“I have been working on some games for the ESP32 and needed some decent quality audio with a minimum number of additional components. I was bouncing between using the DAC and using the I2S bus. The DAC requires less external parts, so I went that way. I ended up creating a very simple library for use in he Arduino IDE. (Note: This only works with ESP32)
DACs
The ESP32 has (2) internal 8 bit DACs. DACs are Digital to Analog Converters. You give them an 8 bit value and they output an analog voltage. The voltage range of the 0-255 8-bit value is roughly Gnd to 3.3V on the ESP32. If you digitize an audio file, you can then play it back through the DAC. The DAC can’t directly drive a basic speaker, but you can connect it to an amplifier or amplified external speakers. The 8-bit quality is not great, but more than good enough for simple games.
The sound data comes from wave (.wav) files. This uses the 8 bit, unsigned, uncompressed format. Wave files can be saved with any sampling rate you want. To get a decent sound you need to sample the analog files at thousands of times per second. I have found that 4000 Hz is about the minimum for anything musical or spoken. 8000 sounds pretty good for most stuff. For reference, CDs are sampled a 44100 Hz (also 16-bit not 8-bit). This means there is a lot of data even for short duration audio. The typical ESP32 board has 2 to 4MB. At an 8000Hz sampling rate that gives you 125 seconds per MB. That is plenty for what I am working on, so I decided to store the data on the ESP32. If that is not good enough, you could use an SD card.”