Enable dbus delay signals for internal processing delay.

The `bluealsad` daemon currently keeps track of its own internal
processing delay, but only presents that to a client when the
'Delay' property is explicitly queried by the client. This means
that any client which relies on D-Bus signals to obtain Delay
updates may never see this internal processing delay (for example
the `bluealsa` ALSA plugin).

The purpose of this commit is to have `bluealsad` emit a D-Bus
PropertiesChanged signal whenever a "significant" change to the
internal processing delay occurs. Not every change is reported
because that might generate thousands of signals per second.

src/a2dp-aac.c

@@ -419,7 +419,7 @@ void *a2dp_aac_enc_thread(struct ba_transport_pcm *t_pcm) {
 			rtp_state_update(&rtp, pcm_frames);
 
 			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
+			ba_transport_pcm_update_processing_delay(t_pcm, asrsync_get_busy_usec(&io.asrs) / 100);
 
 			/* If the input buffer was not consumed, we have to append new data to
 			 * the existing one. Since we do not use ring buffer, we will simply

src/a2dp-aptx-hd.c

@@ -220,7 +220,7 @@ void *a2dp_aptx_hd_enc_thread(struct ba_transport_pcm *t_pcm) {
 			rtp.ts_pcm_frames += pcm_frames;
 
 			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
+			ba_transport_pcm_update_processing_delay(t_pcm, asrsync_get_busy_usec(&io.asrs) / 100);
 
 			/* reinitialize output buffer */
 			ffb_rewind(&bt);

src/a2dp-aptx.c

@@ -201,7 +201,7 @@ void *a2dp_aptx_enc_thread(struct ba_transport_pcm *t_pcm) {
 			asrsync_sync(&io.asrs, pcm_samples / channels);
 
 			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
+			ba_transport_pcm_update_processing_delay(t_pcm, asrsync_get_busy_usec(&io.asrs) / 100);
 
 			/* reinitialize output buffer */
 			ffb_rewind(&bt);

src/a2dp-faststream.c

@@ -228,7 +228,7 @@ void *a2dp_fs_enc_thread(struct ba_transport_pcm *t_pcm) {
 			asrsync_sync(&io.asrs, pcm_frames);
 
 			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
+			ba_transport_pcm_update_processing_delay(t_pcm, asrsync_get_busy_usec(&io.asrs) / 100);
 
 			/* If the input buffer was not consumed (due to codesize limit), we
 			 * have to append new data to the existing one. Since we do not use

src/a2dp-lc3plus.c

@@ -384,7 +384,7 @@ void *a2dp_lc3plus_enc_thread(struct ba_transport_pcm *t_pcm) {
 			rtp_state_update(&rtp, pcm_frames);
 
 			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
+			ba_transport_pcm_update_processing_delay(t_pcm, asrsync_get_busy_usec(&io.asrs) / 100);
 
 			/* If the input buffer was not consumed (due to codesize limit), we
 			 * have to append new data to the existing one. Since we do not use

src/a2dp-ldac.c

@@ -270,7 +270,7 @@ void *a2dp_ldac_enc_thread(struct ba_transport_pcm *t_pcm) {
 			rtp_state_update(&rtp, pcm_frames);
 
 			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
+			ba_transport_pcm_update_processing_delay(t_pcm, asrsync_get_busy_usec(&io.asrs) / 100);
 
 		}
 

src/a2dp-mpeg.c

@@ -323,7 +323,7 @@ void *a2dp_mp3_enc_thread(struct ba_transport_pcm *t_pcm) {
 		rtp_state_update(&rtp, pcm_frames);
 
 		/* update busy delay (encoding overhead) */
-		t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
+		ba_transport_pcm_update_processing_delay(t_pcm, asrsync_get_busy_usec(&io.asrs) / 100);
 
 		/* If the input buffer was not consumed (due to frame alignment), we
 		 * have to append new data to the existing one. Since we do not use

src/a2dp-opus.c

@@ -244,7 +244,7 @@ void *a2dp_opus_enc_thread(struct ba_transport_pcm *t_pcm) {
 			rtp_state_update(&rtp, opus_frame_pcm_frames);
 
 			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
+			ba_transport_pcm_update_processing_delay(t_pcm, asrsync_get_busy_usec(&io.asrs) / 100);
 
 			/* If the input buffer was not consumed (due to encoder frame
 			 * constraint), we have to append new data to the existing one.

src/a2dp-sbc.c

@@ -273,7 +273,7 @@ void *a2dp_sbc_enc_thread(struct ba_transport_pcm *t_pcm) {
 			rtp_state_update(&rtp, pcm_frames);
 
 			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
+			ba_transport_pcm_update_processing_delay(t_pcm, asrsync_get_busy_usec(&io.asrs) / 100);
 
