Difference between revisions of "Rewinding Cams"

Revision as of 10:36, 12 July 2023

Rewinding video on cameras

A limited rewind system is available if you are using the (default) brid.tv player for cameras. This can rewind the video stream by up to several minutes depending on how long you have been watching and how much your computer has buffered.

You can rewind by 10 seconds at a time by pressing the backwards arrow with a 10 inside it, or click on a yellow line to move backwards and forwards in time through the rewind buffer.

There are two important restrictions, You can never rewind further than the time you started watching the camera, and if you switch the player to or from full-screen then the rewind buffer will be cleared to the moment when you did that. So if you want to grab a screen-shot make you you switch to full-screen before the event happens!

You can see how much scroll-back is available to you by (on a desktop/laptop) moving the mouse over the camera window; a grey line will appear near the bottom of the window with a yellow portion indicating how much available rewind is available. On a tablet/phone you can tap the screen to get this line, but watch out in case you also pause the display when you do that!

Bear in mind that the size of the buffer is not constant. Sometimes you will get quite a long time in the buffer and sometimes it may be just a few seconds. This depends on all sorts of technical things that are outside of your (and railcam’s) control.

If you rewind to a point in time (say 1 minute) and leave the player alone then you will probably not be always one minute behind the stream, sometimes your browser will need to clear the buffer and restart from ‘live’ again for reasons I probably don’t want to get into here.

The hls.js viewer also provides a rewind feature - though it operates in a slightly different way.

At the bottom of the viewer is blue line which shows how much time is in the buffer, at the side are two numbers that where you currently are in that buffer. eg "2:40/3:15" shows that there are 3 minutes, 15 seconds in the buffer and you are viewing from position 2:40 in that buffer. The right-hand number should usually be a bit higher than the left as that allows the stream to pause very slightly and not spoil your viewing.

By sliding the white dot in the middle of the line to the left, you can rewind the stream to a position a few seconds, or maybe minutes earlier.