You can find specific versions of these codecs on reputable third-party repositories.
: Specifically listed on Free-Codecs.com as "MX Player Custom Codec 1.49.0 r2" or "aio-1.49.0-build_2.zip". Mx Player 1.49.0 Armv8 Neon Codec Zip Download
Assuming you have downloaded mx_player_1.49.0_armv8_neon_codec.zip : You can find specific versions of these codecs