 			/* If the input buffer was not consumed (due to codesize limit), we
 			 * have to append new data to the existing one. Since we do not use

src/ba-transport-pcm.c

@@ -716,6 +716,22 @@ int ba_transport_pcm_get_hardware_volume(
 	return 0;
 }
 
+void ba_transport_pcm_update_processing_delay(struct ba_transport_pcm *pcm, unsigned int delay) {
+	if (delay == pcm->processing_delay_dms)
+		return;
+	unsigned int diff = delay > pcm->reported_processing_delay_dms ?
+				delay - pcm->reported_processing_delay_dms :
+				pcm->reported_processing_delay_dms - delay;
+	pcm->processing_delay_dms = delay;
+
+	/* To avoid creating a flood of dbus signals, we only notify clients when
+	 * the value changes by more than 10ms */
+	if (diff > 100 || pcm->reported_processing_delay_dms == 0) {
+		pcm->reported_processing_delay_dms = delay;
+		bluealsa_dbus_pcm_update(pcm, BA_DBUS_PCM_UPDATE_DELAY);
+	}
+}
+
 int ba_transport_pcm_get_delay(const struct ba_transport_pcm *pcm) {
 
 	const struct ba_transport *t = pcm->t;

src/ba-transport-pcm.h

@@ -129,6 +129,7 @@ struct ba_transport_pcm {
 	 * the host computational power. It is used to compensate for the time
 	 * required to encode or decode audio. */
 	unsigned int processing_delay_dms;
+	unsigned int reported_processing_delay_dms;
 	/* Positive (or negative) delay reported by the client. */
 	int client_delay_dms;
 
@@ -253,6 +254,10 @@ int ba_transport_pcm_volume_update(
 int ba_transport_pcm_get_hardware_volume(
 		const struct ba_transport_pcm *pcm);
 
+void ba_transport_pcm_update_processing_delay(
+		struct ba_transport_pcm *pcm,
+		unsigned int delay);
+
 int ba_transport_pcm_get_delay(
 		const struct ba_transport_pcm *pcm);
 

src/bluealsa-dbus.c

@@ -538,6 +538,10 @@ static void bluealsa_pcm_open(GDBusMethodInvocation *inv, void *userdata) {
 			goto fail;
 		}
 
+		/* It the transport thread has updated its codec_delay value during its
+		 * start procedure then we inform clients that the delay has changed */
+		 if (pcm->codec_delay_dms > 0)
+			bluealsa_dbus_pcm_update(pcm, BA_DBUS_PCM_UPDATE_DELAY);
 	}
 
 	pthread_mutex_lock(&pcm->mutex);

src/sco-cvsd.c

@@ -79,7 +79,7 @@ void *sco_cvsd_enc_thread(struct ba_transport_pcm *t_pcm) {
 			/* keep data transfer at a constant bit rate */
 			asrsync_sync(&io.asrs, mtu_samples);
 			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
+			ba_transport_pcm_update_processing_delay(t_pcm, asrsync_get_busy_usec(&io.asrs) / 100);
 
 		}
 

src/sco-lc3-swb.c

@@ -85,7 +85,7 @@ void *sco_lc3_swb_enc_thread(struct ba_transport_pcm *t_pcm) {
 			/* keep data transfer at a constant bit rate */
 			asrsync_sync(&io.asrs, codec.frames * LC3_SWB_CODESAMPLES);
 			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
+			ba_transport_pcm_update_processing_delay(t_pcm, asrsync_get_busy_usec(&io.asrs) / 100);
 
 			/* Move unprocessed data to the front of our linear
 			 * buffer and clear the LC3-SWB frame counter. */

src/sco-msbc.c

@@ -92,7 +92,7 @@ void *sco_msbc_enc_thread(struct ba_transport_pcm *t_pcm) {
 			/* keep data transfer at a constant bit rate */
 			asrsync_sync(&io.asrs, msbc.frames * MSBC_CODESAMPLES);
 			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
+			ba_transport_pcm_update_processing_delay(t_pcm, asrsync_get_busy_usec(&io.asrs) / 100);
 
 			/* Move unprocessed data to the front of our linear
 			 * buffer and clear the mSBC frame counter. */

test/test-a2dp.c

@@ -51,6 +51,8 @@ int ba_transport_pcm_state_set(struct ba_transport_pcm *pcm,
 enum ba_transport_pcm_signal ba_transport_pcm_signal_recv(struct ba_transport_pcm *pcm) {
 	(void)pcm; return -1; }
 void ba_transport_pcm_thread_cleanup(struct ba_transport_pcm *pcm) { (void)pcm; }
+void ba_transport_pcm_update_processing_delay(struct ba_transport_pcm *pcm, unsigned int delay) {
+	(void)pcm; (void)delay;}
 
 CK_START_TEST(test_a2dp_codecs_codec_id_from_string) {
 	ck_assert_uint_eq(a2dp_codecs_codec_id_from_string("SBC"), A2DP_CODEC_SBC);