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Crackling and slowing down of project in Reaper

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Crackling and slowing down of project in Reaper

Postby Marbury » Mon Sep 14, 2020 11:52 am

For the life of me I don't know why a new pc with 16 GB ram on an i5 9600 3.70ghz is struggling with a modest project when I try to patch in the Ozone 7 into the main stereo output track. It's bizarre that is sounds horrible, distorted (nothing to do with overloading of audio) and drags along slowing down in tempo. I check task manager and it shows that 38% of the cpu is being used so what can this be folks ?
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Re: Crackling and slowing down of project in Reaper

Postby Hugh Robjohns » Mon Sep 14, 2020 12:04 pm

Sounds like you have a sample rate/clocking issue somewhere?
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Re: Crackling and slowing down of project in Reaper

Postby manwilde » Mon Sep 14, 2020 2:08 pm

Hugh might be on the right track with his suggestion, just this morning something similar happened to me when I opened a 44.1k project while the interface was set to 48k from last night work... the computer was resampling the opened project in real time playback, leading to cracks and noises...
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Re: Crackling and slowing down of project in Reaper

Postby James Perrett » Mon Sep 14, 2020 2:52 pm

Check the sample rate conversion quality in Reaper's project settings. If this is set to Extreme (which is what I normally use) you don't need that many tracks being converted to start loading down the processor.

The solution is to set the project sample rate to match the sample rate of your source files so that, if your interface clock frequency is different, the sample rate conversion is only applied to the final output.
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Re: Crackling and slowing down of project in Reaper

Postby Uncovered Pitch » Mon Sep 14, 2020 3:34 pm

Have you tried putting Ozone on a normal track(which you can call "Stereo Buss") and then routing everything else to that rather than putting it on the master buss? In Reaper it's good practice to keep the master buss completely free of plug-ins. It's to do with its RT(=real-time, main audio thread) CPU handling.

As soon as you put something(and especially CPU-heavy plug-ins like Ozone) on the master buss, the RT CPU spikes up far more than the regular CPU reading would indicate. To see the RT CPU readings you have to enable it in the Performance window. Hope this is the culprit as it's easy to solve!
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Re: Crackling and slowing down of project in Reaper

Postby Marbury » Tue Sep 15, 2020 12:17 am

Not had chance yet to try the suggestions but meanwhile, I would have thought that the CPU only showing at 38% while this is happening would surely indicate that it wasn't overloading it's power ?
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Re: Crackling and slowing down of project in Reaper

Postby Eddy Deegan » Tue Sep 15, 2020 12:39 am

Marbury wrote:Not had chance yet to try the suggestions but meanwhile, I would have thought that the CPU only showing at 38% while this is happening would surely indicate that it wasn't overloading it's power ?

Possibly, possibly not. If you're using the Task Manager then that 38% may represent the percentage of total possible load across all the cores. For example running a single core flat out on a quad core processor will show a load of 25%.

Depending on how the DAW is working with threads, that 38% could represent something going well into cycle saturation, but it's impossible to say for sure.

If you open the Resource Meter then you should be able to see more details on the 'CPU' tab which breaks the load down into the individual logical cores as well as showing the combined load at the top:

resourceMeter.JPG
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Re: Crackling and slowing down of project in Reaper

Postby Ramirez » Tue Sep 15, 2020 7:58 am

Uncovered Pitch wrote:In Reaper it's good practice to keep the master buss completely free of plug-ins. It's to do with its RT(=real-time, main audio thread) CPU handling.

Interesting. Do you have more info/link to a discussion on this?
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Re: Crackling and slowing down of project in Reaper

Postby Uncovered Pitch » Tue Sep 15, 2020 3:28 pm

Ramirez wrote:
Uncovered Pitch wrote:In Reaper it's good practice to keep the master buss completely free of plug-ins. It's to do with its RT(=real-time, main audio thread) CPU handling.

Interesting. Do you have more info/link to a discussion on this?
This is one of the things that everyone over in the Reaper forum seems to agree on. You can easily test it on your system by putting a CPU-intensive plug-in(i.e. Ozone, AA, DynOne etc. ) on the Master buss and looking at the performance meter, then moving that plug-in to a "fake" master buss like I've outlined and compare the figures.

In my tests keeping plug-ins off the master buss has always won. I'm not so much talking about meters or dither plug-ins here as the difference would be a lot less pronounced. Still, I keep the Master buss absolutely free and have my room correction, meters and dither on separate busses. Therefore also don't use the Monitoring section for serious mix work as it suffers from the same problem as the master buss.

