Add music and SFX to your BEX game with the XGM driver :)

[Stef]

Hi guys,

I saw some people getting mad when it comes to add music and SFX in their BEX games so i hope that will help =)
I made a new sound driver for SGDK and wanted to make it available in BEX as well so you will be able to have all the features of the XGM driver inside your BEX games =)
You can find some technical informations the XGM driver here:
chipmusic.org/forums/topic/15673/sega-genesis-new-xgm-driver/

To make it simple the XGM driver allow you to play music (VGM / XGM format) while playing up to 4 SFX (PCM format) at same time.
But the important point for you is that you can use it in BEX and as it uses the Z80 CPU it won't eat any resource from your program (or a very few percent) =)

Here is a folder to demonstrate how to use it:
pc.cd/nuWrtalK

So to explain a bit more the content of the folder:

z80_xgm.bin
  That's the Z80 XGM driver in binary format, the program we load in Z80 memory.
  I recommend you to directly copy this file inside the BasiEgaXorz installation folder.
null.raw
  An empty PCM file, the XGM driver requires it to work properly to don't forget to include it.
  I recommend you to directly copy this file inside the BasiEgaXorz installation folder.
test.bex
  The BEX basic example containing all the code to load and use the Z80 XGM driver.
sor2.xgc
  A compiled XGM music file.
  You can generate them from VGM file (VGM 1.5 at least) by using XGMTool (available in the demo folder).
hat.raw, loop.raw, snare.raw
  Some small PCM samples used to test the SFX support of the XGM driver.
  PCM samples should be 8 bits signed at 14000Khz and size should be aligned to 256 bytes.
  You can convert any WAV files to raw PCM by using the WavToRaw tool (available in the demo folder).
  To align the size of the result RAW file you can use the SizeBnd tool (available in the demo folder),
  by default it aligns size on 256 bytes 

So you almost know everything now, just remember that if you want to use the XGM driver, you first have to init the driver by calling the xgm_init method then you need to setup the vint event so it call xgm_vintProcess at each vint (see test.bex for an example).
When this is done you are ready to use one the following methods from the XGM driver:

xgm_init
  Initialize the XGM driver (load it in Z80 memory, init and wait for ready)

xgm_isPlayingMusic
  Return a value != 0 is the XGM driver is currently playing a music.

xgm_startPlayMusic
  Start music play.
  A1 register should contains the address of the XGM music.
  See test.bex for an example

xgm_stopPlayMusic
  Stop music play.

xgm_resumePlayMusic
  Resume music play after a Stop music command (can be used for pause).

xgm_isPlayingPCM(channel_mask)
  Return the play status of specified channel mask.
  channel_mask = 1 for channel 1
  channel_mask = 2 for channel 2
  channel_mask = 4 for channel 3
  channel_mask = 8 for channel 4
  We can test 2 channels by combining values: if channel_mask = 10 (8 + 2) then we test channel 2 and channel 4.
  In this case if return value = 8 then channel 4 is playing but not channel 2.
  See test.bex for an example

xgm_playPCM
  A1 register should contains the PCM sample address
  D1 register should contains the PCM sample length
  D2 register should contains channel and priority informations in this format:
    (priority << 4) | channel
    where priority is a value between 0 (lowest) and 15 (highest) and channel is a value between 0 and 3.
  See test.bex for an example

xgm_stopPCM
  D2 register should contains channel number (between 0 and 3)
  See test.bex for an example

xgm_setMusicTempo
  Allow to set the music tempo
  By default tempo is set to 60 Hz on NTSC system and 50 Hz on PAL system but you can change it freely.

xgm_getElapsedTime
  Returns the elapsed played music time in frame.

xgm_setBusProtection
  Allow to enable 68000 BUS protection.
  You should use it to prevent the Z80 using the 68000 bus during DMA to avoid PCM playback quality degradation.
  Note that the XGM driver expect DMA operations to happen during VBlank so it works best when that's the case.
  A normal use case of BUS protection:
   xgm_setBusProtection 1
   ' do DMA operations
   xgm_setBusProtection 0

Sorry for the rough integration (as the need of loading song address directly in register) but my knowledge with this language is really limited and i met several issues (how to access asm labels from basic for instance ?) and if someone want to improve the integration (having proper BEX function to call XGM method) then he's welcome =)

Have fun !

Edit: Updated to the last version of XGM driver (SGDK 1.22)

[Deleted]

Stef, you are amazing! Thank you for this I'm gonna mess around with it this evening

[vetea]

Hi Stef and ... Merci beaucoup !!!

