Totday i crossed on something extremely interesting! Not sure if this is a scam or really possible, but certainly worth checking. I thought normal cassettes don’t have the density of storing such an amount of data. So check this out:
It might be that it only contains the metadata of the song it needs to play. But in the end he gives the impression that all data (song and metadata) comes from the tape. Only very high baudrate recordings combined with high compression, 8bit?, etc… might do the trick…right???
Although here it is stated that a 60 minuten tape could only store around 24kbyte per side, way too little to be useful for storing any MP3 inclusief its metadata: