MiSTer FPGA Forum

I haven't used an actual Gameboy Advance for many, many years (if ever?) so I'm not sure how it's supposed to sound, but the GBA sound (with the latest MiSTer core) but it doesn't sound very high quality compared to NES/SNES/Genesis, etc.

Can anybody tell me how accurate the sound is and if there are any settings to improve it?

(Please understand that I'm not criticizing the core at all! I am so incredibly thankful for the hard work of the developers and I'm wondering how close the sound might be, or settings to improve it?)

I don't have an ear for sound accuracy at all, but it sounds about right to me.

The GBA sound chip was not very good, especially compared to the SNES, or even Genesis.

The GBA wasn't known for it's amazing sound to begin with.

GBA sound consists of (minimal improved) Gameboy Sound Channels and 8 Bit Sound DMA.
The later one is the thing you usually hear for music and some sound effects, the GBA Channels are mostly used for other sound effects.


In terms of accuracy: the 8bit sound dma is proven to be cycle accurate, thanks to a testrom provided by Gericom (GBArunner2 developer)
So it plays exactly the same data at exactly the same time as the real GBA.
As it's 8 Bit source only, there is not much to be improved.

GB Channels alone have been tested and compared to real GBA via sound capture. (thanks to jorge and others!)

In terms of mixing:
What is known, is that when a game uses full volume for both soundDMA and GB Channels, the SoundDMA is a bit too loud compared to the GB channels.
It's not clear why this is the case, because the mixing is easy and inside the GB channels it works.
Maybe it's only related to the GBA using a very weak DAC.
However, this should not influence the overall sound quality.


So if you have anything that sounds off, please post it here and others may check.
I fear I'm very bad at hearing those differences.

when a game uses full volume for both soundDMA and GB Channels, the SoundDMA is a bit too loud compared to the GB channels.

Well, the two DMA channels contribute two thirds of the total output level. Or do you mean they are too loud even after taking that into account?

Given how GBA core replicates the horrid sound of world 7 map in Super Mario Advance 4, I would say it's 100% accurate!

https://github.com/MiSTer-devel/GBA_MiSTer/issues/60

yeah,the gba sound chip is azz.

mic_ wrote: ↑Fri Jul 10, 2020 8:43 am

when a game uses full volume for both soundDMA and GB Channels, the SoundDMA is a bit too loud compared to the GB channels.

Well, the two DMA channels contribute two thirds of the total output level. Or do you mean they are too loud even after taking that into account?

Yes, Jorge did some recordings, showing ~1db too much for SoundDMA compared to all GB Channels in the recordings of GBA core on Mister vs both real GBA and DS.

As it's really not much, probably not recognizable for most, i have not added some quirk for it.
I still hope someone will find where this comes from.

All adjustments in the registers are multiple of 2 or at least 25/75%, so having something like ~10% more is not possible the way the registers are designed.

Thanks again so much for all of the information.

Also, a bit off topic but is it normal for the Normmatt BIOS to flash/blink every few seconds? It doesn't happen when I use an official GBA BIOS though.

https://youtu.be/bCmr1H8fwh0

Also, is it possible to stretch the GBA image to fill the CRT? I think I can enable the vga_scaler but then it will scale to the 1080p setting of the HDMI output?

Normmatts BIOS has a few problems.
That being said, it's great that he wrote it and it works well with 95% of the games.

I am really happy that it exists and can be provided together with the core as an instant solution.

Oh, absolutely! I'm extremely thankful for his BIOS and all of the hard work. I just wanted to make sure this was a known-issue and not something weird with my setup/configuration?

If you have flickering in every game, that's not related to Normmatts BIOS.
If you have it only in some games, it may is.

That's all i can say about it.

Hmmm, I'm using the GBA BIOS so it's fine now, but I think the Normatt BIOS only flickered on the BIOS screen (before I selected a ROM).

sofakng wrote: ↑Sun Jul 12, 2020 2:43 am Hmmm, I'm using the GBA BIOS so it's fine now, but I think the Normatt BIOS only flickered on the BIOS screen (before I selected a ROM).

It flashes white every couple of seconds on my setup, I think it's perfectly Normattl...

Phaedrus wrote: ↑Fri Jul 10, 2020 5:02 am The GBA wasn't known for it's amazing sound to begin with.

