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https://codeberg.org/ashley/poke.git
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45 lines
2.9 KiB
Text
45 lines
2.9 KiB
Text
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The Apple Lossless Format
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Apple Lossless supports the following features. Not all of these are implemented in alacconvert, though they are in the codec code provided.
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1. Bit depths 16, 20, 24 and 32 bits.
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2. Any arbitrary integer sample rate from 1 to 384,000 Hz. In theory rates up to 4,294,967,295 (2^32 - 1) Hz could be supported.
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3. From one to eight channels are supported. Channel orders for the supported formats are described as:
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Num Chan Order
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1 mono
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2 stereo (Left, Right)
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3 MPEG 3.0 B (Center, Left, Right)
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4 MPEG 4.0 B (Center, Left, Right, Center Surround)
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5 MPEG 5.0 D (Center, Left, Right, Left Surround, Right Surround)
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6 MPEG 5.1 D (Center, Left, Right, Left Surround, Right Surround, Low Frequency Effects)
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7 Apple AAC 6.1 (Center, Left, Right, Left Surround, Right Surround, Center Surround, Low Frequency Effects)
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8 MPEG 7.1 B (Center, Left Center, Right Center, Left, Right, Left Surround, Right Surround, Low Frequency Effects)
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4. Packet size defaults to 4096 sample frames of audio per packet. Other packet sizes are certainly possible. However, non-default packet sizes are not guaranteed to work properly on all hardware devices that support Apple Lossless. Packets above 16,384 sample frames are not supported.
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This package contains the sources for the Apple Lossless (ALAC) encoder and decoder.
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The "codec" directory contains all the sources necessary for a functioning codec. Also includes is a makefile that will build libalac.a on a UNIX/Linux machine.
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ALACconvert
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The convert-utility directory contains sources to build alacconvert which is a simple utility that demonstrates how to use the included ALAC encoder and decoder.
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alacconvert supports the following formats:
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1. 16- or 24-bit mono or stereo .wav files where the data is little endian integer. Extended WAVE format chunks are not handled.
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2. 16- or 24-bit mono or stereo .caf (Core Audio Format) files as well as certain multi-channel configurations where the data is big or little endian integer. It does no channel order manipulation.
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3. ALAC .caf files.
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Three project are provided to build a command line utility called alacconvert that converts cpm data to ALAC or vice versa. A Mac OS X Xcode project, A Windows Visual Studio project, and a generic UNIX/Linux make file.
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Note: When building on Windows, if you are using a version of Visual Studio before Visual Studio 2010, <stdint.h> is not installed. You will need to acquire this file on your own. It can be put in the same directory as the project.
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