ffmpeg

I love this project thank you!

I did some testing and it's possible to get even cleaner audio by also applying a filter on your audio... for example a high pass and a low pass filter on the raw audio stream...

```
ffmpeg -f s16le -sample_rate 44100 -i audio.raw -af "highpass=f=200, lowpass=f=3000" -f wav file-out.wav
```

Start with the ESP32 ADC/I2S audio-sample path and compare it with the ffmpeg command in the issue. Determine whether highpass and lowpass filtering is intended to run in this project or externally. Done means the scope and implementation location are clarified.

Written by the indexing model from the issue text.