1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
|
#ifndef foosamplehfoo
#define foosamplehfoo
/* $Id$ */
/***
This file is part of PulseAudio.
Copyright 2004-2006 Lennart Poettering
Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
PulseAudio is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation; either version 2 of the License,
or (at your option) any later version.
PulseAudio is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with PulseAudio; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
USA.
***/
#include <inttypes.h>
#include <sys/types.h>
#include <math.h>
#include <pulse/cdecl.h>
/** \page sample Sample Format Specifications
*
* \section overv_sec Overview
*
* PulseAudio is capable of handling a multitude of sample formats, rates
* and channels, transparently converting and mixing them as needed.
*
* \section format_sec Sample Format
*
* PulseAudio supports the following sample formats:
*
* \li PA_SAMPLE_U8 - Unsigned 8 bit integer PCM.
* \li PA_SAMPLE_S16LE - Signed 16 integer bit PCM, little endian.
* \li PA_SAMPLE_S16BE - Signed 16 integer bit PCM, big endian.
* \li PA_SAMPLE_FLOAT32LE - 32 bit IEEE floating point PCM, little endian.
* \li PA_SAMPLE_FLOAT32BE - 32 bit IEEE floating point PCM, big endian.
* \li PA_SAMPLE_ALAW - 8 bit a-Law.
* \li PA_SAMPLE_ULAW - 8 bit mu-Law.
* \li PA_SAMPLE_S32LE - Signed 32 bit integer PCM, little endian.
* \li PA_SAMPLE_S32BE - Signed 32 bit integer PCM, big endian.
*
* The floating point sample formats have the range from -1 to 1.
*
* The sample formats that are sensitive to endianness have convenience
* macros for native endian (NE), and reverse endian (RE).
*
* \section rate_sec Sample Rates
*
* PulseAudio supports any sample rate between 1 Hz and 4 GHz. There is no
* point trying to exceed the sample rate of the output device though as the
* signal will only get downsampled, consuming CPU on the machine running the
* server.
*
* \section chan_sec Channels
*
* PulseAudio supports up to 16 individiual channels. The order of the
* channels is up to the application, but they must be continous. To map
* channels to speakers, see \ref channelmap.
*
* \section calc_sec Calculations
*
* The PulseAudio library contains a number of convenience functions to do
* calculations on sample formats:
*
* \li pa_bytes_per_second() - The number of bytes one second of audio will
* take given a sample format.
* \li pa_frame_size() - The size, in bytes, of one frame (i.e. one set of
* samples, one for each channel).
* \li pa_sample_size() - The size, in bytes, of one sample.
* \li pa_bytes_to_usec() - Calculate the time it would take to play a buffer
* of a certain size.
*
* \section util_sec Convenience Functions
*
* The library also contains a couple of other convenience functions:
*
* \li pa_sample_spec_valid() - Tests if a sample format specification is
* valid.
* \li pa_sample_spec_equal() - Tests if the sample format specifications are
* identical.
* \li pa_sample_format_to_string() - Return a textual description of a
* sample format.
* \li pa_parse_sample_format() - Parse a text string into a sample format.
* \li pa_sample_spec_snprint() - Create a textual description of a complete
* sample format specification.
* \li pa_bytes_snprint() - Pretty print a byte value (e.g. 2.5 MiB).
