diff --git a/pkg/h264/helper.go b/pkg/h264/helper.go
index e06e9f98..e073c4b1 100644
--- a/pkg/h264/helper.go
+++ b/pkg/h264/helper.go
@@ -8,11 +8,12 @@ import (
 )
 
 const (
-	NALUTypePFrame = 1
-	NALUTypeIFrame = 5
-	NALUTypeSEI    = 6
-	NALUTypeSPS    = 7
-	NALUTypePPS    = 8
+	NALUTypePFrame = 1 // Coded slice of a non-IDR picture
+	NALUTypeIFrame = 5 // Coded slice of an IDR picture
+	NALUTypeSEI    = 6 // Supplemental enhancement information (SEI)
+	NALUTypeSPS    = 7 // Sequence parameter set
+	NALUTypePPS    = 8 // Picture parameter set
+	NALUTypeAUD    = 9 // Access unit delimiter
 )
 
 func NALUType(b []byte) byte {
diff --git a/pkg/h264/rtp.go b/pkg/h264/rtp.go
index 9f84f745..0a80bfcc 100644
--- a/pkg/h264/rtp.go
+++ b/pkg/h264/rtp.go
@@ -40,11 +40,13 @@ func RTPDepay(track *streamer.Track) streamer.WrapperFunc {
 			}
 
 			if len(buf) == 0 {
+				// Amcrest IP4M-1051: 9, 7, 8, 6, 28...
+				// Amcrest IP4M-1051: 9, 6, 1
 				switch NALUType(payload) {
 				case NALUTypeIFrame:
 					// fix IFrame without SPS,PPS
 					buf = append(buf, ps...)
-				case NALUTypeSEI:
+				case NALUTypeSEI, NALUTypeAUD:
 					// fix ffmpeg with transcoding first frame
 					i := int(4 + binary.BigEndian.Uint32(payload))