Apple Lossless Audio Coding - Revision history

Multimedia Mike: link to recently open sourced codec

2011-10-28T01:08:47Z

link to recently open sourced codec

← Older revision		Revision as of 18:08, 27 October 2011
Line 4:		Line 4:
	* Samples: http://samples.mplayerhq.hu/A-codecs/lossless/ (luckynight.m4a)		* Samples: http://samples.mplayerhq.hu/A-codecs/lossless/ (luckynight.m4a)

	Lossless ~~audio coding~~ using linear prediction with [[Golomb\|Golomb-Rice]] coding of the difference. Similar to FLAC, although the bitstreams are not compatible. Usually stored in an [[MP4]] container, as a private extension since it is not part of the MPEG-4 standard.		Apple Lossless Audio Coding using linear prediction with [[Golomb\|Golomb-Rice]] coding of the difference. Similar to FLAC, although the bitstreams are not compatible. Usually stored in an [[MP4]] container, as a private extension since it is not part of the MPEG-4 standard.

			On October 27, 2011, ALAC was open sourced under the Apache License 2.0. The source can be found at [http://alac.macosforge.org/ http://alac.macosforge.org/].

	=== Extradata ===		=== Extradata ===

Crybaby: Linkify Golomb-Rice

2007-08-16T07:38:16Z

Linkify Golomb-Rice

← Older revision		Revision as of 00:38, 16 August 2007
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	* Samples: http://samples.mplayerhq.hu/A-codecs/lossless/ (luckynight.m4a)		* Samples: http://samples.mplayerhq.hu/A-codecs/lossless/ (luckynight.m4a)

	Lossless audio coding using linear prediction with Golomb-Rice coding of the difference. Similar to FLAC, although the bitstreams are not compatible. Usually stored in an [[MP4]] container, as a private extension since it is not part of the MPEG-4 standard.		Lossless audio coding using linear prediction with [[Golomb\|Golomb-Rice]] coding of the difference. Similar to FLAC, although the bitstreams are not compatible. Usually stored in an [[MP4]] container, as a private extension since it is not part of the MPEG-4 standard.

	=== Extradata ===		=== Extradata ===

DonDiego: link fix

2007-03-21T17:29:45Z

link fix

← Older revision		Revision as of 10:29, 21 March 2007
Line 4:		Line 4:
	* Samples: http://samples.mplayerhq.hu/A-codecs/lossless/ (luckynight.m4a)		* Samples: http://samples.mplayerhq.hu/A-codecs/lossless/ (luckynight.m4a)

	Lossless audio coding using linear prediction with Golomb-Rice coding of the difference. Similar to FLAC, although the bitstreams are not compatible. Usually stored in an [[~~Apple QuickTime\|~~MP4]] container, as a private extension since it is not part of the MPEG-4 standard.		Lossless audio coding using linear prediction with Golomb-Rice coding of the difference. Similar to FLAC, although the bitstreams are not compatible. Usually stored in an [[MP4]] container, as a private extension since it is not part of the MPEG-4 standard.

	=== Extradata ===		=== Extradata ===

Dashcloud: Update samples link

2006-08-18T03:21:55Z

Update samples link

← Older revision		Revision as of 20:21, 17 August 2006
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	* Company: [[Apple]]		* Company: [[Apple]]
	* Technical Description: http://craz.net/programs/itunes/alac.html		* Technical Description: http://craz.net/programs/itunes/alac.html
	* Samples: http://mplayerhq.hu~~/MPlayer/samples~~/A-codecs/lossless/ (luckynight.m4a)		* Samples: http://samples.mplayerhq.hu/A-codecs/lossless/ (luckynight.m4a)

	Lossless audio coding using linear prediction with Golomb-Rice coding of the difference. Similar to FLAC, although the bitstreams are not compatible. Usually stored in an [[Apple QuickTime\|MP4]] container, as a private extension since it is not part of the MPEG-4 standard.		Lossless audio coding using linear prediction with Golomb-Rice coding of the difference. Similar to FLAC, although the bitstreams are not compatible. Usually stored in an [[Apple QuickTime\|MP4]] container, as a private extension since it is not part of the MPEG-4 standard.

Mat: /* Frame Header */

2006-06-04T18:01:00Z

Frame Header

← Older revision		Revision as of 11:01, 4 June 2006
Line 56:		Line 56:
	\| isverbatim \|\| 1 \|\| if 1, the data is not compressed		\| isverbatim \|\| 1 \|\| if 1, the data is not compressed
	\|-		\|-
	\| if (~~hassize~~) { \|\| \|\|		\| if (hasoutputsamples) { \|\| \|\|
	\|-		\|-
	\| outputsamples \|\| 32 \|\| number of samples (sometimes the value is wrong [1])		\| outputsamples \|\| 32 \|\| number of samples (sometimes the value is wrong [1])

