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+/*
+ 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
+