pa_converters.h (10174B)
1 #ifndef PA_CONVERTERS_H 2 #define PA_CONVERTERS_H 3 /* 4 * $Id$ 5 * Portable Audio I/O Library sample conversion mechanism 6 * 7 * Based on the Open Source API proposed by Ross Bencina 8 * Copyright (c) 1999-2002 Phil Burk, Ross Bencina 9 * 10 * Permission is hereby granted, free of charge, to any person obtaining 11 * a copy of this software and associated documentation files 12 * (the "Software"), to deal in the Software without restriction, 13 * including without limitation the rights to use, copy, modify, merge, 14 * publish, distribute, sublicense, and/or sell copies of the Software, 15 * and to permit persons to whom the Software is furnished to do so, 16 * subject to the following conditions: 17 * 18 * The above copyright notice and this permission notice shall be 19 * included in all copies or substantial portions of the Software. 20 * 21 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 22 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 23 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 24 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR 25 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF 26 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 27 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 28 */ 29 30 /* 31 * The text above constitutes the entire PortAudio license; however, 32 * the PortAudio community also makes the following non-binding requests: 33 * 34 * Any person wishing to distribute modifications to the Software is 35 * requested to send the modifications to the original developer so that 36 * they can be incorporated into the canonical version. It is also 37 * requested that these non-binding requests be included along with the 38 * license above. 39 */ 40 41 /** @file 42 @ingroup common_src 43 44 @brief Conversion functions used to convert buffers of samples from one 45 format to another. 46 */ 47 48 49 #include "portaudio.h" /* for PaSampleFormat */ 50 51 #ifdef __cplusplus 52 extern "C" 53 { 54 #endif /* __cplusplus */ 55 56 57 struct PaUtilTriangularDitherGenerator; 58 59 60 /** Choose an available sample format which is most appropriate for 61 representing the requested format. If the requested format is not available 62 higher quality formats are considered before lower quality formates. 63 @param availableFormats A variable containing the logical OR of all available 64 formats. 65 @param format The desired format. 66 @return The most appropriate available format for representing the requested 67 format. 68 */ 69 PaSampleFormat PaUtil_SelectClosestAvailableFormat( 70 PaSampleFormat availableFormats, PaSampleFormat format ); 71 72 73 /* high level conversions functions for use by implementations */ 74 75 76 /** The generic sample converter prototype. Sample converters convert count 77 samples from sourceBuffer to destinationBuffer. The actual type of the data 78 pointed to by these parameters varys for different converter functions. 79 @param destinationBuffer A pointer to the first sample of the destination. 80 @param destinationStride An offset between successive destination samples 81 expressed in samples (not bytes.) It may be negative. 82 @param sourceBuffer A pointer to the first sample of the source. 83 @param sourceStride An offset between successive source samples 84 expressed in samples (not bytes.) It may be negative. 85 @param count The number of samples to convert. 86 @param ditherState State information used to calculate dither. Converters 87 that do not perform dithering will ignore this parameter, in which case 88 NULL or invalid dither state may be passed. 89 */ 90 typedef void PaUtilConverter( 91 void *destinationBuffer, signed int destinationStride, 92 void *sourceBuffer, signed int sourceStride, 93 unsigned int count, struct PaUtilTriangularDitherGenerator *ditherGenerator ); 94 95 96 /** Find a sample converter function for the given source and destinations 97 formats and flags (clip and dither.) 98 @return 99 A pointer to a PaUtilConverter which will perform the requested 100 conversion, or NULL if the given format conversion is not supported. 101 For conversions where clipping or dithering is not necessary, the 102 clip and dither flags are ignored and a non-clipping or dithering 103 version is returned. 104 If the source and destination formats are the same, a function which 105 copies data of the appropriate size will be returned. 106 */ 107 PaUtilConverter* PaUtil_SelectConverter( PaSampleFormat sourceFormat, 108 PaSampleFormat destinationFormat, PaStreamFlags flags ); 109 110 111 /** The generic buffer zeroer prototype. Buffer zeroers copy count zeros to 112 destinationBuffer. The actual type of the data pointed to varys for 113 different zeroer functions. 114 @param destinationBuffer A pointer to the first sample of the destination. 115 @param destinationStride An offset between successive destination samples 116 expressed in samples (not bytes.) It may be negative. 117 @param count The number of samples to zero. 118 */ 119 typedef void PaUtilZeroer( 120 void *destinationBuffer, signed int destinationStride, unsigned int count ); 121 122 123 /** Find a buffer zeroer function for the given destination format. 