I do max out every mix though so if you're more conservative in your plug-in usage then the extra effort of setting up those "fake" master, monitoring and metering busses may not be worth it.
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Re: Crackling and slowing down of project in Reaper

Postby Ramirez » Tue Sep 15, 2020 4:06 pm

Uncovered Pitch wrote:
Ramirez wrote:
Uncovered Pitch wrote:In Reaper it's good practice to keep the master buss completely free of plug-ins. It's to do with its RT(=real-time, main audio thread) CPU handling.

Interesting. Do you have more info/link to a discussion on this?
This is one of the things that everyone over in the Reaper forum seems to agree on. You can easily test it on your system by putting a CPU-intensive plug-in(i.e. Ozone, AA, DynOne etc. ) on the Master buss and looking at the performance meter, then moving that plug-in to a "fake" master buss like I've outlined and compare the figures.

In my tests keeping plug-ins off the master buss has always won. I'm not so much talking about meters or dither plug-ins here as the difference would be a lot less pronounced. Still, I keep the Master buss absolutely free and have my room correction, meters and dither on separate busses. Therefore also don't use the Monitoring section for serious mix work as it suffers from the same problem as the master buss.

I do max out every mix though so if you're more conservative in your plug-in usage then the extra effort of setting up those "fake" master, monitoring and metering busses may not be worth it.

Goodness, it seems you're right! I've just tried it now.
I was at Total CPU 2.6% / RT CPU 18.2% with an oversampling limiter and metering suite on the master bus.
I copied the same processing chain over to a new track instead, disabled them on the master bus and routed everything via the new track, and I'm down to Total CPU 0.5% / RT CPU 0.9% !
That's a massive difference. What gives?!
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Re: Crackling and slowing down of project in Reaper

Postby blinddrew » Tue Sep 15, 2020 11:01 pm

Interesting. I've always used a dummy master bus as it means I can load my reference tracks in as normal files and not worry about duplicate processing etc. The only thing that sits on my master bus is Sonarworks so I can just toggle it off and on as required when jumping to headphones.
I had always just assumed that Sonarworks was just really CPU hungry, I may have been doing them a disservice. :oops:
But I'm not going to change anything as it suits my workflow. :)
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Re: Crackling and slowing down of project in Reaper

Postby Ramirez » Wed Sep 16, 2020 10:38 pm

blinddrew wrote:Interesting. I've always used a dummy master bus as it means I can load my reference tracks in as normal files and not worry about duplicate processing etc. The only thing that sits on my master bus is Sonarworks so I can just toggle it off and on as required when jumping to headphones.
I had always just assumed that Sonarworks was just really CPU hungry, I may have been doing them a disservice. :oops:
But I'm not going to change anything as it suits my workflow. :)

Are you aware of the 'Monitoring FX' section in Reaper? I've got it set up so that outputs 3/4 from Reaper always goes through Sonarworks to my RME's headphone out. 1/2 ges to the monitors, so no need to switch Sonarworks on and off, and no risk of rendering the final mix through it either!
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Re: Crackling and slowing down of project in Reaper

Postby blinddrew » Wed Sep 16, 2020 10:40 pm

I think it's probably clear that I was not! :D
I shall have a shufti at that in due course. Thank you. :thumbup:
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Re: Crackling and slowing down of project in Reaper

Postby Marbury » Thu Sep 17, 2020 6:35 pm

James Perrett wrote:Check the sample rate conversion quality in Reaper's project settings. If this is set to Extreme (which is what I normally use) you don't need that many tracks being converted to start loading down the processor.

The solution is to set the project sample rate to match the sample rate of your source files so that, if your interface clock frequency is different, the sample rate conversion is only applied to the final output.

Thanks, I have set the playback sample rate and the render sample rate to extreme HQ.

My usual way of mastering is to just render the wav from Reaper and use Ozone7 as a standalone. It seems to work for me as I like to think of it as separate to the creative music making. I just had it on the Stereo master track of an older project before I had started to process outside of Reaper.
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Re: Crackling and slowing down of project in Reaper

Postby James Perrett » Thu Sep 17, 2020 8:07 pm

Marbury wrote:
James Perrett wrote:Check the sample rate conversion quality in Reaper's project settings. If this is set to Extreme (which is what I normally use) you don't need that many tracks being converted to start loading down the processor.

The solution is to set the project sample rate to match the sample rate of your source files so that, if your interface clock frequency is different, the sample rate conversion is only applied to the final output.

Thanks, I have set the playback sample rate and the render sample rate to extreme HQ.

I think you may have misinterpreted my post. The important thing to check is the sample rate of all your files and the sample rate of your interface (as displayed in the top right hand corner). These should be the same. If you really need sample rate conversion, you are more likely to encounter crackling and stuttering problems with the extreme HQ setting.
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