wtf is cyd-music-player?

CYD Music Player is firmware for a small, cheap touchscreen hardware board known as the CYD, short for Cheap Yellow Display, built around the ESP32 chip. It turns that board into a standalone, offline music player that reads MP3 and WAV files from a memory card and plays them through a separate audio chip, without needing an internet connection or a phone app. The player has a retro, neon-style visual theme with a real-time spectrum visualizer that reacts to the music as it plays, along with sliders you can drag with your finger to change the song position, volume, and screen brightness. It organizes your music library automatically into songs, artists, albums, playlists, and favorites based on the file and folder names on the memory card. There is also a setting to flip the screen colors, useful because different versions of the CYD hardware display colors differently. Setting it up does not require writing or compiling any code. The firmware is distributed as a ready-made file that can be installed directly from a web browser using a flashing tool, or downloaded and installed offline. After installing it, the touchscreen needs to be calibrated once by tapping four crosshairs on the screen. To add music, you format a memory card, create a folder named music at the top level, and copy MP3 or WAV files into it, optionally organized into artist and album subfolders for better sorting. On the hardware side, getting audio out of the device requires wiring up a separate small audio chip called a PCM5102A digital to analog converter to specific pins on the CYD board, since the board itself does not include a high quality audio output.