Video on low bandwidth

[isotoxin]

No any correct video frames received on low bandwidth. As user, I expect decrease video fps (frames per second), but I just get broken image. Totally broken - digital noise. Lower bitrate is not solution when desktop sharing, because I want to read text of shared desktop and I agree to get frames updates ones per 10 seconds, but correct image - not unreadable blurred image.
How to reproduce: just do video call via tcp (disable udp) and share desktop (my resolution is 1920x1200). uTox or qTox - no matter.
Hint: using lossy packets - is bad idea for video. At least, key frames should be transferred lossless.

Better video quality can be obtained with following algorithm:

1. put solid frame (not just separate independent lossy packets) to send queue
2. send key frames lossless, other frames - lossy. Important! lossless mean that whole frame must be droped, not only some packets, otherwise we get broken image
3. ignore new frames while send queue is busy (sending previous frame in progress)

[seankhl]

Can someone give an update on this? Is there any documentation for the bitrate adjustment algorithm, or can someone at least point me to where in the code this is?

I'm very interested in improving the bitrate adjustment algorithm, and possibly doing something like @Rotkaermota suggested, where we can trade off between adjusting the framerate and the bitrate. There should also be a gpu implementation for at the very least on-board Intel chips so that we can take advantage of that hardware and compete with mainstream clients. I am a somewhat experienced gpu programmer so I would be willing to take a look at this.

But in addition, I've experienced similar problems, where these adjustments result in fully corrupted video frames (grey blocks and unacceptable noise)! There must be a bug in the algorithm, as this is not acceptable result from bitrate adjustment.

[GrayHatter]

toxcore uses whatever bitrate you give it, so that part would be a client issue.

Shouldn't be too hard to add an extra API function to send a lossless frame. That's something that could then be implemented client side.

[GrayHatter]

replaced by #1479 and #1525