From b2ea8e8533a86b026a17a828ba359727cf3bd172 Mon Sep 17 00:00:00 2001
From: Juliusz Chroboczek <jch@irif.fr>
Date: Tue, 11 May 2021 19:59:24 +0200
Subject: [PATCH] Move isKeyframe into its own file.

---
 rtpconn/codec.go     | 112 +++++++++++++++++++++++++++++++++++++++++++
 rtpconn/rtpreader.go | 106 ----------------------------------------
 2 files changed, 112 insertions(+), 106 deletions(-)
 create mode 100644 rtpconn/codec.go

diff --git a/rtpconn/codec.go b/rtpconn/codec.go
new file mode 100644
index 0000000..f2e0dd9
--- /dev/null
+++ b/rtpconn/codec.go
@@ -0,0 +1,112 @@
+package rtpconn
+
+import (
+	"strings"
+
+	"github.com/pion/rtp"
+	"github.com/pion/rtp/codecs"
+)
+
+// isKeyframe determines if packet is the start of a keyframe.
+// It returns (true, true) if that is the case, (false, true) if that is
+// definitely not the case, and (false, false) if the information cannot
+// be determined.
+func isKeyframe(codec string, packet *rtp.Packet) (bool, bool) {
+	switch strings.ToLower(codec) {
+	case "video/vp8":
+		var vp8 codecs.VP8Packet
+		_, err := vp8.Unmarshal(packet.Payload)
+		if err != nil || len(vp8.Payload) < 1 {
+			return false, false
+		}
+
+		if vp8.S != 0 && vp8.PID == 0 && (vp8.Payload[0]&0x1) == 0 {
+			return true, true
+		}
+		return false, true
+	case "video/vp9":
+		var vp9 codecs.VP9Packet
+		_, err := vp9.Unmarshal(packet.Payload)
+		if err != nil || len(vp9.Payload) < 1 {
+			return false, false
+		}
+		if !vp9.B {
+			return false, true
+		}
+
+		if (vp9.Payload[0] & 0xc0) != 0x80 {
+			return false, false
+		}
+
+		profile := (vp9.Payload[0] >> 4) & 0x3
+		if profile != 3 {
+			return (vp9.Payload[0] & 0xC) == 0, true
+		}
+		return (vp9.Payload[0] & 0x6) == 0, true
+	case "video/h264":
+		if len(packet.Payload) < 1 {
+			return false, false
+		}
+		nalu := packet.Payload[0] & 0x1F
+		if nalu == 0 {
+			// reserved
+			return false, false
+		} else if nalu <= 23 {
+			// simple NALU
+			return nalu == 5, true
+		} else if nalu == 24 || nalu == 25 || nalu == 26 || nalu == 27 {
+			// STAP-A, STAP-B, MTAP16 or MTAP24
+			i := 1
+			if nalu == 25 || nalu == 26 || nalu == 27 {
+				// skip DON
+				i += 2
+			}
+			for i < len(packet.Payload) {
+				if i+2 > len(packet.Payload) {
+					return false, false
+				}
+				length := uint16(packet.Payload[i])<<8 |
+					uint16(packet.Payload[i+1])
+				i += 2
+				if i+int(length) > len(packet.Payload) {
+					return false, false
+				}
+				offset := 0
+				if nalu == 26 {
+					offset = 3
+				} else if nalu == 27 {
+					offset = 4
+				}
+				if offset >= int(length) {
+					return false, false
+				}
+				n := packet.Payload[i+offset] & 0x1F
+				if n == 5 {
+					return true, true
+				} else if n >= 24 {
+					// is this legal?
+					return false, false
+				}
+				i += int(length)
+			}
+			if i == len(packet.Payload) {
+				return false, true
+			}
+			return false, false
+		} else if nalu == 28 || nalu == 29 {
+			// FU-A or FU-B
+			if len(packet.Payload) < 2 {
+				return false, false
+			}
+			if (packet.Payload[1] & 0x80) == 0 {
+				// not a starting fragment
+				return false, true
+			}
+			return (packet.Payload[1]&0x1F == 5), true
+		}
+		return false, false
+
+	default:
+		return false, false
+	}
+}
diff --git a/rtpconn/rtpreader.go b/rtpconn/rtpreader.go
index f7e5990..107fdd4 100644
--- a/rtpconn/rtpreader.go
+++ b/rtpconn/rtpreader.go
@@ -3,120 +3,14 @@ package rtpconn
 import (
 	"io"
 	"log"
-	"strings"
 
