In one of my last blogs, I gave an overview of the USB Class 2 Audio functionality provided by the AudioTools library
Many users were struggeling to get the process of receiving data via USB and writing to I2S stable and working properly. In this blog I am providing a deep dive of the releated challenges and the solution approaches:
Here is a simple basic sketch that demonstrates the standard processing logic:
#include "AudioTools.h"
| # | Platform | Mode | Key settings | Test |
|---|---|---|---|---|
| 1 | ESP32 | TX | defaults (enable_multi_sample_rate=false) |
Record 5s with arecord, play back, verify clean sine |
| 2 | ESP32 | RX | defaults | Play test.wav with aplay, verify rxXfer > 0, MeasuringStream output |
| 3 | ESP32 | RXTX | enable_ep_in=true, enable_ep_out=true |
Record AND play simultaneously |
| 4 | RP2040 | TX | defaults | Record with arecord, verify clean sine |
Yesterday I was ask to extend my Arduino AudioTools library to support RTTTL. To be honest, I had no clue what this is, so I had to look it up: RTTTL stands for Ring Tone Text Transfer Language and was developed by Nokia to transfer ringtones to cellphones.
It basically descibes the notes and durations in simple text form. My library supports different sound generators and also provides the frequencies of all notes: so all I needed was to provide a parser for RTTTL and link it up with the existing functionality.
The new class is called RTTTOutput and you just provide the generator and output device in the constructor and then you can play the audio by printing the RTTTS string
| /** | |
| * A Simple exension of the WiFiUDP class which makes sure that the basic Stream | |
| * functioinaltiy which is used as AudioSource and AudioSink | |
| * @ingroup communications | |
| * @author Phil Schatzmann | |
| * @copyright GPLv3 | |
| */ | |
| class UDPStream : public Stream { |
| #!/usr/bin/env python | |
| import argparse | |
| import re | |
| import os | |
| import subprocess | |
| import sys | |
| from termcolor import colored | |
| # update the following default values to what is relevant for your system |