Old 04-24-2012, 01:24 PM   #1
Spectralis
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Default Real Time CPU

Hi, I'm trying to figure out why Reaper shows only 10% FX CPU use but maxes out Real Time CPU use. It doesn't matter how I change the buffer size or whether I use ASIO/WDM drivers, RT CPU is always maxed out. What is using all the CPU?

I have a AMD 6X 1090T CPU and 16GB RAM so it's a reasonably powerful PC.

Task Manager reports 16-20% cpu use when i play the project. I have the buffers set very high Reaper still breaks up and registers 100% Real Time CPU. This is really bizarre and frustrating.

Buffers: WDM 185ms
ASIO 2048 Samples
Wave Out 371ms

It doesn't matter what the buffer size is RT CPU is always 100%.

Last edited by Spectralis; 04-24-2012 at 02:47 PM.
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Old 04-24-2012, 02:53 PM   #2
Spectralis
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I think I've found the answer:

http://www.kvraudio.com/forum/viewto...er=asc&start=0

"Solved! I can't believe how easy it was, i'm so stupid! Ok, so the problem was that REAPER was not using all cores for live FX processing. In Preferences->Audio->Buffering, tick the "Allow live FX multiprocessing on" and choose how many cores you want. Apparently, it might impare performance, but i'm not sure how. I just asked the poster on the REAPER forums, and I will update this when I get his answer."

It seems a bit daft that Reaper doesn't automatically detect all the CPU's and use them accordingly as standard. Then if this needs to be changed it can be done manually in the 'Options' settings rather than the other way round.
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Old 04-26-2012, 08:55 AM   #3
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I've set 'Allow live FX multiprocessing' to use '6' cores but it's not solved the problem.

I'm using SynthMaster 2.5 set to 'Better' or 'Best' sound quality in Reaper which reports:

FX CPU 22%

RT CPU 133%

The sound breaks up and judders.

This is a real PITA. Either Reaper is terribly inefficient or I am for not setting it up right. Any help pleeeeease?
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Old 04-26-2012, 09:04 AM   #4
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Quote:
Originally Posted by Spectralis View Post
I've set 'Allow live FX multiprocessing' to use '6' cores but it's not solved the problem.

I'm using SynthMaster 2.5 set to 'Better' or 'Best' sound quality in Reaper which reports:

FX CPU 22%

RT CPU 133%

The sound breaks up and judders.

This is a real PITA. Either Reaper is terribly inefficient or I am for not setting it up right. Any help pleeeeease?

This is bothering me too. I get stutters too with a high latency and cpu is quite low.

What is THE RTCPU thing anyway?
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Old 04-26-2012, 09:22 AM   #5
Spectralis
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Quote:
Originally Posted by faun2500 View Post
This is bothering me too. I get stutters too with a high latency and cpu is quite low.

What is THE RTCPU thing anyway?
I really don't know either. I'm pulling my hair out trying to figure out why Reaper 4 struggles to cope with relatively low plugin loads. It doesn't make a difference using bigger latencies either. I really like Reaper but this is seriously making me consider changing DAW.

I've searched on this forum and on KVR for an answer but no one seems to have a definitive answer. All I can surmise is that Reaper can't cope with certain plugins or plugin loads and throws a wobbly. It doesn't seem to use all 6 CPU cores even though it is set to do so.

In the SynthMaster example I gave above Win 7 Task Manager is reporting only 7% CPU use yet Reaper 4 is reporting 133% RT CPU. WTF?
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Old 04-26-2012, 09:38 AM   #6
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RT CPU is "Real Time CPU". It's the amount of CPU required in order to maintain real time audio. Thus, anything over 100% means audio drop outs. If your CPU can't do what is required within a specific time then it doesn't matter how much CPU is used.

Sounds like you are both using too small an audio buffer and/or are running at too high a sample rate. Best to post all the relevant info, like what audio interface and what settings you are using. People on this forum are great and will help given the info.

PS - Reaper is one of the most efficient DAWs out there... but don't take my word for it - search on Google.
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Old 04-26-2012, 10:16 AM   #7
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Originally Posted by n0rd View Post
People on this forum are great and will help given the info.

I agree with that, I've been around here a while now and have had endless problems sorted out. lol.

I'm recording at 96k using an RME fireface UC on windows 7 64 and reaper 64, 16g RAM.

Do you think that making my songs now at 96k sample rate could be causing problems?
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Old 04-26-2012, 10:16 AM   #8
Spectralis
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Quote:
Originally Posted by n0rd View Post
RT CPU is "Real Time CPU". It's the amount of CPU required in order to maintain real time audio. Thus, anything over 100% means audio drop outs. If your CPU can't do what is required within a specific time then it doesn't matter how much CPU is used.

Sounds like you are both using too small an audio buffer and/or are running at too high a sample rate. Best to post all the relevant info, like what audio interface and what settings you are using. People on this forum are great and will help given the info.

PS - Reaper is one of the most efficient DAWs out there... but don't take my word for it - search on Google.
Thanks for your reply. I'm using ASIO4ALL driver. But even when I use WDM or WaveOut it makes no difference to performance. I'm outputting to USB Speakers.

ASIO4ALL:
Sample rate: 44.1kHz
ASIO Buffer Size = 2048

WaveOut:
Sample rate: 44.1kHz
Buffers: 4 x 2048 = 185ms

WDM Kernal Streaming:
Sample rate: 44.1kHz
Buffers: 8 x 1024 = 185ms

I'm using 3 x UAD-1. I have 'Anticipative FX processing' switched off. Win 7 Resource Monitor reports that Reaper 4 is using 5% CPU during playback.
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Old 05-25-2021, 04:08 PM   #9
incognitocas
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Default I have this same issue

Quote:
Originally Posted by Spectralis View Post
I think I've found the answer:

http://www.kvraudio.com/forum/viewto...er=asc&start=0

"Solved! I can't believe how easy it was, i'm so stupid! Ok, so the problem was that REAPER was not using all cores for live FX processing. In Preferences->Audio->Buffering, tick the "Allow live FX multiprocessing on" and choose how many cores you want. Apparently, it might impare performance, but i'm not sure how. I just asked the poster on the REAPER forums, and I will update this when I get his answer."

It seems a bit daft that Reaper doesn't automatically detect all the CPU's and use them accordingly as standard. Then if this needs to be changed it can be done manually in the 'Options' settings rather than the other way round.
The latency is so bad. If I even try and use plugins in real time and listen to myself without latency issues, its impossible. I have fewer issues with Audacity! I recently purchased reaper, and I'm extremely frustrated. The popping and crackling is so bad it's unusable. I don't know what to do.
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Old 05-31-2021, 06:36 PM   #10
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@incognitocas;

What OS, CPU, I/O are you using? In order for the forums to help you, we need more information.

Also, what are your settings in Preferences > Audio > Buffering?
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