From 497594f53f2600d360b1399be72c70717e4439a9 Mon Sep 17 00:00:00 2001
From: Alexey Khit <alexey.khit@gmail.com>
Date: Mon, 6 Feb 2023 11:46:00 +0300
Subject: [PATCH] Fix buggy SDP parsing

---
 pkg/rtsp/helpers.go   | 35 ++++++++++++++++++++++++++++++-----
 pkg/rtsp/rtsp_test.go | 23 +++++++++++++++++++++++
 pkg/streamer/media.go | 12 +++---------
 pkg/webrtc/conn.go    |  8 ++++++--
 4 files changed, 62 insertions(+), 16 deletions(-)

diff --git a/pkg/rtsp/helpers.go b/pkg/rtsp/helpers.go
index 893f3b87..ea9d13a6 100644
--- a/pkg/rtsp/helpers.go
+++ b/pkg/rtsp/helpers.go
@@ -4,8 +4,10 @@ import (
 	"bytes"
 	"github.com/AlexxIT/go2rtc/pkg/streamer"
 	"github.com/pion/rtcp"
+	"github.com/pion/sdp/v3"
 	"net/url"
 	"regexp"
+	"strconv"
 	"strings"
 )
 
@@ -21,8 +23,8 @@ s=-
 t=0 0`
 
 func UnmarshalSDP(rawSDP []byte) ([]*streamer.Media, error) {
-	medias, err := streamer.UnmarshalSDP(rawSDP)
-	if err != nil {
+	sd := &sdp.SessionDescription{}
+	if err := sd.Unmarshal(rawSDP); err != nil {
 		// fix multiple `s=` https://github.com/AlexxIT/WebRTC/issues/417
 		re, _ := regexp.Compile("\ns=[^\n]+")
 		rawSDP = re.ReplaceAll(rawSDP, nil)
@@ -30,16 +32,28 @@ func UnmarshalSDP(rawSDP []byte) ([]*streamer.Media, error) {
 		// fix SDP header for some cameras
 		if i := bytes.Index(rawSDP, []byte("\nm=")); i > 0 {
 			rawSDP = append([]byte(sdpHeader), rawSDP[i:]...)
-			medias, err = streamer.UnmarshalSDP(rawSDP)
+			sd = &sdp.SessionDescription{}
+			err = sd.Unmarshal(rawSDP)
 		}
+
 		if err != nil {
 			return nil, err
 		}
 	}
 
-	// fix bug in ONVIF spec
-	// https://www.onvif.org/specs/stream/ONVIF-Streaming-Spec-v241.pdf
+	medias := streamer.UnmarshalMedias(sd.MediaDescriptions)
+
 	for _, media := range medias {
+		// Check buggy SDP with fmtp for H264 on another track
+		// https://github.com/AlexxIT/WebRTC/issues/419
+		for _, codec := range media.Codecs {
+			if codec.Name == streamer.CodecH264 && codec.FmtpLine == "" {
+				codec.FmtpLine = findFmtpLine(codec.PayloadType, sd.MediaDescriptions)
+			}
+		}
+
+		// fix bug in ONVIF spec
+		// https://www.onvif.org/specs/stream/ONVIF-Streaming-Spec-v241.pdf
 		switch media.Direction {
 		case streamer.DirectionRecvonly, "":
 			media.Direction = streamer.DirectionSendonly
@@ -51,6 +65,17 @@ func UnmarshalSDP(rawSDP []byte) ([]*streamer.Media, error) {
 	return medias, nil
 }
 
