Covox ADPCM - Revision history

Sembiance: samples

2025-05-14T14:46:56Z

samples

← Older revision		Revision as of 07:46, 14 May 2025
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	* Company: [[Covox]]		* Company: [[Covox]]
	* Samples: [http://samples.mplayerhq.hu/A-codecs/CovoxFormats/ http://samples.mplayerhq.hu/A-codecs/CovoxFormats/]		* Samples: [http://samples.mplayerhq.hu/A-codecs/CovoxFormats/ http://samples.mplayerhq.hu/A-codecs/CovoxFormats/]
			* Samples: {{DexvertSamples\|audio/covoxADPCM}}

	This is a family of [[ADPCM]] formats used for compressing 8-bit unsigned [[PCM]]. They were invented by Covox for use with the Covox Speech Thing, Sound Master, and other Covox sound output devices. There are 2-,3- and 4-bit ADPCM formats.		This is a family of [[ADPCM]] formats used for compressing 8-bit unsigned [[PCM]]. They were invented by Covox for use with the Covox Speech Thing, Sound Master, and other Covox sound output devices. There are 2-,3- and 4-bit ADPCM formats.

Trixter at 08:11, 16 January 2017

2017-01-16T08:11:53Z

@@ Line 42: / Line 42: @@
 == ADPCM decoding ==
-This is generalized decoding procedure for all know ADPCM variants. <i>n</i> will denote the number of bits used in ADPCM (<i>n</i>=2 for 2-bit ADPCM, etc).
+The Covox method of ADPCM does not match other methods; please see the SPUTTER source code by Adrienne Cousins for one implementation of how to decode Covox ADPCM.
 [[Category:Audio Codecs]]
 [[Category:ADPCM Audio Codecs]]
 [[Category:Undiscovered Audio Codecs]]

Trixter at 23:50, 4 April 2007

2007-04-04T23:50:20Z

← Older revision		Revision as of 16:50, 4 April 2007
Line 2:		Line 2:
	* Samples: [http://samples.mplayerhq.hu/A-codecs/CovoxFormats/ http://samples.mplayerhq.hu/A-codecs/CovoxFormats/]		* Samples: [http://samples.mplayerhq.hu/A-codecs/CovoxFormats/ http://samples.mplayerhq.hu/A-codecs/CovoxFormats/]

	This is a family of [[ADPCM]] formats used for compressing 8-bit unsigned [[PCM]] for Covox Sound Master. There are 2-,3- and 4-bit ADPCM formats.		This is a family of [[ADPCM]] formats used for compressing 8-bit unsigned [[PCM]]. They were invented by Covox for use with the Covox Speech Thing, Sound Master, and other Covox sound output devices. There are 2-,3- and 4-bit ADPCM formats.

	== Header ==		== Header ==

	File header consists of 16 bytes:		File header consists of 16 bytes:

	FF 55 FF AA FF 55 FF AA		FF 55 FF AA FF 55 FF AA xx yy pp pp pp pp 00 00
	<type> - ~~1 byte~~		xx - encoding type
	unknown/unused ~~- 7 bytes~~		yy - playback rate (rate != sample rate, rather the timer tick rate divisor used for playback)
			pp - unsigned longint meant to indicate unpacked size (mostly unused)
			00 - unknown/unused

	Type may be one of the following:		Type may be one of the following:
	* 0x08 - raw 8-bit unsigned PCM
	* 0x82 - 2-bit ADPCM		* 0x01 - 1-bit ADPCM
	* 0x83 - 3-bit ADPCM		* 0x02 - 2-bit ADPCM
	* 0x84 - 4-bit ADPCM		* 0x03 - 3-bit ADPCM
			* 0x04 - 4-bit ADPCM
			* 0x08 - raw 8-bit unsigned PCM
			* 0x81 - 1-bit ADPCM with silence encoding
			* 0x82 - 2-bit ADPCM with silence encoding
			* 0x83 - 3-bit ADPCM with silence encoding
			* 0x84 - 4-bit ADPCM with silence encoding
			* 0x88 - 8-bit PCM with silence encoding

			The first 8 bytes are a unique code guaranteed not to show up inside the rest of file. This means that multiple PCM files can be concatenated together and the locations found by looking for the headers.

