SOLVED DSP running very high for no obvious reason

Getting Stuff Done How do I .... ?
#1

EDIT:
My sincere apologies. The problem was caused by caps stereo delay which i forgot to remove. Now Im back at ~20%. Could the caps plugins age be causing library problems?

Good evening

Ive run into a problem on a session for which I cannot understand the reason.
My DSP has gone crazy, constantly between 50-100%, when it was previously round 20%
I’ve removed all the non bundled plugins except Sitala, which usually doesn’t give high DSP problems and hasn’t before in this session.

Here is my session log:
2025-10-19T18:59:31 [ERROR]: AlsaSeqMidiIO: Device initialization failed.
2025-10-19T18:59:31 [WARNING]: AlsaMidiOut: failed to open midi device ‘142:0’.
2025-10-19T18:59:31 [ERROR]: AlsaSeqMidiIO: Device initialization failed.
2025-10-19T18:59:31 [WARNING]: AlsaMidiIn: failed to open midi device ‘142:0’.
2025-10-19T18:59:31 [ERROR]: AlsaSeqMidiIO: Device initialization failed.
2025-10-19T18:59:31 [WARNING]: AlsaMidiOut: failed to open midi device ‘143:0’.
2025-10-19T18:59:31 [ERROR]: AlsaSeqMidiIO: Device initialization failed.
2025-10-19T18:59:31 [WARNING]: AlsaMidiIn: failed to open midi device ‘143:0’.
2025-10-19T18:59:31 [INFO]: Scanning folders for bundled LV2s: /opt/Ardour-8.12.0/lib/LV2
2025-10-19T18:59:31 [WARNING]: VST3</home/mel/.vst3/DragonflyRoomReverb.vst3>: Invalid VST3 Module Path: ‘’
2025-10-19T18:59:31 [WARNING]: VST3</home/mel/.vst3/DragonflyHallReverb.vst3>: Invalid VST3 Module Path: ‘’
2025-10-19T18:59:31 [WARNING]: VST3</home/mel/.vst3/DragonflyEarlyReflections.vst3>: Invalid VST3 Module Path: ‘’
2025-10-19T18:59:32 [INFO]: xjadeo version: 0.8.14
2025-10-19T18:59:32 [INFO]: harvid version: 901
2025-10-19T18:59:33 [INFO]: Loading menus from /opt/Ardour-8.12.0/etc/ardour.menus
2025-10-19T18:59:33 [INFO]: Loaded custom session defaults.
2025-10-19T18:59:33 [INFO]: Cannot set I/O Priority for disk read/write thread
2025-10-19T18:59:33 [INFO]: Loading user ui scripts file /home/mel/.config/ardour8/ui_scripts
2025-10-19T18:59:33 [INFO]: Loading plugin order file /home/mel/.config/ardour8/plugin_metadata/plugin_order
2025-10-19T18:59:34 [INFO]: Loading history from /home/mel/Music/Untitled-2025-10-19-18-59-17/Untitled-2025-10-19-18-59-17.history
2025-10-19T18:59:34 [INFO]: Untitled-2025-10-19-18-59-17: no history file “/home/mel/Music/Untitled-2025-10-19-18-59-17/Untitled-2025-10-19-18-59-17.history” for this session.
2025-10-19T19:02:08 [INFO]: Searching for export formats in /home/mel/.config/ardour8/export:/opt/Ardour-8.12.0/share/export
2025-10-19T19:02:56 [INFO]: Encode command: { /opt/Ardour-8.12.0/bin/ffmpeg_harvid -f f32le -acodec pcm_f32le -ac 2 -ar 48000 -i pipe:0 -f mp3 -acodec mp3 -q:a 2 -metadata comment=Created with Ardour -y /home/mel/Music/Untitled-2025-10-19-18-59-17/export/400hz_session.mp3 }
2025-10-19T19:03:46 [WARNING]: aux send ID 4 appears to be in use already
2025-10-19T19:03:46 [WARNING]: aux send ID 11 appears to be in use already
2025-10-19T19:03:46 [WARNING]: aux send ID 4 appears to be in use already
2025-10-19T19:03:46 [WARNING]: aux send ID 11 appears to be in use already
2025-10-19T19:03:46 [WARNING]: aux send ID 11 appears to be in use already
2025-10-19T19:03:46 [WARNING]: aux send ID 4 appears to be in use already
2025-10-19T19:03:46 [WARNING]: aux send ID 11 appears to be in use already
2025-10-19T19:03:46 [WARNING]: aux send ID 4 appears to be in use already
2025-10-19T19:03:46 [WARNING]: aux send ID 4 appears to be in use already
2025-10-19T19:03:46 [WARNING]: aux send ID 4 appears to be in use already
2025-10-19T19:03:46 [WARNING]: aux send ID 4 appears to be in use already
2025-10-19T19:03:46 [WARNING]: aux send ID 11 appears to be in use already
2025-10-19T19:03:46 [WARNING]: aux send ID 12 appears to be in use already
2025-10-19T19:03:46 [WARNING]: aux send ID 4 appears to be in use already
2025-10-19T19:03:46 [WARNING]: aux send ID 11 appears to be in use already
2025-10-19T19:03:46 [WARNING]: aux send ID 22 appears to be in use already
2025-10-19T19:03:46 [WARNING]: aux send ID 15 appears to be in use already
2025-10-19T19:03:46 [INFO]: Cannot set I/O Priority for disk read/write thread
2025-10-19T19:03:47 [INFO]: Loading user ui scripts file /home/mel/.config/ardour8/ui_scripts
2025-10-19T19:03:47 [INFO]: Loading plugin order file /home/mel/.config/ardour8/plugin_metadata/plugin_order
2025-10-19T19:03:50 [INFO]: Loading history from /home/mel/Music/livingInAnotheWorld/SHAMElivingInAnotheWorld.history

