ao_coreaudio: remember volume between chapters

Author: pigoz

libao2/ao_coreaudio.c

@@ -118,6 +118,9 @@ typedef struct ao_coreaudio_s
 
 static ao_coreaudio_t *ao = NULL;
 
+/* variable to store the volume when changing between audio units */
+static Float32 temp_vol = -1.0;
+
 /**
  * \brief add data to ringbuffer
  */
@@ -581,6 +584,14 @@ int device_id, display_help = 0;
 		goto err_out1;
 	}
 
+	if (temp_vol >= 0) {
+		err = AudioUnitSetParameter(ao->theOutputUnit, kHALOutputParam_Volume, kAudioUnitScope_Global, 0, temp_vol, 0);
+		if (err) {
+			ao_msg(MSGT_AO, MSGL_WARN, "could not restore the HAL output volume: [%4.4s]\n", (char *)&err);
+			goto err_out2;
+		}
+	}
+
 	size =  sizeof(AudioStreamBasicDescription);
 	err = AudioUnitSetProperty(ao->theOutputUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, 0, &inDesc, size);
 
@@ -1137,6 +1148,12 @@ static void uninit(int immed)
 {
   OSStatus            err = noErr;
 
+  err = AudioUnitGetParameter(ao->theOutputUnit, kHALOutputParam_Volume, kAudioUnitScope_Global, 0, &temp_vol);
+  if(err) {
+    temp_vol = -1.0; // backing off to standard volume
+    ao_msg(MSGT_AO, MSGL_WARN, "could not save HAL output volume: [%4.4s]\n", (char *)&err);
+  }
+
   if (!immed) {
     long long timeleft=(1000000LL*av_fifo_size(ao->buffer))/ao_data.bps;
     ao_msg(MSGT_AO,MSGL_DBG2, "%d bytes left @%d bps (%d usec)\n", av_fifo_size(ao->buffer), ao_data.bps, (int)timeleft);