TT#14008 restart DTX and delay buffers after shutdown

DTX and delay buffers and their timers are shut down during the codec
negotiation phase, which also happens for the offer side while
processing an answer. If the codec negotiation routine determines that
the existing codec handlers can be kept intact, we must restart the DTX
and delay buffers that have previously been shut down.

Buffer objects are never freed during a shutdown, therefore we simply
need to restore the contained references to indicate that these buffers
are active again.

closes #1481

Change-Id: I57181ba1655fd781a7c543ee31aa67fd179ba89b

daemon/codec.c

@@ -260,6 +260,7 @@ static void __dtx_shutdown(struct dtx_buffer *dtxb);
 static struct codec_handler *__input_handler(struct codec_handler *h, struct media_packet *mp);
 
 static void __delay_frame_process(struct delay_buffer *, struct delay_frame *dframe);
+static void __dtx_restart(struct codec_handler *h);
 static void __delay_buffer_setup(struct delay_buffer **dbufp,
 		struct codec_handler *h, struct call *call, unsigned int delay);
 static void __delay_buffer_shutdown(struct delay_buffer *dbuf, bool);
@@ -483,6 +484,7 @@ reset:
 
 no_handler_reset:
 	__delay_buffer_setup(&handler->delay_buffer, handler, handler->media->call, handler->media->buffer_delay);
+	__dtx_restart(handler);
 	// check if we have multiple decoders transcoding to the same output PT
 	struct codec_handler *output_handler = NULL;
 	if (output_transcoders)
@@ -3142,19 +3144,24 @@ static void __delay_buffer_free(void *p) {
 	mutex_destroy(&dbuf->lock);
 }
 static void __dtx_setup(struct codec_ssrc_handler *ch) {
-	if (!decoder_has_dtx(ch->decoder) || ch->dtx_buffer)
+	if (!decoder_has_dtx(ch->decoder))
 		return;
 
 	if (!rtpe_config.dtx_delay)
 		return;
 
-	struct dtx_buffer *dtx =
-		ch->dtx_buffer = obj_alloc0("dtx_buffer", sizeof(*dtx), __dtx_free);
-	dtx->ct.tt_obj.tt = &codec_timers_thread;
-	dtx->ct.timer_func = __dtx_send_later;
-	dtx->csh = obj_get(&ch->h);
-	dtx->call = obj_get(ch->handler->media->call);
-	mutex_init(&dtx->lock);
+	struct dtx_buffer *dtx = ch->dtx_buffer;
+	if (!dtx) {
+		dtx = ch->dtx_buffer = obj_alloc0("dtx_buffer", sizeof(*dtx), __dtx_free);
+		dtx->ct.tt_obj.tt = &codec_timers_thread;
+		dtx->ct.timer_func = __dtx_send_later;
+		mutex_init(&dtx->lock);
+	}
+
+	if (!dtx->csh)
+		dtx->csh = obj_get(&ch->h);
+	if (!dtx->call)
+		dtx->call = obj_get(ch->handler->media->call);
 	dtx->ptime = ch->ptime;
 	if (dtx->ptime <= 0)
 		dtx->ptime = ch->handler->source_pt.codec_def->default_ptime;
@@ -3165,6 +3172,13 @@ static void __dtx_setup(struct codec_ssrc_handler *ch) {
 	dtx->clockrate = ch->handler->source_pt.clock_rate;
 	dtx->tspp = dtx->ptime * dtx->clockrate / 1000;
 }
+static void __dtx_buffer_restart(void *p, void *arg) {
+	struct codec_ssrc_handler *ch = p;
+	__dtx_setup(ch);
+}
+static void __dtx_restart(struct codec_handler *h) {
+	ssrc_hash_foreach(h->ssrc_hash, __dtx_buffer_restart, NULL);
+}
 static void __delay_buffer_setup(struct delay_buffer **dbufp,
 		struct codec_handler *h, struct call *call, unsigned int delay)
 {
@@ -3173,21 +3187,19 @@ static void __delay_buffer_setup(struct delay_buffer **dbufp,
 
 	struct delay_buffer *dbuf = *dbufp;
 
-	if (dbuf) {
-		// update options
-		dbuf->delay = delay;
-		return;
+	if (!dbuf) {
+		if (!delay)
+			return;
+		dbuf = obj_alloc0("delay_buffer", sizeof(*dbuf), __delay_buffer_free);
+		dbuf->ct.tt_obj.tt = &codec_timers_thread;
+		dbuf->ct.timer_func = __delay_send_later;
+		dbuf->handler = h;
+		mutex_init(&dbuf->lock);
 	}
-	if (!delay)
-		return;
 
-	dbuf = obj_alloc0("delay_buffer", sizeof(*dbuf), __delay_buffer_free);
-	dbuf->ct.tt_obj.tt = &codec_timers_thread;
-	dbuf->ct.timer_func = __delay_send_later;
-	dbuf->handler = h;
-	dbuf->call = obj_get(call);
+	if (!dbuf->call)
+		dbuf->call = obj_get(call);
 	dbuf->delay = delay;
-	mutex_init(&dbuf->lock);
 
 	*dbufp = dbuf;
 }