Bug Report NVENC ignoring bitrate constraints when FPS >60 since upgrading from 770 to 970

[Aeryn]

http://pastebin.com/BbrkUjjb

I thought i fixed this but apparently not.

It does it with CBR or VBR enabled. For example, i can use 5000kbit bitrate with 900p, 60fps and it will run almost exactly 5000kbit, but if i set 10'000kbit and 120fps, it will do whatever it feels like (20-60mbit for example, depending on the scene)

that effect still happens at low framerates, making streaming for example 450p120 completely impossible because of bitrate spiking to 10mbit+ while using CBR at 3000kbit.

With faster NVENC on the new GPU's, i wanted to local record some high resolution, high FPS footage but it has proven impossible even though it seems like there is nothing otherwise stopping me from doing it. CBR, VBR work as intended at 60fps or below and then completely stop functioning at 120fps on automatic preset or the half dozen others that i've tried.

let me know if there's anything i can do to help diagnose etc

 

[Lain]

I don't think there's anything that can be done about it at the moment. NVenc has some technical limitations and might not be recommended for streaming, but rather mostly for recording.

 

[Aeryn]

It works fine @60fps and it records fine at 120 (nowhere near encoder limits) - i don't remember it being broken like that on my last GPU

kinda disappointing if the horsepower is there to record at 1080p+ and 120fps, but there is no ratecontrol for it

 

[Lain]

...Oh. 120fps. Why didn't I read the title. Why didn't I fully read the post? Having problems recording 120fps. Oh. Well! Well. ...Well.

Ahem.. What I meant to say is that oh. >60fps isn't really something we really support. Not really anything anyone other than 120fps monitors can watch either, unless you're just mostly watching it for yourself I suppose. Youtube won't allow it either, will just convert it to a lower resolution regardless. You could probably stream it, but very few people would be able to decode at 120fps because flash is terrible at decoding. And very few people would have 120fps monitors to watch it as well.

I guess it's just mostly "I don't know".

 

[Aeryn]

Me and some friends use 144hz monitors, and it's not necessarily for streaming. We send files a lot or generally record stuff offline. It just seemed really weird to me to have it like this:

CBR 5000kbit gives 5000kbit bitrate with x264 at 60fps
CBR 5000kbit gives 5000kbit bitrate with x264 at 120fps
CBR 5000kbit gives 5000kbit bitrate with nvenc at 60fps
CBR 5000kbit gives 30'000 - 60'000kbit bitrate with nvenc at 120fps - wat


After some more attention, it seems that i was overlooking the "quality" option in OBS which might apply to NVENC (i don't use it for x264) so i will experiment with that a little but i don't know if it will improve anything