Use relative paths (e.g., song1.mp3 ) if the M3U file is in the same folder as your music. Use absolute paths (e.g., C:\Users\... ) if it is stored elsewhere.
To be recognized by most players, the file should follow the format. Each entry consists of two lines: 140.m3u
For IPTV or web radio, the duration in the #EXTINF line is usually set to -1 because the length is unknown. Use relative paths (e