WSS File Format

Introduction

WSS files are used since OFP times to store sound data and its file format is pretty much like the RIFF WAVE file format used for .wav files.

File Format

Offset	Datatype	Content	Description
0	char[4]	"WSS0"	file signature
4	ulong	<compression>	if <compression> == 8 the PCM data is compressed, otherwise <compression> == 0
8	ushort	<format tag>	defines in which format the data is saved. Always 0x0001 in WSS files
10	ushort	<channels>	number of channels: 1=mono, 2=stereo
12	ulong	<sample rate>	sample rate in Hz (e.g. 44100Hz)
16	ulong	<bytes/second>	<sample rate> * <block align>
20	ushort	<block align>	<channels> * (<bits/sample> / 8)
22	ushort	<bits/sample>	usually 0x0010 in WSS files
24	ushort	<unknown>	unknown value
26	byte[fileSize-26]	<soundData>	here the PCM data of the sound is stored

Decompression

If the <soundData> is compressed the following (C#) code can be used for decompression:

PCMData = new Int16[soundData.Length];
for (int j = 0; j < PCMData.Length; j++)
{
  SByte srcSample = (SByte)soundData[j];
  if (srcSample != 0)
  {
    double asFloat = Math.Abs(srcSample) / 28.12574042515172;
    asFloat *= 2.3025850929940456840; //ln(10)
    asFloat *= 1.4426950408889634070; //log2(e)
    double rnd = Math.Round(asFloat);
    double mantisse = Math.Pow(2.0, asFloat - rnd);
    asFloat = mantisse * Math.Pow(2, rnd);
    if (srcSample < 0) asFloat *= -1;
    Int32 asInt = (int)Math.Round(asFloat);
    asInt = (j == 0) ? asInt : (asInt + PCMData[j - 1]);
    if (asInt > short.MaxValue) asInt = short.MaxValue;
    if (asInt < short.MinValue) asInt = short.MinValue;
    PCMData[j] = (Int16)asInt;
  }
  else PCMData[j] = (j == 0) ? (Int16)0 : PCMData[j - 1];
}