sdk/lib/3rdparty/libsamplerate/samplerate.h

   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