Hi there,

We are developing an application to take a live stream from a webcam and
broadcast it to our various players. According to
http://www.macromedia.com/devnet/flash/articles/flv_live.html the equation for
calculating upstream bandwidth in kbps is (width*height*fps)/1000.

This means that a decent sized video at a semi-decent frame rate (320x240,
10fps) should be using 768kbps. Since most people are lucky to have an
upstream connection of 256kbps this means that we'll never be able to get video
to the server with this quality.

The weird thing is that we were previously using the UMedia player which only
used 20k bandwidth (upstream) for the same settings. Am I missing something
fundamental or is this really the way things are with FMS?

Cheers,

Dave Keen

The formula is a good guideline, but is not the end of the equation. Increasing
the keyframe interval and decreasing the quality will result in decreased
bandwidth requirements. Live video works the same way as recorded video in
terms of bandwidth... higher quality and more keyframes = more bandwidth.

Even 70% quality @ 320x240 video is going to require a fair amount of
bandwidth (70% seems to be the line between acceptable and crap). After doing
some testing, you may find that a smaller video image works better for your
purposes, if you prefer to go with higher quality images.

Incidentally, the formula you mentioned doesn't account for audio bandwidth
requirements. Don't forget the overhead there. Audio doesn't require nearly as
much bandwidth as video, but it still needs to be considered.