electro-music.com   Dedicated to experimental electro-acoustic
and electronic music
 
    Front Page  |  Radio
 |  Media  |  Forum  |  Wiki  |  Links
Forum with support of Syndicator RSS
 FAQFAQ   CalendarCalendar   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   LinksLinks
 RegisterRegister   ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in  Chat RoomChat Room 
 Forum index » How-tos » Ambiophonic Sound Reproduction
CPU Usage oddity
Post new topic   Reply to topic
Page 1 of 1 [4 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
Shike



Joined: Dec 31, 2014
Posts: 4
Location: US

PostPosted: Sun Apr 10, 2016 1:40 pm    Post subject: CPU Usage oddity Reply with quote  Mark this post and the followings unread

Greetings,

When using AmbiophonicDSP I noticed an odd issue. If you are not feeding it any sound the CPU usage can skyrocket (from 7% utilization to 30% easy).

The only way I have found around this thus far is to feed a test signal at -191dB to both inputs of the DSP. Seems like when no sound is fed the DSP goes crazy?

I'm not too concerned since I did find a workaround and my application is largely overkill, but thought it was worth bringing up in the hopes that it may eventually get fixed.
Back to top
View user's profile Send private message
hrastprogrammer



Joined: Oct 16, 2008
Posts: 261
Location: CPU
Audio files: 103

PostPosted: Sat Apr 16, 2016 10:09 pm    Post subject: Reply with quote  Mark this post and the followings unread

I don't own this plugin, so I am just guessing, but it is most likely a denormals problem.

To the developers ...

If you are using SSE instructions then enable FTZ (Flush To Zero) and DAZ (Denormals are Zero) CPU flags:

https://software.intel.com/en-us/node/513376

Or just mix a small amount of white noise (below -120dB) at appropriate stages inside a signal chain - input, output, etc.

_________________
https://www.hrastprogrammer.com/hrastwood/
https://hrastprogrammer.bandcamp.com/
Back to top
View user's profile Send private message Visit poster's website
mosc
Site Admin


Joined: Jan 31, 2003
Posts: 18197
Location: Durham, NC
Audio files: 212
G2 patch files: 60

PostPosted: Mon Apr 18, 2016 9:58 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for both posts. I'm on the verge of doing a complete rewrite of this plugin so it will run on both OSX and Windows.

I was unable to duplicate this CPU load on my machine. I wonder if there is something going on with particular VST hosts, or OS versions.

_________________
--Howard
my music and other stuff
Back to top
View user's profile Send private message Send e-mail Visit poster's website AIM Address
hrastprogrammer



Joined: Oct 16, 2008
Posts: 261
Location: CPU
Audio files: 103

PostPosted: Mon Apr 18, 2016 9:24 pm    Post subject: Reply with quote  Mark this post and the followings unread

Yes, it could be VST host related. I stumbled upon denormals problem during the development of my Tranzistow synthesizer. So, I turned on DAZ/FTZ flags (because my audio processing code is mostly SSE3 assembler) and mixed some very low amplitude white noise at the output stage, just in case. This is very cheap operation and couldn't hurt anything ...
_________________
https://www.hrastprogrammer.com/hrastwood/
https://hrastprogrammer.bandcamp.com/
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic
Page 1 of 1 [4 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
 Forum index » How-tos » Ambiophonic Sound Reproduction
Jump to:  

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Forum with support of Syndicator RSS
Powered by phpBB © 2001, 2005 phpBB Group
Copyright © 2003 through 2009 by electro-music.com - Conditions Of Use