Question / Help OBS and Broadwell-E

Jehos

New Member
Here's the deal, I'm researching a single-box solution for streaming and recording gameplay simultaneously. For now I'm playing Overwatch, if that matters.

My wishlist:
- Run modern games
- Stream to Twitch at 720p60/3500bps
- Record to disk at 1080p60 with no obvious compression artifacts

My current setup is an i7-6700 (non-K), 32GB RAM, EVGA GTX1060 SC, and a Samsung 850 Evo as the single drive in my system. My native screen resolution is 1440p60.

Streaming I've got a pretty good handle on. I'm downscaling to 720p60 on the Video tab using the Lanczos 32 sample downscale filter. Then on the Output tab I'm using x264, no scaling, CBR @ 3500, veryfast. Stream goes to Twitch, recording goes to MP4, and while I flirt with 100% CPU usage, I don't get any real slowdowns. Video quality isn't great, but it's better than most of the streams I've watched.

However, if I do anything that requires my system to do two encodes at once, it chokes. I either have to turn quality down, or I get game lag, stutters in the recording, stutters in the stream, or all of the above. So, I'm trying to figure out a new system. Money isn't much of an object, I'll spend for quality. I'm just trying to figure out what I need.

Can someone explain how OBS uses cores? I'm specifically trying to understand things like how more cores impacts the following:

- Multiple down-scales
- CPU usage preset in x264

What I'm trying to figure out is whether to get a 6 core, 8 core, or 10 core processor to allow me to basically take one capture and encode it twice at the same time, at high quality, without slowing down gameplay. I would love to be able to do what I'm doing with the streaming, but be able to drop the stream CPU preset to "faster", and also change my recording to be 1080p60/12.5kbps at fast or even medium preset.
 

C-Dude

Member
Your pc should be fine for both streaming and recording. Record with NVENC and a high bitrate (around 60000 for 1080p60) and that won't take up much power at all. Stream with the same settings that you are using currently.
You may need to get a hard drive to record to. Plus it doesn't ware out as easily as an SSD.

OBS isn't optimized to use a ton of cores just as most other programs.
Encoding twice with the x264 encoder (at decent quality) is not possible even with top of the line hardware.

This article tells you how to set up local recordings: https://obsproject.com/forum/resour...lity-recording-and-multiple-audio-tracks.221/

With NVENC you should be able to record and stream at the same time. Either use CQP which will give you a larger file but insane quality. Or a high bitrate of around 60000 which I already mentioned. You won't get artifacts but it is slightly noticible, however it really doesn't matter if you are uploading to something like youtube where it will be way compressed again.
 

Jehos

New Member
I'm so glad I asked before spending money! For some reason I never noticed that I can mix encoding methods for recording and streaming.

I just tested and on the Video tab I'm setting the output to 1080p60. Output tab for streamingI'm re-sizing that to 720p60 using x264. I can get the CPU preset all the way down to medium before I start really pushing my CPU, and my stream looks even better. Recording I'm using NVENC at indistinguishable quality and it looks great. File sizes aren't too bad either, looks like about 100MB/minute or so, depending on motion.

Thank you so much. I've been searching the forums here and elsewhere and for whatever reason it just never clicked that I could offload the encoding for recording to disk to my GPU while still using the CPU for the higher quality low bitrate encoding for the stream.
 
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