Audio input in mic.h doesn't work

[aroehl78]

For audio input to work for ESP32, please add the dma buffer to the private section and use i2s_channel_read.

i2s_read is legacy.

Here is the updated code for mic.h:

  private:
    int micGain = 32; // 0 - 64
    int samples_read = 0;
	static const int dmaBufferLength = 64;  //AR - added
    static const int16_t bufferLen = dmaBufferLength * 4;
    uint16_t inputBuf[bufferLen];
    int mBufIndex = 0;

    #if IS_ESP8266()
      System.println("Mic class not yet implemented for ESP8266");
      void readMic() {
        // TBC
      }
    #elif IS_ESP32()
      inline
      void readMic() {
        size_t bytesIn = 0;
        esp_err_t result = i2s_channel_read(rx_handle, inputBuf, bufferLen, &bytesIn, portMAX_DELAY);  // AR - changed
        if (result == ESP_OK && bytesIn > 0) {
          samples_read = bytesIn / 2; // stereo 16 bit samples
        }
      }
    #endif

I tested it and it works wonderfully.