diff --git a/flv.go b/flv.go
index bb03bd7..28cfd6b 100644
--- a/flv.go
+++ b/flv.go
@@ -251,11 +251,11 @@ func (self *Demuxer) ReadPacket() (pkt av.Packet, err error) {
 				pkt.Idx = int8(self.videostreamidx)
 				pkt.CompositionTime = tsToTime(tag.CompositionTime)
 				pkt.IsKeyFrame = tag.FrameType == flvio.FRAME_KEY
-				if typ := h264parser.CheckNALUsType(tag.Data); typ != h264parser.NALU_AVCC {
-					err = fmt.Errorf("flv: h264 nalu format=%d invalid", typ)
+				var ok bool
+				if pkt.Data, ok = h264parser.FindDataNALUInAVCCNALUs(tag.Data); !ok {
+					err = fmt.Errorf("flv: input h264 format invalid")
 					return
 				}
-				pkt.Data = tag.Data[4:]
 				break loop
 			}