1 /* 2 ** Copyright (c) 2002-2016, Erik de Castro Lopo <erikd@mega-nerd.com> 3 ** All rights reserved. 4 ** 5 ** This code is released under 2-clause BSD license. Please see the 6 ** file at : https://github.com/erikd/libsamplerate/blob/master/COPYING 7 */ 8 9 /* 10 ** API documentation is available here: 11 ** http://www.mega-nerd.com/SRC/api.html 12 */ 13 14 #ifndef SAMPLERATE_H 15 #define SAMPLERATE_H 16 17 #ifdef __cplusplus 18 extern "C" { 19 #endif /* __cplusplus */ 20 21 22 /* Opaque data type SRC_STATE. */ 23 typedef struct SRC_STATE_tag SRC_STATE ; 24 25 /* SRC_DATA is used to pass data to src_simple() and src_process(). */ 26 typedef struct 27 { const float *data_in ; 28 float *data_out ; 29 30 long input_frames, output_frames ; 31 long input_frames_used, output_frames_gen ; 32 33 int end_of_input ; 34 35 double src_ratio ; 36 } SRC_DATA ; 37 38 /* 39 ** User supplied callback function type for use with src_callback_new() 40 ** and src_callback_read(). First parameter is the same pointer that was 41 ** passed into src_callback_new(). Second parameter is pointer to a 42 ** pointer. The user supplied callback function must modify *data to 43 ** point to the start of the user supplied float array. The user supplied 44 ** function must return the number of frames that **data points to. 45 */ 46 47 typedef long (*src_callback_t) (void *cb_data, float **data) ; 48 49 /* 50 ** Standard initialisation function : return an anonymous pointer to the 51 ** internal state of the converter. Choose a converter from the enums below. 52 ** Error returned in *error. 53 */ 54 55 SRC_STATE* src_new (int converter_type, int channels, int *error) ; 56 57 /* 58 ** Initilisation for callback based API : return an anonymous pointer to the 59 ** internal state of the converter. Choose a converter from the enums below. 60 ** The cb_data pointer can point to any data or be set to NULL. Whatever the 61 ** value, when processing, user supplied function "func" gets called with 62 ** cb_data as first parameter. 63 */ 64 65 SRC_STATE* src_callback_new (src_callback_t func, int converter_type, int channels, 66 int *error, void* cb_data) ; 67 68 /* 69 ** Cleanup all internal allocations. 70 ** Always returns NULL. 71 */ 72 73 SRC_STATE* src_delete (SRC_STATE *state) ; 74 75 /* 76 ** Standard processing function. 77 ** Returns non zero on error. 78 */ 79 80 int src_process (SRC_STATE *state, SRC_DATA *data) ; 81 82 /* 83 ** Callback based processing function. Read up to frames worth of data from 84 ** the converter int *data and return frames read or -1 on error. 85 */ 86 long src_callback_read (SRC_STATE *state, double src_ratio, long frames, float *data) ; 87 88 /* 89 ** Simple interface for performing a single conversion from input buffer to 90 ** output buffer at a fixed conversion ratio. 91 ** Simple interface does not require initialisation as it can only operate on 92 ** a single buffer worth of audio. 93 */ 94 95 int src_simple (SRC_DATA *data, int converter_type, int channels) ; 96 97 /* 98 ** This library contains a number of different sample rate converters, 99 ** numbered 0 through N. 100 ** 101 ** Return a string giving either a name or a more full description of each 102 ** sample rate converter or NULL if no sample rate converter exists for 103 ** the given value. The converters are sequentially numbered from 0 to N. 104 */ 105 106 const char *src_get_name (int converter_type) ; 107 const char *src_get_description (int converter_type) ; 108 const char *src_get_version (void) ; 109 110 /* 111 ** Set a new SRC ratio. This allows step responses 112 ** in the conversion ratio. 113 ** Returns non zero on error. 114 */ 115 116 int src_set_ratio (SRC_STATE *state, double new_ratio) ; 117 118 /* 119 ** Get the current channel count. 120 ** Returns negative on error, positive channel count otherwise 121 */ 122 123 int src_get_channels (SRC_STATE *state) ; 124 125 /* 126 ** Reset the internal SRC state. 127 ** Does not modify the quality settings. 128 ** Does not free any memory allocations. 129 ** Returns non zero on error. 130 */ 131 132 int src_reset (SRC_STATE *state) ; 133 134 /* 135 ** Return TRUE if ratio is a valid conversion ratio, FALSE 136 ** otherwise. 137 */ 138 139 int src_is_valid_ratio (double ratio) ; 140 141 /* 142 ** Return an error number. 143 */ 144 145 int src_error (SRC_STATE *state) ; 146 147 /* 148 ** Convert the error number into a string. 149 */ 150 const char* src_strerror (int error) ; 151 152 /* 153 ** The following enums can be used to set the interpolator type 154 ** using the function src_set_converter(). 155 */ 156 157 enum 158 { 159 SRC_SINC_BEST_QUALITY = 0, 160 SRC_SINC_MEDIUM_QUALITY = 1, 161 SRC_SINC_FASTEST = 2, 162 SRC_ZERO_ORDER_HOLD = 3, 163 SRC_LINEAR = 4, 164 } ; 165 166 /* 167 ** Extra helper functions for converting from short to float and 168 ** back again. 169 */ 170 171 void src_short_to_float_array (const short *in, float *out, int len) ; 172 void src_float_to_short_array (const float *in, short *out, int len) ; 173 174 void src_int_to_float_array (const int *in, float *out, int len) ; 175 void src_float_to_int_array (const float *in, int *out, int len) ; 176 177 178 #ifdef __cplusplus 179 } /* extern "C" */ 180 #endif /* __cplusplus */ 181 182 #endif /* SAMPLERATE_H */ 183 184