MP3 audio itself is a digital audio codec, which can contain whatever it is that was encoded into the file. a guitar and piano instrument in a track will always use the correct instruments playing it back. specifically, MIDI files uses General MIDI, which has a list of instrument information that is identical across several devices, so e.g. MIDI isn't a type of sound or genre per se, simply a set of generalized instructions introduced so that different pieces of sound hardware and software can easily communicate. I dont knowĪs others have mentioned here already, MIDIs of music from other sources in Doom wads were recreated by others in MIDI sequencers. Or they could ask someone to make them the audio. If what you are saying is true, then how do map authors get their midi audio for their maps? do they just download it from the internet from some source, or do they go through the inconvenience of making a new midi audio from scratch just like you and obsidian stated? Most MIDI songs that came from some other format are far more likely to have been rewritten from scratch by listening to the song over and over again, as Obsidian stated. Trying to parse a waveform into various instruments and notes, automatically, is an incredibly complex task: it would be like trying to use a speech-to-text program to record the multitude of conversations occurring simultaneously in a sports stadium. The MIDI audio format is more like a notation of how audio is meant to be played using quantities such as pitch, duration, velocity, et cetera: for playback, the program processes the instructions in real-time to produce a song. The MP3 audio format is a compressed waveform, effectively a digitized reproduction of the sound vibrations that we've come to understand as audio: when a program is asked to play the MP3, it simply handles the waveform as-is. While MP3 and MIDI may both qualify as "audio formats", they are fundamentally different in how they store the audio data and how that data is processed.