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DTMF detector fails for 48KHz audio #10

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bert2 opened this issue Jan 13, 2018 · 1 comment
Closed

DTMF detector fails for 48KHz audio #10

bert2 opened this issue Jan 13, 2018 · 1 comment
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@bert2
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bert2 commented Jan 13, 2018 •
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DTMF detector is not working correctly with audio files that have a sample a rate of 48 KHz.

Expected Behavior

  • Detector should work with 48 KHz audio.

Current Behavior

  • When 48 KHz audio is fed to the detector it will miss actual DTMF tones and find false positives.

Possible Cause

  • NAudio's WdlResamplingSampleProvider seems to be unable to suppress aliasing effects when downsampling from 48 KHz to 8 KHz

Steps to Reproduce

  1. Run integration test AudioFileTests.ShouldDownsample48KHzCorrectly()

Possible Solution

  • Try another of NAudio's resamplers
  • Low-pass filter the audio data with cut-off at 8 KHz before downsampling
@bert2
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bert2 commented Feb 20, 2020

Unable to reproduce issue in 1.0.0.

@bert2 bert2 closed this as completed Feb 20, 2020
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