IPVMU Certified | 12/10/14 11:43pm
I think you have a good understanding of an ideal 'dual streaming' application. Here's why it helps:
The first stream (the one flowing to your monitoring center) is presumably lower FPS/higher compressed/lower resolution than the second stream flowing to the NVR.
Since the live video is uploaded to the internet and to a remote site, smaller bandwidth means less expensive internet connections, etc.
The second stream (to the local storage recorder) is likely much more bandwidth, but higher FPS/lower compression/higher resolution. Since local storage means bandwidth in not restricted by an ISP (and transported a comparatively short distance), it makes sense to use more bandwidth.
Presumably, if some event is noticed remotely by the monitoring staff, they can download or review the 'higher quality' recording from onsite storage. They can do this only when needed, so 'dual streaming' helps make things more economical.
That's just one angle to this, and if there are more questions, just ask!
I took and passed (got certified) one of the IP cam basics classes you taught. The answer you gsave me is the answer I gave our team almost verbatim...however, I qualified it with, "This is my understanding of it." And, I thought I did understand dual stream as a fairly simple thing. What you described is exactly what we do. I was a monitor, monitoring manager, and then video review manager before I became a salesman. But, all that answer got me was an incredulous look from the group and one of the IT guys said there is more to it and maybe we don't need dual stream cameras. I do not know all of the offerings in the IP market but I thought dual stream was a fairly ubiquitous and beneficial option...The point of their whole conversation was that they were trying to tell the owner that dual stream cameras were no longer necessary. Concern stemming from potentially using different than our usual cameras on the VMS platform we use. My understanding is that we would need dual stream to remotely monitor regardless of the VMS because of the bandwidth issue.
By they way, they came and asked me what I knew about dual stream because, "I seem to have a lot of IP cam knowledge." I don't, I know I don't. What bothers me is their potential lack of knowledge by thinking I have a lot. And, they are talking about using the high stream (less compressed stream) from a 5mp Acti E38A to remotely monitor. They said the testing (after one day) was not spitting out that much data in the high stream. I have a feeling they don't have the cam configured in a way and/or in a scene that is giving good data.
Is there more to it from another angle that I don't understand... or is it that simple in total? I am lost and worried that they may steer our ownership in a direction where they really don't know what they are talking about.
Thanks for your time,
IPVM did a full mulsti-streaming test and review of VMS' that actively use it for everything from bandwidth optimization to server-side advanced motion detection.
VMS Multi-streaming Comparison
Another benefit of multi-streaming is that most PCs (usually onsite) can not handle either video card or CPU decoding many high megapixel cameras at once. The system chokes when you display 16+FullHD or 3Mp or 5Mp cameras at once. In addition, the monitor resolution does not allow you to see the full detail. Also, many camera at these high megapixels do not show 30 frames per second. Thus, monitor can look choppy and hard to watch.
By using a second stream, you lower the load the PC has in addition to the bandwidth, and can view a high frame rate, low bandwidth stream.
I also like to set up 1 stream for live viewing, 1 for recording, 1 for SD card recording, and 1 for mobile access. This way, changing a setting for 1 stream doesnt effect another stream.
Many cameras can now push out 6-10 unique streams.
Some confusion might come from memorized profiles inside the camera (combination of pre settings) that you can call by cgi commands, Axis is doing since the begining, and real simultaneous multiple streams ... some cameras share their CPU to try to deliver the maximum, fps and res + motion + wdr + .., but sometimes you will never get what you expect, because ... it won't even leave the Ethernet interface ..... (some cameras tells you I send 70 Mbits, but when you measure it ... you get 45 Mbit max..)
Some TW companies like Acti, but also Merit Lilin offer "hiddden profiles"inside the stream so that they claim they can reach very good bandwidth levels by over compressing (putting a low hidden CBR) and putting some very long Gop.