From 438525e8ec7cba9ab4094b1234affa3fc4213bb8 Mon Sep 17 00:00:00 2001
From: Frank <91616163+softhack007@users.noreply.github.com>
Date: Sat, 23 Sep 2023 16:48:45 +0200
Subject: [PATCH] AR: use bandpass filter for analog input

Many bad quality analog mics are not centered properly at 1.6V, but stuck at 0V or stuck at 3.3V in silence. The bandpass filter removes DC offsets and improve signal quality.
---
 usermods/audioreactive/audio_reactive.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/usermods/audioreactive/audio_reactive.h b/usermods/audioreactive/audio_reactive.h
index f65e61ec..692714ec 100644
--- a/usermods/audioreactive/audio_reactive.h
+++ b/usermods/audioreactive/audio_reactive.h
@@ -1175,6 +1175,7 @@ class AudioReactive : public Usermod {
           DEBUGSR_PRINTLN(F("AR: Analog Microphone (left channel only)."));
           audioSource = new I2SAdcSource(SAMPLE_RATE, BLOCK_SIZE);
           delay(100);
+          useBandPassFilter = true;  // PDM bandpass filter seems to help for bad quality analog
           if (audioSource) audioSource->initialize(audioPin);
           break;
         #endif