From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Fri, 15 May 2020 17:41:46 +0000 (+0200)
Subject: When reconnecting an SRT input, try to use the same slot as last time.
X-Git-Tag: 2.0.0~34
X-Git-Url: https://git.sesse.net/?p=nageru;a=commitdiff_plain;h=c9af508251685ef34a1d2cf42330ae6795dd91eb

When reconnecting an SRT input, try to use the same slot as last time.
---

diff --git a/nageru/mixer.cpp b/nageru/mixer.cpp
index 212041b..a773d6c 100644
--- a/nageru/mixer.cpp
+++ b/nageru/mixer.cpp
@@ -559,6 +559,9 @@ void Mixer::configure_card(unsigned card_index, CaptureInterface *capture, CardT
 	}
 	card->capture.reset(capture);
 	card->is_fake_capture = (card_type == CardType::FAKE_CAPTURE);
+	if (card->is_fake_capture) {
+		card->fake_capture_counter = fake_capture_counter++;
+	}
 	card->is_cef_capture = (card_type == CardType::CEF_INPUT);
 	card->may_have_dropped_last_frame = false;
 	card->type = card_type;
@@ -1428,22 +1431,35 @@ void Mixer::handle_hotplugged_cards()
 #ifdef HAVE_SRT
 	// Same, for SRT inputs.
 	// TODO: On disconnect and reconnect, we might want to use the stream ID
-	// to find the slot it used to go into?
 	for (SRTSOCKET sock : hotplugged_srt_cards_copy) {
-		// Look for a fake capture card where we can stick this in.
-		int free_card_index = -1;
-		for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
-			if (cards[card_index].is_fake_capture) {
-				free_card_index = card_index;
-				break;
-			}
-		}
-
 		char name[256];
 		int namelen = sizeof(name);
 		srt_getsockopt(sock, /*ignored=*/0, SRTO_STREAMID, name, &namelen);
 		string stream_id(name, namelen);
 
+		// Look for a fake capture card where we can stick this in.
+		// Prioritize ones that previously held SRT streams with the
+		// same stream ID, if any exist -- and it multiple exist,
+		// take the one that disconnected the last.
+		int first_free_card_index = -1, last_matching_free_card_index = -1;
+		for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
+			CaptureCard *card = &cards[card_index];
+			if (!card->is_fake_capture) {
+				continue;
+			}
+			if (first_free_card_index == -1) {
+				first_free_card_index = card_index;
+			}
+			if (card->last_srt_stream_id == stream_id &&
+			    (last_matching_free_card_index == -1 ||
+			     card->fake_capture_counter >
+				cards[last_matching_free_card_index].fake_capture_counter)) {
+				last_matching_free_card_index = card_index;
+			}
+		}
+
+		const int free_card_index = (last_matching_free_card_index != -1)
+			? last_matching_free_card_index : first_free_card_index;
 		if (free_card_index == -1) {
 			if (stream_id.empty()) {
 				stream_id = "no name";
@@ -1461,6 +1477,7 @@ void Mixer::handle_hotplugged_cards()
 			FFmpegCapture *capture = new FFmpegCapture(sock, stream_id);
 			capture->set_card_index(free_card_index);
 			configure_card(free_card_index, capture, CardType::FFMPEG_INPUT, /*output=*/nullptr, /*override_card_as_live=*/true);
+			card->last_srt_stream_id = stream_id;
 			card->queue_length_policy.reset(free_card_index);
 			capture->set_card_disconnected_callback(bind(&Mixer::bm_hotplug_remove, this, free_card_index));
 			capture->start_bm_capture();
diff --git a/nageru/mixer.h b/nageru/mixer.h
index ff8a197..235dd8d 100644
--- a/nageru/mixer.h
+++ b/nageru/mixer.h
@@ -510,11 +510,19 @@ private:
 	// frame rate is integer, will always stay zero.
 	unsigned fractional_samples = 0;
 
+	// Monotonic counter that lets us know which slot was last turned into
+	// a fake capture. Used for SRT re-plugging.
+	unsigned fake_capture_counter = 0;
+
 	mutable std::mutex card_mutex;
 	bool has_bmusb_thread = false;
 	struct CaptureCard {
 		std::unique_ptr<bmusb::CaptureInterface> capture;
 		bool is_fake_capture;
+		// If is_fake_capture is true, contains a monotonic timer value for when
+		// it was last changed. Otherwise undefined. Used for SRT re-plugging.
+		int fake_capture_counter;
+		std::string last_srt_stream_id = "<default, matches nothing>";  // Used for SRT re-plugging.
 		CardType type;
 		std::unique_ptr<DeckLinkOutput> output;