Old 03-17-2018, 04:01 PM   #1
arsvivendi
Human being with feelings
 
Join Date: Mar 2018
Location: Torrance, CA
Posts: 17
Default New and Curious

Hello Reaper community!

I've spent a few months learning Reaper before registering in the forum (to spare you all the basic questions) but as I use Reaper, I've noticed something I can't find explained anywhere.

It concerns recording and CPU behavior. There's a particular Guitar Rig 5 plugin (Orbiting Berlin) that chews up a lot of RT CPU (~20%). When software monitoring live guitar on my 15" 2017 MBP at 96kHz, 256 samples, it's totally smooth. Record-armed and monitored. As soon as I hit cmd+R to write the recording, my RT longest-block exceeds the max 2.67ms and audio breaks up. RT CPU does not exceed even 40% in either case.

I'm wondering why hitting record would cause the rt longest-block to jump up on an already-record-armed track? Running Reaper version 5.77; audio interface Apogee Element88.

Louis
arsvivendi is offline   Reply With Quote
Old 03-18-2018, 10:58 AM   #2
DVDdoug
Human being with feelings
 
Join Date: Jul 2010
Location: Silicon Valley, CA
Posts: 2,779
Default

Quote:
the max 2.67ms and audio breaks up. RT CPU does not exceed even 40% in either case.
I can't give you a specific answer but CPU utilization doesn't tell the whole story...

All it takes is for some task (writing to the hard drive?) to "hog" the system a few-milliseconds too long. The operating system doesn't get-around to reading the buffer in time, and your buffer overflows.

(With playback/monitoring, the danger is buffer underflow when the buffer doesn't get re-filled in time.)
DVDdoug is online now   Reply With Quote
Old 03-18-2018, 10:48 PM   #3
arsvivendi
Human being with feelings
 
Join Date: Mar 2018
Location: Torrance, CA
Posts: 17
Default

Thanks for your help! Very interesting, overflow vs. underflow.

So do I need to make it easier for Reaper to write to disk?
Or will it always double the rt longest-block when I write to disk?
To me it doesn't seem like sending the audio stream to disk should add so much time. Would love to know what Reaper is doing under the hood, or where I can find this information!
arsvivendi is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -7. The time now is 07:12 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.