1 | /* |
2 | libmpg123: MPEG Audio Decoder library |
3 | |
4 | separate header just for audio format definitions not tied to |
5 | library code |
6 | |
7 | copyright 1995-2020 by the mpg123 project |
8 | free software under the terms of the LGPL 2.1 |
9 | see COPYING and AUTHORS files in distribution or http://mpg123.org |
10 | */ |
11 | |
12 | #ifndef MPG123_ENC_H |
13 | #define MPG123_ENC_H |
14 | |
15 | /** \file fmt123.h Audio format definitions. */ |
16 | |
17 | /** \defgroup mpg123_enc mpg123 PCM sample encodings |
18 | * These are definitions for audio formats used by libmpg123 and |
19 | * libout123. |
20 | * |
21 | * @{ |
22 | */ |
23 | |
24 | /** An enum over all sample types possibly known to mpg123. |
25 | * The values are designed as bit flags to allow bitmasking for encoding |
26 | * families. |
27 | * This is also why the enum is not used as type for actual encoding variables, |
28 | * plain integers (at least 16 bit, 15 bit being used) cover the possible |
29 | * combinations of these flags. |
30 | * |
31 | * Note that (your build of) libmpg123 does not necessarily support all these. |
32 | * Usually, you can expect the 8bit encodings and signed 16 bit. |
33 | * Also 32bit float will be usual beginning with mpg123-1.7.0 . |
34 | * What you should bear in mind is that (SSE, etc) optimized routines may be |
35 | * absent for some formats. We do have SSE for 16, 32 bit and float, though. |
36 | * 24 bit integer is done via postprocessing of 32 bit output -- just cutting |
37 | * the last byte, no rounding, even. If you want better, do it yourself. |
38 | * |
39 | * All formats are in native byte order. If you need different endinaness, you |
40 | * can simply postprocess the output buffers (libmpg123 wouldn't do anything |
41 | * else). The macro MPG123_SAMPLESIZE() can be helpful there. |
42 | */ |
43 | enum mpg123_enc_enum |
44 | { |
45 | /* 0000 0000 0000 1111 Some 8 bit integer encoding. */ |
46 | MPG123_ENC_8 = 0x00f |
47 | /* 0000 0000 0100 0000 Some 16 bit integer encoding. */ |
48 | , MPG123_ENC_16 = 0x040 |
49 | /* 0100 0000 0000 0000 Some 24 bit integer encoding. */ |
50 | , MPG123_ENC_24 = 0x4000 |
51 | /* 0000 0001 0000 0000 Some 32 bit integer encoding. */ |
52 | , MPG123_ENC_32 = 0x100 |
53 | /* 0000 0000 1000 0000 Some signed integer encoding. */ |
54 | , MPG123_ENC_SIGNED = 0x080 |
55 | /* 0000 1110 0000 0000 Some float encoding. */ |
56 | , MPG123_ENC_FLOAT = 0xe00 |
57 | /* 0000 0000 1101 0000 signed 16 bit */ |
58 | , MPG123_ENC_SIGNED_16 = (MPG123_ENC_16|MPG123_ENC_SIGNED|0x10) |
59 | /* 0000 0000 0110 0000 unsigned 16 bit */ |
60 | , MPG123_ENC_UNSIGNED_16 = (MPG123_ENC_16|0x20) |
61 | /* 0000 0000 0000 0001 unsigned 8 bit */ |
62 | , MPG123_ENC_UNSIGNED_8 = 0x01 |
63 | /* 0000 0000 1000 0010 signed 8 bit */ |
64 | , MPG123_ENC_SIGNED_8 = (MPG123_ENC_SIGNED|0x02) |
65 | /* 0000 0000 0000 0100 ulaw 8 bit */ |
66 | , MPG123_ENC_ULAW_8 = 0x04 |
67 | /* 0000 0000 0000 1000 alaw 8 bit */ |
68 | , MPG123_ENC_ALAW_8 = 0x08 |
69 | /* 0001 0001 1000 0000 signed 32 bit */ |
70 | , MPG123_ENC_SIGNED_32 = MPG123_ENC_32|MPG123_ENC_SIGNED|0x1000 |
71 | /* 0010 0001 0000 0000 unsigned 32 bit */ |
72 | , MPG123_ENC_UNSIGNED_32 = MPG123_ENC_32|0x2000 |
73 | /* 0101 0000 1000 0000 signed 24 bit */ |
74 | , MPG123_ENC_SIGNED_24 = MPG123_ENC_24|MPG123_ENC_SIGNED|0x1000 |
75 | /* 0110 0000 0000 0000 unsigned 24 bit */ |
76 | , MPG123_ENC_UNSIGNED_24 = MPG123_ENC_24|0x2000 |
