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detrites

Spoiler: it's hardware.

And the opening line sounds like a challenge:

> Given that the much more powerful 16-bit Amiga 500 is unable to play MP3’s,

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> Spoiler: it's hardware.

Yeah, this isn't MP3 on a C64. It's a C64 controlling an external MP3 player.

I think mp3 playback requires a reasonably fast multiply instruction, and the original 68000's 70 cycles per mul @ 7MHz, or 100000 muls per second doesn't qualify.

Some info here, claims a 68020 at 50Mhz (@10 MIPS) can just pull it off:

https://eab.abime.net/showthread.php?t=78994

Might mean an A500 (@1.4 MIPS) could do it if you were happy waiting 10-15 minutes for the audio of a 3 min mp3 to begin.

I don’t think a stock A500 could do that, having 1MB RAM, max.

Where would you store 3 minutes of uncompressed audio? At CD quality, that’s about 30MB.

Given the likely output quality you'd probably choose something like 32Kbps encoding for the mp3, which should fit 3 mins in 720KB. (Not sure how it'd affect CPU requirements?)

It's not that bad-sounding:

http://www.knowzy.com/Computers/Audio/Digital_Audio_Files/au...

But that machine cannot decompress that at real time. The comment I replied to said that would be solvable by adding a few minutes of buffering, but that requires a buffer to hold uncompressed audio.

Wow, how far we have come.

MOD is superior to MP3 anyway :)

I think a stock Atari Falcon is capable of playing mp3 thanks to the DSP (56001), but it still isn't a walk in the park even with that (in combination with a 68030 as the main CPU).

It took many years until MP3 decoding on a stock Falcon was possible. While the machine was generally available, there was no MP3 implementation, and the belief was that it was impossible.

The C64 didn't have any kind of PCM output, so it basically has to be. Early SID chips had a voltage glitch you could use for 1-bit ("speaker-style") output, and a few games used it for some effects. But you couldn't get music out of it in any real sense.

Four-bit (the amplitude of the "click" caused by the SID's voltage leak is proportional to the volume, which is four-bit). There are many demos that used it for digitized music, and Rob Hubbard's Skate or Die! intro tune used it as a practical fourth voice. See also the original Covox Voice Master.

There are also other techniques (found after the computer's heyday), up to 8 bits 44.1 KHz:

https://www.livet.se/mahoney/c64-files/Musik_RunStop_Technic...

PS. it might not really be 8 bits, but only 93 or 107 different values (6..7 bits). More details: https://csdb.dk/forums/?roomid=11&topicid=103092&showallpost...

> in any real sense

I would be sure that if Tim Follin decided to just use that, he would have "made full sense" (cpr. "Agent X" and "Chronos", ZX Spectrum).

As fully signed up C64/SID fanboy, Chronos on the Speccy is probably my favourite piece of music in any game.. Absolute 1-bit sheer heaven..

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