[vardump]

I'd guess about 1 MB order of magnitude. That would be a butt-load even for samples.

1 MB would be enough for 45 seconds audio at 8 bit PCM @22 kHz. If they're half competent, they could use ADPCM or much better (and cheaper to decode too!) vector quantization.

With VQ, you could go even down to ~1 bits (~6 minutes of audio per megabyte) per sample while maintaining good audio quality. Decoding is very simple, so 6502 would have plenty of oomph to do that.

[Zardoz84]

Using the trivial BTc encoding, you could archive a good compression ratio and generate audio without using a DAC . https://www.romanblack.com/picsound.htm

[dTal]

MB == Metric Buttload.

Makes sense.

[childintime]

> [Vector quantization] Decoding is very simple.

Do you have an encoder/decoder to point us to?

[vardump]

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-mus...

There's some decoder code there as well.

[enthdegree]

Arithmetic coded uniform quantization works very well and is straightforward to implement!