Audio Input Level too Low

The issues found when using the Input/Output Manager panel
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Joined: Tue Aug 30, 2016 1:16 pm
Real Name: Max xx

Audio Input Level too Low

Post by maxbax0808 » Tue Aug 30, 2016 1:27 pm

First off: I really like this Software, it´s Simple and get´s the Job done very well!
But there is one major Problem I have. And that is that the Input Level of my "What you hear" Input from my Soundblaster Card is too quiet (only 0% to 1%) with maximum Windows Volume.
I tried everything I know of but it just won´t work.

QLC+ Version: 4.10.4
Operating System: Windows 10 64bit
Soundcard: Creative Soundblaster Z

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Joined: Wed Sep 28, 2016 5:43 pm
Real Name: toobs

Re: Audio Input Level too Low

Post by toob » Thu Sep 29, 2016 11:56 am

Same here. Windows mixer all up full on every channel and still on 3% max seen in QLC+ Please add a booster gain control within the program?

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Joined: Tue Jun 14, 2016 5:07 am
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Re: Audio Input Level too Low

Post by starwolf73 » Fri Dec 30, 2016 4:59 pm

Great software but same here, I would like to use the audio trigger but for some reason the audio is extreme low around 3-5%. If I put everything to 100% I get around 20% but that included lots of distortion (power speaker need to be low down for this test case).

As request a GAIN option will be very welcome.

I use a Presonus Studiolive 16.4.2 with the latest drivers. I even try on another laptop with a different build-in sound card and same thing. So I doubt it is related to the Presonus drivers.

Anyone had success using this widget? And on which OS?

OS: Windows 7 64bits
QLC+: 4.10.5b


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Posts: 231
Joined: Mon Sep 12, 2016 7:15 pm
Location: Belgium
Real Name: Fredje Gallon

Re: Audio Input Level too Low

Post by GGGss » Fri Jan 06, 2017 4:09 pm

I think I might be on something...
in ... apture.cpp
on line 230 you are averaging the audio levels...
If we want to have a clue about the mood of the music - averaging is a way

BUT (!) we are triggering things based on peak levels. Ergo no averaging of the signal.
I think this explains why audio levels in the spectra-meters are so low - they are the average of levels seen.

Please change the line 198 from

Code: Select all

            pwrSum += m_audioBuffer[i];

Code: Select all

            if(m_audioBuffer[i] > pwrMax) pwrMax=m_audioBuffer[i];
and line 230 from

Code: Select all

 m_signalPower = pwrSum / m_captureSize;

Code: Select all

  m_signalPower = pwrMax; 
of course pwrMax should be declared so change line 184 to

Code: Select all

quint64 pwrMax = 0;
Actually we should do a RMS measurement but I don't have a clue how to.

I hope this will settle this issue...

Kind regards,

PS: reminder for myself: ... formation/
All electric machines work on smoke... when the smoke escapes... they don't work anymore

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Posts: 2000
Joined: Sun Apr 12, 2015 9:09 am
Location: Italy
Real Name: Massimo Callegari

Re: Audio Input Level too Low

Post by mcallegari » Fri Jan 06, 2017 4:30 pm

You got it wrong.
I don't change lines of code on demand. You change the lines and you test, then report if you obtained any improvement.
The average of the SUM of the FFT results provides the signal magnitude, so the global audio volume. I din't invent it. It's a well known formula you can find online.

This audio volume thing has been reported a million of times and still I don't see it.
Most likely it depends on the audio card, cause my stupid microphone on Linux (gain @70%) shows this
Screenshot_20170106_172707.png (3.02 KiB) Viewed 1592 times

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Posts: 231
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Location: Belgium
Real Name: Fredje Gallon

Re: Audio Input Level too Low

Post by GGGss » Fri Jan 06, 2017 5:42 pm

I will try to compile my own version as suggested... This will be the first time I do something like that - so bare me a minute or two (read: many hours)
Or if someone else is more experienced compiling please do help me and report back.

Sorry to say Mr. Callegari - whatever I try I'm stuck with these results (see image in annex)
From the same source (line-in != microphone) I recorded a small sample.
If I use audacity to analyse the results (see image2), you'd expect to get peaks in the -3dB range (almost clipping so to say)
QLC+ is not reflecting that. Audacity & qlc+ are using the same audio source at the time of recording...
audio-levels.png (11.4 KiB) Viewed 1585 times
In answer to your point where you reveal that the code is general knowledge - I have knowledge about Hanning, Blackman et al. The FFT needs to be averaged to reflect the amplitude of the sample in measuring. Yes you are right (see my PS: above - this was my source)
And again: since we are triggering on peaks in levels - we cannot use average values in amplitude - we need max. values.

I'll try it out in the next days and report back.

I don't want to be rude or anything (as a newby on this forum). I simply try to add my experience and knowledge to your project. Rest assure that I'm admiring your work with great enthousiasm ;-) As a former Chamsys operator finding and using QLC+ has been the best thing since ... well 20+ years being a light-engineer.

Thanks for your feedback.
Enjoy your weekend,
All electric machines work on smoke... when the smoke escapes... they don't work anymore

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Joined: Tue Sep 20, 2016 8:30 pm
Real Name: Marcin Sikorski

Re: Audio Input Level too Low

Post by msikorsk » Wed Jan 18, 2017 2:44 pm

same issue here. OSX with audio Loopback. Very low signal level.
Wouldn't be a simple fix to add signal gain control? As you said, different sound cards, different signals. Shouldn't be a big deal to amplify it before midget master control (for example at audio input setup)

Have a good day,

Marcin Sikorski

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Real Name: Caleb Grayson

Re: Audio Input Level too Low

Post by CalebGrayson » Mon Jul 10, 2017 11:42 pm

the audio for me is also very low — always has been from versions maybe 3 to current 4.11.0.
it own't take internal sound, either, as i set input to be my Kontrol S8 audio card out and nothing happens. i have to rout our the booth out of the Kontrol S8 mixer into the line in on my MacBookPro and only with the booth out maxed into a maxed MBP line in preamp do i get really good level readings.

also, i can't figure out a way to set a MIDI controller to change the masterfader on the Audio widget.

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Re: Audio Input Level too Low

Post by wersonnst » Mon Jul 24, 2017 4:07 am

Had the same issue with low level.

I tried the code from GGGss which cause in an variable mismatch error
so I done a few simple changes.

The best results I have with

Code: Select all

196           pwrSum += -1 * m_audioBuffer[i] * 15;
197     else
198           pwrSum += m_audioBuffer[i] * 15;
in ... apture.cpp

With that the input level controls the Audio Trigger from very gentle to mostly all flicker. Depends on the show were to use what.
The implementation of an Extra Gain or boost level would be nice.

@ mcallegari
I don,t find the word's how to thank you for this piece of nice software and all your outstanding work , so we can work with QLC+ and enjoy the world's people with the best light show's and make them smile. :)
Thank YOU.

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