Disclaimer – This is the testing carried out by Ian Justin, this is not carried out by Adobe in a lab. This testing consists of Ian Justin, 6 meeting room instances, 6 cameras and monitoring and capturing the bandwidth display in the meeting room. This is not intended to be a scientific test, it is however, representative of a typical user experience in my view.
There is technically no limit to the number of cameras that can be used in Connect, the largest number of live feeds I have used personally is just under 50 cameras as part of a proof of concept for a client, and very distracting.
The number of cameras you can display in Connect depends on your end-user bandwidth, what other things you are doing with the bandwidth (VoIP?), the quality of the camera feeds you will accept and whether you are hoping to enhance the experience of your attendees or just trying to prove a point.
The number of cameras you should use in a good presentation is probably one if you want to engage your audience, two cameras if you want to show interactions, maybe five to six cameras if you have a panel answering questions and ten or more cameras if you want to create the best opportunity to have at least one unhelpful distraction happening in your session at any one time.
The caveat here is that some schools or training classes aim to have the feel of participants in a classroom and the trainer or teacher will want to see the audience. This is possible, but be aware that engaging your audience with compelling content, quizzes and interactions is likely a better way to keep their attention vs. postage-stamp video feeds.
The real practical issue is to determine just how valuable multiple cameras might be in a meeting room or classroom. The real technical issue here is the bandwidth available to view these camera feeds at the end-user side.
So to the technical side – I carried out some live testing to see how the bandwidth taken by cameras increased with the number of cameras and with the quality of the feeds. As you should be aware, you can use the ‘Room Bandwidth’ feature in Connect to constrain the meeting to operate in nominally LAN, DSL or Modem bandwidths and that was the primary option used to manage quality in these tests.
Changing the room bandwidth will lower the resolution and frame rate (fps) of the cameras and as such lower the bandwidth taken overall.
The summary of the results, badly presented I grant you, is shown in Figure 1 below. In the following notes we can dissect some of the numbers.
Figure 1
The tests were carried out at the bandwidth settings on the left side of the spreadsheet as follows:
- LAN – 480p and up to 15fps
- DSL – 240p and up to 10fps
- Modem – 240p and up to 10fps
- Modem – 120p and up to 4fps
The last of the modem settings (120p and up to 4fps) had the video quality slider taken all the way tot he right to get the most bandwidth-efficient video possible.
Figure 4
- LAN – 480p and up to 15fps
- 260 kbits/s
- DSL – 240p and up to 10fps
- 160 kbits/s
- Modem – 240p and up to 10fps
- 78 kbits/s
- Modem – 120p and up to 4fps
- 18 kbits/s
- LAN – 480p and up to 15fps
- 10 Cameras – 2,599 kbits/s (2.6 mbits/s)
- 20 Cameras – 5,197 kbits/s (5.2 mbits/s)
- 50 Cameras – 12,993 kbits/s (12.9 mbits/s)
- DSL – 240p and up to 10fps
- 10 Cameras – 1,629 kbits/s (1.6 mbits/s)
- 20 Cameras – 3,257kbits/s (3.2 mbits/s)
- 50 Cameras – 8,143 kbits/s (8.1 mbits/s)
- Modem – 240p and up to 10fps
- 10 Cameras – 776 kbits/s
- 20 Cameras – 1,522 kbits/s (1.5 mbits/s)
- 50 Cameras – 3,879 kbits/s (3.9 mbits/s)
- Modem – 120p and up to 4fps
- 10 Cameras – 181 kbits/s
- 20 Cameras – 362 kbits/s
- 50 Cameras – 905 kbits/s
This is almost impossible to answer, but I personally try to manage my meetings to a 1 mbit/s limit, meaning I monitor bandwidth and drop quality when I see things get in the high 900 kbits/s. the average connection speed in the US is around 8 mbits/s but as most internet users will tell you it is not often up there consistently.
It is also important to remember that if you are in a corporate environment with multiple people attending from an office, you are growing the required bandwidth in leaps and bounds as the signals pass out of your office to the servers, then back in again for each user in the case of streaming video.
Important – Remember that in this scenario, there is no VoIP, no pre-recorded video and not screen-sharing and these would all be fighting for the bandwidth as well. VoIP should always take priority so the camera feeds would potentially suffer.