53 lines
2.5 KiB
Text
53 lines
2.5 KiB
Text
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////////////////////////////////////////////////////////////////////////////
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// **** WAVPACK **** //
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// Hybrid Lossless Wavefile Compressor //
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// Copyright (c) 1998 - 2004 Conifer Software. //
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// All Rights Reserved. //
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// Distributed under the BSD Software License (see license.txt) //
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////////////////////////////////////////////////////////////////////////////
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This package contains a tiny version of the WavPack 4.0 decoder that might
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be used in a "resource limited" CPU environment or form the basis for a
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hardware decoding implementation. It is packaged with a demo command-line
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program that accepts a WavPack audio file on stdin and outputs a RIFF wav
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file to stdout. The program is standard C, and a win32 executable is
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included which was compiled under MS Visual C++ 6.0 using this command:
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cl /O1 /DWIN32 wvfilter.c wputils.c unpack.c float.c metadata.c words.c bits.c
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WavPack data is read with a stream reading callback. No direct seeking is
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provided for, but it is possible to start decoding anywhere in a WavPack
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stream. In this case, WavPack will be able to provide the sample-accurate
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position when it synchs with the data and begins decoding.
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For demonstration purposes this uses a single static copy of the
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WavpackContext structure, so obviously it cannot be used for more than one
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file at a time. Also, this decoder will not handle "correction" files, plays
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only the first two channels of multi-channel files, and is limited in
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resolution in some large integer or floating point files (but always
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provides at least 24 bits of resolution). It also will not accept WavPack
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files from before version 4.0.
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To make this code viable on the greatest number of hardware platforms, the
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following are true:
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speed is about 4x realtime on an AMD K6 300 MHz
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("high" mode 16/44 stereo; normal mode is about twice that fast)
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no floating-point math required; just 32b * 32b = 32b int multiply
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large data areas are static and less than 4K total
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executable code and tables are less than 32K
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no malloc / free usage
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To maintain compatibility on various platforms, the following conventions
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are used:
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a "short" must be 16-bits
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a "long" must be 32-bits
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an "int" must be at least 16-bits, but may be larger
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a "char" must default to signed
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Questions or comments should be directed to david@wavpack.com
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