VQ is a very well known technique. For something quick, you might be interested to check this blog post about (unmodified) C64 playing high quality audio at 44.

VQ is a very well known technique. For something quick, you might be interested to check this blog post about (unmodified) C64 playing high quality audio at 44.1/48 kHz, VQ compressed down to 96-128 kbit/s: https://brokenbytes.blogspot.com/2018/03/a-48khz-digital-music-player-for.html https://brokenbytes.blogspot.com/2018/03/a-48khz-digital-mus... There's some decoder code there as well.