Thursday, August 10, 2017

Doing some testing with the flight recorder remote configuration code.

One interesting thing I observed during this testing is that I can no longer overload the macOS client that easily. I did an udpate to more recent code, so I am wondering if some recent code change improved things on the performance front. Here is an example of quick recovery.

I wonder if this has something to do with recent tests I was doing on the frame rate front.

Update: after playing with it for a while, the machine started spinning its fans, and I understood: it's just that now I have air conditioning in this room, so the machine is just dealing with the load much more easily. But I can overload it by putting a bit of "heat" on the GPU side (running Tao3D at the same time).

I don't see any effect of the frame rate on the encoder, it really seems to be ignored. However, the dwGOPLength field (interval between I-frames) has an interesting effect.

Here is what we have with a variation of the GOP length of 100 (default);

Here is what we have with a variation of the GOP length of 1:

Notice how the network bandwidth increases sharply, as well as the typical queue length (although this is much harder to say, because this one seems highly dependent on machine temperature).

Here is with a GOP of 10:

Here is with a GOP of 1000:

Also did some experiments with the dwAvgBitRate, trying to set it to a very low value (8000). There is no reduction in queue length (if anything, it seems to be the opposite), and the frame sizes seems to always peak at 16384. But there is obviously a sharp effect on the bandwidth being used.

No real observable difference between H264 profiles 77 and 66. Profile 83 is not accepted. Hi Profile (100) also does not seem to make much of a difference.

Also not much of a difference switching values for ePresetConfig.

Interesting, also got another one of these instances where after killing Tao3D, the NVIDIA driver seems to be stuck. There are no update to the spice client. It stays like this for a long time, it's a bit unpredictable. After doing kill -9 for the spice streaming agent multiple times, I finally got it back.