Lanaccess | Cámara Centro

SITE CAMERA: OPTIMAL SOLUTION FOR
VIDEORECORDERS REMOTE MANAGEMENT

Site Camera technology features

Site Camera technology offers easy and smooth remote management of videorecorders without affecting the recording quality:

Single camera smooth remote real time video display
Multicamera smooth remote real time video display
Single camera smooth remote video recordings display (speeds up the search of relevant video recording fragments)
Multicamera smooth remote video recordings display (speeds up the search of relevant video recording fragments)
Download of just the relevant video recording fragments

Remote management

When an organization has a large installed base of videorecorders spread over a large territory usually the communication bandwidth between the control center and each device is limited. This is the usual case, for example, of bank offices and other organizations with a large number of branches in several sectors like distribution, logistics, leisure or energy.


In this kind of installations usually the following needs arise:
Record video in the remote branches with the maximum possible quality
Display real time video smoothly in the control center
(with a reasonable frame rate), in order to quickly identify any incident and react if necessary. Sometimes a single camera is displayed, frequently all the cameras at the same time.




When configuring the videorecorder these two needs are contradictory. If a better video quality is configured the bandwidth is larger, which means lower frame rate when remotely displaying video. On the contrary, if a better frame rate adapted to the available bandwidth is configured the video quality drops and when an incident happens the recording quality is worse than desired.

A first basic rule to optimize the management of remote videorecorders is to select videorecorders with state-of-the-art compression technology, because it will be more efficient and therefore require less bandwidth and hard disk capacity. Nowadays H264 should be the best choice, followed by MPEG4. Other algorithms like JPEG, MJPEG, MPEG2 or proprietary algorithms should be avoided because they are less efficient.

Is any H264 videorecorder a good option for a remote installation?

Any H264 videorecorder will be better than a videorecorder that makes use of less efficient compression algorithms, but to achieve an optimal management it is necessary to break the duality between recorded video quality and smooth remote video display.

One of the techniques used in these cases is the double flow. This technique generates two video flows per camera. The video flow for video recording has a better quality, while the second video flow, used for smooth real time video transmission, has a lower quality and it is therefore better transmitted though a limited bandwidth. This technique is useful and improves the remote management of the videorecorders. However, it solves only partially the needs of this kind of installations.

If we analyze in more detail the real time video display needs of a remote operator:

The operator wants to smoothly display one camera. The double flow solves this need.
The operator also wants to smoothly and in a synchronized way display all the cameras at the same time. The double flow cannot solve this need. The independent flows of each camera are aggregated when they are displayed simultaneously, overfilling the bandwidth and losing the smoothness.

On the other hand, the operator will also manage the recorded video, ideally in two different phases:
When an incident happens, in a first phase the operator should select the cameras and intervals of time relevant for its management. In a general case, if the recorded video quality is high and the available bandwidth low, this search can be slow and tedious, or even require downloading a large interval of recorded video, which delays the incident analysis. It is very useful for the operator to have tools that help him performing this task.
If the videorecorder offers features to easily search the relevant fragments of video, the second phase is to download the recorded video at the maximum available quality.

Site Camera, the optimal solution

The Site Camera technology from Lanaccess gives answer to all remote management needs, both for real time display and recorded video searches. Basically it makes use of two different techniques:
Multiplexing (or mosaics generation). A single video flow can include many cameras in a mosaic-like format, optimizing available communication bandwidth.
Transcoding. A video recording can be re-encoded to adapt it to the available bandwidth, easing the search process.

Real time video display

To compare the different techniques and technologies let’s suppose that in a concrete case the available bandwidth is just 128 kbps but the desired quality for the recorded video requires 500 kbps. Let’s suppose as well that the video is recorded at 4CIF@6fps.

One camera real time video display: (*)
If neither double flow nor Site Camera are available the same video flow that is recorded will be transmitted. Only a fraction of the generated images can be transmitted, just one image every 2 to 3 seconds is displayed.
If double flow is available the real time video display is optimal, a video flow adapted to the available bandwidth is transmitted, for example at CIF resolution and 6 frames per second .
If Site Camera feature is available the real time video display is optimal, a video flow adapted to the available bandwidth is transmitted, for example at CIF resolution and 6 frames per second.

All cameras real time video display: (*)
If neither double flow nor Site Camera are available the remote real time video display is worse. If 4 cameras are displayed simultaneously just one image every 12 to 16 seconds is displayed.
If double flow is available the bandwidth of the cameras is aggregated. Displaying 4 cameras simultaneously just one image every 2 seconds is displayed per camera.
If Site Camera is available the video display is optimal. A video flow with the 4 cameras adapted to the available bandwidth is transmitted, and 6 frames per second for all cameras are displayed.

Recordings search and download

There are significant differences when searching the relevant fragments of video. Double flow gives no advantage to perform this task. Let’s suppose that the operator knows that an incident has happened within a period of one hour, but he does not know which cameras can give relevant information.

If Site Camera is not available usually the operator downloads all the recordings and then displays them locally. Just the download will take nearly 16 hours through the 128 kbps of available bandwidth. Once downloaded, the search process begins, and the operator selects the relevant fragments.
If Site Camera is available the operator begins the search immediately. The video recording of all 4 cameras are remotely displayed in mosaic-like format, the relevant fragments are selected and just these fragments are downloaded. Supposing that the relevant fragments are 5 minutes of 3 of the cameras, they are downloaded in less than 1 hour, that is, 16 times faster than the previous case.



(*) The frame rate values are not intended to be exact but just an estimation to give an order of magnitude to compare technologies. Real observed values can vary depending on different configuration options