Why do the earbuds have the sound files in mp3 format rather than some raw uncompressed format? Doesn't this mean that the earbuds must now have a mp3 decoder?
Is there a resource-usage argument for preferring mp3?
I dunno how big the sound files are, but mp3 is going to use a lot less storage than uncompressed PCM. Using a smaller flash chip saves money on the BOM.
Bluetooth headphones already need to manage several formats to decode, and the chipset that does that may also decode mp3, and mp3 is easy to work with to prepare the files.
Bluetooth audio uses SBC codec by default (unless your device something modern like aac or apt-x) right? I imagine that there's probably some all-in-one decoding chip that includes various codecs.
MP3 decoding is just math. If you have enough CPU to decode a compressed audio stream, it doesn't cost anything to also have it decode MP3.
Sure, you could store those clips in a more appropriate codec, but what do you gain? It's dead simple to encode an MP3, every audio editor from the last couple decades can do it. How common is SBC support?
If MP3 decoding is free, and MP3 encoding is free, why bother spending any effort at all on anything else? Sometimes good enough is good enough and cheap and easy wins over correct every time.
Bluetooth headphones already need to manage several formats to decode, and the chipset that does that may also decode mp3, and mp3 is easy to work with to prepare the files.