Creative SB0350 Programming Manual page 128

B-4 File Format
Block Type 1
This is a digitized sound data block. The Block Header is organized as follows:
The header is followed immediately by the digitized sound data.
Here is a discussion of various fields:
BYTE bBlockID;
BYTE nBlockLen[3];
BYTE bTimeConstant;
BYTE bPackMethod;
bBlockID
The Block Type identifier is 1.
nBlockLen
Length of the block (in bytes), excluding the bBlockID and nBlockLen
fields.
The value here will be the digitized sound data length plus 2.
bTimeConstant
This is a 1-byte field which indicates the Time Constant of the digitized
sound data of this block. The Time Constant is defined as follows:
Time Constant = 65536 - (256 000 000/( channels * sampling rate))
The channels parameter is 1 for mono and 2 for stereo.
Only the high byte of the result is stored here. For instance, for a
10000Hz mono digitized sound, the Time Constant is set to 9C hex using
the following calculation:
Time Constant
bPackMethod
This is an 1 byte field which indicates the packing method used by the
digitized sound data of this block. It is defined as:
Value Meaning
0 8-bit PCM
1 Creative 8-bit to 4-bit ADPCM
2 Creative 8-bit to 3-bit ADPCM
3 Creative 8-bit to 2-bit ADPCM
// == 1
// 3-byte block length
// Packing Method
= 65536 - (256 000 000 / 10 000)
= 39936 (09C00H)