source: trunk/asma/Docs/Sap.txt @ 49

SAP file divides into two parts. First part (in text format) describes
player/music type and contains credits for the song. Second part (in binary
format) contains player and music data formed into Atari Binary File format.


First part - text info
~~~~~~~~~~~~~~~~~~~~~~
For identification of the format, it always starts with "SAP" string.
After that the credits follow. However, this is not fixed order, just a
recommendation. Each line should end with EOL string (0D 0A).

Credits tags:
AUTHOR "" - Name of composer. For ASMA purposes, the name should consist of 
            real name and nickname (scene handle) in parentheses. No scene
            group allowed. If song was composed by more authors, use "&".
            Examples: 
            AUTHOR "Dariusz Duma (Dhor)"
            AUTHOR "Lukasz Sychowicz (X-Ray) & Piotr Swierszcz (Samurai)"
NAME "" - Song title. No restrictions, except for it shouldn't contain
          quotation marks. Use apostrophes instead.
          Example:
          NAME "Jocky Wilson's Darts Challenge"
DATE "" - Copyright year or yrar of creation. If exact date is known, it can
          also be included in DD/MM/YYYY format.
          Examples:
          DATE "1986"
          DATE "1993-94"
          DATE "28/08/1997"
          DATE "12/2001" 

After that the player info follows:
TYPE      - player type (see below)
PLAYER    - address of player part which will be executed in 1/50 sec
            intervals (or as defined with FASTPLAY)
MUSIC     - address with music data (for C type)
INIT      - address of player part which will init player (for all types
            except C)
SONGS     - number of songs. If SONGS tag not defined, the default value is
            0.
DEFSONG   - first song which will be played when .sap will be loaded (i.e.
            the main game theme). This value is counted from zero (if there
            are 5 songs in the file and the last is the default, the value
            will be DEFSONG 4). The default is 0 if DEFSONG not defined.
FASTPLAY  - number of lines between each call of playing routine (312 by
            default, which is one screen - 1/50 of sec.). For example for
            double-speed tune put here the value 156 (312/2). 99% of tunes
            are single-speed which means that you don't have to define the
            FASTPLAY variable for them. Works for player TYPE "B".
            Another values recommended: 104 (triple speed), 78 (quadruple
            speed)
STEREO - tune uses dual POKEY configuration.

commands PLAYER, MUSIC, INIT contain addresses in hexadecimal format. Both
lower- and uppercase characters are allowed for the number.

PLAYER A000
PLAYER 1234
MUSIC  f42e

commands SONGS, DEFSONG contain decimal numbers:

SONGS 10
DEFSONG 9

command TYPE contains single character which describes player type. The
following player types are supported:

TYPE C - player from CMC (Chaos Music Composer). In this case, also these
         commands must appear: PLAYER, MUSIC. Additionaly you can define
         SONGS and DEFSONG. Player will be initialized as follows:

         lda #$70
         ldx #<MUSIC
         ldy #>MUSIC
         jsr PLAYER+3
         lda #$00
         ldx #DEFSONG
         jsr PLAYER+3

         in 1/50 intervals will be executed:

         jsr PLAYER+6

         This is just internal structure already contained in SAP player, you
         don't have to add this code to the CMC player.

TYPE B - any player. In this case, also these commands must appear: PLAYER,
         INIT. Additionaly you can define SONGS and DEFSONG. Player will be initialized as follows:

         lda #DEFSONG
         jsr INIT

         in 1/50 intervals will be executed:

         jsr PLAYER

TYPE S - SoftSynth. Like type "C", this type is temporary, and is used only
         for special type of songs, that were composed using program
         SoftSynth.
TYPE D - Digital. In SAP file with this type, there must be also defined 
         commands "INIT" and "PLAYER". "PLAYER" (like in type B) sets 
         address of procedure that will be called in 1/50s intervals and 
         (like in type B) must end with RTS opcode. INIT this time is a bit
         different. It sets address of procedure that will be called (with 
         number of song in register A) to initialize program, but it can't
         end with RTS. It should start playing digis in endless loop. In SAP
         player two ANTIC registers $D40A and $D40B are emulated. They help
         playing samples. D40B register increases its contents each two
         screen lines. D40A holds CPU till the end of actually drawn line.
         SAP emulates Atari in PAL with disabled screen. It means that we
         have 312 lines per screen, each taking 105 CPU cycles and 9 cycles
         of memory refresh (114 cycles per line).

One more type is recognized by SAP player - TYPE M. Right now it's exactly
the same as TYPE B but this differentiation is for future SAP releases.

Planned features:
TYPE R - Registers. In this type, binary part is not an Atari binary file.
         This part contains values that will be directly written to Pokey
         registers ($D200-$D208) in 1/50s intervals (or intervals defined
         with FASTPLAY tag).
TIME xx:xx - Song duration. This is actually already supported by SAP WinAMP
             plug-in. It's still unclear how will subsongs be handled with
             TIME tag. Possibly it will also support tenths or hundredths of
             second (xx:xx.x or xx:xx.xx).

Example of the header:
SAP
AUTHOR "Jakub Husak"
NAME "Inside"
DATE "1990"
SONGS 3
DEFSONG 0
TYPE B
INIT 0F80
PLAYER 247F


Second part - binary data
~~~~~~~~~~~~~~~~~~~~~~~~~
This part contains player and music data represented in Atari binary file
format. This format has two bytes header FF,FF. The following two bytes tell
the loader where to load data, and next two bytes tell where the data end.
Init data block ($02E2,$02E3) is not supported.

A little example:

FF FF 00 20 04 20 01 42 A3 04 D5
\___/ \_________/ \____________/
  A        B            C

A - Binary file header identification (always FF FF)
B - Load addres (StartAddr, EndAddr in LO,HI order - $2000 to $2004)
C - Data (that will be loaded from StartAddr)

This example will load values 01,42,A3,04,D5 into memory from $2000 to $2004.


How to create .SAP file
~~~~~~~~~~~~~~~~~~~~~~~
First of all we need to rip music from a game or a demo and save it in Atari
binary file. Next we can create a text file with description (as described
above), then we can make .sap file by linking these two files. We can do that
using DOS command "copy", e.g.:

copy /b music.txt+music.bin music.sap

The file is made now!
If you didn't find that song in ASMA, feel free to send it to pg@dspaudio.com
with all needed information (see ASMA.TXT for details). The song should be
then included in the nearest ASMA update.