Creative Voice (VOC) file format

(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	2's Comp of Ver. # + 1234h (VOC-HDR puts 29 11)

  
  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]

---

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





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 sizeof 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