Streaming Cameras

We have two cameras which provide a livestream via argos. The streams are viewable by anyone with a Raven password, and there is a backdoor for others -- ask if it is needed.

These cameras are trivial to use, and it is recommended to use both at once and let the remote audience decide which is performing better.

The livestream as viewed will be delayed by around 20-40 seconds. This is inevitable from the use of HLS, which breaks the video into segments of around 4 seconds each, and the greater part of the delay is arguably client-side. This does mean that no two clients will be completely in synchrony, and they will lag any Zoom-based solution considerably.

To turn either on, plug its ethernet lead into either of the two sockets behind the projector screen. The black lead is for the blackboard camera, the white lead for the (white) screen camera. After 90s to 2 minutes, argos should have settled down and be streaming. You will need to reload the page to see the update.

To turn either off, unplug it. It will take 90s to 2 minutes for the server to notice and remove the stream.

If briefly unplugged, it will take about three minutes to recover itself.

Neither records (beyond the recording implicit in producing a delay of a few tens of seconds).

It is unclear how many simultaneous users they can support. I would hope that a dozen high-bandwidth users would be no problem, whereas a hundred will certainly make it fall over. Running both cameras at once is fine.

Should the server itself fall over, including due to a power cut, this service is not currently automatically restarted.

They should not be left running, nor used without the knowledge and permission of the speaker, for to do so would risk breaking data protection and privacy legislation.

PTZ

The dome-shaped camera appeared copes with a high dynamic range, i.e. both dark and bright regions in the same image. So it works reasonably when the projector screen is used. Its high-resolution stream is 1440p, so better than Zoom.

It also can be aimed and zoomed remotely, and thus can be set to show the projector screen and the whole blackboard, or, at maximum zoom, just half the blackboard with the projector screen. A random collection of people can adjust its aim remotely via a webpage. Ask if you think you should be added to this list.

The adaptive livestream it produces can be found on argos PTZ, on a page which currently requires a Raven password. It produces a 16:9 image, and the audio is quite reasonable.

Sometimes it produces scrolling dark and light bands on the projector screen. This phenomenon is still being investigated. Turning on the room lights, to reduce the contrast between the screen and the rest of the image, may help, as does zooming more into the screen so it is a larger fraction of the total image.

Fixed

In November 2021 our first camera appeared on the back wall of the TCM Seminar Room, in order to facilitate hybrid seminars. It is rigidly mounted, and aimed at the blackboard. It cannot cope at all with small, bright, things such as the projector screen, so it is best for blackboard seminars. Its low light performance is better than the newer camera, its audio is somewhat poorer. Its image is 4:3.

If it is very dark, it will switch to greyscale. It switches back to colour automatically when light levels improve.