From 71f1e445e1ec3c55371009297d0403318726ee46 Mon Sep 17 00:00:00 2001
From: Alexey Khit <alexey.khit@gmail.com>
Date: Wed, 23 Aug 2023 06:52:33 +0300
Subject: [PATCH] Fix 400 response on PLAY for Reolink Doorbell #562

---
 pkg/rtsp/conn.go     | 3 +++
 pkg/rtsp/consumer.go | 8 ++++++--
 pkg/rtsp/server.go   | 4 +++-
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/pkg/rtsp/conn.go b/pkg/rtsp/conn.go
index c68a2675..2edf9215 100644
--- a/pkg/rtsp/conn.go
+++ b/pkg/rtsp/conn.go
@@ -38,6 +38,7 @@ type Conn struct {
 	conn      net.Conn
 	keepalive int
 	mode      core.Mode
+	playOK    bool
 	reader    *bufio.Reader
 	sequence  int
 	session   string
@@ -156,6 +157,8 @@ func (c *Conn) Handle() (err error) {
 					return
 				}
 				c.Fire(res)
+				// for playing backchannel only after OK response on play
+				c.playOK = true
 				continue
 
 			case "OPTI", "TEAR", "DESC", "SETU", "PLAY", "PAUS", "RECO", "ANNO", "GET_", "SET_":
diff --git a/pkg/rtsp/consumer.go b/pkg/rtsp/consumer.go
index d1874025..4bddd77b 100644
--- a/pkg/rtsp/consumer.go
+++ b/pkg/rtsp/consumer.go
@@ -86,7 +86,7 @@ func (c *Conn) packetWriter(codec *core.Codec, channel, payloadType uint8) core.
 	}
 
 	handlerFunc := func(packet *rtp.Packet) {
-		if c.state == StateNone {
+		if c.state == StateNone || !c.playOK {
 			return
 		}
 
@@ -102,6 +102,10 @@ func (c *Conn) packetWriter(codec *core.Codec, channel, payloadType uint8) core.
 			Payload: packet.Payload,
 		}
 
+		if !video {
+			packet.Marker = true // better to have marker on all audio packets
+		}
+
 		size := 12 + len(packet.Payload)
 
 		if n+4+size > len(buf) {
@@ -130,7 +134,7 @@ func (c *Conn) packetWriter(codec *core.Codec, channel, payloadType uint8) core.
 
 		n += 4 + size
 
-		if video && !packet.Marker {
+		if !packet.Marker {
 			return // collect continious video packets to buffer
 		}
 
diff --git a/pkg/rtsp/server.go b/pkg/rtsp/server.go
index 5c69fb68..15b3f84b 100644
--- a/pkg/rtsp/server.go
+++ b/pkg/rtsp/server.go
@@ -157,7 +157,9 @@ func (c *Conn) Accept() error {
 
 		case MethodRecord, MethodPlay:
 			res := &tcp.Response{Request: req}
-			return c.WriteResponse(res)
+			err = c.WriteResponse(res)
+			c.playOK = true
+			return err
 
 		case MethodTeardown:
 			res := &tcp.Response{Request: req}