Revert "libobs: Remove unused volmeter code"

This reverts commit 07d30cbff9a0720fb4425f6790de65a7760d0fdd.

libobs/obs-audio-controls.c

@@ -73,6 +73,7 @@ struct obs_volmeter {
 	DARRAY(struct meter_cb) callbacks;
 
 	enum obs_peak_meter_type peak_meter_type;
+	unsigned int update_ms;
 	float prev_samples[MAX_AUDIO_CHANNELS][4];
 
 	float magnitude[MAX_AUDIO_CHANNELS];
@@ -782,6 +783,8 @@ obs_volmeter_t *obs_volmeter_create(enum obs_fader_type type)
 
 	volmeter->type = type;
 
+	obs_volmeter_set_update_interval(volmeter, 50);
+
 	return volmeter;
 fail:
 	obs_volmeter_destroy(volmeter);
@@ -863,6 +866,29 @@ void obs_volmeter_set_peak_meter_type(obs_volmeter_t *volmeter,
 	pthread_mutex_unlock(&volmeter->mutex);
 }
 
+void obs_volmeter_set_update_interval(obs_volmeter_t *volmeter,
+				      const unsigned int ms)
+{
+	if (!volmeter || !ms)
+		return;
+
+	pthread_mutex_lock(&volmeter->mutex);
+	volmeter->update_ms = ms;
+	pthread_mutex_unlock(&volmeter->mutex);
+}
+
+unsigned int obs_volmeter_get_update_interval(obs_volmeter_t *volmeter)
+{
+	if (!volmeter)
+		return 0;
+
+	pthread_mutex_lock(&volmeter->mutex);
+	const unsigned int interval = volmeter->update_ms;
+	pthread_mutex_unlock(&volmeter->mutex);
+
+	return interval;
+}
+
 int obs_volmeter_get_nr_channels(obs_volmeter_t *volmeter)
 {
 	int source_nr_audio_channels;

libobs/obs-audio-controls.h

@@ -231,6 +231,34 @@ EXPORT void
 obs_volmeter_set_peak_meter_type(obs_volmeter_t *volmeter,
 				 enum obs_peak_meter_type peak_meter_type);
 
+/**
+ * @brief Set the update interval for the volume meter
+ * @param volmeter pointer to the volume meter object
+ * @param ms update interval in ms
+ *
+ * This sets the update interval in milliseconds that should be processed before
+ * the resulting values are emitted by the levels_updated signal. The resulting
+ * number of audio samples is rounded to an integer.
+ *
+ * Please note that due to way obs does receive audio data from the sources
+ * this is no hard guarantee for the timing of the signal itself. When the
+ * volume meter receives a chunk of data that is multiple the size of the sample
+ * interval, all data will be sampled and the values updated accordingly, but
+ * only the signal for the last segment is actually emitted.
+ * On the other hand data might be received in a way that will cause the signal
+ * to be emitted in shorter intervals than specified here under some
+ * circumstances.
+ */
+EXPORT void obs_volmeter_set_update_interval(obs_volmeter_t *volmeter,
+					     const unsigned int ms);
+
+/**
+ * @brief Get the update interval currently used for the volume meter
+ * @param volmeter pointer to the volume meter object
+ * @return update interval in ms
+ */
+EXPORT unsigned int obs_volmeter_get_update_interval(obs_volmeter_t *volmeter);
+
 /**
  * @brief Get the number of channels which are configured for this source.
  * @param volmeter pointer to the volume meter object