Improve metadata output -- maybe it works reliably now. Add call to get audio parameters from back ends, to be able to give volume metadata.

audio.h

@@ -3,6 +3,16 @@
 
 #include <stdint.h>
 
+typedef struct {
+  double airplay_volume;
+  double current_volume_dB;
+  int minimum_volume_dB;
+  int maximum_volume_dB;
+  int has_true_mute;
+  int is_muted;
+  int valid;
+} audio_parameters;
+
 typedef struct {
     void (*help)(void);
     char *name;
@@ -28,6 +38,9 @@ typedef struct {
 
     // may be NULL, in which case soft volume is applied
     void (*volume)(double vol);
+    
+    // may be NULL, in which case soft volume parameters are used
+    void (*parameters)(audio_parameters* info);
 } audio_output;
 
 audio_output *audio_get_output(char *name);

audio_alsa.c

@@ -43,6 +43,7 @@ static void stop(void);
 static void flush(void);
 static uint32_t delay(void);
 static void volume(double vol);
+static void parameters(audio_parameters* info);
 static int has_mute=0;
 static int has_db_vol=0;
 static double set_volume;
@@ -57,7 +58,8 @@ audio_output audio_alsa = {
     .flush = &flush,
     .delay = &delay,
     .play = &play,
-    .volume = NULL
+    .volume = NULL, // to be set later on...
+    .parameters = NULL // to be set later on...
 };
 
 static pthread_mutex_t alsa_mutex = PTHREAD_MUTEX_INITIALIZER;
@@ -158,6 +160,7 @@ static int init(int argc, char **argv) {
        (snd_mixer_selem_ask_playback_vol_dB(alsa_mix_elem,alsa_mix_maxv,&alsa_mix_maxdb)==0)) {
       has_db_vol=1;
       audio_alsa.volume = &volume; // insert the volume function now we know it can do dB stuff
+      audio_alsa.parameters = &parameters; // likewise the parameters stuff
       if (alsa_mix_mindb==-9999999) {
         // trying to say that the lowest vol is mute, maybe? Raspberry Pi does this
         if (snd_mixer_selem_ask_playback_vol_dB(alsa_mix_elem,alsa_mix_minv+1,&alsa_mix_mindb)==0)
@@ -314,6 +317,15 @@ static void stop(void) {
 	  // close_alsa_device();
 }
 
+static void parameters(audio_parameters* info) {
+  info->has_true_mute=has_mute;
+  info->is_muted = ((has_mute) && (set_volume == -144.0));
+  info->minimum_volume_dB=alsa_mix_mindb;
+  info->maximum_volume_dB=alsa_mix_maxdb;
+  info->airplay_volume=set_volume;
+  info->current_volume_dB=vol2attn(set_volume,alsa_mix_maxdb,alsa_mix_mindb);
+}
+
 static void volume(double vol) {
   set_volume=vol;
   double vol_setting = vol2attn(vol,alsa_mix_maxdb,alsa_mix_mindb);

audio_ao.c

@@ -127,5 +127,6 @@ audio_output audio_ao = {
     .flush = NULL,
     .delay = NULL,
     .play = &play,
-    .volume = NULL
+    .volume = NULL,
+    .parameters = NULL
 };

audio_dummy.c

@@ -81,5 +81,6 @@ audio_output audio_dummy = {
     .flush = NULL,
     .delay = NULL,
     .play = &play,
-    .volume = NULL
+    .volume = NULL,
+    .parameters = NULL
 };

audio_pipe.c

@@ -86,5 +86,6 @@ audio_output audio_pipe = {
     .flush = NULL,
     .delay = NULL,
     .play = &play,
-    .volume = NULL
+    .volume = NULL,
+    .parameters = NULL
 };

audio_pulse.c

@@ -148,5 +148,6 @@ audio_output audio_pulse = {
     .flush = NULL,
     .delay = NULL,
     .play = &play,
-    .volume = NULL
+    .volume = NULL,
+    .parameters = NULL
 };

audio_sndio.c

@@ -82,5 +82,6 @@ audio_output audio_sndio = {
 	.flush = NULL,
 	.delay = NULL,
 	.play = &play,
-	.volume = &volume
+	.volume = &volume,
+	.parameters = NULL
 };

common.c

@@ -399,6 +399,8 @@ void command_stop(void) {
 // See http://tangentsoft.net/audio/atten.html for data on good attenuators.
 // We want a smooth attenuation function, like, for example, the ALPS RK27 Potentiometer transfer functions referred to at the link above.
 
