output: convert audio_output.config_audio_format to boolean

src/output_control.c

@@ -78,16 +78,12 @@ audio_output_open(struct audio_output *ao,
 	ao->in_audio_format = *audio_format;
 	ao->chunk = NULL;
 
-	if (audio_format_defined(&ao->config_audio_format)) {
-		/* copy config_audio_format to out_audio_format only if the
-		   device is not yet open; if it is already open,
-		   plugin->open() may have modified out_audio_format,
-		   and the value is already ok */
-		if (!ao->open)
-			ao->out_audio_format =
-				ao->config_audio_format;
-	} else {
+	if (!ao->config_audio_format) {
+		/* no audio format is configured: copy in->out, let
+		   the output's open() method determine the effective
+		   out_audio_format */
 		ao->out_audio_format = ao->in_audio_format;
+
 		if (ao->open)
 			audio_output_close(ao);
 	}

src/output_init.c

@@ -112,15 +112,15 @@ audio_output_init(struct audio_output *ao, const struct config_param *param,
 
 	pcm_convert_init(&ao->convert_state);
 
-	if (format) {
+	ao->config_audio_format = format != NULL;
+	if (ao->config_audio_format) {
 		bool ret;
 
-		ret = audio_format_parse(&ao->config_audio_format, format,
+		ret = audio_format_parse(&ao->out_audio_format, format,
 					 error);
 		if (!ret)
 			return false;
-	} else
-		audio_format_clear(&ao->config_audio_format);
+	}
 
 	ao->thread = NULL;
 	notify_init(&ao->notify);
@@ -128,7 +128,8 @@ audio_output_init(struct audio_output *ao, const struct config_param *param,
 	ao->mutex = g_mutex_new();
 
 	ao->data = ao_plugin_init(plugin,
-				  format ? &ao->config_audio_format : NULL,
+				  ao->config_audio_format
+				  ? &ao->out_audio_format : NULL,
 				  param, error);
 	if (ao->data == NULL)
 		return false;

src/output_internal.h

@@ -53,6 +53,12 @@ struct audio_output {
 	void *data;
 
 	/**
+	 * This flag is true, when the audio_format of this device is
+	 * configured in mpd.conf.
+	 */
+	bool config_audio_format;
+
+	/**
 	 * Has the user enabled this device?
 	 */
 	bool enabled;
@@ -83,12 +89,6 @@ struct audio_output {
 	 */
 	struct audio_format out_audio_format;
 
-	/**
-	 * The audio_format which was configured.  Only set if
-	 * convertAudioFormat is true.
-	 */
-	struct audio_format config_audio_format;
-
 	struct pcm_convert_state convert_state;
 
 	/**