There's not a lot of audio hardware: https://www.gamedev.net/tutorials/progr ... t-1-r1823/ - and IIRC, it could be tricky to get glitch-free playback even on real hardware

It usually involved software mixing, with very low bitrate 8-bit samples (due to limited cart space, and most people listening through the little mono internal speaker anyway)

The sound is just as good as the original hardware, but it doesn't have the hum/hiss issues that the real hardware does. I have had AGBs with the De-hum/de-hiss kit that Handheld legend sells, and it doesn't sound as clean even with that as the MiSTer does, especially if you add an amp, even clean amp(I haven't tried the all in one de-hum/de-hiss kit, just the one that's the caps you solder yourself individually). With the Final Fantasy Advanced sound patches the games do sound better, not as good as SNES, but they just won't due to how the GBA handles all it's sound in software over the CPU(other than the z80 sounds, which only a few games use)

I have both the GBA consolizer as well as a MiSTer and I compared them both to a original GBA as well as a GBA SP.
The GBA consolizer and the MiSTer sounds the same.

With a unmodded GBA (both original and SP), the sound is tinny and there hisses and hums from the cheap speaker and bad audio amp the GBA uses.
Which if you use quality headphones or PC speakers the sound improves over the stock speaker.

So with all that said the MiSTer sounds to me about as close as you can get without that crap GBA speaker.

Keep in mind as what others said above the GBA lacks any sound hardware and relies on the CPU to render sound in software.
So it's no where as good as the SNES.

sofakng wrote: ↑Fri Jul 10, 2020 5:54 pm Thanks again so much for all of the information.

Also, a bit off topic but is it normal for the Normmatt BIOS to flash/blink every few seconds? It doesn't happen when I use an official GBA BIOS though.

https://youtu.be/bCmr1H8fwh0

Also, is it possible to stretch the GBA image to fill the CRT? I think I can enable the vga_scaler but then it will scale to the 1080p setting of the HDMI output?

I spent reading and saw that to stretch the image, is it possible? I guess it's the original scale and they don't want to change it.

You just need to supply a compatible 240p video mode if you want to use the scaler with an SD TV.

Regarding sound accuracy, I do notice a difference in the 'gameboy sound channels' when testing between a gameboy player (on a gamecube with digital out) and this GBA core. There is a slight difference in Wario Land 4 when Wario does his fast swimming animation. The 'bubbly' 8bit sound is slightly different.

How much is it feasible to implement a low pass filter for the sound?

Audio Filters are already a feature: https://github.com/MiSTer-devel/Filters ... ters_Audio
You can set it in the menu as well as globally for all cores in the ini, e.g."afilter_default=LPF2000_3tap.txt

SuperBabyHix wrote: ↑Wed Oct 27, 2021 8:07 pm Audio Filters are already a feature: https://github.com/MiSTer-devel/Filters ... ters_Audio
You can set it in the menu as well as globally for all cores in the ini, e.g."afilter_default=LPF2000_3tap.txt

Has anyone produced a guide on what they do and which ones are best for each core? I’m having trouble understanding which one I should be using where and under which circumstances

With the exception of the SNES specific one the rest are pretty generic. If you open the filter files there are more details about the filters. For example Arcade LPF 2khz 1st has a description: "LPF 2khz 1st Order combined with 2nd order at 20khz".

I myself don't have enough knowledge about filters to be able to explain what that means, but it gives a starting place to research. I believe, though, it describes the rate at which those frequencies roll off. In general the lower the frequency the filter passes the less treble there will be. So for the Arcade LPF 2Khz 1st I believe it will roll off all frequencies above 2khz at a certain dB/octave and then anything above 20khz and a different rate of db/octave (probably roll off more).

Again, I have a very rudimentary understanding, so someone with more knowledge please correct me.

My advice for anything audio is always, try it all and use whatever sounds best to you.

EvilRyu wrote: ↑Thu Oct 28, 2021 11:20 am

SuperBabyHix wrote: ↑Wed Oct 27, 2021 8:07 pm Audio Filters are already a feature: https://github.com/MiSTer-devel/Filters ... ters_Audio
You can set it in the menu as well as globally for all cores in the ini, e.g."afilter_default=LPF2000_3tap.txt

Has anyone produced a guide on what they do and which ones are best for each core? I’m having trouble understanding which one I should be using where and under which circumstances

Issue is that what low pass filter is very subjective, what filters to use if any depends on your setup, your equipment and your taste.
Some home audio equipment do have their own low pass filters (some intentional, some are not), and if that's the case you want to avoid additional filters. Like how there a debate on whats the "correct" Sega Genesis audio options.

Thank you both for the responses.