[Stef]

You're welcome ! I updated the message to give more informations. Just ask here if you need assistance

[lunchbox]

Nice!! Thanks for the infos Stef. I managed to get Shiru's 4 Channel sound engine working easily within BEX. This works out great for Sega CD Games using CD Audio and just sfx samples. I may have to try XGM to see how it stacks up

[Deleted]

I saw in the chiptune thread that there are bugs on the hardware - is this still an issue? Example program worked perfectly!

Edit: I tested some TFM tracks (converted in VGM Music Maker 1.1 to the VGM format), used the xgm tool to convert it to a compile xgc file, and ran it in the BEX rom. It sounded fine (from what I could tell), but it played faster than it should have. Any idea on what could be causing that? Is there another VGM tracker out there besides Shiru's VGMM (no longer supported) or Deflemask (can't import TFM modules, which all of my music is written in)?

[Stef]

Bugs are resolved since a long time now =)
The problem with speed can comes from the internal timing used in VGM file. If VGM are made for PAL system then they will be played too quickly on NTSC systems when converted to XGM. It needs to be played on a PAL system then...
I will add some command to the XGMTool to take care of that (convert music speed between PAL and NTSC).

[Deleted]

Awesome, Stef looking forward to it

[theelf]

Great work Stef, thanks!

[mekanaizer]

Mar 4, 2015 17:54:36 GMT -5 @elusive said:

I saw in the chiptune thread that there are bugs on the hardware - is this still an issue? Example program worked perfectly!

Edit: I tested some TFM tracks (converted in VGM Music Maker 1.1 to the VGM format), used the xgm tool to convert it to a compile xgc file, and ran it in the BEX rom. It sounded fine (from what I could tell), but it played faster than it should have. Any idea on what could be causing that? Is there another VGM tracker out there besides Shiru's VGMM (no longer supported) or Deflemask (can't import TFM modules, which all of my music is written in)?

There are a couple of trackers made for the MD itself been the best this one: (more of a novelty)
chipmusic.org/forums/topic/15355/prodigy-tracker-genesismd/

Aside from those you pointed, VGMM and Deflemask, there is this old one:
www.pascalorama.com/article.php?news=30

There are more but I can't remember right now. A beleave there is one thou in Japanese for the FM Towns that works with the MD too. I bet there are more but lost in time and the web.

[nathan999]

Thank you very much for this. We had a BEX project we started in 2013 and it was somewhat abandoned for several reasons, one of them being my lame integration of the TFM player (running in BEX code) and a ADPCM player (running in the Z80) which sounded prety dire and had many glitches.

Last week we decided to finish the game and release it no matter this issue, and now your player comes as a godsend


At least the game will have proper sound/music. Thanks!

[Stef]

Really pleased to heard that ! I sincerely hope it will meet your expectations

[Davidian]

Hi Stef,

Thanks for the XGM support for BEX.

As na_th_an posted above, we are finishing an old development and XGM is a blast

But i'm having some troubles with samples in my VGMs. XGM plays perfectly in SGDK but in BEX samples sound pitched and very poor.

For this game i'm using VGMM and 8khz samples (samples are the same that i'm using in Antarex).

Here are the music samples captured from Kega Fusion.

Basiegaxorz --> drive.google.com/file/d/0Byg7tmMNqW5jb041ajFEa3FmM3M/view?usp=sharing
SGDK --> drive.google.com/file/d/0Byg7tmMNqW5jY2FhT2ROaHloWjg/view?usp=sharing

Any ideas?

[Stef]

Thanks for the comment Davidian
XGM plays better with 14 Khz samples as the driver internally plays at 14 Khz but here i think the difference comes from the basic program which, for some reasons, seems to interrupt a lot the Z80 CPU and so hurts a lot on the XGM playback processing !
Did you try to do a simple XGM play without anything else running ? In my SOR2 test it was working correctly so i definitely think there is something in your basic program which make something wrong on the Z80 CPU.

[Davidian]

Hi,

I've doing more tests.

The code i'm using is playing a song and three sounds when you press A, B or C. Samples for SFX sound great.

I've noticed that Deflemask or VGM MM vmg files exported as 1.60 samples don't sound and for 150 they sound with poor sound. But if i press button A for example to play a SFX, samples in the music start to sound and the quality is great drive.google.com/file/d/0Byg7tmMNqW5jM19OdmtxM2hfOGs/view?usp=sharing

Here is my .BEX file, and some sources if you wanna test them

www.dropbox.com/s/8qt3cpsiidd55qo/sources.rar?dl=0