Real Time CPU

I think I've found the answer: "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.

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?

OK I've found the answer to the problem. It has nothing to do with the computer, audio card or any hardware related issue. Just as the SOS article describes, Reaper assigns CPU load per track. What this means is that if you have too many plugins on a track or a single plugin on a track that is CPU intensive then it causes the audio to crackle. I know this to be a fact because I loaded six instances of SynthMaker into Reaper and as long as I kept each instance at 8 voice polyphony in 'Best' sound quality mode there were no glitches and everything played back perfectly even though CPU load was 94% for all six cores. IOW load too many or too CPU intensive plugins into a single track and Reaper will crackle. Distribute the load over multiple track and Reaper will playback fine. Who knew, eh? That begs the question, Is there anyway round this?

I and the vast majority of users on here use 24bit 44.1 or 48 for recording. 96, to be honest, is pretty much irrelevant unless your target audience is teenagers with very very good home stereo systems capable of reproducing 24/96 wavs, or..... bats. You are using a ton of cpu processing power to very little advantage at 96. or for that matter even at 88.2

also i have found another influence on RTCPU, the "anticipative FX processing" settings. i was wondering why i was having trouble with a previously working song (though cpu maxed out) seems there is a bug or something with reaper, i have to 'bump' the setting eg turn the switch on/off or change the number and back. then i have a dramatic change in the RTCPU and all is good

There's a lot of misinformation in this thread. Rt CPU is CPU used for things like: tine stretching, live resampling, pulling stuff in from disk. Have you been messing with the play rate? What sample rate are you using? Have you ticked resampling or time stretch options up to a higher quality setting?

I tried running as a dedicated process and the audio still broke up at a high setting. Why are plugin developers creating single core plugins when computers have been multi-core for ages? It creates an artificial limitation with plugins that use a lot of juice. I wonder how many other synth plugins are limited to single core?

For a typical serial pipeline it is true. As an analogy, think of water flowing down an empty garden hose. Water can't come out the end before first flowing through the middle. However, fluid dynamics and software coding are rarely "typical" in real world implementations.

I done some test and it seems ozone 5 maximizer on iir 3 with transient recovery sends the RT CPU number over the CPU number. Now I know that setting causing me problems I will make sure I have that turned off during tracking. Pretty easy solution for me but I will have to ignore the CPU meter and only check RTCPU. Bit silly really. :)

And what do you think about that ?