=============================================================================
		   Sound Effects in Descent and Descent 2	    5-01-2002
=============================================================================

By Valery V. Anisimovsky (samael@avn.mccme.ru)

In this document I'll try to describe how sound effects are stored in the
.PIG/.S11/.S22 resource files of Interplay/Parallax games Descent 1 and
Descent 2.

The files this document deals with have extensions: .PIG, .S11, .S22.

Throughout this document I use C-like notation.

All numbers in all structures described in this document are stored in files
using little-endian (Intel) byte order.

======================
1. Descent 1 Sound FX
======================

In Descent 1 all sound files are stored in DESCENT.PIG file except for one
file: DIGITEST.RAW which is in DESCENT.HOG.
As to Descent 1 (v1.0) .PIG file, it has the following header:

struct PIGHeader
{
  DWORD nFiles;
  DWORD nSoundFiles;
};

nFiles -- this is the number of non-sound files in the PIG,

nSoundFiles -- this is the number of RAW sounds in the PIG.

Following the header go (nFiles) records describing non-sound files.
What we need to know about these records that each of them is 17 bytes long.

After those records go (nSoundFiles) records describing sounds. Each record
has the following format:

struct DSNDEntry
{
  char	szFileName[8];
  DWORD nSamples;
  DWORD dwFileSize;
  DWORD dwFileStart;
};

szFileName -- this is the name for sound padded with zeroes. Note that
there're some 8 bytes long filenames which are thus not zero-terminated.

nSamples -- the number of samples in RAW file.

dwFileSize -- the size of RAW file (in bytes).

dwFileStart -- the starting position of the RAW file relative to the beginning
of data files in PIG. That is, to get the starting position of the RAW file
relative to the beginning of the PIG file you need to add (dwFileStart) to
(sizeof(PIGHeader)+nFiles*17+nSoundFiles*sizeof(DSNDEntry)).

So, starting at that position goes RAW 8-bit unsigned mono data.
All sound files in Descent 1 .PIG should be played at 11025 Hz.

Note that Descent v1.4 has slightly different .PIG file. Namely, it starts
with a DWORD value which is the position (relative to the .PIG file beginning)
of PIGHeader. Starting at that position is a PIGHeader which is just the same
to the described above.

======================
2. Descent 2 Sound FX
======================

In Descent 2 all sound files are stored in DESCENT2.S11 and DESCENT2.S22
except for DIGITEST.RAW in DESCENT2.HOG.
.S11 and .S22 files have the following header:

struct DSNDHeader
{
  char	szID[4];
  DWORD dwDummy;
  DWORD nFiles;
};

szID -- string ID is always "DSND",

dwDummy -- ??? looks like has no reasonable meaning,

nFiles -- the number of files in .S11/.S22 file.

After the header go (nFiles) DSNDEntry records (just the same as for Descent 1).
Just like in Descent 1, (dwFileStart) field of each entry is the starting
position of the RAW file relative to the beginning of RAW files. That is,
to get the starting position of the RAW file relative to the beginning of
the .S11/.S22 file you need to add (dwFileStart) to
(sizeof(DSNDHeader)+nFiles*sizeof(DSNDEntry)).

Each file in .S11/.S22 is 8-bit unsigned RAW. RAWs from .S11 should be played
at 11025 Hz and from .S22 -- at 22050 Hz.

-------------------------------------------

Valery V. Anisimovsky (samael@avn.mccme.ru)
http://bim.km.ru/gap/
http://www.anxsoft.newmail.ru
http://anx.da.ru
On these sites you can find my GAP program which can deal with PIG/S11/S22
resource files, extract RAWs from them and play back those RAWs.
There's also complete source code of GAP and all its plug-ins there,
including DSND plug-in, which could be used for further details on how you
can deal with this format.