Greetings.

I was just wondering if anybody knew an easy way to convert a song to that NES or Atari "chiptune sound" by applying an effect in audacity (or with another free program).

It'd be an interesting effect to have on the tool-belt, that's for sure.

Just as a reference for what I mean by "chiptune style," I'd like to have an effect that can convert existing modern music to something that sounds like this: http://www.ymck.net/sound/magical8bitPlugSample.mp3

Have no idea if such an effect exists, but I know of people that make new tunes using virtual instruments ( VST and the likes ), that sound that way.
I would think that such an effect would actually need to generate sound, based on the input, rather than being a linear effect over the input.

Edit: Never mind, what I wrote here only works for synthesized music, but no modern digital audio. Applying these "chiptune sound" effects might have otherwise been possible.

Here's an example of what I'm talking about. Yes it's a YTMND thing, but it does show that it's possible, and it's exactly what I'm looking for too.

http://epic8bitconversion.ytmnd.com/

It's actually pretty cool.

Some obvious fake (getting fewer audible instruments by chopping away 8 sample bits? yeah, right...), but the method *really* used there seems promising. Obviously this dude has got hold of a MIDI-file of the song. If you can get one and have synthesizer software, you can put e.g. a SID-Synth (commodore soundchip) on the MIDI-track, and there goes your 8bit-Sound.

"Converting" seems impossible to me, because each and every single instrument had to be treated in a way that cannot be done on a sum mix. Best bet is resynthesizing.

I am a chipmusic composer and agree I to this There is no way possible using a filter to make any music sound like chipmusic.

I think that's rather symbolic, like, making the tune sound like computer-music from the 8-bit era.

There's a free software to convert WAV files into C64 digitized sound: the sound is similar to NES and Atari digitized audio and may be good for the purpose. The created file can be reproduced using the emulator and recorded to PC..

EDIT:
I found two useful links to you:
http://www.student.oulu.fi/~vtatila/nes_sound.html
WAV2Digi (the software I mentioned before)

It's basically the same problem as WAV to MIDI, though, and everybody here will know what I mean.

It seems to me that wav2digi just reduces the file to a low samplerate and 4 bit, which can be played back on the c64 as galway noise.