audio.h

   1 #ifndef _AUDIO_H
   2 #define _AUDIO_H
   3
   4 #include <libconfig.h>
   5 #include <stdint.h>
   6
   7 typedef struct {
   8   double current_volume_dB;
   9   int32_t minimum_volume_dB;
  10   int32_t maximum_volume_dB;
  11 } audio_parameters;
  12
  13 typedef struct {
  14   void (*help)(void);
  15   char *name;
  16
  17   // start of program
  18   int (*init)(int argc, char **argv);
  19   // at end of program
  20   void (*deinit)(void);
  21
  22   void (*start)(int sample_rate, int sample_format);
  23
  24   // block of samples
  25   void (*play)(void *buf, int samples);
  26   void (*stop)(void);
  27
  28   // may be null if not implemented
  29   void (*flush)(void);
  30
  31   // returns the delay before the next frame to be sent to the device would actually be audible.
  32   // almost certainly wrong if the buffer is empty, so put silent buffers into it to make it busy.
  33   // will change dynamically, so keep watching it. Implemented in ALSA only.
  34   // returns a negative error code if there's a problem
  35   int (*delay)(long *the_delay); // snd_pcm_sframes_t is a signed long
  36
  37   // may be NULL, in which case soft volume is applied
  38   void (*volume)(double vol);
  39
  40   // may be NULL, in which case soft volume parameters are used
  41   void (*parameters)(audio_parameters *info);
  42
  43   // may be NULL, in which case software muting is used.
  44   void (*mute)(int do_mute);
  45
  46 } audio_output;
  47
  48 audio_output *audio_get_output(char *name);
  49 void audio_ls_outputs(void);
  50 void parse_general_audio_options(void);
  51
  52 #endif //_AUDIO_H