Mat: /* Frame Header */

2006-06-04T18:00:24Z

Frame Header

← Older revision		Revision as of 11:00, 4 June 2006
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	\| channels \|\| 3 \|\| Number of channel -1 (Should be the same than in extradata ???)		\| channels \|\| 3 \|\| Number of channel -1 (Should be the same than in extradata ???)
	\|-		\|-
	\| ??? \|\| 4 \|\| ???		\| ??? \|\| 4 \|\| ??? (seem to be always 0)
	\|-		\|-
	\| ??? \|\| 12 \|\| ???		\| ??? \|\| 12 \|\| ??? (seem to be always 0)
	\|-		\|-
	\| hasoutputsamples \|\| 1 \|\| the number of samples is stored in the header		\| hasoutputsamples \|\| 1 \|\| the number of samples is stored in the header

Mat: /* Frame Header */

2006-06-04T17:52:57Z

Frame Header

← Older revision		Revision as of 10:52, 4 June 2006
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	\| if (hassize) { \|\| \|\|		\| if (hassize) { \|\| \|\|
	\|-		\|-
	\| outputsamples \|\| 32 \|\| number of samples		\| outputsamples \|\| 32 \|\| number of samples (sometimes the value is wrong [1])
	\|-		\|-
	\| } \|\| \|\|		\| } \|\| \|\|
	\|}		\|}


			[1] http://www1.mplayerhq.hu/MPlayer/samples/A-codecs/lossless/luckynight.m4a need + 32 and http://www1.mplayerhq.hu/MPlayer/samples/A-codecs/lossless/ALAC/old_midi_stuff.m4a + 112

	=== Verbatim frame ===		=== Verbatim frame ===

Mat at 16:50, 26 May 2006

2006-05-26T16:50:21Z

← Older revision		Revision as of 09:50, 26 May 2006
Line 106:		Line 106:
	:''right = mid - ((difference * interlacing_leftweight) >> interlacing_shift)''		:''right = mid - ((difference * interlacing_leftweight) >> interlacing_shift)''
	:''left = right + difference''		:''left = right + difference''

			It seems we have interlacing_leftweight == interlacing_shift in most of the samples

			=== Frame Footer ===
			{\| border="1"
			! Syntax !! Number of bits !! Semantics
			\|-
			\| EOF \|\| 3 \|\| should be always 7
			\|}

	[[Category:Lossless Audio Codecs]]		[[Category:Lossless Audio Codecs]]
	[[Category:Audio Codecs]]		[[Category:Audio Codecs]]

Multimedia Mike: sample link

2006-05-25T21:40:54Z

sample link

← Older revision		Revision as of 14:40, 25 May 2006
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	* FOURCCS: alac		* FOURCCS: alac
	* Company: [[Apple]]		* Company: [[Apple]]
	* Technical Description: [http://craz.net/programs/itunes/alac.html http://~~craz~~.~~net~~/~~programs~~/~~itunes~~/~~alac~~.~~html]~~		* Technical Description: http://craz.net/programs/itunes/alac.html
			* Samples: http://mplayerhq.hu/MPlayer/samples/A-codecs/lossless/ (luckynight.m4a)

	Lossless audio coding using linear prediction with Golomb-Rice coding of the difference. Similar to FLAC, although the bitstreams are not compatible. Usually stored in an [[Apple QuickTime\|MP4]] container, as a private extension since it is not part of the MPEG-4 standard.		Lossless audio coding using linear prediction with Golomb-Rice coding of the difference. Similar to FLAC, although the bitstreams are not compatible. Usually stored in an [[Apple QuickTime\|MP4]] container, as a private extension since it is not part of the MPEG-4 standard.

Mat at 21:18, 25 May 2006

2006-05-25T21:18:35Z

← Older revision		Revision as of 14:18, 25 May 2006
Line 4:		Line 4:

	Lossless audio coding using linear prediction with Golomb-Rice coding of the difference. Similar to FLAC, although the bitstreams are not compatible. Usually stored in an [[Apple QuickTime\|MP4]] container, as a private extension since it is not part of the MPEG-4 standard.		Lossless audio coding using linear prediction with Golomb-Rice coding of the difference. Similar to FLAC, although the bitstreams are not compatible. Usually stored in an [[Apple QuickTime\|MP4]] container, as a private extension since it is not part of the MPEG-4 standard.

			=== Extradata ===

			{\| border="1"
			! Syntax !! Number of bits !! Semantics
			\|-
			\|atom size \|\| 32 \|\| (0x24), big-endian
			\|-
			\|tag \|\| 32 \|\| 'alac'
			\|-
			\|??? \|\| 32 \|\| zero ?
			\|-
			\|max sample per frame \|\| 32 \|\|
			\|-
			\|??? \|\| 8 \|\| zero ?
			\|-
			\|sample size \|\| 8 \|\|
			\|-
			\|rice history mult \|\| 8 \|\|
			\|-
			\|rice initial history \|\| 8 \|\|
			\|-
			\|rice kmodifier \|\| 8 \|\|
			\|-
			\|channels \|\| 8 \|\| ?
			\|-
			\|??? \|\| 16 \|\|
			\|-
			\|max coded frame size \|\| 32 \|\|
			\|-
			\|bitrate \|\| 32 \|\| ?
			\|-
			\|samplerate \|\| 32 \|\|
			\|}

	=== Frame Header ===		=== Frame Header ===