audio.h

   1 #ifndef _AUDIO_H
   2 #define _AUDIO_H
   3
   4 #include <stdint.h>
   5 #include <libconfig.h>
   6
   7 typedef struct {
   8   double airplay_volume;
   9   double current_volume_dB;
  10   int minimum_volume_dB;
  11   int maximum_volume_dB;
  12   int has_true_mute;
  13   int is_muted;
  14   int valid;
  15 } audio_parameters;
  16
  17 typedef struct {
  18     void (*help)(void);
  19     char *name;
  20
  21     // start of program
  22     int (*init)(int argc, char **argv, config_t* cfgp);
  23     // at end of program
  24     void (*deinit)(void);
  25
  26     void (*start)(int sample_rate);
  27
  28     // block of samples
  29     void (*play)(short buf[], int samples);
  30     void (*stop)(void);
  31
  32     // may be null if not implemented
  33     void (*flush)(void);
  34
  35     // returns the delay before the next frame to be sent to the device would actually be audible.
  36     // almost certainly wrong if the buffer is empty, so put silent buffers into it to make it busy.
  37     // will change dynamically, so keep watching it. Implemented in ALSA only.
  38     uint32_t (*delay)();
  39
  40     // may be NULL, in which case soft volume is applied
  41     void (*volume)(double vol);
  42
  43     // may be NULL, in which case soft volume parameters are used
  44     void (*parameters)(audio_parameters* info);
  45 } audio_output;
  46
  47 audio_output *audio_get_output(char *name);
  48 void audio_ls_outputs(void);
  49
  50 #endif //_AUDIO_H