1 files changed, 143 insertions, 0 deletions
diff --git a/vendor/github.com/pion/rtp/codecs/vp8_packet.go b/vendor/github.com/pion/rtp/codecs/vp8_packet.go
new file mode 100644
index 0000000..7ade7da
--- /dev/null
+++ b/vendor/github.com/pion/rtp/codecs/vp8_packet.go
@@ -0,0 +1,143 @@
+package codecs
+
+// VP8Payloader payloads VP8 packets
+type VP8Payloader struct{}
+
+const (
+	vp8HeaderSize = 1
+)
+
+// Payload fragments a VP8 packet across one or more byte arrays
+func (p *VP8Payloader) Payload(mtu int, payload []byte) [][]byte {
+	/*
+	 * https://tools.ietf.org/html/rfc7741#section-4.2
+	 *
+	 *       0 1 2 3 4 5 6 7
+	 *      +-+-+-+-+-+-+-+-+
+	 *      |X|R|N|S|R| PID | (REQUIRED)
+	 *      +-+-+-+-+-+-+-+-+
+	 * X:   |I|L|T|K| RSV   | (OPTIONAL)
+	 *      +-+-+-+-+-+-+-+-+
+	 * I:   |M| PictureID   | (OPTIONAL)
+	 *      +-+-+-+-+-+-+-+-+
+	 * L:   |   TL0PICIDX   | (OPTIONAL)
+	 *      +-+-+-+-+-+-+-+-+
+	 * T/K: |TID|Y| KEYIDX  | (OPTIONAL)
+	 *      +-+-+-+-+-+-+-+-+
+	 *  S: Start of VP8 partition.  SHOULD be set to 1 when the first payload
+	 *     octet of the RTP packet is the beginning of a new VP8 partition,
+	 *     and MUST NOT be 1 otherwise.  The S bit MUST be set to 1 for the
+	 *     first packet of each encoded frame.
+	 */
+
+	maxFragmentSize := mtu - vp8HeaderSize
+
+	payloadData := payload
+	payloadDataRemaining := len(payload)
+
+	payloadDataIndex := 0
+	var payloads [][]byte
+
+	// Make sure the fragment/payload size is correct
+	if min(maxFragmentSize, payloadDataRemaining) <= 0 {
+		return payloads
+	}
+	for payloadDataRemaining > 0 {
+		currentFragmentSize := min(maxFragmentSize, payloadDataRemaining)
+		out := make([]byte, vp8HeaderSize+currentFragmentSize)
+		if payloadDataRemaining == len(payload) {
+			out[0] = 0x10
+		}
+
+		copy(out[vp8HeaderSize:], payloadData[payloadDataIndex:payloadDataIndex+currentFragmentSize])
+		payloads = append(payloads, out)
+
+		payloadDataRemaining -= currentFragmentSize
+		payloadDataIndex += currentFragmentSize
+	}
+
+	return payloads
+}
+
+// VP8Packet represents the VP8 header that is stored in the payload of an RTP Packet
+type VP8Packet struct {
+	// Required Header
+	X   uint8 /* extended controlbits present */
+	N   uint8 /* (non-reference frame)  when set to 1 this frame can be discarded */
+	S   uint8 /* start of VP8 partition */
+	PID uint8 /* partition index */
+
+	// Optional Header
+	I         uint8  /* 1 if PictureID is present */
+	L         uint8  /* 1 if TL0PICIDX is present */
+	T         uint8  /* 1 if TID is present */
+	K         uint8  /* 1 if KEYIDX is present */
+	PictureID uint16 /* 8 or 16 bits, picture ID */
+	TL0PICIDX uint8  /* 8 bits temporal level zero index */
+
+	Payload []byte
+}
+
+// Unmarshal parses the passed byte slice and stores the result in the VP8Packet this method is called upon
+func (p *VP8Packet) Unmarshal(payload []byte) ([]byte, error) {
+	if payload == nil {
+		return nil, errNilPacket
+	}
+
+	payloadLen := len(payload)
+
+	if payloadLen < 4 {
+		return nil, errShortPacket
+	}
+
+	payloadIndex := 0
+
+	p.X = (payload[payloadIndex] & 0x80) >> 7
+	p.N = (payload[payloadIndex] & 0x20) >> 5
+	p.S = (payload[payloadIndex] & 0x10) >> 4
+	p.PID = payload[payloadIndex] & 0x07
+
+	payloadIndex++
+
+	if p.X == 1 {
+		p.I = (payload[payloadIndex] & 0x80) >> 7
+		p.L = (payload[payloadIndex] & 0x40) >> 6
+		p.T = (payload[payloadIndex] & 0x20) >> 5
+		p.K = (payload[payloadIndex] & 0x10) >> 4
+		payloadIndex++
+	}
+
+	if p.I == 1 { // PID present?
+		if payload[payloadIndex]&0x80 > 0 { // M == 1, PID is 16bit
+			payloadIndex += 2
+		} else {
+			payloadIndex++
+		}
+	}
+
+	if p.L == 1 {
+		payloadIndex++
+	}
+
+	if p.T == 1 || p.K == 1 {
+		payloadIndex++
+	}
+
+	if payloadIndex >= payloadLen {
+		return nil, errShortPacket
+	}
+	p.Payload = payload[payloadIndex:]
+	return p.Payload, nil
+}
+
+// VP8PartitionHeadChecker checks VP8 partition head
+type VP8PartitionHeadChecker struct{}
+
+// IsPartitionHead checks whether if this is a head of the VP8 partition
+func (*VP8PartitionHeadChecker) IsPartitionHead(packet []byte) bool {
+	p := &VP8Packet{}
+	if _, err := p.Unmarshal(packet); err != nil {
+		return false
+	}
+	return p.S == 1
+}