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IDProjectCategoryView StatusLast Update
0007894ardourbugspublic2020-04-29 23:47
Reporterlack Assigned To 
Status newResolutionopen 
PlatformLinuxOSUbuntuOS Version19.10
Product Version5.12 
Summary0007894: Latency Measurement Tool should allow me to proceed even with inverted wiring
DescriptionI have Soundcraft Notepad-12FX external mixer with USB IO. When I attempted to automatically measure the latency, I connected the USB to the AUX bus and hardwired it to the input 0000001, selected the right ALSA audio equivalents in Ardour, and started the measurement. As I adjusted the mixer levels I immediately got reasonable-looking results, but with it ended with: "Systemic latency: 593 samples (13.447ms) (inverted - bad wiring)"

At this point the latency was measured, but I couldn't proceed - The "Use results" button was grayed-out.

After an adventure using two stereo cables and some alligator clips to fix the inversion, the final latency measurement was identical to the one when I hard-wired with the inversion.

I think I should have been allowed to proceed to use the originally-detected values, even though the signal was inverted. I think the warning about the inversion is useful, but shouldn't be blocking since the main point of the tool (measuring latency) doesn't seem to depend on the inversion.

Maybe if I click "Use results" with a detected signal inversion, there should be a small popup dialog warning me about why this signal inversion is important (I'm actually not sure why it matters - Everything this hardware does sounds correct to my ears), but let me proceed anyway after confirming I have read the warning.
Steps To ReproduceMeasure latency with an inverted signal path.
TagsNo tags attached.



2020-03-15 17:39

administrator   ~0021025

Is the reported number realistic? It's usually a result of an invalid measurement, crosstalk, and not simply a polarity inversion.


2020-04-25 16:04

reporter   ~0023911

I have the exact same issue with a Soundcraft Signature 12MTK Mixer. Using the "hacked" cable trick worked. As user lack I suggest not greying out the "use results" button for this specific issue.


2020-04-29 23:47

reporter   ~0024006

I have the same problem with my device (Berhinger FCA1616). Inputs's polarity is inverted. But why are they ? This is not documented in the manual of the device.

Issue History

Date Modified Username Field Change
2020-02-02 20:34 lack New Issue
2020-03-15 17:39 x42 Note Added: 0021025
2020-04-25 16:04 perplex Note Added: 0023911
2020-04-29 23:47 elgoun Note Added: 0024006