Microsoft ADPCM - Revision history

Lord Nightmare: fix links

2019-04-04T03:10:33Z

fix links

← Older revision		Revision as of 20:10, 3 April 2019
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	int AdaptCoeff2 [] = { 0, -256, 0, 64, 0, -208, -232 } ;		int AdaptCoeff2 [] = { 0, -256, 0, 64, 0, -208, -232 } ;

	The adaptation table comes from Jayant's 1973 [[https://archive.org/details/bstj52-7-1119~~\|paper]~~] (Table VIII, 'DPCM' column, B=4).		The adaptation table comes from Jayant's 1973 paper [https://archive.org/details/bstj52-7-1119] (Table VIII, 'DPCM' column, B=4).
	This paper, along with its companion [[https://archive.org/details/bstj52-7-1105~~\|paper]~~] originally coined the term "ADPCM".		This paper, along with its companion paper [https://archive.org/details/bstj52-7-1105] originally coined the term "ADPCM".

	The relevant values from the paper are:		The relevant values from the paper are:

Lord Nightmare: clean up links to papers, changed to link to archive.org pages for said papers rather than direct to pdfs

2019-04-04T03:08:52Z

clean up links to papers, changed to link to archive.org pages for said papers rather than direct to pdfs

← Older revision		Revision as of 20:08, 3 April 2019
Line 53:		Line 53:
	int AdaptCoeff2 [] = { 0, -256, 0, 64, 0, -208, -232 } ;		int AdaptCoeff2 [] = { 0, -256, 0, 64, 0, -208, -232 } ;

	The adaptation table comes from Jayant's 1973 ~~paper~~ https://~~ia902600.us.~~archive.org/~~31/items~~/bstj52-7-1119~~/bstj52-7-1119.pdf~~ (Table VIII, 'DPCM' column, B=4).		The adaptation table comes from Jayant's 1973 [[https://archive.org/details/bstj52-7-1119\|paper]] (Table VIII, 'DPCM' column, B=4).
	This paper, along with its companion ~~paper~~ https://~~ia902601.us.~~archive.org/~~13/items~~/bstj52-7-1105~~/bstj52-7-1105.pdf~~ originally coined the term "ADPCM".		This paper, along with its companion [[https://archive.org/details/bstj52-7-1105\|paper]] originally coined the term "ADPCM".

	The relevant values from the paper are:		The relevant values from the paper are:

Lord Nightmare: fix an error in the last sentence

2019-02-20T20:53:28Z

fix an error in the last sentence

← Older revision		Revision as of 13:53, 20 February 2019
Line 63:		Line 63:
	To obtain the table used by Microsoft ADPCM, multiply the values from Jayant's table by 256 and round down. The adaptation table holds the absolute step size values for signed input nybbles of		To obtain the table used by Microsoft ADPCM, multiply the values from Jayant's table by 256 and round down. The adaptation table holds the absolute step size values for signed input nybbles of
	{ 0, 1, 2, 3, 4, 5, 6, 7, -8, -7, -6, -5, -4, -3, -2, -1 }		{ 0, 1, 2, 3, 4, 5, 6, 7, -8, -7, -6, -5, -4, -3, -2, -1 }
	in that order, so take the ~~absolute~~ value of the nybble and use that as an offset into the table.		in that order, so take the unsigned value of the (signed) nybble and use that as an offset into the table.

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

Lord Nightmare: add note about the predictor values, and that others can be added

2017-12-28T20:41:32Z

add note about the predictor values, and that others can be added

← Older revision		Revision as of 13:41, 28 December 2017
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	A monaural block begins with the following preamble:		A monaural block begins with the following preamble:

	byte 0 block predictor (~~should be~~ in the range [0..6])		byte 0 block predictor (builtin predictors are in the range [0..6] but others can be manually defined)
	bytes 1-2 initial delta		bytes 1-2 initial delta
	bytes 3-4 sample 1		bytes 3-4 sample 1
Line 49:		Line 49:
	768, 614, 512, 409, 307, 230, 230, 230		768, 614, 512, 409, 307, 230, 230, 230
	} ;		} ;
			// These are the 'built in' set of 7 predictor value pairs; additional values can be added to this table by including them as metadata chunks in the WAVE header
	int AdaptCoeff1 [] = { 256, 512, 0, 192, 240, 460, 392 } ;		int AdaptCoeff1 [] = { 256, 512, 0, 192, 240, 460, 392 } ;
	int AdaptCoeff2 [] = { 0, -256, 0, 64, 0, -208, -232 } ;		int AdaptCoeff2 [] = { 0, -256, 0, 64, 0, -208, -232 } ;

Lord Nightmare: clarify 'short' ID

2017-10-30T06:18:01Z

clarify 'short' ID

← Older revision		Revision as of 23:18, 29 October 2017
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	* FOURCC: 'm','s',0x00,0x02		* FOURCC: 'm','s',0x00,0x02
	* Company: [[Microsoft]]		* Company: [[Microsoft]]
	* wFormatTag ID: WAVE_FORMAT_ADPCM or MS_ADPCM		* wFormatTag ID: WAVE_FORMAT_ADPCM
			* 'short' ID: MS_ADPCM
	* ACM Codec: 'msadp32.acm' (included in Windows 95+)		* ACM Codec: 'msadp32.acm' (included in Windows 95+)

