Question / Help Can OBS do lossless recording?

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WayZHC

Member
Yes it can but not recommended. But go to settings and Advanced tab and add custom x264 command: crf=0
0 will be lossless. Bitrate will be huge but i guess you know what you are doing since you asked for it.
 
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Smashbro29

Member
I know the file will be massive, is it gonna hit the CPU any harder? Other than a huge file why is this not recommended?
 
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WayZHC

Member
Well i don't think it's very cpu heavy but it requires a lot HDD bandwidth. So if you are planning to record lossless gaming(?), make sure you record to another HDD. It's gonna hit your fps if recording to same HDD as where the game runs.
 
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Smashbro29

Member
WayZHC said:
Well i don't think it's very cpu heavy but it requires a lot HDD bandwidth. So if you are planning to record lossless gaming(?), make sure you record to another HDD. It's gonna hit your fps if recording to same HDD as where the game runs.
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Ok but assuming video has its own dedicated HDD I should be fine right?

I set the x264 CPU preset to ultrafast (because from my rudimentary knowledge it doesn't matter if it's a local recording and it takes a lot of stress off the CPU)

 
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WayZHC

Member
With a dedicated HDD you'll be fine.

And i always recommend using Veryfast but test and see if you like the quality using Ultrafast. Veryfast will be better quality but again test and see if it's worth the extra cpu usage or not.

E: Hmmm. i really don't know is there any difference between ultrafast and veryfast when using lossless capturing. Test and see :p
 
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WayZHC

Member
crf will override those video encoding settings but not audio. For audio with lossless video I'd recommend using 320Kbps AAC.
 
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Smashbro29

Member
Thanks so much for your help. I think that's everything. In truth if I'm not streaming something on PC I see no reason not to use slow as I'm assuming the quality will be nothing short of amazing.

Does OBS have a screenshot function?
 
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Smashbro29

Member
It would seem that using my Avermedia Live Gamer HD in this fashion to get 720p at 60fps coupled with playing Sonic Generations (my usual benchmark game) at full settings even using very fast positively chews through my CPU rendering the game very annoying to play.

How strange.
 
Krazy

Krazy

Town drunk
The slow preset is going to bring your machine to a crawl, you don't need to do this for local recordings. Slow preset is basically something you would use after editing and doing the final encode or something.

Also, crf=0 WILL actually increase your CPU usage quite a bit.
 
Krazy

Krazy

Town drunk
Yes, but generally you can compensate for the faster presets with more bitrate.

The trick with high quality, low performance impact local recordings is using the faster presets and using a lot of bitrate.

This is basically how you want to do it: viewtopic.php?f=18&t=2972

OBS/x264 isn't really designed for lossless recording, so while crf=0 will enable lossless encoding, it can really kill your performance and give you rather unreasonable file sizes. There are probably better options for lossless recording.
 
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