Question / Help Preset Problems - Anything Below Medium DOA

[FerretBomb]

Prefacing, I'm a Twitch Partner, so the below log is going to be outside the normal ranges. It also contains several test streams, checking various option combinations to try and fix the problem.

https://gist.github.com/c6885f6a1ca276d62c8b

That out of the way, to condense things down:
My rig can run 1080p@60fps on Medium x264 smoothly. (Humblebrag over.)
Even if I drop to 720p@30fps (or lower), for some reason it can't handle Slow, or Slower.

The logfile shows no significant issues on my end (less than 0.25% late/duped/skipped combined on 720@30 Slower), but the Twitch stream quickly goes into slideshow mode, only displaying one frame every few seconds, though the audio continues normally. I unfortunately did not locally record the test. Jumping up to *any* preset Medium or higher restores a smooth stream with steady playback.

Even if Slower is patently unnecessary, I'd very much like to eliminate this glass floor if at all possible, as I suspect it may be a symptom of another underlying problem.

 

[Boildown]

05:15:46: x264: MB rate (489600) > level limit (245760)

06:40:01: x264: DPB size (8 frames, 65280 mbs) > level limit (4 frames, 32768 mbs)

Have you tried manually setting the level to 5.2? Presets slower than Medium would require even higher levels for the same resolution and framerate because of more reference frames (or maybe its b-frames, I forget). Not sure that the encoder even respects the level setting but may as well eliminate it as a possible cause. And if you didn't know, OBS doesn't set the level correctly when using x264 encoding in all situations.

Maybe their transcoder can't handle decoding those presets, as there is an increased CPU usage on the decode side as well. Can you try it with Twitch's transcoding turned off?

How is your recording to disk? Does it look normal when played back?

Have you tried turning CFR on? It wouldn't surprise me if their transcoder choked in variable bitrate video. Also, if you have CFR off then you can't believe your duplicated frames numbers... some frames might have been duplicated but x264 just varied the framerate instead, which means you have a problem but it won't be reflected in the duplicated frames numbers.

You're using a c920 webcam which is notorious for causing bad performance when in 1080p mode. Have you tested without the webcam?

 

[FerretBomb]

I have not manually set the level. What would the setting be for that?
I've been using my (non-partnered) testing stream for... well. Testing. So there's no transcoding factoring in.
I'll have to run another test later. I'd mentioned that I had forgotten to record the tests locally; I'd neglected to set auto-record on the fresh install on the new system.

 

[Boildown]

Edited my post above for more ideas and a link to the level bug I put in.

I think you'd just do "level=5.2", but as I record with NVEnc which auto-sets the level correctly, and the default level is fine for my stream, I've never needed to set it myself, so that could be wrong.

 

[Boildown]

Curious to see if fixing the level has any affect on this. Because if it does, then its a bug that needs to be fixed (the incorrect level setting), as a lot of people are running in to it. If it doesn't, then this bug can pretty much be ignored in favor of the multiplatform development.