*/
/** \file
* Constants and routines for sample type handling */
PA_C_DECL_BEGIN
/** Maximum number of allowed channels */
#define PA_CHANNELS_MAX 32
/** Maximum allowed sample rate */
#define PA_RATE_MAX (48000*4)
/** Sample format */
typedef enum pa_sample_format {
PA_SAMPLE_U8, /**< Unsigned 8 Bit PCM */
PA_SAMPLE_ALAW, /**< 8 Bit a-Law */
PA_SAMPLE_ULAW, /**< 8 Bit mu-Law */
PA_SAMPLE_S16LE, /**< Signed 16 Bit PCM, little endian (PC) */
PA_SAMPLE_S16BE, /**< Signed 16 Bit PCM, big endian */
PA_SAMPLE_FLOAT32LE, /**< 32 Bit IEEE floating point, little endian, range -1 to 1 */
PA_SAMPLE_FLOAT32BE, /**< 32 Bit IEEE floating point, big endian, range -1 to 1 */
PA_SAMPLE_S32LE, /**< Signed 32 Bit PCM, little endian (PC) */
PA_SAMPLE_S32BE, /**< Signed 32 Bit PCM, big endian (PC) */
PA_SAMPLE_MAX, /**< Upper limit of valid sample types */
PA_SAMPLE_INVALID = -1 /**< An invalid value */
} pa_sample_format_t;
#ifdef WORDS_BIGENDIAN
/** Signed 16 Bit PCM, native endian */
#define PA_SAMPLE_S16NE PA_SAMPLE_S16BE
/** 32 Bit IEEE floating point, native endian */
#define PA_SAMPLE_FLOAT32NE PA_SAMPLE_FLOAT32BE
/** Signed 32 Bit PCM, native endian */
#define PA_SAMPLE_S32NE PA_SAMPLE_S32BE
/** Signed 16 Bit PCM reverse endian */
#define PA_SAMPLE_S16RE PA_SAMPLE_S16LE
/** 32 Bit IEEE floating point, reverse endian */
#define PA_SAMPLE_FLOAT32RE PA_SAMPLE_FLOAT32LE
/** Signed 32 Bit PCM reverse endian */
#define PA_SAMPLE_S32RE PA_SAMPLE_S32LE
#else
/** Signed 16 Bit PCM, native endian */
#define PA_SAMPLE_S16NE PA_SAMPLE_S16LE
/** 32 Bit IEEE floating point, native endian */
#define PA_SAMPLE_FLOAT32NE PA_SAMPLE_FLOAT32LE
/** Signed 32 Bit PCM, native endian */
#define PA_SAMPLE_S32NE PA_SAMPLE_S32LE
/** Signed 16 Bit PCM reverse endian */
#define PA_SAMPLE_S16RE PA_SAMPLE_S16BE
/** 32 Bit IEEE floating point, reverse endian */
#define PA_SAMPLE_FLOAT32RE PA_SAMPLE_FLOAT32BE
/** Signed 32 Bit PCM reverse endian */
#define PA_SAMPLE_S32RE PA_SAMPLE_S32BE
#endif
/** A Shortcut for PA_SAMPLE_FLOAT32NE */
#define PA_SAMPLE_FLOAT32 PA_SAMPLE_FLOAT32NE
/** A sample format and attribute specification */
typedef struct pa_sample_spec {
pa_sample_format_t format; /**< The sample format */
uint32_t rate; /**< The sample rate. (e.g. 44100) */
uint8_t channels; /**< Audio channels. (1 for mono, 2 for stereo, ...) */
} pa_sample_spec;
/** Type for usec specifications (unsigned). May be either 32 or 64 bit, depending on the architecture */
typedef uint64_t pa_usec_t;
/** Return the amount of bytes playback of a second of audio with the specified sample type takes */
size_t pa_bytes_per_second(const pa_sample_spec *spec) PA_GCC_PURE;
/** Return the size of a frame with the specific sample type */
size_t pa_frame_size(const pa_sample_spec *spec) PA_GCC_PURE;
/** Return the size of a sample with the specific sample type */
size_t pa_sample_size(const pa_sample_spec *spec) PA_GCC_PURE;
/** Calculate the time the specified bytes take to play with the specified sample type */
pa_usec_t pa_bytes_to_usec(uint64_t length, const pa_sample_spec *spec) PA_GCC_PURE;
/** Calculates the number of bytes that are required for the specified time. \since 0.9 */
size_t pa_usec_to_bytes(pa_usec_t t, const pa_sample_spec *spec) PA_GCC_PURE;
/** Return non-zero when the sample type specification is valid */
int pa_sample_spec_valid(const pa_sample_spec *spec) PA_GCC_PURE;
/** Return non-zero when the two sample type specifications match */
int pa_sample_spec_equal(const pa_sample_spec*a, const pa_sample_spec*b) PA_GCC_PURE;
/** Return a descriptive string for the specified sample format. \since 0.8 */
const char *pa_sample_format_to_string(pa_sample_format_t f) PA_GCC_PURE;
/** Parse a sample format text. Inverse of pa_sample_format_to_string() */
pa_sample_format_t pa_parse_sample_format(const char *format) PA_GCC_PURE;
/** Maximum required string length for pa_sample_spec_snprint() */
#define PA_SAMPLE_SPEC_SNPRINT_MAX 32
/** Pretty print a sample type specification to a string */
char* pa_sample_spec_snprint(char *s, size_t l, const pa_sample_spec *spec);
/** Pretty print a byte size value. (i.e. "2.5 MiB") */
char* pa_bytes_snprint(char *s, size_t l, unsigned v);
PA_C_DECL_END
#endif
|
