Block diagram
Creative Voice File is a container file format for digital audio wave data. Initial revisions were able to support only unsigned 8-bit PCM and ADPCM data, later versions were revised to add support for 16-bit PCM and a-law / u-law formats.
This format was actively used in 1990s, around the advent of Creative's sound cards (Sound Blaster family). It was a popular choice for a digital sound container in lots of games and multimedia software due to simplicity and availability of Creative's recording / editing tools.
This page hosts a formal specification of Creative Voice File using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
meta:
id: creative_voice_file
title: Creative Voice File
file-extension: voc
xref:
justsolve: Creative_Voice_File
mime: audio/x-voc
wikidata: Q27967410
license: CC0-1.0
endian: le
doc: |
Creative Voice File is a container file format for digital audio
wave data. Initial revisions were able to support only unsigned
8-bit PCM and ADPCM data, later versions were revised to add support
for 16-bit PCM and a-law / u-law formats.
This format was actively used in 1990s, around the advent of
Creative's sound cards (Sound Blaster family). It was a popular
choice for a digital sound container in lots of games and multimedia
software due to simplicity and availability of Creative's recording
/ editing tools.
doc-ref: 'https://wiki.multimedia.cx/index.php?title=Creative_Voice'
# https://fabiensanglard.net/reverse_engineering_strike_commander/docs/Creative%20Voice%20(VOC)%20file%20format.txt
seq:
- id: magic
contents:
- 'Creative Voice File'
- 0x1a
- id: header_size
type: u2
doc: Total size of this main header (usually 0x001A)
- id: version
type: u2
- id: checksum
type: u2
doc: 'Checksum: this must be equal to ~version + 0x1234'
- id: blocks
type: block
repeat: eos
doc: Series of blocks that contain the actual audio data
types:
block:
seq:
- id: block_type
type: u1
enum: block_types
doc: Byte that determines type of block content
- id: body_size1
type: u2
if: block_type != block_types::terminator
- id: body_size2
type: u1
if: block_type != block_types::terminator
- id: body
size: body_size
type:
switch-on: block_type
cases:
'block_types::sound_data': block_sound_data
'block_types::silence': block_silence
'block_types::marker': block_marker
#'block_types::text': block_text
'block_types::repeat_start': block_repeat_start
#'block_types::repeat_end': always_empty_block
'block_types::extra_info': block_extra_info
'block_types::sound_data_new': block_sound_data_new
if: block_type != block_types::terminator
doc: Block body, type depends on block type byte
instances:
body_size:
value: body_size1 + (body_size2 << 16)
if: block_type != block_types::terminator
doc: |
body_size is a 24-bit little-endian integer, so we're
emulating that by adding two standard-sized integers
(body_size1 and body_size2).
block_sound_data:
doc-ref: 'https://wiki.multimedia.cx/index.php?title=Creative_Voice#Block_type_0x01:_Sound_data'
seq:
- id: freq_div
type: u1
doc: Frequency divisor, used to determine sample rate
- id: codec
type: u1
enum: codecs
- id: wave
size-eos: true
instances:
sample_rate:
value: 1000000.0 / (256 - freq_div)
block_silence:
doc-ref: 'https://wiki.multimedia.cx/index.php?title=Creative_Voice#Block_type_0x03:_Silence'
seq:
- id: duration_samples
type: u2
doc: Duration of silence, in samples
- id: freq_div
type: u1
doc: Frequency divisor, used to determine sample rate
instances:
sample_rate:
value: 1000000.0 / (256 - freq_div)
duration_sec:
value: duration_samples / sample_rate
doc: Duration of silence, in seconds
block_marker:
doc-ref: 'https://wiki.multimedia.cx/index.php?title=Creative_Voice#Block_type_0x04:_Marker'
seq:
- id: marker_id
type: u2
doc: Marker ID
block_repeat_start:
doc-ref: 'https://wiki.multimedia.cx/index.php?title=Creative_Voice#Block_type_0x06:_Repeat_start'
seq:
- id: repeat_count_1
type: u2
doc: Number of repetitions minus 1; 0xffff means infinite repetitions
block_extra_info:
doc-ref: 'https://wiki.multimedia.cx/index.php?title=Creative_Voice#Block_type_0x08:_Extra_info'
seq:
- id: freq_div
type: u2
doc: Frequency divisor
- id: codec
type: u1
enum: codecs
- id: num_channels_1
type: u1
doc: Number of channels minus 1 (0 = mono, 1 = stereo)
instances:
num_channels:
value: num_channels_1 + 1
doc: Number of channels (1 = mono, 2 = stereo)
sample_rate:
value: 256000000.0 / (num_channels * (65536 - freq_div))
block_sound_data_new:
doc-ref: 'https://wiki.multimedia.cx/index.php?title=Creative_Voice#Block_type_0x09:_Sound_data_.28New_format.29'
seq:
- id: sample_rate
type: u4
- id: bits_per_sample
type: u1
- id: num_channels
type: u1
- id: codec
type: u2
enum: codecs
- id: reserved
size: 4
- id: wave
size-eos: true
enums:
block_types:
0: terminator
1: sound_data
2: sound_data_cont
3: silence
4: marker
5: text
6: repeat_start
7: repeat_end
8: extra_info
9: sound_data_new
# https://wiki.multimedia.cx/index.php?title=Creative_Voice#Supported_codec_ids
codecs:
0x00: pcm_8bit_unsigned
0x01: adpcm_4bit # 4 bits to 8 bits Creative ADPCM
0x02: adpcm_2_6bit # 3 bits to 8 bits Creative ADPCM (AKA 2.6 bits)
0x03: adpcm_2_bit # 2 bits to 8 bits Creative ADPCM
0x04: pcm_16bit_signed # 16 bits signed PCM
0x06: alaw
0x07: ulaw
0x0200: adpcm_4_to_16bit # 4 bits to 16 bits Creative ADPCM