 	"github.com/pion/rtp"
-	"github.com/pion/rtp/codecs"
 	"github.com/pion/webrtc/v3"
 
 	"github.com/jech/galene/packetcache"
 	"github.com/jech/galene/rtptime"
 )
 
-// isKeyframe determines if packet is the start of a keyframe.
-// It returns (true, true) if that is the case, (false, true) if that is
-// definitely not the case, and (false, false) if the information cannot
-// be determined.
-func isKeyframe(codec string, packet *rtp.Packet) (bool, bool) {
-	switch strings.ToLower(codec) {
-	case "video/vp8":
-		var vp8 codecs.VP8Packet
-		_, err := vp8.Unmarshal(packet.Payload)
-		if err != nil || len(vp8.Payload) < 1 {
-			return false, false
-		}
-
-		if vp8.S != 0 && vp8.PID == 0 && (vp8.Payload[0]&0x1) == 0 {
-			return true, true
-		}
-		return false, true
-	case "video/vp9":
-		var vp9 codecs.VP9Packet
-		_, err := vp9.Unmarshal(packet.Payload)
-		if err != nil || len(vp9.Payload) < 1 {
-			return false, false
-		}
-		if !vp9.B {
-			return false, true
-		}
-
-		if (vp9.Payload[0] & 0xc0) != 0x80 {
-			return false, false
-		}
-
-		profile := (vp9.Payload[0] >> 4) & 0x3
-		if profile != 3 {
-			return (vp9.Payload[0] & 0xC) == 0, true
-		}
-		return (vp9.Payload[0] & 0x6) == 0, true
-	case "video/h264":
-		if len(packet.Payload) < 1 {
-			return false, false
-		}
-		nalu := packet.Payload[0] & 0x1F
-		if nalu == 0 {
-			// reserved
-			return false, false
-		} else if nalu <= 23 {
-			// simple NALU
-			return nalu == 5, true
-		} else if nalu == 24 || nalu == 25 || nalu == 26 || nalu == 27 {
-			// STAP-A, STAP-B, MTAP16 or MTAP24
-			i := 1
-			if nalu == 25 || nalu == 26 || nalu == 27 {
-				// skip DON
-				i += 2
-			}
-			for i < len(packet.Payload) {
-				if i+2 > len(packet.Payload) {
-					return false, false
-				}
-				length := uint16(packet.Payload[i])<<8 |
-					uint16(packet.Payload[i+1])
-				i += 2
-				if i+int(length) > len(packet.Payload) {
-					return false, false
-				}
-				offset := 0
-				if nalu == 26 {
-					offset = 3
-				} else if nalu == 27 {
-					offset = 4
-				}
-				if offset >= int(length) {
-					return false, false
-				}
-				n := packet.Payload[i + offset] & 0x1F
-				if n == 5 {
-					return true, true
-				} else if n >= 24 {
-					// is this legal?
-					return false, false
-				}
-				i += int(length)
-			}
-			if i == len(packet.Payload) {
-				return false, true
-			}
-			return false, false
-		} else if nalu == 28 || nalu == 29 {
-			// FU-A or FU-B
-			if len(packet.Payload) < 2 {
-				return false, false
-			}
-			if (packet.Payload[1] & 0x80) == 0 {
-				// not a starting fragment
-				return false, true
-			}
-			return (packet.Payload[1]&0x1F == 5), true
-		}
-		return false, false
-
-	default:
-		return false, false
-	}
-}
-
 func readLoop(conn *rtpUpConnection, track *rtpUpTrack) {
 	writers := rtpWriterPool{conn: conn, track: track}
 	defer func() {