code.delx.au - pulseaudio/blob - src/pulse/sample.h

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