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