+// Note that the max_db and min_db are given as dB*100
+
 double vol2attn(double vol, long max_db, long min_db) { 
 
 // We use a little coordinate geometry to build a transfer function from the volume passed in to the device's dynamic range.

player.c

@@ -95,7 +95,7 @@ static int32_t last_seqno_read;
 
 
 // interthread variables
-static double volume = 1.0;
+static double software_mixer_volume = 1.0;
 static int fix_volume = 0x10000;
 static pthread_mutex_t vol_mutex = PTHREAD_MUTEX_INITIALIZER;
 
@@ -133,6 +133,8 @@ static pthread_cond_t flowcontrol;
 
 static int64_t first_packet_time_to_play; // nanoseconds
 
+static audio_parameters audio_information;
+
 // stats
 static uint64_t missing_packets,late_packets,too_late_packets,resend_requests; 
 
@@ -740,7 +742,7 @@ static int stuff_buffer_soxr(short *inptr, short *outptr, int stuff) {
     }
 
     // finally, adjust the volume, if necessary
-    if (volume!=1.0) {
+    if (software_mixer_volume!=1.0) {
       // pthread_mutex_lock(&vol_mutex);
       op=outptr;
       for (i=0; i<frame_size+stuff; i++) {
@@ -780,6 +782,7 @@ static void *player_thread_func(void *arg) {
   int64_t minimum_dac_queue_size = 1000000;
   int32_t minimum_buffer_occupancy = BUFFER_FRAMES;
   int32_t maximum_buffer_occupancy = 0;
+  audio_information.valid=0;
   
   int play_samples;
   int64_t current_delay;
@@ -1031,25 +1034,42 @@ void player_volume(double f) {
 // Here, we ask for an attenuation we will apply in software. The dB range of a value from 1 to 65536 is about 48.1 dB (log10 of 65536 is 4.8164).
 // Thus, we ask our vol2attn function for an appropriate dB between -48.1 and 0 dB and translate it back to a number.
  
-  double linear_volume = pow(10,vol2attn(f,0,-4810)/1000);
+  double scaled_volume = vol2attn(f,0,-4810);
+  double linear_volume = pow(10,scaled_volume/1000);
     
   if(f == -144.0)
     linear_volume = 0.0;
   
   if (config.output->volume) {
-      config.output->volume(f);
-      linear_volume=1.0; // no attenuation needed
-  } 
+      config.output->volume(f); // volume will be sent as metadata by the config.output device
+      linear_volume=1.0; // no attenuation needed -- this value is used as a flag to avoid calculations
+  }
+  
+  
+  if (config.output->parameters)
+    config.output->parameters(&audio_information);
+  else {
+    audio_information.airplay_volume = f;
+    audio_information.minimum_volume_dB = -4810;
+    audio_information.maximum_volume_dB = 0;
+    audio_information.current_volume_dB = scaled_volume;
+    audio_information.has_true_mute = 0;
+    audio_information.is_muted = 0;
+  }
+  audio_information.valid=1;
   pthread_mutex_lock(&vol_mutex);
-  volume = linear_volume;
-  fix_volume = 65536.0 * volume;
+  software_mixer_volume = linear_volume; 
+  fix_volume = 65536.0 * software_mixer_volume;  
   pthread_mutex_unlock(&vol_mutex);
+  
   char *dv = malloc(64); // will be freed in the metadata thread
   if (dv) {
     memset(dv,0,64);
-    snprintf(dv,63,"%.2f",f);
+    snprintf(dv,63,"%.2f,%.2f,%.2f,%.2f",audio_information.airplay_volume,audio_information.current_volume_dB/100.0,audio_information.minimum_volume_dB/100.0,audio_information.maximum_volume_dB/100.0);
     send_ssnc_metadata('pvol',dv,strlen(dv),1);
   }
+
+  
 }
 
