160 lines
5.9 KiB
C
160 lines
5.9 KiB
C
/*
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libmpg123: MPEG Audio Decoder library
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separate header just for audio format definitions not tied to
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library code
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copyright 1995-2020 by the mpg123 project
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free software under the terms of the LGPL 2.1
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see COPYING and AUTHORS files in distribution or http://mpg123.org
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*/
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#ifndef MPG123_ENC_H
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#define MPG123_ENC_H
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/** \file fmt123.h Audio format definitions. */
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/** \defgroup mpg123_enc mpg123 PCM sample encodings
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* These are definitions for audio formats used by libmpg123 and
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* libout123.
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*
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* @{
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*/
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/** An enum over all sample types possibly known to mpg123.
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* The values are designed as bit flags to allow bitmasking for encoding
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* families.
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* This is also why the enum is not used as type for actual encoding variables,
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* plain integers (at least 16 bit, 15 bit being used) cover the possible
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* combinations of these flags.
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*
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* Note that (your build of) libmpg123 does not necessarily support all these.
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* Usually, you can expect the 8bit encodings and signed 16 bit.
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* Also 32bit float will be usual beginning with mpg123-1.7.0 .
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* What you should bear in mind is that (SSE, etc) optimized routines may be
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* absent for some formats. We do have SSE for 16, 32 bit and float, though.
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* 24 bit integer is done via postprocessing of 32 bit output -- just cutting
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* the last byte, no rounding, even. If you want better, do it yourself.
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*
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* All formats are in native byte order. If you need different endinaness, you
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* can simply postprocess the output buffers (libmpg123 wouldn't do anything
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* else). The macro MPG123_SAMPLESIZE() can be helpful there.
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*/
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enum mpg123_enc_enum
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{
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/* 0000 0000 0000 1111 Some 8 bit integer encoding. */
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MPG123_ENC_8 = 0x00f
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/* 0000 0000 0100 0000 Some 16 bit integer encoding. */
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, MPG123_ENC_16 = 0x040
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/* 0100 0000 0000 0000 Some 24 bit integer encoding. */
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, MPG123_ENC_24 = 0x4000
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/* 0000 0001 0000 0000 Some 32 bit integer encoding. */
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, MPG123_ENC_32 = 0x100
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/* 0000 0000 1000 0000 Some signed integer encoding. */
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, MPG123_ENC_SIGNED = 0x080
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/* 0000 1110 0000 0000 Some float encoding. */
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, MPG123_ENC_FLOAT = 0xe00
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/* 0000 0000 1101 0000 signed 16 bit */
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, MPG123_ENC_SIGNED_16 = (MPG123_ENC_16|MPG123_ENC_SIGNED|0x10)
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/* 0000 0000 0110 0000 unsigned 16 bit */
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, MPG123_ENC_UNSIGNED_16 = (MPG123_ENC_16|0x20)
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/* 0000 0000 0000 0001 unsigned 8 bit */
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, MPG123_ENC_UNSIGNED_8 = 0x01
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/* 0000 0000 1000 0010 signed 8 bit */
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, MPG123_ENC_SIGNED_8 = (MPG123_ENC_SIGNED|0x02)
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/* 0000 0000 0000 0100 ulaw 8 bit */
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, MPG123_ENC_ULAW_8 = 0x04
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/* 0000 0000 0000 1000 alaw 8 bit */
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, MPG123_ENC_ALAW_8 = 0x08
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/* 0001 0001 1000 0000 signed 32 bit */
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, MPG123_ENC_SIGNED_32 = MPG123_ENC_32|MPG123_ENC_SIGNED|0x1000
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/* 0010 0001 0000 0000 unsigned 32 bit */
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, MPG123_ENC_UNSIGNED_32 = MPG123_ENC_32|0x2000
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/* 0101 0000 1000 0000 signed 24 bit */
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, MPG123_ENC_SIGNED_24 = MPG123_ENC_24|MPG123_ENC_SIGNED|0x1000
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/* 0110 0000 0000 0000 unsigned 24 bit */
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, MPG123_ENC_UNSIGNED_24 = MPG123_ENC_24|0x2000
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/* 0000 0010 0000 0000 32bit float */
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, MPG123_ENC_FLOAT_32 = 0x200
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/* 0000 0100 0000 0000 64bit float */
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, MPG123_ENC_FLOAT_64 = 0x400
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/* Any possibly known encoding from the list above. */
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, MPG123_ENC_ANY = ( MPG123_ENC_SIGNED_16 | MPG123_ENC_UNSIGNED_16
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| MPG123_ENC_UNSIGNED_8 | MPG123_ENC_SIGNED_8
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| MPG123_ENC_ULAW_8 | MPG123_ENC_ALAW_8
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| MPG123_ENC_SIGNED_32 | MPG123_ENC_UNSIGNED_32
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| MPG123_ENC_SIGNED_24 | MPG123_ENC_UNSIGNED_24
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| MPG123_ENC_FLOAT_32 | MPG123_ENC_FLOAT_64 )
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};
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/** Get size of one PCM sample with given encoding.