	== Markers ==		== Markers ==

	There are two types of markers known:		There are two types of markers known:

Kostya: Fill info about 3- and 2-bit ADPCM too

2007-04-03T06:26:05Z

Fill info about 3- and 2-bit ADPCM too

← Older revision		Revision as of 23:26, 2 April 2007
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	* FF AA AA AA - end of sound		* FF AA AA AA - end of sound

	== 4-bit ADPCM ==		For 3-bit ADPCM they are cut to 3 bytes (FF 55 55 and FF AA AA respectively).

			After silence block ADPCM decoding state should be reset.

			== ADPCM decoding ==

			This is generalized decoding procedure for all know ADPCM variants. <i>n</i> will denote the number of bits used in ADPCM (<i>n</i>=2 for 2-bit ADPCM, etc).

	Decoding procedure:		Decoding procedure:
	# ~~read~~ 4 bytes		# look at the next 3 or 4 bytes, if they make a marker, do action for this marker
	# if they make a marker, do action for this marker		# read <i>n</i> bytes
	# decode 8 deltas from it by taking high bits from 4 values and shifting them		# decode 8 deltas from them by taking high bits from <i>n</i> values and shifting them
	# apply these deltas to get decoded values		# apply these deltas to get decoded values

	Update procedure:		Update procedure:

	mul = step_table[step] * mult_table[delta & 7];		high_bit = 1 << (n-1);
	if(delta & 8)		low_bits = (1 << (n-1)) - 1;
			mul = step_table[step] * mult_table[delta & low_bits];
			if(delta & high_bit)
	val -= mul;		val -= mul;
	else		else
	val += mul;		val += mul;
	val = clip(val, 0, 0xFFFF);		val = clip(val, 0, 0xFFFF);
	step = clip(step + step_update_table[delta & 7], 0, 71);		step = clip(step + step_update_table[delta & low_bits], 0, step_max);

			== ADPCM Tables ==

	Step table:		{\| border="1" cellpadding="5" style="border-collapse: collapse; border-style: dashed; border-color: #2f6fab;"
			\|- bgcolor="#f0f0f0" \|
			! Value !! 4-bit ADPCM !! 3-bit ADPCM !! 2-bit ADPCM
			\|-
			\| Max. step value \|\| 72 \|\| 96 \|\| 80
			\|-
			\| Step update table
			\| -8, -6, -4, -2, 2, 4, 8, 16
			\| -4, -2, 4, 16
			\| -6, 6
			\|-
			\| Multiplication table
			\| 0.5, 1.0, 2.0, 3.0, 4.5, 5.0, 9.0, 12.0
			\| 1.0, 1.5, 2.0, 2.5
			\| 1.0, 3.0
			\|}

			Step table (it has much more values than needed):

	0x0080, 0x008C, 0x0098, 0x00A6, 0x00B5, 0x00C5, 0x00D7, 0x00EB,		0x0080, 0x008C, 0x0098, 0x00A6, 0x00B5, 0x00C5, 0x00D7, 0x00EB,
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	0x2000, 0x22E5, 0x260E, 0x2980, 0x2D41, 0x315A, 0x35D1, 0x3AB0,		0x2000, 0x22E5, 0x260E, 0x2980, 0x2D41, 0x315A, 0x35D1, 0x3AB0,
	0x4000, 0x45CB, 0x4C1C, 0x52FF, 0x5A82, 0x62B4, 0x6BA2, 0x7560,		0x4000, 0x45CB, 0x4C1C, 0x52FF, 0x5A82, 0x62B4, 0x6BA2, 0x7560,
	0x8000, 0x8B96, 0x9838, 0xA5FF, 0xB505, 0xC567, 0xD745, 0xEAC1		0x8000, 0x8B96, 0x9838, 0xA5FF, 0xB505, 0xC567, 0xD745, 0xEAC1,