+func findFmtpLine(payloadType uint8, descriptions []*sdp.MediaDescription) string {
+	s := strconv.Itoa(int(payloadType))
+	for _, md := range descriptions {
+		codec := streamer.UnmarshalCodec(md, s)
+		if codec.FmtpLine != "" {
+			return codec.FmtpLine
+		}
+	}
+	return ""
+}
+
 // urlParse fix bugs:
 // 1. Content-Base: rtsp://::ffff:192.168.1.123/onvif/profile.1/
 // 2. Content-Base: rtsp://rtsp://turret2-cam.lan:554/stream1/
diff --git a/pkg/rtsp/rtsp_test.go b/pkg/rtsp/rtsp_test.go
index e7024f4e..39d5cae4 100644
--- a/pkg/rtsp/rtsp_test.go
+++ b/pkg/rtsp/rtsp_test.go
@@ -20,6 +20,7 @@ func TestURLParse(t *testing.T) {
 }
 
 func TestMultipleSinSDP(t *testing.T) {
+	// https://github.com/AlexxIT/WebRTC/issues/417
 	s := `v=0
 o=- 91674849066 1 IN IP4 192.168.1.123
 s=RtspServer
@@ -50,3 +51,25 @@ a=control:track1
 	assert.Nil(t, err)
 	assert.NotNil(t, medias)
 }
+
+func TestFindFmtp(t *testing.T) {
+	// https://github.com/AlexxIT/WebRTC/issues/419
+	s := `v=0
+o=- 1675628282 1675628283 IN IP4 192.168.1.123
+s=streamed by the RTSP server
+t=0 0
+m=video 0 RTP/AVP 96
+a=rtpmap:96 H264/90000
+a=control:track0
+m=audio 0 RTP/AVP 8
+a=rtpmap:0 pcma/8000/1
+a=control:track1
+a=framerate:25
+a=range:npt=now-
+a=fmtp:96 packetization-mode=1;profile-level-id=64001F;sprop-parameter-sets=Z0IAH5WoFAFuQA==,aM48gA==
+`
+	medias, err := UnmarshalSDP([]byte(s))
+	assert.Nil(t, err)
+	assert.NotNil(t, medias)
+	assert.NotEqual(t, "", medias[0].Codecs[0].FmtpLine)
+}
diff --git a/pkg/streamer/media.go b/pkg/streamer/media.go
index 5765c75d..bcb5ae08 100644
--- a/pkg/streamer/media.go
+++ b/pkg/streamer/media.go
@@ -166,14 +166,8 @@ func (c *Codec) Match(codec *Codec) bool {
 		(c.Channels == codec.Channels || codec.Channels == 0)
 }
 
-func UnmarshalSDP(rawSDP []byte) ([]*Media, error) {
-	sd := &sdp.SessionDescription{}
-	if err := sd.Unmarshal(rawSDP); err != nil {
-		return nil, err
-	}
-
-	var medias []*Media
-	for _, md := range sd.MediaDescriptions {
+func UnmarshalMedias(descriptions []*sdp.MediaDescription) (medias []*Media) {
+	for _, md := range descriptions {
 		media := UnmarshalMedia(md)
 
 		if media.Direction == DirectionSendRecv {
@@ -187,7 +181,7 @@ func UnmarshalSDP(rawSDP []byte) ([]*Media, error) {
 		medias = append(medias, media)
 	}
 
-	return medias, nil
+	return
 }
 
 func MarshalSDP(name string, medias []*Media) ([]byte, error) {
diff --git a/pkg/webrtc/conn.go b/pkg/webrtc/conn.go
index eb4d5974..059dd545 100644
--- a/pkg/webrtc/conn.go
+++ b/pkg/webrtc/conn.go
@@ -2,6 +2,7 @@ package webrtc
 
 import (
 	"github.com/AlexxIT/go2rtc/pkg/streamer"
+	"github.com/pion/sdp/v3"
 	"github.com/pion/webrtc/v3"
 )
 
@@ -90,12 +91,15 @@ func (c *Conn) SetOffer(offer string) (err error) {
 	if err = c.Conn.SetRemoteDescription(sdOffer); err != nil {
 		return
 	}
+
 	rawSDP := []byte(c.Conn.RemoteDescription().SDP)
-	medias, err := streamer.UnmarshalSDP(rawSDP)
-	if err != nil {
+	sd := &sdp.SessionDescription{}
+	if err = sd.Unmarshal(rawSDP); err != nil {
 		return
 	}
 
+	medias := streamer.UnmarshalMedias(sd.MediaDescriptions)
+
 	// sort medias, so video will always be before audio
 	// and ignore application media from Hass default lovelace card
 	for _, media := range medias {