N-GBS Music Engine

DJ Bouche (Andrew Lim)

2011-12-20



Known Games and Variants

Super Mario Land - NGBS0 (Song Table 0x663C)

Super Mario Land 2 - NGBS1 

Super Mario Bros DX - NGBS0



This is based on studying the GBS.  The data was first found by poking real-time RAM in an emulator.



Song Format:

NGBS0:	nn ll ll aa aa bb bb cc cc dd dd

NGBS1:	nn ll ll mm mm aa aa bb bb cc cc dd dd

                nn - ?????

		llll - pointer to length table

		mmmm - pointer to ???

		aaaa - pointer to channel 1 sequence

		bbbb - pointer to channel 2 sequence

		cccc - pointer to channel 3 sequence

                dddd - pointer to channel 4 sequence



Length Table:

	Contains tick value for each length index (0-F), one byte for each



Track Sequence:

	Looping track - aa aa bb bb cc cc dd dd ..... FF FF pp pp

	Non-looping track - aa aa bb bb 00 00



		aaaa, bbbb, cccc, dddd, ... - pointer to patterns (command streams)

		pppp - pointer to the loop point in the track sequence



		Note that if 00 00 is reached in any track sequence, it ends the entire song (all other tracks stop processing too).



Command Stream:



    Added in NGBS1

        9B xx - Loop Start

              xx - Number of loops

        9C - Loop End



    Basic Commands

	00 - end of command stream

        99 - unknown

	9D xx yy zz - set channel info

		For Ch 1 and 2

			xx - Volume Envelope

			yy - ??

			zz - Duty (bits 6 and 7)

		For Ch 3

			yyxx - Address of Waveform

			yy - ??

		For Ch 4

			Is just read as a note, I think, as Ch4 doesn't use this command

	A0-AF - set note length (A0 is length index 0, AF is length index F)

	01 - Note Rest

	Anything else, that is not 01, A0-AF, or any recognized command above, is interpreted as a note.

		For Ch 1-3:

			Note is an even number (it is actually an index to a 16-bit word table of frequencies)

			02 is C0, 04 is C#0, 06 is D0, etc.

			Odd numbers will work but they will point to invalid (misaligned) frequencies

		For Ch 4:

			02, 03, 04, 05 .. etc correspond to a drum note

			How those drum notes are specified I don't know yet



Super Mario Land's Auto-pan:

	

	Don't know where this is yet, it's not part of the song data, at all..



Noise drum notes:

	

	Don't know yet.





Here is the overworld song decoded to BPCSPK3, with comments:



*Song 07 - 6FDA (0A66) - Length Table 6F66 (09F2)*



( *Track 00 - 76ED (1179)*

  *Pattern 00 - 7728 (11B4)*

 &GBP[0x62][0x00][0x80]  64 / 8 / 24  O1 g 32  < g   *End Pattern*

:  *Pattern 01 - 775E (11EA)*

 16 / O2 e/e/e/e/e/e/e/e/ > c/c/c/c 64 / 16 / > f# 32 f# 16 / << e/e/e/e/e/e/e/e/ > c/c/c/c 64 / 12 / 4  > f# 16 / 32  < f#   *End Pattern*

  *Pattern 02 - 7866 (12F2)*

 16 / O3 cd < a > d 12  < g 4 b 16 /gaf 12 b 4 a 16 d 64 / 16 / > cd < a > d 12  < g 4 b 16 /gcc/c////   *End Pattern*

  *Loop to Position 01* 

|

( *Track 01 - 76F7 (1183)*

  *Pattern 00 - 7715 (11A1)*

 &GBP[0x92][0x00][0x80]  8  O3 e/d#/dc/// 24  < g 32  < g   *End Pattern*

:  *Pattern 01 - 77A2 (122E)*

 16  O3 e/ 12 d 4 c 12 / 4 e 48 / 12 c 4 d 8 e/e/ 16 dcefga/cc < ag 12 / 4  > c 32 / 16  < fgab 16 / >> g 32 g 16  < e/ 12 d 4 c 12 / 4 e 48 / 12 c 4 d 8 e/e/ 16 dcag > c 12  < e 4 d 16 /ccde 12 / 4 c 32 / 16 fecd 12 / 4  > g 16 / 32  < g   *End Pattern*

  *Pattern 02 - 7832 (12BE)*

 16 / O3 ab > c 16  < b 12 / 4 g 32 / 16 f/ 12 g 4 f 16 / 8 e/f/f#/g/ 16 /ab > c 16  < b 12 / 4 g 32 / 16  > d#d/c 64 /   *End Pattern*

  *Loop to Position 01* 

|

( *Track 02 - 7701 (118D)*

  *Pattern 00 - 7735 (11C1)*

 &WAV[0x6F3B][0x9C7]  8  O4 g/f#/fe// 32 / << g   *End Pattern*

:  *Pattern 01 - 780E (129A)*

 $a~(16  O2 c 12  > g 4  << g 16  > c > g < c > g# < c > g# < c > a < c > a < c > a# < a > a# < f > a < f > a < e > g < e > gdeff# 64 /)   *End Pattern*

  *Pattern 02 - 780E (129A)*

 $a *End Pattern*

  *Pattern 03 - 7893 (131F)*

 16  O2 f > c < f > c < e > c < e > c < d > a < d > a 8 c/d/d#/e/ 16  < f > c < f > c < e > c < e > c < g# > d# < g# > d# 4 g/g/ 8 f/e/d/   *End Pattern*

  *Loop to Position 01* 

|

( *Track 03 - 770D (1199)*

  *Pattern 00 - 7746 (11D2)*

 12  O8 f 4 f 16 a# 12 f 4 f 16 a# 8 /f// 12 a# 4 f 16 f   *End Pattern*

:  *Pattern 01 - 78C3 (134F)*

 16  O8 f 12 f 4 f 16 a# 12 f 4 f 16 f 12 f 4 f 16 a# 12 f 4 f   *End Pattern*

  *Loop to Position 01*