124 @return 125 A pointer to a PaUtilZeroer which will perform the requested 126 zeroing. 127 */ 128 PaUtilZeroer* PaUtil_SelectZeroer( PaSampleFormat destinationFormat ); 129 130 /*----------------------------------------------------------------------------*/ 131 /* low level functions and data structures which may be used for 132 substituting conversion functions */ 133 134 135 /** The type used to store all sample conversion functions. 136 @see paConverters; 137 */ 138 typedef struct{ 139 PaUtilConverter *Float32_To_Int32; 140 PaUtilConverter *Float32_To_Int32_Dither; 141 PaUtilConverter *Float32_To_Int32_Clip; 142 PaUtilConverter *Float32_To_Int32_DitherClip; 143 144 PaUtilConverter *Float32_To_Int24; 145 PaUtilConverter *Float32_To_Int24_Dither; 146 PaUtilConverter *Float32_To_Int24_Clip; 147 PaUtilConverter *Float32_To_Int24_DitherClip; 148 149 PaUtilConverter *Float32_To_Int16; 150 PaUtilConverter *Float32_To_Int16_Dither; 151 PaUtilConverter *Float32_To_Int16_Clip; 152 PaUtilConverter *Float32_To_Int16_DitherClip; 153 154 PaUtilConverter *Float32_To_Int8; 155 PaUtilConverter *Float32_To_Int8_Dither; 156 PaUtilConverter *Float32_To_Int8_Clip; 157 PaUtilConverter *Float32_To_Int8_DitherClip; 158 159 PaUtilConverter *Float32_To_UInt8; 160 PaUtilConverter *Float32_To_UInt8_Dither; 161 PaUtilConverter *Float32_To_UInt8_Clip; 162 PaUtilConverter *Float32_To_UInt8_DitherClip; 163 164 PaUtilConverter *Int32_To_Float32; 165 PaUtilConverter *Int32_To_Int24; 166 PaUtilConverter *Int32_To_Int24_Dither; 167 PaUtilConverter *Int32_To_Int16; 168 PaUtilConverter *Int32_To_Int16_Dither; 169 PaUtilConverter *Int32_To_Int8; 170 PaUtilConverter *Int32_To_Int8_Dither; 171 PaUtilConverter *Int32_To_UInt8; 172 PaUtilConverter *Int32_To_UInt8_Dither; 173 174 PaUtilConverter *Int24_To_Float32; 175 PaUtilConverter *Int24_To_Int32; 176 PaUtilConverter *Int24_To_Int16; 177 PaUtilConverter *Int24_To_Int16_Dither; 178 PaUtilConverter *Int24_To_Int8; 179 PaUtilConverter *Int24_To_Int8_Dither; 180 PaUtilConverter *Int24_To_UInt8; 181 PaUtilConverter *Int24_To_UInt8_Dither; 182 183 PaUtilConverter *Int16_To_Float32; 184 PaUtilConverter *Int16_To_Int32; 185 PaUtilConverter *Int16_To_Int24; 186 PaUtilConverter *Int16_To_Int8; 187 PaUtilConverter *Int16_To_Int8_Dither; 188 PaUtilConverter *Int16_To_UInt8; 189 PaUtilConverter *Int16_To_UInt8_Dither; 190 191 PaUtilConverter *Int8_To_Float32; 192 PaUtilConverter *Int8_To_Int32; 193 PaUtilConverter *Int8_To_Int24; 194 PaUtilConverter *Int8_To_Int16; 195 PaUtilConverter *Int8_To_UInt8; 196 197 PaUtilConverter *UInt8_To_Float32; 198 PaUtilConverter *UInt8_To_Int32; 199 PaUtilConverter *UInt8_To_Int24; 200 PaUtilConverter *UInt8_To_Int16; 201 PaUtilConverter *UInt8_To_Int8; 202 203 PaUtilConverter *Copy_8_To_8; /* copy without any conversion */ 204 PaUtilConverter *Copy_16_To_16; /* copy without any conversion */ 205 PaUtilConverter *Copy_24_To_24; /* copy without any conversion */ 206 PaUtilConverter *Copy_32_To_32; /* copy without any conversion */ 207 } PaUtilConverterTable; 208 209 210 /** A table of pointers to all required converter functions. 211 PaUtil_SelectConverter() uses this table to lookup the appropriate 212 conversion functions. The fields of this structure are initialized 213 with default conversion functions. Fields may be NULL, indicating that 214 no conversion function is available. User code may substitue optimised 215 conversion functions by assigning different function pointers to 216 these fields. 217 218 @note 219 If the PA_NO_STANDARD_CONVERTERS preprocessor variable is defined, 220 PortAudio's standard converters will not be compiled, and all fields 221 of this structure will be initialized to NULL. In such cases, users 222 should supply their own conversion functions if the require PortAudio 223 to open a stream that requires sample conversion. 224 225 @see PaUtilConverterTable, PaUtilConverter, PaUtil_SelectConverter 226 */ 227 extern PaUtilConverterTable paConverters; 228 229 230 /** The type used to store all buffer zeroing functions. 231 @see paZeroers; 232 */ 233 typedef struct{ 234 PaUtilZeroer *ZeroU8; /* unsigned 8 bit, zero == 128 */ 235 PaUtilZeroer *Zero8; 236 PaUtilZeroer *Zero16; 237 PaUtilZeroer *Zero24; 238 PaUtilZeroer *Zero32; 239 } PaUtilZeroerTable; 240 241 242 /** A table of pointers to all required zeroer functions. 243 PaUtil_SelectZeroer() uses this table to lookup the appropriate 244 conversion functions. The fields of this structure are initialized 245 with default conversion functions. User code may substitue optimised 246 conversion functions by assigning different function pointers to 247 these fields. 248 249 @note 250 If the PA_NO_STANDARD_ZEROERS preprocessor variable is defined, 251 PortAudio's standard zeroers will not be compiled, and all fields 252 of this structure will be initialized to NULL. In such cases, users 253 should supply their own zeroing functions for the sample sizes which 254 they intend to use. 255 256 @see PaUtilZeroerTable, PaUtilZeroer, PaUtil_SelectZeroer 257 */ 258 extern PaUtilZeroerTable paZeroers; 259 260 #ifdef __cplusplus 261 } 262 #endif /* __cplusplus */ 263 #endif /* PA_CONVERTERS_H */