Run test-flow / FFT with locally stored audio-file?

QA401
1

Hi,

Planning to run the following setup:
QA401 -> transducer amp -> ref speaker -> “DUT” which is a microphone
-> XLR+phantom -> mic-pre -> QA401

The DUT also has USB-audio class output via an internal ADC that needs to be tested (not part of the XLR signal chain)

Question:

  • Can we somehow pipe the captured chirp to the same analysis process?
    i.e. we will capture the usb-audio to a local .wav file then hopefully be able to pipe it to the QA software!

/d

2

Hi @audio-dav, Your first setup should work fine where you are using the QA401 DAC to drive a speaker and then capture that back into the QA401. The first link below is similar problem, but comparing a mic to a reference mic. But in your case, you can readily capture the chirp and compare to a mask.

For your question about loading a captured chirp into the QA401 software…that’s not currently possible but it’s a very reasonable feature request for the future (but not near term, unfortunately).

  1. Mic Comparisons under Tractor
3

Thanks for reply Matt,

Any alternatives to solve the USB-audio capture?
I’d rather not do [mic -> adc -> usb audio device] -> usb cable to computer -> USB-soundcard/DAC -> output it back to the QA401.

4

Not at this point. Just to make sure I understand: Is what you are looking for the ability to load a WAV file and then have analysis performed on that WAV file both in the app and also via Tractor?

5

in our case, we’ll run dotnet core on linux, so primarily needed here.
but of course it’s nice being able to test it on windows in the QAxx app.

I can see two solutions

  1. load raw wav
  • where the file is something we capture via a raw usb-cdc/libusb ourselves
  • or via standard usb-audio to disk, or even better, pipe the audio directly to the QAxx app via “stdin”
  1. offer class-compliant usb-audio input as an option.
  • in this case it’s important we can use both QA401 + the additional USB-audio in or out at the same time.
6

Hi @audio-dav, currently there’s the ability to File->Import a time series. This will let you pull in a time-series you’ve previously exported. If you had an external program that was writing the WAV, you could also have it write out a time series and then File->Import that.

But I think what we need to do here is:

  1. Add the ability to import a WAV from the file menu
  2. Add the ability to import a WAV or time series programmatically
  3. Add a test in Tractor that will force a WAV file to be loaded in QAAnalyzer.exe

I don’t have an idea when the above will be done, but they are on the list.

# TIME SERIES
# 5/20/2020  9:57 AM
# Units: Volts
# Sample Rate: 48000
# Pre Buffer Size: 2048
# Data Points: 16384
# Atten Enabled: False
# Time, Output Left Data, output Right Data, Input Left Data, Input Right Data
0.042666667, -0.113730041, -0.113730041,-0.102785794, 0.000000925
0.042687500, -0.127531189, -0.127531189,-0.117832134, 0.000018351
0.042708333, -0.139162639, -0.139162639,-0.130867125, 0.000026370
0.042729167, -0.148425763, -0.148425763,-0.141663462, -0.000019739
7

good to know it’s planned! thx!

how about allowing an additional usb-audio input?
(you could still require the QA40x to be connected)

8

Hi @audio-dav, there’s now the ability to import a wav file. See the 1.909 release notes.

9

fantastic! thanks matt!
any chance to see streaming input (pipe or socket) or usb-audio-class as a next step? :slight_smile:

10

No, that’s not in the plans currently and probably won’t be added unless a really good use-case presents. The WAV import makes sense so that you can pull a wav from a remote server (an http address should work for the file name). This should permit testing mic sensitivity/frequency response on a internet connected device.