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 - BPM in Mod2PSG2

Reply to topic
Author Message
  • Joined: 01 Feb 2014
  • Posts: 462
Reply with quote
BPM in Mod2PSG2
Post Posted: Mon Oct 21, 2019 4:47 pm
Quick question: How can I calculate BPM in Mod2PSG2? It‘s been a while since I used it last. What do I have to do if I aim for a specific speed? Does the „speed“ value refer to the number of frames that pass between each step in the pattern editor?
  View user's profile Send private message
  • Joined: 04 Nov 2004
  • Posts: 267
  • Location: Deutschland
Reply with quote
Post Posted: Mon Oct 21, 2019 5:18 pm
Hallo,
the BPM is fixed to 150 (60 * 2,5) or 125 (50 * 2,5), because playback is meant to be frame-synchronized. Yes, the speed value is the number of frames between pattern rows. It has three additional bits for "sub-frames".

For example, if you set speed to 1.125 (= 9), every eighth row would be delayed for an additional frame. That would give you something similar to a BPM of 133 or 111. Then you can multiply this speed value with the number of rows you'd like to have at that BPM.
  View user's profile Send private message Visit poster's website
  • Joined: 01 Feb 2014
  • Posts: 462
Reply with quote
Post Posted: Mon Oct 21, 2019 7:27 pm
Thanks for the explanation. It makes sense, but I‘m still not sure I understand it correctly. How many lines does your example use per quarter note? I‘m guessing eight?
  View user's profile Send private message
  • Joined: 04 Nov 2004
  • Posts: 267
  • Location: Deutschland
Reply with quote
Post Posted: Mon Oct 21, 2019 10:15 pm
If I search for it, I only find that a quarter note in module world is supposed to be 4 or 8 rows and equal to a "beat". But it's your own choice how you want to subdivide the notes and their timing.

The standard appears to be for a speed value of 6, with 4 rows per beat. That's 24 ticks per beat. Per minute there are 3600 or 3000 ticks. Divided by the 24 ticks, that's the BPM of 150 or 125.

Lets say BPM is "beats per minute", TPM is "ticks per minute" and TPB is "ticks per beat". The TPM is fixed to 3600 or 3000.

If you want to have a specific BPM, you can:
- Calculate: TPB = TPM / BPM
- Solve: rows per beat * speed value = TPB

You can try with rows per beat (or quarter note) of 4 or 8, but because the speed value has a limited accuracy (1/8), it can be a bit tricky to get a good result.

For the example I can multiply the speed value with 3 or 6:
- TPB = 3600 / 133.333 = 27, or 3000 / 111.111 = 27
- For rows per beat of 4 the multiplicator would be 6:
4 * (1.125 * 6) = 27
- For rows per beat of 8 the multiplicator would be 3:
8 * (1.125 * 3) = 27
  View user's profile Send private message Visit poster's website
  • Joined: 01 Feb 2014
  • Posts: 462
Reply with quote
Post Posted: Tue Oct 22, 2019 6:38 am
Got it. It all makes sense now. Thank you.
  View user's profile Send private message
Reply to topic



Back to the top of this page

Back to SMS Power!