Creative Voice (VOC) file format
--------------------------------

~From: galt@dsd.es.com

(byte numbers are hex!)

    HEADER (bytes 00-19)
    Series of DATA BLOCKS (bytes 1A+) [Must end w/ Terminator Block]

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

HEADER:
=======
     byte #     Description
     ------     ------------------------------------------
     00-12      "Creative Voice File"
     13         1A (eof to abort printing of file)
     14-15      Offset of first datablock in .voc file (std 1A 00
                in Intel Notation)
     16-17      Version number (minor,major) (VOC-HDR puts 0A 01)
     18-19      1's Comp of Ver. # + 1234h (VOC-HDR puts 29 11)

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

DATA BLOCK:
===========

   Data Block:  TYPE(1-byte), SIZE(3-bytes), INFO(0+ bytes)
   NOTE: Terminator Block is an exception -- it has only the TYPE byte.

      TYPE   Description     Size (3-byte int)   Info
      ----   -----------     -----------------   -----------------------
      00     Terminator      (NONE)              (NONE)
      01     Sound data      2+length of data    *
      02     Sound continue  length of data      Voice Data
      03     Silence         3                   **
      04     Marker          2                   Marker# (2 bytes)
      05     ASCII           length of string    null terminated string
      06     Repeat          2                   Count# (2 bytes)
      07     End repeat      0                   (NONE)
      08     Extended        4                   ***

      *Sound Info Format:       **Silence Info Format:
       ---------------------      ----------------------------
       00   Sample Rate           00-01  Length of silence - 1
       01   Compression Type      02     Sample Rate
       02+  Voice Data

    ***Extended Info Format:
       ---------------------
       00-01  Time Constant: Mono: 65536 - (256000000/sample_rate)
                             Stereo: 65536 - (25600000/(2*sample_rate))
       02     Pack
       03     Mode: 0 = mono
                    1 = stereo


  Marker#           -- Driver keeps the most recent marker in a status byte
  Count#            -- Number of repetitions + 1
                         Count# may be 1 to FFFE for 0 - FFFD repetitions
                         or FFFF for endless repetitions
  Sample Rate       -- SR byte = 256-(1000000/sample_rate)
  Length of silence -- in units of sampling cycle
  Compression Type  -- of voice data
                         8-bits    = 0
                         4-bits    = 1
                         2.6-bits  = 2
                         2-bits    = 3
                         Multi DAC = 3+(# of channels) [interesting--
                                       this isn't in the developer's manual]


---------------------------------------------------------------------------------
Addendum submitted by Votis Kokavessis:

After some experimenting with .VOC files I found out that there is a Data Block Type 9, which is not covered in the VOC.TXT file. Here is what I was able to discover about this block type:
  
  
TYPE: 09
SIZE: 12 + length of data
INFO: 12 (twelve) bytes
  
INFO STRUCTURE:
  
Bytes 0-1: (Word) Sample Rate (e.g. 44100)
Bytes 2-3: zero (could be that bytes 0-3 are a DWord for Sample Rate)
Byte 4: Sample Size in bits (e.g. 16)
Byte 5: Number of channels (e.g. 1 for mono, 2 for stereo)
Byte 6: Unknown (equal to 4 in all files I examined)
Bytes 7-11: zero
----------------------------------------------------------------------------------
Detailed description of new data blocks (VOC files version 1.20 and above):

        (Source is fax from Barry Boone at Creative Labs, 405/742-6622)

BLOCK 8 - digitized sound attribute extension, must preceed block 1.
          Used to define stereo, 8 bit audio
        BYTE bBlockID;       // = 8
        BYTE nBlockLen[3];   // 3 byte length
        WORD wTimeConstant;  // time constant = same as block 1
        BYTE bPackMethod;    // same as in block 1
        BYTE bVoiceMode;     // 0-mono, 1-stereo

        Data is stored left, right

BLOCK 9 - data block that supersedes blocks 1 and 8.  
          Used for stereo, 16 bit.

        BYTE bBlockID;          // = 9
        BYTE nBlockLen[3];      // length 12 plus length of sound
        DWORD dwSamplesPerSec;  // samples per second, not time const.
        BYTE bBitsPerSample;    // e.g., 8 or 16
        BYTE bChannels;         // 1 for mono, 2 for stereo
        WORD wFormat;           // see below
        BYTE reserved[4];       // pad to make block w/o data 
                                // have a size of 16 bytes

        Valid values of wFormat are:

                0x0000  8-bit unsigned PCM
                0x0001  Creative 8-bit to 4-bit ADPCM
                0x0002  Creative 8-bit to 3-bit ADPCM
                0x0003  Creative 8-bit to 2-bit ADPCM
                0x0004  16-bit signed PCM
                0x0006  CCITT a-Law
                0x0007  CCITT u-Law
                0x02000 Creative 16-bit to 4-bit ADPCM

        Data is stored left, right
