Duck DK3 IMA ADPCM - Revision history

Reimar at 19:14, 16 July 2008

2008-07-16T19:14:36Z

← Older revision		Revision as of 12:14, 16 July 2008
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	* Audio ID: 0x0062		* Audio ID: 0x0062
	* Company: [[On2\|Duck/On2]]		* Company: [[On2\|Duck/On2]]
	* Samples: http://samples.mplayerhq.hu/V-codecs/~~DUCK~~/ ~~(sonic3dblast_intro.avi)~~		* Samples: http://samples.mplayerhq.hu/A-codecs/DK3/

	Some Sega Saturn game CDs contain [[Microsoft Audio/Video Interleaved\|AVI]] files which store audio using the Duck DK3 IMA ADPCM algorithm. DK3 ADPCM data can be decoded using the same tables as are used to decode [[IMA ADPCM]] data while using a slightly modified variant of the IMA ADPCM algorithm. The name DK3 apparently comes from the fact that 3 ADPCM nibbles decode to 4 16-bit PCM samples, in contrast to Duck's [[Duck DK4 IMA ADPCM\|DK4 IMA ADPCM]] algorithm, in which 4 ADPCM nibbles decode to 4 16-bit PCM samples.		Some Sega Saturn game CDs contain [[Microsoft Audio/Video Interleaved\|AVI]] files which store audio using the Duck DK3 IMA ADPCM algorithm. DK3 ADPCM data can be decoded using the same tables as are used to decode [[IMA ADPCM]] data while using a slightly modified variant of the IMA ADPCM algorithm. The name DK3 apparently comes from the fact that 3 ADPCM nibbles decode to 4 16-bit PCM samples, in contrast to Duck's [[Duck DK4 IMA ADPCM\|DK4 IMA ADPCM]] algorithm, in which 4 ADPCM nibbles decode to 4 16-bit PCM samples.

Multimedia Mike: link to a specific sample

2008-07-15T04:07:50Z

link to a specific sample

← Older revision		Revision as of 21:07, 14 July 2008
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	* Audio ID: 0x0062		* Audio ID: 0x0062
	* Company: [[On2\|Duck/On2]]		* Company: [[On2\|Duck/On2]]
			* Samples: http://samples.mplayerhq.hu/V-codecs/DUCK/ (sonic3dblast_intro.avi)

	Some Sega Saturn game CDs contain [[Microsoft Audio/Video Interleaved\|AVI]] files which store audio using the Duck DK3 IMA ADPCM algorithm. DK3 ADPCM data can be decoded using the same tables as are used to decode [[IMA ADPCM]] data while using a slightly modified variant of the IMA ADPCM algorithm. The name DK3 apparently comes from the fact that 3 ADPCM nibbles decode to 4 16-bit PCM samples, in contrast to Duck's [[Duck DK4 IMA ADPCM\|DK4 IMA ADPCM]] algorithm, in which 4 ADPCM nibbles decode to 4 16-bit PCM samples.		Some Sega Saturn game CDs contain [[Microsoft Audio/Video Interleaved\|AVI]] files which store audio using the Duck DK3 IMA ADPCM algorithm. DK3 ADPCM data can be decoded using the same tables as are used to decode [[IMA ADPCM]] data while using a slightly modified variant of the IMA ADPCM algorithm. The name DK3 apparently comes from the fact that 3 ADPCM nibbles decode to 4 16-bit PCM samples, in contrast to Duck's [[Duck DK4 IMA ADPCM\|DK4 IMA ADPCM]] algorithm, in which 4 ADPCM nibbles decode to 4 16-bit PCM samples.

Multimedia Mike: minor factual nitpick

2006-10-04T16:51:33Z

minor factual nitpick

← Older revision		Revision as of 09:51, 4 October 2006
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	byte 15 initial diff channel index		byte 15 initial diff channel index

	After processing the block preamble, a stream of DK3 data is decoded nibble by nibble, just like ~~any~~ ADPCM ~~data~~. The low nibble is decoded first (bits 3-0), then the high nibble. When decoding the stream, it is useful to conceptualize it as a stream of nibbles:		After processing the block preamble, a stream of DK3 data is decoded nibble by nibble, just like many ADPCM algorithms. The low nibble is decoded first (bits 3-0), then the high nibble. When decoding the stream, it is useful to conceptualize it as a stream of nibbles:

	n0 n1 n2 n3 n4 n5 n6 n7 ...		n0 n1 n2 n3 n4 n5 n6 n7 ...

Multimedia Mike: mainly a game format

2006-03-24T23:03:02Z

mainly a game format

← Older revision		Revision as of 16:03, 24 March 2006
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	[[Category:ADPCM Audio Codecs]]		[[Category:ADPCM Audio Codecs]]
	[[Category:IMA ADPCM Audio Codecs]]		[[Category:IMA ADPCM Audio Codecs]]
			[[Category:Game Formats]]

Multimedia Mike at 20:54, 4 February 2006

2006-02-04T20:54:26Z

New page

* Audio ID: 0x0062
* Company: [[On2|Duck/On2]]

Some Sega Saturn game CDs contain [[Microsoft Audio/Video Interleaved|AVI]] files which store audio using the Duck DK3 IMA ADPCM algorithm. DK3 ADPCM data can be decoded using the same tables as are used to decode [[IMA ADPCM]] data while using a slightly modified variant of the IMA ADPCM algorithm. The name DK3 apparently comes from the fact that 3 ADPCM nibbles decode to 4 16-bit PCM samples, in contrast to Duck's [[Duck DK4 IMA ADPCM|DK4 IMA ADPCM]] algorithm, in which 4 ADPCM nibbles decode to 4 16-bit PCM samples.

All multi-byte values are encoded in little-endian format. The length of a single block of DK3 data is encoded in the nBlockAlign field of an AVI file's [[WAVEFORMATEX]] header.

The DK3 algorithm encodes a sum channel and a difference channel, rather than left and right channels, using the standard IMA ADPCM algorithm and tables. Note that the encoding implies that the format only supports stereo data. A block of DK3 has a 16-byte preamble with the following information:

bytes 0-1 unknown
bytes 2-3 sample rate
bytes 4-9 unknown
bytes 10-11 initial sum channel predictor
bytes 12-13 initial diff channel predictor
byte 14 initial sum channel index
byte 15 initial diff channel index

After processing the block preamble, a stream of DK3 data is decoded nibble by nibble, just like any ADPCM data. The low nibble is decoded first (bits 3-0), then the high nibble. When decoding the stream, it is useful to conceptualize it as a stream of nibbles:

n0 n1 n2 n3 n4 n5 n6 n7 ...

where the nibbles were arranged in the original bytestream as:

byte0 byte1 byte2 byte3
n1n0 n3n2 n5n4 n7n6 ...

Each set of 3 nibbles decodes to 4 16-bit PCM samples using this process (note that the diff value is initialized to the same value as the diff predictor):

* get next ADPCM nibble in stream
* update sum channel predictor and index using nibble
* get next ADPCM nibble in stream
* update diff channel predictor and index using nibble
* diff value = (diff value + diff predictor) / 2
* next left channel PCM sample = sum channel + diff value
* next right channel PCM sample = sum channel - diff value
* get next ADPCM nibble in stream
* update sum channel predictor and index using nibble
* next left channel PCM sample = sum channel + diff value
* next right channel PCM sample = sum channel - diff value

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