add resetFragments() to all fragment-based decoders (#637)

pkg/format/rtph265/decoder.go

@@ -35,8 +35,8 @@ type Decoder struct {
 	MaxDONDiff int
 
 	firstPacketReceived bool
-	fragmentsSize       int
 	fragments           [][]byte
+	fragmentsSize       int
 
 	// for Decode()
 	frameBuffer     [][]byte
@@ -52,9 +52,14 @@ func (d *Decoder) Init() error {
 	return nil
 }
 
+func (d *Decoder) resetFragments() {
+	d.fragments = d.fragments[:0]
+	d.fragmentsSize = 0
+}
+
 func (d *Decoder) decodeNALUs(pkt *rtp.Packet) ([][]byte, error) {
 	if len(pkt.Payload) < 2 {
-		d.fragments = d.fragments[:0] // discard pending fragments
+		d.resetFragments()
 		return nil, fmt.Errorf("payload is too short")
 	}
 
@@ -63,7 +68,7 @@ func (d *Decoder) decodeNALUs(pkt *rtp.Packet) ([][]byte, error) {
 
 	switch typ {
 	case h265.NALUType_AggregationUnit:
-		d.fragments = d.fragments[:0] // discard pending fragments
+		d.resetFragments()
 
 		payload := pkt.Payload[2:]
 
@@ -95,7 +100,7 @@ func (d *Decoder) decodeNALUs(pkt *rtp.Packet) ([][]byte, error) {
 
 	case h265.NALUType_FragmentationUnit:
 		if len(pkt.Payload) < 3 {
-			d.fragments = d.fragments[:0] // discard pending fragments
+			d.resetFragments()
 			return nil, fmt.Errorf("payload is too short")
 		}
 
@@ -103,7 +108,7 @@ func (d *Decoder) decodeNALUs(pkt *rtp.Packet) ([][]byte, error) {
 		end := (pkt.Payload[2] >> 6) & 0x01
 
 		if start == 1 {
-			d.fragments = d.fragments[:0] // discard pending fragments
+			d.resetFragments()
 
 			if end != 0 {
 				return nil, fmt.Errorf("invalid fragmentation unit (can't contain both a start and end bit)")
@@ -118,7 +123,7 @@ func (d *Decoder) decodeNALUs(pkt *rtp.Packet) ([][]byte, error) {
 			return nil, ErrMorePacketsNeeded
 		}
 
-		if len(d.fragments) == 0 {
+		if d.fragmentsSize == 0 {
 			if !d.firstPacketReceived {
 				return nil, ErrNonStartingPacketAndNoPrevious
 			}
@@ -128,7 +133,7 @@ func (d *Decoder) decodeNALUs(pkt *rtp.Packet) ([][]byte, error) {
 
 		d.fragmentsSize += len(pkt.Payload[3:])
 		if d.fragmentsSize > h265.MaxAccessUnitSize {
-			d.fragments = d.fragments[:0]
+			d.resetFragments()
 			return nil, fmt.Errorf("NALU size (%d) is too big, maximum is %d", d.fragmentsSize, h265.MaxAccessUnitSize)
 		}
 
@@ -139,16 +144,14 @@ func (d *Decoder) decodeNALUs(pkt *rtp.Packet) ([][]byte, error) {
 		}
 
 		nalus = [][]byte{joinFragments(d.fragments, d.fragmentsSize)}
-		d.fragments = d.fragments[:0]
+		d.resetFragments()
 
 	case h265.NALUType_PACI:
-		d.fragments = d.fragments[:0] // discard pending fragments
-		d.firstPacketReceived = true
+		d.resetFragments()
 		return nil, fmt.Errorf("PACI packets are not supported (yet)")
 
 	default:
-		d.fragments = d.fragments[:0] // discard pending fragments
-		d.firstPacketReceived = true
+		d.resetFragments()
 		nalus = [][]byte{pkt.Payload}
 	}