The bandwidth used by CoreNexa will be adjusted for the best experience based on the user‘s network connection.
1:1 video calling
Upstream and Downstream
- 500 kbps (up/down) for High-quality video (default resolution)
- 1.2 Mbps (up/down) for HD (720p) video
- 2.5 Mbps (up/down) for FullHD (1080p) video
Group meetings and webinars
Upstream
- Number of users x resolution bandwidth
- 500 kbps up for High-quality video (default resolution)
- 1.2 Mbps (up/down) for HD (720p) video
- 2.5 Mbps (up/down) for FullHD (1080p) video
Downstream
- This will depend on the number of attendees and the resolutions they are sending. There will be a maximum of 3.5 Mbps used no matter how many users are in a meeting. The last two talking users will get the bandwidth they are sending and the remainder of the bandwidth is divided up between the remainder of the users.
Bandwidth requirements by resolution
Video is the largest consumer of bandwidth in CoreNexa. There isn’t even a close second place, so we’ll focus on identifying how to calculate the bandwidth required for a meeting.
General calculations for the different available video modes:
CoreNexa Video Modes | Horizontal Resolution | Vertical Resolution | Color Bits (depth) | fps | Single Frame Size (bits) | Single Frame Size (Mbit) | Single Frame Size (MByte) | Approximate Bandwidth (Mbps) | Approximate Bandwidth (MBps) | w/CoreNexa Compression (est. Kbps) | (est Mbps) | (est MBps) |
Low | 172 | 96 | 32 | 30 | 528384 | 0.504 | 0.063 | 15.12 | 1.89 | 150 | 0.15 | 0.02 |
Standard | 352 | 192 | 32 | 30 | 2162688 | 2.063 | 0.258 | 61.88 | 7.73 | 300 | 0.29 | 0.04 |
High (Default) | 640 | 360 | 32 | 30 | 7372800 | 7.031 | 0.879 | 210.94 | 26.37 | 400 | 0.39 | 0.05 |
HD (720p) | 1280 | 720 | 32 | 30 | 29491200 | 28.125 | 3.516 | 843.75 | 105.47 | 700 | 0.68 | 0.09 |
Full HD (1080p) | 1920 | 1080 | 32 | 30 | 66355200 | 63.281 | 7.910 | 1898.44 | 237.30 | 2000 | 1.95 | 0.24 |
Notes:
Kbps = Kilo bits per second (1024 bits sent per second)
Mbps = Mega bits per second (1024 Kbps = 1048576 bits sent per second)
MBps = Mega Bytes per second (8 bits in a byte, divide Mbps/8 = 131072 Bytes sent per second)
Single Frame Size = Horizontal Resolution (pixels across) x Vertical Resolution (pixels down) x Color Bits (depth = bits per pixel)
Approximate Bandwidth = Estimated without transmission overhead
Inbound video from participants
This is the calculation of the remote user’s upstream bandwidth available to the Internet (which is almost always less than their downstream bandwidth). We recommend utilizing ‘High’ resolution mode (640×360) for most meeting participants and this is the default unless a user changes it. This is adequate and the best compromise vs. bandwidth use.
In the CoreNexa Desktop Client, users have control over their upstream bandwidth use. For each camera on the user’s computer are the following settings:

The frame rate will be automatically tuned based on the bandwidth allowed and the resolution set. The defaults are the settings seen above. But, if a user sets their resolution to HD or Full HD and does not adjust the upstream Bandwidth allowed, the Frame Rate will be adjusted to try to compensate.
Outbound video to each participant
The total video outbound to each participant is controlled by the RNode. The system has a maximum bandwidth setting so that even if there are 100 people in a meeting, the video streams for the current talker and previous talker will be optimized and all other videos will share the remaining bandwidth available for the meeting.
This system setting is set to 3584 Kbps (3.5 Mbps).
Calculation examples
Assumptions are for one office with 10 users watching and sending video at ‘High’ resolution:
Upstream (to the Internet) = 10 users x 0.39 Mbps (from table above) = 3.9 Mbps
Downstream (from the Internet) = 10 users x 3.5 Mbps (max downstream per user) = 35 Mbps
What if all of the users set their cameras to Full HD:
Upstream (to the Internet) = 10 users x 1.95 Mbps (from table above) = 19.5 Mbps
Downstream (from the Internet) = 10 users x 3.5 Mbps (max downstream per user) = 35 Mbps
These are estimates and do not consider traffic transmission overhead.
Miscellaneous
For screen sharing only (no video thumbnail): 100 kbps
For audio VoIP: 60-80 kbps
For Phone: 60-100 kbps