1 /* 2 ** Copyright (C) 2002-2011 Erik de Castro Lopo <erikd@mega-nerd.com> 3 ** 4 ** This program is free software; you can redistribute it and/or modify 5 ** it under the terms of the GNU General Public License as published by 6 ** the Free Software Foundation; either version 2 of the License, or 7 ** (at your option) any later version. 8 ** 9 ** This program is distributed in the hope that it will be useful, 10 ** but WITHOUT ANY WARRANTY; without even the implied warranty of 11 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 ** GNU General Public License for more details. 13 ** 14 ** You should have received a copy of the GNU General Public License 15 ** along with this program; if not, write to the Free Software 16 ** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA. 17 */ 18 19 /* 20 ** This code is part of Secret Rabbit Code aka libsamplerate. A commercial 21 ** use license for this code is available, please see: 22 ** http://www.mega-nerd.com/SRC/procedure.html 23 */ 24 25 /* 26 ** API documentation is available here: 27 ** http://www.mega-nerd.com/SRC/api.html 28 */ 29 30 #ifndef SAMPLERATE_H 31 #define SAMPLERATE_H 32 33 #ifdef __cplusplus 34 extern "C" { 35 #endif /* __cplusplus */ 36 37 38 /* Opaque data type SRC_STATE. */ 39 typedef struct SRC_STATE_tag SRC_STATE ; 40 41 /* SRC_DATA is used to pass data to src_simple() and src_process(). */ 42 typedef struct 43 { float *data_in, *data_out ; 44 45 long input_frames, output_frames ; 46 long input_frames_used, output_frames_gen ; 47 48 int end_of_input ; 49 50 double src_ratio ; 51 } SRC_DATA ; 52 53 /* SRC_CB_DATA is used with callback based API. */ 54 typedef struct 55 { long frames ; 56 float *data_in ; 57 } SRC_CB_DATA ; 58 59 /* 60 ** User supplied callback function type for use with src_callback_new() 61 ** and src_callback_read(). First parameter is the same pointer that was 62 ** passed into src_callback_new(). Second parameter is pointer to a 63 ** pointer. The user supplied callback function must modify *data to 64 ** point to the start of the user supplied float array. The user supplied 65 ** function must return the number of frames that **data points to. 66 */ 67 68 typedef long (*src_callback_t) (void *cb_data, float **data) ; 69 70 /* 71 ** Standard initialisation function : return an anonymous pointer to the 72 ** internal state of the converter. Choose a converter from the enums below. 73 ** Error returned in *error. 74 */ 75 76 SRC_STATE* src_new (int converter_type, int channels, int *error) ; 77 78 /* 79 ** Initilisation for callback based API : return an anonymous pointer to the 80 ** internal state of the converter. Choose a converter from the enums below. 81 ** The cb_data pointer can point to any data or be set to NULL. Whatever the 82 ** value, when processing, user supplied function "func" gets called with 83 ** cb_data as first parameter. 84 */ 85 86 SRC_STATE* src_callback_new (src_callback_t func, int converter_type, int channels, 87 int *error, void* cb_data) ; 88 89 /* 90 ** Cleanup all internal allocations. 91 ** Always returns NULL. 92 */ 93 94 SRC_STATE* src_delete (SRC_STATE *state) ; 95 96 /* 97 ** Standard processing function. 98 ** Returns non zero on error. 99 */ 100 101 int src_process (SRC_STATE *state, SRC_DATA *data) ; 102 103 /* 104 ** Callback based processing function. Read up to frames worth of data from 105 ** the converter int *data and return frames read or -1 on error. 106 */ 107 long src_callback_read (SRC_STATE *state, double src_ratio, long frames, float *data) ; 108 109 /* 110 ** Simple interface for performing a single conversion from input buffer to 111 ** output buffer at a fixed conversion ratio. 112 ** Simple interface does not require initialisation as it can only operate on 113 ** a single buffer worth of audio. 114 */ 115 116 int src_simple (SRC_DATA *data, int converter_type, int channels) ; 117 118 /* 119 ** This library contains a number of different sample rate converters, 120 ** numbered 0 through N. 121 ** 122 ** Return a string giving either a name or a more full description of each 123 ** sample rate converter or NULL if no sample rate converter exists for 124 ** the given value. The converters are sequentially numbered from 0 to N. 125 */ 126 127 const char *src_get_name (int converter_type) ; 128 const char *src_get_description (int converter_type) ; 129 const char *src_get_version (void) ; 130 131 /* 132 ** Set a new SRC ratio. This allows step responses 133 ** in the conversion ratio. 134 ** Returns non zero on error. 135 */ 136 137 int src_set_ratio (SRC_STATE *state, double new_ratio) ; 138 139 /* 140 ** Reset the internal SRC state. 141 ** Does not modify the quality settings. 142 ** Does not free any memory allocations. 143 ** Returns non zero on error. 144 */ 145 146 int src_reset (SRC_STATE *state) ; 147 148 /* 149 ** Return TRUE if ratio is a valid conversion ratio, FALSE 150 ** otherwise. 151 */ 152 153 int src_is_valid_ratio (double ratio) ; 154 155 /* 156 ** Return an error number. 157 */ 158 159 int src_error (SRC_STATE *state) ; 160 161 /* 162 ** Convert the error number into a string. 163 */ 164 const char* src_strerror (int error) ; 165 166 /* 167 ** The following enums can be used to set the interpolator type 168 ** using the function src_set_converter(). 169 */ 170 171 enum 172 { 173 SRC_SINC_BEST_QUALITY = 0, 174 SRC_SINC_MEDIUM_QUALITY = 1, 175 SRC_SINC_FASTEST = 2, 176 SRC_ZERO_ORDER_HOLD = 3, 177 SRC_LINEAR = 4, 178 } ; 179 180 /* 181 ** Extra helper functions for converting from short to float and 182 ** back again. 183 */ 184 185 void src_short_to_float_array (const short *in, float *out, int len) ; 186 void src_float_to_short_array (const float *in, short *out, int len) ; 187 188 void src_int_to_float_array (const int *in, float *out, int len) ; 189 void src_float_to_int_array (const float *in, int *out, int len) ; 190 191 192 #ifdef __cplusplus 193 } /* extern "C" */ 194 #endif /* __cplusplus */ 195 196 #endif /* SAMPLERATE_H */ 197 198