 void player_flush(uint32_t timestamp) {

rtsp.c

@@ -797,7 +797,12 @@ static void handle_set_parameter_parameter(rtsp_conn_info *conn,
 //    'pend' -- play stream end. No arguments
 //    'pfls' -- play stream flush. No arguments
 //    'prsm' -- play stream resume. No arguments
-//    'pvol' -- play volume. The volume is sent as a string.
+//    'pvol' -- play volume. The volume is sent as a string -- "airplay_volume,volume,lowest_volume,highest_volume,has_true_mute,is_muted"
+//              volume, lowest_volume and highest_volume are given in dB
+//              is_muted is 1 if [true] mute is enabled, 0 otherwise. 
+//              The "airplay_volume" is what's sent to the player, and is from 0.00 down to -30.00, with -144.00 meaning mute.
+//              This is linear on the volume control slider of iTunes or iOS AirPLay
+//
 //    'mdst' -- a sequence of metadata is about to start
 //    'mden' -- a sequence of metadata has ended
 //    'snam' -- the name of the originator -- e.g. "Joe's iPhone" or "iTunes...".
@@ -894,7 +899,7 @@ void metadata_open(void) {
     char* path = malloc(pl+1);
     snprintf(path, pl+1, "%s/%s", config.meta_dir, fn);
 
-    fd = open(path, O_WRONLY);
+    fd = open(path, O_WRONLY | O_NONBLOCK);
     //if (fd < 0)
     //    debug(1, "Could not open metadata FIFO %s. Will try again later.", path);
 
@@ -907,18 +912,19 @@ static void metadata_close(void) {
 }
 
 ssize_t non_blocking_write(int fd, const void *buf, size_t count) {
-//  debug(1,"writing %u to pipe...",count);
+  // debug(1,"writing %u to pipe...",count);
   // we are assuming that the count is always smaller than the FIFO's buffer
   struct pollfd ufds[1];
   ssize_t reply;  
   do {
     ufds[0].fd=fd;
     ufds[0].events = POLLOUT;
-    int rv = poll(ufds,1,1000);
+    int rv = poll(ufds,1,5000);
     if (rv==-1)
       debug(1,"error waiting for pipe to unblock...");
     if (rv==0)
       debug(1,"timeout waiting for pipe to unblock");
+    reply=write(fd,buf,count);
     if ((reply==-1) && ((errno == EAGAIN) || (errno == EWOULDBLOCK)))
       debug(1,"writing to pipe will block...");
 //    else
@@ -940,12 +946,12 @@ void metadata_process(uint32_t type,uint32_t code,char *data,uint32_t length) {
     return;
   char thestring[1024];
   snprintf(thestring,1024,"<type>%x</type><code>%x</code><length>%u</length>\n",type,code,length);
-  ret = write(fd, thestring, strlen(thestring));
+  ret = non_blocking_write(fd, thestring, strlen(thestring));
   if (ret < 1)
     return;
   if ((data!=NULL) && (length>0)) {
     snprintf(thestring,1024,"<data encoding=\"base64\">\n");
-    ret = write(fd, thestring, strlen(thestring));
+    ret = non_blocking_write(fd, thestring, strlen(thestring));
     if (ret < 1)    // no reader
       return;
     // here, we write the data in base64 form using our nice base64 encoder
@@ -963,7 +969,7 @@ void metadata_process(uint32_t type,uint32_t code,char *data,uint32_t length) {
     	if (base64_encode_so(remaining_data, towrite_count, outbuf, &outbuf_size)==NULL)
     		debug(1,"Error encoding base64 data.");
    		//debug(1,"Remaining count: %d ret: %d, outbuf_size: %d.",remaining_count,ret,outbuf_size);    	
-     	ret = write(fd,outbuf,outbuf_size);
+     	ret = non_blocking_write(fd,outbuf,outbuf_size);
      	if (ret<0)
      	  return;
     	remaining_data+=towrite_count;
@@ -973,7 +979,7 @@ void metadata_process(uint32_t type,uint32_t code,char *data,uint32_t length) {
      	//	return;
     }
     snprintf(thestring,1024,"</data>\n");
-    ret = write(fd, thestring, strlen(thestring));
+    ret = non_blocking_write(fd, thestring, strlen(thestring));
     if (ret < 1)    // no reader
       return;
   }
@@ -1070,8 +1076,8 @@ static void handle_set_parameter_metadata(rtsp_conn_info *conn,
 
 static void handle_set_parameter(rtsp_conn_info *conn,
                                  rtsp_message *req, rtsp_message *resp) {
-     if (!req->contentlength)
-         debug(1, "received empty SET_PARAMETER request.");
+     //if (!req->contentlength)
+     //    debug(1, "received empty SET_PARAMETER request.");
 
     char *ct = msg_get_header(req, "Content-Type");