Help request - Exporting DPCM Sample to Separate DMC Files for NES Audio Playback

[xanmankey]

Hi,

First of all, I just wanted to say thanks for the awesome DAW! I've had a really good time working with FamiStudio so far, so I just wanted to say thanks for all the work that people have put into the project.

I'm currently running a Linux build on version 4.4.2. My goal is to export the song in such a way that I can include it in an iNES ROM (currently configured to support either the MMC1 or MMC3 mappers), assembled using ca65.

My current approach is using the MMC3 mapper, with the intent of swapping $C000-$DFFF in memory to load new DMC files (because I have way too many of them) for song playback whenever necessary. My memory config contains segments for each 8KB worth of samples:

DPCM0:   load = PRG_SAMPLES, type = ro, offset = $00000; # Bank 0
DPCM1:   load = PRG_SAMPLES, type = ro, offset = $02000; # Bank 1
DPCM2:   load = PRG_SAMPLES, type = ro, offset = $04000; # Bank 2
... # 32 8KB banks

and my code includes these samples:

.segment "DPCM0"
    .incbin "sample0.dmc"
.segment "DPCM1"
    .incbin "sample1.dmc"
... # other memory segments

However, I haven't been able to find a way to export each used DPCM Sample as a dmc file. I set the corresponding bank numbers for each sample in the editor (the song can be seen below)

but when I export FamiStudio Music Code with the settings below, there's only a single dmc file.

I'm completely new to NES development, so I'm sure I'm misunderstanding something or missing some information. I was able to get playback for the other 4 channels to function properly on export using the ca_65 audio engine, but any approach at DPCM that I've made thus far has just resulted in garbage noise.

Any help or guidance that you can provide is appreciated! Please let me know if there's more information that I can provide that might be helpful for assisting.

Best,
Xander

[BleuBleu]

Hi.

I think you can achieve what you are trying to do.

1. Enable DPCM bank switching in the project setting (first gear on top of project explorer)

2. For each sample, assign them the desired Bank Number.

3. Export to sound engine, look in the log to make sure it split it into banks correctly.

When you do this, you will be responsible from swapping in/out the correct samples before (or during) the playback of a song. This will likely require you to implement famistudio_dpcm_bank_callback in the sound engine.

-Mat

[xanmankey]

Thanks for the prompt response, I was able to export separate .dmc files! A couple quick follow-ups:

• For some reason if I checked the "Separate Files" box when exporting FamiStudio Music Code, I would always get a crash (stacktrace below). I tried to change the song and pattern names, as well as the format, but I wasn't able to avoid a crash.

   at FamiStudio.LinuxDialog.ShowGtkFileDialog() in /home/mat/Github/FamiStudio/FamiStudio/Source/Platform/Linux/LinuxDialog.cs:line 531
   at FamiStudio.LinuxDialog.ShowFileDialog() in /home/mat/Github/FamiStudio/FamiStudio/Source/Platform/Linux/LinuxDialog.cs:line 512
   at FamiStudio.LinuxDialog..ctor(DialogMode mode, String title, String& defaultPath, String extensions, Boolean multiselect) in /home/mat/Github/FamiStudio/FamiStudio/Source/Platform/Linux/LinuxDialog.cs:line 328
   at FamiStudio.Platform.ShowPlatformBrowseFolderDialog(String title, String& defaultPath) in /home/mat/Github/FamiStudio/FamiStudio/Source/Platform/Linux/Platform.cs:line 121
   at FamiStudio.Platform.ShowBrowseFolderDialog(String title, String& defaultPath) in /home/mat/Github/FamiStudio/FamiStudio/Source/Platform/Desktop/Platform.cs:line 140
   at FamiStudio.ExportDialog.ExportFamiTone2Music(Boolean famiStudio) in /home/mat/Github/FamiStudio/FamiStudio/Source/App/Common/Dialogs/ExportDialog.cs:line 1290
   at FamiStudio.ExportDialog.Export(Boolean repeatLast) in /home/mat/Github/FamiStudio/FamiStudio/Source/App/Common/Dialogs/ExportDialog.cs:line 1416
   at FamiStudio.ExportDialog.<ShowDialogAsync>b__189_0(DialogResult r) in /home/mat/Github/FamiStudio/FamiStudio/Source/App/Common/Dialogs/ExportDialog.cs:line 1433
   at FamiStudio.Dialog.Close(DialogResult res) in /home/mat/Github/FamiStudio/FamiStudio/Source/App/Desktop/Dialog.cs:line 105
   at FamiStudio.MultiPropertyDialog.ButtonYes_Click(Control sender) in /home/mat/Github/FamiStudio/FamiStudio/Source/App/Desktop/MultiPropertyDialog.cs:line 202
   at FamiStudio.Button.TriggerClickEvent(PointerEventArgs e, Boolean left) in /home/mat/Github/FamiStudio/FamiStudio/Source/App/Common/Controls/Button.cs:line 222
   at FamiStudio.Button.OnPointerDown(PointerEventArgs e) in /home/mat/Github/FamiStudio/FamiStudio/Source/App/Common/Controls/Button.cs:line 242
   at FamiStudio.Control.SendPointerDown(PointerEventArgs e) in /home/mat/Github/FamiStudio/FamiStudio/Source/App/Common/Controls/Control.cs:line 94
   at FamiStudio.FamiStudioWindow.MouseButtonCallback(IntPtr window, Int32 button, Int32 action, Int32 mods) in /home/mat/Github/FamiStudio/FamiStudio/Source/App/Desktop/FamiStudioWindow.cs:line 530```

• Also, I'm still unable to play DPCM samples; instead I get a popping noise each time a sample tries to play, so I assume I implemented bank switching or initialized the MMC3 mapper incorrectly in my code. My current implementation of famistudio_dpcm_bank_callback is

proc famistudio_dpcm_bank_callback
    ; The bank number is passed in the Y register.
    ; We must preserve A and X.
    
    ; MMC3 logic
    pha ; Save A
    txa ; Save X (by pushing it to A, then stack)
    pha

    ; Write to the MMC3 selection register to trigger bank select mode to swap $C000-$DFFF ($8000)
    ; Bit 6 (0 indexed) -> alternate mode (swap $C000-$DFFF)
    ; bits 2 and 1; register 6, controls $C000-$DFFF bank
    ; lda #%01000110 ; Get bank number from Y into A
    lda #%00000111
    sta $8000

    ; Write the bank number from Y to the PRG bank register ($8001)
    tya
    sta $8001

    ; Restore X and A
    pla
    tax ; (pop A from stack, restore to X)
    pla ; (pop A from stack, restore to A)
    
    rts
.endproc

and I disabled interrupts during initialization. I also made sure the DPCM channel wasn't silenced, so I was curious if you had any idea what the popping sound might be indicative of? I can provide more code if it'll be helpful.