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* This is included both in libmpg123 and libout123. Both offer
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* an API function to provide the macro results from library
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* compile-time, not that of you application. This most likely
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* does not matter as I do not expect any fresh PCM sample
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* encoding to appear. But who knows? Perhaps the encoding type
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* will be abused for funny things in future, not even plain PCM.
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* And, by the way: Thomas really likes the ?: operator.
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* \param enc the encoding (mpg123_enc_enum value)
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* \return size of one sample in bytes
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*/
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#define MPG123_SAMPLESIZE(enc) ( \
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(enc) < 1 \
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? 0 \
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: ( (enc) & MPG123_ENC_8 \
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? 1 \
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: ( (enc) & MPG123_ENC_16 \
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? 2 \
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: ( (enc) & MPG123_ENC_24 \
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? 3 \
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: ( ( (enc) & MPG123_ENC_32 \
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|| (enc) == MPG123_ENC_FLOAT_32 ) \
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? 4 \
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: ( (enc) == MPG123_ENC_FLOAT_64 \
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? 8 \
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: 0 \
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) ) ) ) ) )
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/** Representation of zero in differing encodings.
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* This exists to define proper silence in various encodings without
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* having to link to libsyn123 to do actual conversions at runtime.
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* You have to handle big/little endian order yourself, though.
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* This takes the shortcut that any signed encoding has a zero with
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* all-zero bits. Unsigned linear encodings just have the highest bit set
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* (2^(n-1) for n bits), while the nonlinear 8-bit ones are special.
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* \param enc the encoding (mpg123_enc_enum value)
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* \param siz bytes per sample (return value of MPG123_SAMPLESIZE(enc))
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* \param off byte (octet) offset counted from LSB
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* \return unsigned byte value for the designated octet
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*/
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#define MPG123_ZEROSAMPLE(enc, siz, off) ( \
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(enc) == MPG123_ENC_ULAW_8 \
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? (off == 0 ? 0xff : 0x00) \
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: ( (enc) == MPG123_ENC_ALAW_8 \
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? (off == 0 ? 0xd5 : 0x00) \
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: ( (((enc) & (MPG123_ENC_SIGNED|MPG123_ENC_FLOAT)) || (siz) != ((off)+1)) \
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? 0x00 \
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: 0x80 \
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) ) )
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/** Structure defining an audio format.
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* Providing the members as individual function arguments to define a certain
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* output format is easy enough. This struct makes is more comfortable to deal
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* with a list of formats.
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* Negative values for the members might be used to communicate use of default
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* values.
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*/
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struct mpg123_fmt
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{
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long rate; /**< sampling rate in Hz */
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int channels; /**< channel count */
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/** encoding code, can be single value or bitwise or of members of
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* mpg123_enc_enum */
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int encoding;
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};
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/* @} */
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#endif
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