Lord Nightmare: add wFormatTag ID

2017-10-30T02:41:16Z

add wFormatTag ID

← Older revision		Revision as of 19:41, 29 October 2017
Line 2:		Line 2:
	* FOURCC: 'm','s',0x00,0x02		* FOURCC: 'm','s',0x00,0x02
	* Company: [[Microsoft]]		* Company: [[Microsoft]]
			* wFormatTag ID: WAVE_FORMAT_ADPCM or MS_ADPCM
	* ACM Codec: 'msadp32.acm' (included in Windows 95+)		* ACM Codec: 'msadp32.acm' (included in Windows 95+)

Lord Nightmare: fix typo

2017-10-29T02:07:19Z

fix typo

← Older revision		Revision as of 19:07, 28 October 2017
Line 2:		Line 2:
	* FOURCC: 'm','s',0x00,0x02		* FOURCC: 'm','s',0x00,0x02
	* Company: [[Microsoft]]		* Company: [[Microsoft]]
	* ACM Codec: '~~msadpm32~~.acm' (included in Windows 95+)		* ACM Codec: 'msadp32.acm' (included in Windows 95+)

	This format is Microsoft's own custom variation of the ADPCM concept.		This format is Microsoft's own custom variation of the ADPCM concept.

Lord Nightmare: add acm codec info

2017-10-29T02:06:49Z

add acm codec info

← Older revision		Revision as of 19:06, 28 October 2017
Line 2:		Line 2:
	* FOURCC: 'm','s',0x00,0x02		* FOURCC: 'm','s',0x00,0x02
	* Company: [[Microsoft]]		* Company: [[Microsoft]]
			* ACM Codec: 'msadpm32.acm' (included in Windows 95+)

	This format is Microsoft's own custom variation of the ADPCM concept.		This format is Microsoft's own custom variation of the ADPCM concept.

Lord Nightmare: add another Jayant paper, some clarification

2017-10-27T09:17:01Z

add another Jayant paper, some clarification

← Older revision		Revision as of 02:17, 27 October 2017
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	int AdaptCoeff2 [] = { 0, -256, 0, 64, 0, -208, -232 } ;		int AdaptCoeff2 [] = { 0, -256, 0, 64, 0, -208, -232 } ;

	The ~~AdaptationTable~~ comes from Jayant's 1973 paper https://ia902600.us.archive.org/31/items/bstj52-7-1119/bstj52-7-1119.pdf Table VIII, 'DPCM' column, B=4. The values from ~~this~~ paper are:		The adaptation table comes from Jayant's 1973 paper https://ia902600.us.archive.org/31/items/bstj52-7-1119/bstj52-7-1119.pdf (Table VIII, 'DPCM' column, B=4).
			This paper, along with its companion paper https://ia902601.us.archive.org/13/items/bstj52-7-1105/bstj52-7-1105.pdf originally coined the term "ADPCM".

			The relevant values from the paper are:
	{ 0.9, 0.9, 0.9, 0.9, 1.2, 1.6, 2.0, 2.4 }		{ 0.9, 0.9, 0.9, 0.9, 1.2, 1.6, 2.0, 2.4 }
	and Microsoft added an implicit '3.0' value as a 9th entry.		and Microsoft added an implicit '3.0' value as a 9th entry, for a final table of:
			{ 0.9, 0.9, 0.9, 0.9, 1.2, 1.6, 2.0, 2.4, 3.0 }

	To obtain the table used by Microsoft ADPCM, multiply the values from Jayant's table by 256 and round down. The adaptation table holds the absolute step size values for signed input nybbles of		To obtain the table used by Microsoft ADPCM, multiply the values from Jayant's table by 256 and round down. The adaptation table holds the absolute step size values for signed input nybbles of

Lord Nightmare: formatting

2017-10-27T08:39:49Z

formatting

← Older revision		Revision as of 01:39, 27 October 2017
Line 49:		Line 49:
	int AdaptCoeff2 [] = { 0, -256, 0, 64, 0, -208, -232 } ;		int AdaptCoeff2 [] = { 0, -256, 0, 64, 0, -208, -232 } ;

	The AdaptationTable comes from Jayant's 1973 paper https://ia902600.us.archive.org/31/items/bstj52-7-1119/bstj52-7-1119.pdf Table VIII, 'DPCM' column, B=4. The values from this paper are { 0.9, 0.9, 0.9, 0.9, 1.2, 1.6, 2.0, 2.4 }, and Microsoft added an implicit '3.0' value as a 9th entry.		The AdaptationTable comes from Jayant's 1973 paper https://ia902600.us.archive.org/31/items/bstj52-7-1119/bstj52-7-1119.pdf Table VIII, 'DPCM' column, B=4. The values from this paper are:
			{ 0.9, 0.9, 0.9, 0.9, 1.2, 1.6, 2.0, 2.4 }
			and Microsoft added an implicit '3.0' value as a 9th entry.

	To obtain the table used by Microsoft ADPCM, multiply the values from Jayant's table by 256 and round down. The adaptation table holds the absolute step size values for signed input nybbles of { 0, 1, 2, 3, 4, 5, 6, 7, -8, -7, -6, -5, -4, -3, -2, -1 } in that order, so take the absolute value of the nybble and use that as an offset into the table.		To obtain the table used by Microsoft ADPCM, multiply the values from Jayant's table by 256 and round down. The adaptation table holds the absolute step size values for signed input nybbles of
			{ 0, 1, 2, 3, 4, 5, 6, 7, -8, -7, -6, -5, -4, -3, -2, -1 }
			in that order, so take the absolute value of the nybble and use that as an offset into the table.

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