine, the PC will send out the same data to the remote site. Due the data stream is very big, we need arrange enough bandwidth for it. Otherwise, the video stream will be blocked on the network.

 

   For example, If we set the recording speed of each camera is 25/30 fps (PAL/NTSC) at one DVR machine, the video streaming rate of each one camera will be around 500K bps (bit per second) only under CIF (352x288/320x240) resolution. Regularly, we need prepare 2 ~ 4 times bandwidth for this video stream (Cisco recommends us to prepare 4 times of the communication bandwidth for the data rate). Let us say 2 times. So, at lease, we need prepare 1M bps for this video stream (Only for 1 camera). It is meaning that we want to send more cameras video out to remote and we need more bandwidth. Most of the remote monitoring will use internet or VPN. From the above analysis, it is almost impossible to view several cameras from the remote DVR at one time by through internet. If the VPN network is used, it need expense a very high cost to rent a very huge bandwidth to set up a video security network.

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2. Dual-Video Streaming card

   The Dual-Video Streaming card can offer 2 independent video streams. One is for the local recording. The other is for the remote monitoring. To achieve this feature, this kind of card need use 2 independent image compression engines.

 

   Due to these 2 engines are independent with each other, we can give them the different conditions to compression the video. For examples, they can have different frame rate, different compression rate, different GOP size, even different image resolution.

   A brief function block is shown in the above figure. The engine 1 is used for local recording. We can set its recording speed at 25/30 fps. To fit the communication bandwidth, we can set the engine 2 run at 3 fps and transfer its video stream to remote site. By this way, we can get a high speed recording speed or high image resolution at the DVR and execute the remote video monitoring in an adjustable video speed which will be decided by the available bandwidth.

Dual-Video Streaming is the best resolution to perform the remote video security in the internet. The Dual-Video streaming cards offered by most of our competitors only provide one MPEG4 stream and one JPEG stream, or one H.264 stream and one JPEG stream. But our Dual-Video streaming cards can offer 2 MPEG4 streams, or 2 H.264 stream. This advantage can reduce the data rate not only at the local site but also at the network


Surveillance Index

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