Forums

Sega Master System / Mark III / Game Gear
SG-1000 / SC-3000 / SF-7000 / OMV
Home - Forums - Games - Scans - Maps - Cheats - Credits
Music - Videos - Development - Hacks - Translations - Homebrew

View topic - Arcade Voices patches

Reply to topic Goto page Previous  1, 2
Author Message
  • Joined: 05 Sep 2013
  • Posts: 3873
  • Location: Stockholm, Sweden
Reply with quote
Post Posted: Sat Jan 06, 2024 1:24 pm
I know what's PCM and PWM. What I meant is that I suspect this code really does a 1-bit PCM, no PWM or PDM of any sort. And it's not exactly the same thing.

I suspect here the source data is basically just getting the sign bit from the original wave file. 0 when the wave is positive, 1 when negative - or the other way around it doesn't really matter.

Honestly I'm not sure how can I prove this. Probably I could amplify the arcade .wav file until each single sample is either +MAX or -MAX and see if is sounds like what we get from the game...

I'll try.
  View user's profile Send private message Visit poster's website
  • Site Admin
  • Joined: 19 Oct 1999
  • Posts: 14772
  • Location: London
Reply with quote
Post Posted: Sat Jan 06, 2024 1:37 pm
That’s exactly what I did to approximate the 1-bit data when experimenting with it myself; it’s less correct than a “dithered” or “error diffusion” conversion to 1 bit, but for a few examples where I felt I had matching data, it sounded very similar to me.

For Alex Kidd: The Lost Stars, I couldn’t find a software tool that would give me the PCM data, so I approximated it by recording the output of MAME and then guessed at the approximate sample rate. I guess Sega might have used some PCM data as the input but I’m not sure how they would have done sample rate conversion.
  View user's profile Send private message Visit poster's website
Reply to topic Goto page Previous  1, 2



Back to the top of this page

Back to SMS Power!