	~~Step update table:~~		0x00C0, 0x00D1, 0x00E4, 0x00F9, 0x0110, 0x0128, 0x0143, 0x0160,
			0x0180, 0x01A3, 0x01C9, 0x01F2, 0x021F, 0x0250, 0x0286, 0x02C0,
	-8, -6, -4, -2, 2, 4, 8, ~~16};~~		0x0300, 0x0346, 0x0391, 0x03E4, 0x043E, 0x04A0, 0x050C, 0x0581,
	~~Multiplication table:~~		0x0600, 0x068B, 0x0723, 0x07C8, 0x087C, 0x0941, 0x0A17, 0x0B01,
			0x0C00, 0x0D16, 0x0E45, 0x0F90, 0x10F8, 0x1282, 0x142E, 0x1602,
	~~0.5~~, ~~1.0~~, ~~2.0~~, ~~3.0~~, ~~4.5~~, ~~5.0~~, ~~9.0~~, ~~12.0};~~		0x1800, 0x1A2C, 0x1C8A, 0x1F20, 0x21F1, 0x2503, 0x285D, 0x2C04,

	~~== 3-bit ADPCM ==~~		0x0240, 0x0274, 0x02AD, 0x02EB, 0x032F, 0x0378, 0x03C9, 0x0420,
			0x0480, 0x04E8, 0x055A, 0x05D6, 0x065D, 0x06F1, 0x0791, 0x0841,
	~~== 2-bit ADPCM ==~~		0x0900, 0x09D1, 0x0AB4, 0x0BAC, 0x0CBA, 0x0DE1, 0x0F23, 0x1082,
			0x1200, 0x13A1, 0x1568, 0x1758, 0x1975, 0x1BC3, 0x1E46, 0x2103,
			0x2400, 0x2742, 0x2AD0, 0x2EB0, 0x32E9, 0x3785, 0x3C8B, 0x4206,
			0x4800, 0x4E84, 0x559F, 0x5D5F, 0x65D3, 0x6F0A, 0x7917, 0x840C,

			0x02C0, 0x0300, 0x0345, 0x0391, 0x03E4, 0x043E, 0x04A0, 0x050B,
			0x0580, 0x05FF, 0x068A, 0x0722, 0x07C7, 0x087B, 0x0940, 0x0A16,
			0x0B00, 0x0BFF, 0x0D15, 0x0E44, 0x0F8E, 0x10F7, 0x1280, 0x142D,
			0x1600, 0x17FE, 0x1A2A, 0x1C88, 0x1F1D, 0x21EE, 0x2500, 0x2859,
			0x2C00, 0x2FFB, 0x3453, 0x3910, 0x3E3A, 0x43DB, 0x4A00, 0x50B2,
			0x5800, 0x5FF7, 0x68A6, 0x721F, 0x7C73, 0x87B7, 0x93FF, 0xA165,

			0x03C0, 0x0417, 0x0476, 0x04DD, 0x054E, 0x05C9, 0x064F, 0x06E1,
			0x0780, 0x082E, 0x08EB, 0x09BA, 0x0A9B, 0x0B91, 0x0C9D, 0x0DC1,
			0x0F00, 0x105C, 0x11D7, 0x1374, 0x1537, 0x1722, 0x193A, 0x1B83,
			0x1E00, 0x20B7, 0x23AD, 0x26E8, 0x2A6D, 0x2E44, 0x3274, 0x3705,
			0x3C00, 0x416E, 0x475A, 0x4DCF, 0x54DA, 0x5C88, 0x64E8, 0x6E0A,
			0x7800, 0x82DC, 0x8EB4, 0x9B9F, 0xA9B5, 0xB911, 0xC9D1, 0xDC15

