Jack2 1.9.6

samplerate.h

00001 /*
00002 ** Copyright (C) 2002-2008 Erik de Castro Lopo <erikd@mega-nerd.com>
00003 **
00004 ** This program is free software; you can redistribute it and/or modify
00005 ** it under the terms of the GNU General Public License as published by
00006 ** the Free Software Foundation; either version 2 of the License, or
00007 ** (at your option) any later version.
00008 **
00009 ** This program is distributed in the hope that it will be useful,
00010 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
00011 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00012 ** GNU General Public License for more details.
00013 **
00014 ** You should have received a copy of the GNU General Public License
00015 ** along with this program; if not, write to the Free Software
00016 ** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
00017 */
00018 
00019 /*
00020 ** This code is part of Secret Rabibt Code aka libsamplerate. A commercial
00021 ** use license for this code is available, please see:
00022 **              http://www.mega-nerd.com/SRC/procedure.html
00023 */
00024 
00025 /*
00026 ** API documentation is available here:
00027 **     http://www.mega-nerd.com/SRC/api.html
00028 */
00029 
00030 #ifndef SAMPLERATE_H
00031 #define SAMPLERATE_H
00032 
00033 #ifdef __cplusplus
00034 extern "C" {
00035 #endif  /* __cplusplus */
00036 
00037 
00038 /* Opaque data type SRC_STATE. */
00039 typedef struct SRC_STATE_tag SRC_STATE ;
00040 
00041 /* SRC_DATA is used to pass data to src_simple() and src_process(). */
00042 typedef struct
00043 {       float   *data_in, *data_out ;
00044 
00045         long    input_frames, output_frames ;
00046         long    input_frames_used, output_frames_gen ;
00047 
00048         int             end_of_input ;
00049 
00050         double  src_ratio ;
00051 } SRC_DATA ;
00052 
00053 /* SRC_CB_DATA is used with callback based API. */
00054 typedef struct
00055 {       long    frames ;
00056         float   *data_in ;
00057 } SRC_CB_DATA ;
00058 
00059 /*
00060 ** User supplied callback function type for use with src_callback_new()
00061 ** and src_callback_read(). First parameter is the same pointer that was
00062 ** passed into src_callback_new(). Second parameter is pointer to a
00063 ** pointer. The user supplied callback function must modify *data to
00064 ** point to the start of the user supplied float array. The user supplied
00065 ** function must return the number of frames that **data points to.
00066 */
00067 
00068 typedef long (*src_callback_t) (void *cb_data, float **data) ;
00069 
00070 /*
00071 **      Standard initialisation function : return an anonymous pointer to the
00072 **      internal state of the converter. Choose a converter from the enums below.
00073 **      Error returned in *error.
00074 */
00075 
00076 SRC_STATE* src_new (int converter_type, int channels, int *error) ;
00077 
00078 /*
00079 **      Initilisation for callback based API : return an anonymous pointer to the
00080 **      internal state of the converter. Choose a converter from the enums below.
00081 **      The cb_data pointer can point to any data or be set to NULL. Whatever the
00082 **      value, when processing, user supplied function "func" gets called with
00083 **      cb_data as first parameter.
00084 */
00085 
00086 SRC_STATE* src_callback_new (src_callback_t func, int converter_type, int channels,
00087                                 int *error, void* cb_data) ;
00088 
00089 /*
00090 **      Cleanup all internal allocations.
00091 **      Always returns NULL.
00092 */
00093 
00094 SRC_STATE* src_delete (SRC_STATE *state) ;
00095 
00096 /*
00097 **      Standard processing function.
00098 **      Returns non zero on error.
00099 */
00100 
00101 int src_process (SRC_STATE *state, SRC_DATA *data) ;
00102 
00103 /*
00104 **      Callback based processing function. Read up to frames worth of data from
00105 **      the converter int *data and return frames read or -1 on error.
00106 */
00107 long src_callback_read (SRC_STATE *state, double src_ratio, long frames, float *data) ;
00108 
00109 /*
00110 **      Simple interface for performing a single conversion from input buffer to
00111 **      output buffer at a fixed conversion ratio.
00112 **      Simple interface does not require initialisation as it can only operate on
00113 **      a single buffer worth of audio.
00114 */
00115 
00116 int src_simple (SRC_DATA *data, int converter_type, int channels) ;
00117 
00118 /*
00119 ** This library contains a number of different sample rate converters,
00120 ** numbered 0 through N.
00121 **
00122 ** Return a string giving either a name or a more full description of each
00123 ** sample rate converter or NULL if no sample rate converter exists for
00124 ** the given value. The converters are sequentially numbered from 0 to N.
00125 */
00126 
00127 const char *src_get_name (int converter_type) ;
00128 const char *src_get_description (int converter_type) ;
00129 const char *src_get_version (void) ;
00130 
00131 /*
00132 **      Set a new SRC ratio. This allows step responses
00133 **      in the conversion ratio.
00134 **      Returns non zero on error.
00135 */
00136 
00137 int src_set_ratio (SRC_STATE *state, double new_ratio) ;
00138 
00139 /*
00140 **      Reset the internal SRC state.
00141 **      Does not modify the quality settings.
00142 **      Does not free any memory allocations.
00143 **      Returns non zero on error.
00144 */
00145 
00146 int src_reset (SRC_STATE *state) ;
00147 
00148 /*
00149 ** Return TRUE if ratio is a valid conversion ratio, FALSE
00150 ** otherwise.
00151 */
00152 
00153 int src_is_valid_ratio (double ratio) ;
00154 
00155 /*
00156 **      Return an error number.
00157 */
00158 
00159 int src_error (SRC_STATE *state) ;
00160 
00161 /*
00162 **      Convert the error number into a string.
00163 */
00164 const char* src_strerror (int error) ;
00165 
00166 /*
00167 ** The following enums can be used to set the interpolator type
00168 ** using the function src_set_converter().
00169 */
00170 
00171 enum
00172 {
00173         SRC_SINC_BEST_QUALITY           = 0,
00174         SRC_SINC_MEDIUM_QUALITY         = 1,
00175         SRC_SINC_FASTEST                        = 2,
00176         SRC_ZERO_ORDER_HOLD                     = 3,
00177         SRC_LINEAR                                      = 4,
00178 } ;
00179 
00180 /*
00181 ** Extra helper functions for converting from short to float and
00182 ** back again.
00183 */
00184 
00185 void src_short_to_float_array (const short *in, float *out, int len) ;
00186 void src_float_to_short_array (const float *in, short *out, int len) ;
00187 
00188 void src_int_to_float_array (const int *in, float *out, int len) ;
00189 void src_float_to_int_array (const float *in, int *out, int len) ;
00190 
00191 
00192 #ifdef __cplusplus
00193 }               /* extern "C" */
00194 #endif  /* __cplusplus */
00195 
00196 #endif  /* SAMPLERATE_H */
00197