Chat

Author Topic: Game Boy stereo and more...  (Read 2062 times)

Offline B00daW

  • Newbie
  • Posts: 7
  • Delek FTW
Game Boy stereo and more...
« on: September 16, 2016, 01:36:47 pm »
Looking over the sound specifications of Game Boy, it appears that there are more features to consider to make it stand out from the 2a0x/NES/Famicom. :)  (Aside from the fact that the sound registers' method of modification and delivery are entirely different. ;) )

1.) Stereo:  Obviously there is a register to output the each of the 4 channels to a specified stereo out. > http://gbdev.gg8.se/wiki/articles/Sound_Controller#FF25_-_NR51_-_Selection_of_Sound_output_terminal_.28R.2FW.29

As the PC Engine currently has support for in Deflemask, stereo adds additional quality and control to the user's creations for consumption.

2.) Stereo Fine-tune Volume:  Another wonderful thing about Game Boy's stereo mode is that it is capable of fine-tuning the stereo DACs by additional values.  > http://gbdev.gg8.se/wiki/articles/Sound_Controller#FF24_-_NR50_-_Channel_control_.2F_ON-OFF_.2F_Volume_.28R.2FW.29

This would mean that if others, and especially the WAV channel have supplied volume levels that it is possible to attenuate volume values by an additional 3 bits (0-7).

Talking to Savestate, I have shown him the merit of these registers for FTM2GBMC since there was a high demand for enabling stereo sound in Game Boy for our sound competitions.  > http://battleofthebits.org/academy/GroupThread/12151/FTM2GBMC+-+Make+Gameboy+Music+in+FamiTracker%21/  He has enabled them in his software.

3.) Multichip Support:  With the same register that the stereo DAC values are written the Game Boy can enable an external chip from the cart to be routed to one or both of the stereo DACs as well.  This would be good for future-proofing of Deflemask for when additional flash carts come out with additional sound chip logic or FPGAs/CPLDs etc on them.  Currently as you emulate multiple hardware platforms, you could allow for multiple chips with the Game Boy being the host system and route the additional chip through its stereo outputs. :) > http://old.pinouts.ru/Game/CartridgeGameBoy_pinout.shtml

Someone would create an MBC (memory banking chip) with internal sound registers just like VRC6 on the cart and wire the audio out from the MBC/Audio chip to pin 31 of the cart. :)

Offline Pegmode

  • Member
  • Posts: 135
  • Allergic to FM
Game Boy stereo and more...
« Reply #1 on: September 17, 2016, 06:56:23 pm »
1.) Stereo:
Hmm Hard panning is already a thing in DefleMask for the Game Boy but based on the GB Dev Wiki page you're suggesting the capability for soft panning? That'd be pretty nice.

2.) Stereo Fine-tune Volume:
More Volume levels for the wave channel would be extremely useful. The current solution to get more than 4 volume levels is to have multiple copies of wavetables with different amplitudes, which takes away 2-4 out of the 32 wavetables that DefleMask supports. Having more Volume levels for the wavetable would allow space for more wavetable effects, which is a problem I've been running into. (or we could get support for more than 32 wavetables ;))

3.) Multichip Support:
I've recently had some discussions about this and I think multichip is a very cool idea but I feel that it falls outside of the scope of Deflemask. Similar requests usually get shot down but ignoring that; do you know of anyone who is designing a multichip cart and if so, if they get produced will they be available to more than a very small number of people? If either of these are untrue then I don't think Deflemask would support it.


There's my 2 cents.