	[[Category:Audio Codecs]]		[[Category:Audio Codecs]]
	[[Category:ADPCM Audio Codecs]]		[[Category:ADPCM Audio Codecs]]
	[[Category:Undiscovered Audio Codecs]]		[[Category:Undiscovered Audio Codecs]]

Multimedia Mike: /* 4-bit ADPCM */ make a numbered list

2007-03-26T17:14:34Z

4-bit ADPCM: make a numbered list

← Older revision		Revision as of 10:14, 26 March 2007
Line 26:		Line 26:

	Decoding procedure:		Decoding procedure:
	1. read 4 bytes		# read 4 bytes
	2. if they make a marker, do action for this marker		# if they make a marker, do action for this marker
	3. decode 8 deltas from it by taking high bits from 4 values and shifting them		# decode 8 deltas from it by taking high bits from 4 values and shifting them
	4. apply these deltas to get decoded values		# apply these deltas to get decoded values

	Update procedure:		Update procedure:

Kostya: That's all I know about it

2007-03-26T10:44:26Z

That's all I know about it

New page

* Company: [[Covox]]
* Samples: [http://samples.mplayerhq.hu/A-codecs/CovoxFormats/ http://samples.mplayerhq.hu/A-codecs/CovoxFormats/]

This is a family of [[ADPCM]] formats used for compressing 8-bit unsigned [[PCM]] for Covox Sound Master. There are 2-,3- and 4-bit ADPCM formats.

== Header ==
File header consists of 16 bytes:

FF 55 FF AA FF 55 FF AA
<type> - 1 byte
unknown/unused - 7 bytes

Type may be one of the following:
* 0x08 - raw 8-bit unsigned PCM
* 0x82 - 2-bit ADPCM
* 0x83 - 3-bit ADPCM
* 0x84 - 4-bit ADPCM

== Markers ==
There are two types of markers known:

* FF 55 55 55 - silence block, next 16-bit little-endian value specifies number of silence samples - 27
* FF AA AA AA - end of sound

== 4-bit ADPCM ==

Decoding procedure:
1. read 4 bytes
2. if they make a marker, do action for this marker
3. decode 8 deltas from it by taking high bits from 4 values and shifting them
4. apply these deltas to get decoded values

Update procedure:

mul = step_table[step] * mult_table[delta & 7];
if(delta & 8)
val -= mul;
else
val += mul;
val = clip(val, 0, 0xFFFF);
step = clip(step + step_update_table[delta & 7], 0, 71);

Step table:

0x0080, 0x008C, 0x0098, 0x00A6, 0x00B5, 0x00C5, 0x00D7, 0x00EB,
0x0100, 0x0117, 0x0130, 0x014C, 0x016A, 0x018B, 0x01AF, 0x01D6,
0x0200, 0x022E, 0x0261, 0x0298, 0x02D4, 0x0316, 0x035D, 0x03AB,
0x0400, 0x045D, 0x04C2, 0x0530, 0x05A8, 0x062B, 0x06BA, 0x0756,
0x0800, 0x08B9, 0x0983, 0x0A60, 0x0B50, 0x0C56, 0x0D74, 0x0EAC,
0x1000, 0x1173, 0x1307, 0x14C0, 0x16A1, 0x18AD, 0x1AE9, 0x1D58,
0x2000, 0x22E5, 0x260E, 0x2980, 0x2D41, 0x315A, 0x35D1, 0x3AB0,
0x4000, 0x45CB, 0x4C1C, 0x52FF, 0x5A82, 0x62B4, 0x6BA2, 0x7560,
0x8000, 0x8B96, 0x9838, 0xA5FF, 0xB505, 0xC567, 0xD745, 0xEAC1

Step update table:

-8, -6, -4, -2, 2, 4, 8, 16};
Multiplication table:

0.5, 1.0, 2.0, 3.0, 4.5, 5.0, 9.0, 12.0};

== 3-bit ADPCM ==

== 2-bit ADPCM ==

[[Category:Audio Codecs]]
[[Category:ADPCM Audio Codecs]]
[[Category:Undiscovered Audio Codecs]]