77 | /* 0000 0010 0000 0000 32bit float */ |
78 | , MPG123_ENC_FLOAT_32 = 0x200 |
79 | /* 0000 0100 0000 0000 64bit float */ |
80 | , MPG123_ENC_FLOAT_64 = 0x400 |
81 | /* Any possibly known encoding from the list above. */ |
82 | , MPG123_ENC_ANY = ( MPG123_ENC_SIGNED_16 | MPG123_ENC_UNSIGNED_16 |
83 | | MPG123_ENC_UNSIGNED_8 | MPG123_ENC_SIGNED_8 |
84 | | MPG123_ENC_ULAW_8 | MPG123_ENC_ALAW_8 |
85 | | MPG123_ENC_SIGNED_32 | MPG123_ENC_UNSIGNED_32 |
86 | | MPG123_ENC_SIGNED_24 | MPG123_ENC_UNSIGNED_24 |
87 | | MPG123_ENC_FLOAT_32 | MPG123_ENC_FLOAT_64 ) |
88 | }; |
89 | |
90 | /** Get size of one PCM sample with given encoding. |
91 | * This is included both in libmpg123 and libout123. Both offer |
92 | * an API function to provide the macro results from library |
93 | * compile-time, not that of you application. This most likely |
94 | * does not matter as I do not expect any fresh PCM sample |
95 | * encoding to appear. But who knows? Perhaps the encoding type |
96 | * will be abused for funny things in future, not even plain PCM. |
97 | * And, by the way: Thomas really likes the ?: operator. |
98 | * \param enc the encoding (mpg123_enc_enum value) |
99 | * \return size of one sample in bytes |
100 | */ |
101 | #define MPG123_SAMPLESIZE(enc) ( \ |
102 | (enc) < 1 \ |
103 | ? 0 \ |
104 | : ( (enc) & MPG123_ENC_8 \ |
105 | ? 1 \ |
106 | : ( (enc) & MPG123_ENC_16 \ |
107 | ? 2 \ |
108 | : ( (enc) & MPG123_ENC_24 \ |
109 | ? 3 \ |
110 | : ( ( (enc) & MPG123_ENC_32 \ |
111 | || (enc) == MPG123_ENC_FLOAT_32 ) \ |
112 | ? 4 \ |
113 | : ( (enc) == MPG123_ENC_FLOAT_64 \ |
114 | ? 8 \ |
115 | : 0 \ |
116 | ) ) ) ) ) ) |
117 | |
118 | /** Representation of zero in differing encodings. |
119 | * This exists to define proper silence in various encodings without |
120 | * having to link to libsyn123 to do actual conversions at runtime. |
121 | * You have to handle big/little endian order yourself, though. |
122 | * This takes the shortcut that any signed encoding has a zero with |
123 | * all-zero bits. Unsigned linear encodings just have the highest bit set |
124 | * (2^(n-1) for n bits), while the nonlinear 8-bit ones are special. |
125 | * \param enc the encoding (mpg123_enc_enum value) |
126 | * \param siz bytes per sample (return value of MPG123_SAMPLESIZE(enc)) |
127 | * \param off byte (octet) offset counted from LSB |
128 | * \return unsigned byte value for the designated octet |
129 | */ |
130 | #define MPG123_ZEROSAMPLE(enc, siz, off) ( \ |
131 | (enc) == MPG123_ENC_ULAW_8 \ |
132 | ? (off == 0 ? 0xff : 0x00) \ |
133 | : ( (enc) == MPG123_ENC_ALAW_8 \ |
134 | ? (off == 0 ? 0xd5 : 0x00) \ |
135 | : ( (((enc) & (MPG123_ENC_SIGNED|MPG123_ENC_FLOAT)) || (siz) != ((off)+1)) \ |
136 | ? 0x00 \ |
137 | : 0x80 \ |
138 | ) ) ) |
139 | |
140 | /** Structure defining an audio format. |
141 | * Providing the members as individual function arguments to define a certain |
142 | * output format is easy enough. This struct makes is more comfortable to deal |
143 | * with a list of formats. |
144 | * Negative values for the members might be used to communicate use of default |
145 | * values. |
146 | */ |
147 | struct mpg123_fmt |
148 | { |
149 | long rate; /**< sampling rate in Hz */ |
150 | int channels; /**< channel count */ |
151 | /** encoding code, can be single value or bitwise or of members of |
152 | * mpg123_enc_enum */ |
153 | int encoding; |
154 | }; |
155 | |
156 | /** @} */ |
157 | |
158 | #endif |
159 | |
160 | |