Question / Help Streaming in 4K / 2160p possible?

[Martin Schmidt]

(yes, I used the search, but found no answer)

Hi,

is OBS capable of streaming and recording in 4K / 2160p? I'm currently using a PC with a Blackmagic Decklink Card and consider an update to a 4K Capture Card. Of course the PC has to be powerful enough and the streaming Server has to accept this resolution.

Thanks!

Martin

 

[D2ultima]

I don't believe OBS has good support for such high resolutions yet; neither does x264 for rendering that high especially in real-time. Also, you'd need to actually capture something natively rendered at 4K for the 4K capture card to be useful, so you'd need a gaming PC capable of 4K gaming on a 4K screen AND a separate PC capable of rendering 4K 30fps (60fps 4K ain't happening).

And even if you could, 3500 bitrate is nowhere near enough, so streaming is out. Recording may not be.

 

[Martin Schmidt]

Thanks for your answer. The 4K source is no problem, since I use OBS not for games but for video and there is plenty of 4K cameras for HDMI and HD-SDI. Maybe I'll get the card anyway and check out what is possible.

 

[D2ultima]

No problem. Just making sure. There's lots of people out there who will stream Xbox 360 at 1080p or some similar crap "because they can", even though it's all being upscaled from a lower size, so when you said 4K I figured I'd better lay it all out just in case. Good luck!

 

[Jack0r]

At the moment, 1080p streaming is in 75-90% of the cases not recommended because even that needs too much bitrate to look good. What did youtube use for their 4k videos again, 30mbps or 50?
OBS shouldnt be a problem, its just that noone will be able to watch it or it will look like crap unless it shows a still picture.
Apart of the severe cpu usage for en- and decoding, your viewers will need the best possible connection and high download speeds to even start watching. Then most video players currently use flash, which will add even more problems.
But you can of course record for your own usage or youtube uploads (I heard they now support 8k)

 

[D2ultima]

The preview does not show correctly when the base resolution is above 1440p. It stutters and hitches, even though the resulting video (with a downscale) is fine, which is why I said I couldn't be certain that OBS itself can manage 4K in real-time. There was some user on the forum a few days ago who had that issue when going above a certain resolution as he was trying to downscale, but I've never seen anyone use OBS to record 4K

Even using NVENC and Quicksync may be an issue as well. I know for a fact NVENC breaks if I try to record above 60fps even at 1080p, so there are going to be limitations on the hardware-based encoders even if they could support 4K (as much as nVidia likes to say they do, their GPUs don't support 4K as well as AMD's now-2-year-old tech does).

 

[Jack0r]

Gave it a quick test, very fast preset gave high cpu encoding usage, superfast preset uses up to 80% of my i7 4770. Preview was smooth. The hardware encoders of course have their own limitations.

 

[D2ultima]

You had a 4K input on hand? Wow. Something I couldn't test.

 

[Jack0r]

I used my monitor capture and let obs upscale it to 3840 × 2160, then I tried to record a bf hardline video from youtube (fullscreen and 1080p quality) to put some stress on the encoder. In this case it of course has to capture less pixels which probably lowered the resource usage a bit, so expect a real recording to use even more resources.
Currently someone should probably plan to get one of those 6+ Core Intel's and maybe a 980 or TitanX if he wants to use the same pc to run programs/games at the same time.

 

[D2ultima]

The guy who was trying had a separate PC for it, and was using a capture card of 1440p, and bumped the res to 4K so he could downscale. I want to see someone try with an actual 4K (or post 1080p input) to see. Upscaling is one thing, but your source would make a difference.

If I ever find someone with a legit 4K screen I'll force them under threat of PC destruction ask them to test for me.

 

[JohnB]

Sorry to bring back an old thread, but seeing as this is relevant to both OP and D2ultima, here you go:

Elite: Dangerous (my very first time playing it, and I suck) at 2160p 60 FPS 30Mbps (no audio) broadcasted using OBS-MP:
http://www.hitbox.tv/video/698312

My 5960x at 4.5GHz struggled HARD with this, even at the veryfast preset.

 

[FerretBomb]

Could you post a logfile from this? I'm actually kind of shocked that a 5960x could swing 4K@60; more SMP Xeon territory there, so I'm curious about frame dupes, lates, and skips. 4K@30 would be where I'd have ballparked it topping out.

 

[JohnB]

I believe this is the relevant excerpt:
05:52:47.928: ---------------------------------
05:52:47.928: [x264 encoder: 'streaming_h264'] preset: veryfast
05:52:47.928: [x264 encoder: 'streaming_h264'] profile: high
05:52:47.928: [x264 encoder: 'streaming_h264'] settings:
05:52:47.928: bitrate: 30000
05:52:47.928: buffer size: 30000
05:52:47.928: crf: 0 (0 when CBR is enabled)
05:52:47.928: fps_num: 60
05:52:47.928: fps_den: 1
05:52:47.928: width: 3840
05:52:47.928: height: 2160
05:52:47.928: keyint: 250
05:52:47.928: vfr: off
05:52:47.928: cbr: on
05:52:47.936: [Media Foundation AAC: 'Track1']: encoder created
05:52:47.936: bitrate: 160
05:52:47.936: channels: 2
05:52:47.936: sample rate: 44100
05:52:47.936: bits-per-sample: 16
05:52:47.936:
05:52:47.936: [rtmp stream: 'adv_stream'] Connecting to RTMP URL rtmp://live.lhr.hitbox.tv/push...
05:52:50.442: [rtmp stream: 'adv_stream'] Connection to rtmp://live.lhr.hitbox.tv/push successful
05:52:50.443: ==== Streaming Start ===============================================
06:13:31.176: [rtmp stream: 'adv_stream'] User stopped the stream
06:13:31.371: Output 'adv_stream': stopping
06:13:31.371: Output 'adv_stream': Total frames: 74606
06:13:31.371: Output 'adv_stream': Number of skipped frames: 1163 (1.55886%)
06:13:31.371: Output 'adv_stream': Number of dropped frames: 2675 (3.5855%)
06:13:31.371: ==== Streaming Stop ================================================

The process was running at Normal priority, so competing for CPU cycles with all other software and the game.