Here’s the session archive link:

I’m on Ardour 8.12 from here. Debian Trixie tuned up to @X42s instructions. 2017 Thinkstation P500 in performance mode.
Many thanks

#2

Hi,

With no disrespect to the developers CAPS, SWH, TAP, CMT and others were collections of LADSPA Plugins dating back to the earliest days of Linux Audio. It was the only Linux-native format at the time and it was slim pickings for the slowly emerging DAWs. For reasons I don’t fully understand there seemed to be very little quality control on the collections and they were comprised of anything from really great DSP to not quite finished stuff to proof-of-concept experimental stuff and everything in between. There are some real classics and multiple speaker blowers all hiding and waiting for the wrong parameter to be tweaked. A few years after LV2 replaced LADSPA some people took these collections and ported them to LV2 but it mostly appears like there was no real evaluation of the quality of the code, they were simply ported over to LV2 so they could continue to confound people with their puzzling mix of great DSP and utter woofer shredding madness. It’s true some of this DSP (ie GVerb) became the foundation for some much improved versions and some of them were curated into the MOD Duo project but I think at this point in time there are not many good reasons to use these sets in their original collections…

#3

Was [near] silence sent to the plugin? If so, perhaps an issue caused by Denormals - though by default Ardour sets CPU flags to prevent that (Preferences > Performances > Processor handling).

Plugins should not depend on external libraries to begin with…

–

For future reference there is Ardour Menu > Window > Plugin DSP Load - where one can find plugins that require significant CPU (sort by worst-case load).

#4

The C*APS plugins are pretty decent though. I’m surprised that they cause issues, and they’re rather well documented too (see CAPS - 0.9.26).

And since airwindows, the lack of a custom UI is, once again, a feature :slight_smile:

EDIT: The change log for CAPS 0.9.26 (link above) has the following entry:

  • DDDelay removed, needs more work

Is that the plugin you refer to?

#5

Haha, yes and no… I see there is now the ‘Consolidated’ AW version with many removed and a basic GUI for the included ones… But the old collections (perhaps excluding CAPS) have much bigger problems than missing UI’s. What drives me nuts is things like Kdenlive are still dropping these collections wholesale into their Video Editor again with seemingly no code evaluation.

#6

Thanks Glen
Theres just a few old ones that i really like the sound of, but i get the
point and will think twice before using them again

#7

Thanks Robin
I temporarily forgot the DSP load window. What was happening was the dsp
counter would turn red, the sound would stop for a moment and an ardour is
not responding - force quit/wait dialog kept coming.
I asked about the libraries because I previously had a problem with another
plugin which you told me was related to libc version. I am not
knowledgeable about it really, I just try to learn as I go along :exploding_head:
I appreciate you and everybody else’s help