Total rework RTMP client

internal/http/http.go

@@ -54,7 +54,10 @@ func handleHTTP(url string) (core.Producer, error) {
 		return multipart.NewClient(res)
 
 	case "video/x-flv":
-		client := flv.NewClient(res.Body)
+		var client *flv.Client
+		if client, err = flv.NewClient(res.Body); err != nil {
+			return nil, err
+		}
 		if err = client.Describe(); err != nil {
 			return nil, err
 		}

internal/rtmp/rtmp.go

@@ -1,13 +1,15 @@
 package rtmp
 
 import (
+	"io"
+	"net/http"
+
 	"github.com/AlexxIT/go2rtc/internal/api"
 	"github.com/AlexxIT/go2rtc/internal/streams"
 	"github.com/AlexxIT/go2rtc/pkg/core"
+	"github.com/AlexxIT/go2rtc/pkg/flv"
 	"github.com/AlexxIT/go2rtc/pkg/rtmp"
 	"github.com/rs/zerolog/log"
-	"io"
-	"net/http"
 )
 
 func Init() {
@@ -17,14 +19,14 @@ func Init() {
 }
 
 func streamsHandle(url string) (core.Producer, error) {
-	conn := rtmp.NewClient(url)
+	client, err := rtmp.Dial(url)
-	if err := conn.Dial(); err != nil {
+	if err != nil {
 		return nil, err
 	}
-	if err := conn.Describe(); err != nil {
+	if err = client.Describe(); err != nil {
 		return nil, err
 	}
-	return conn, nil
+	return client, nil
 }
 
 func apiHandle(w http.ResponseWriter, r *http.Request) {
@@ -40,8 +42,7 @@ func apiHandle(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	res := &http.Response{Body: r.Body, Request: r}
+	client, err := flv.NewClient(r.Body)
-	client, err := rtmp.Accept(res)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return

pkg/core/helpers.go

@@ -11,6 +11,7 @@ import (
 )
 
 const (
+	BufferSize      = 64 * 1024 // 64K
 	ConnDialTimeout = time.Second * 3
 	ConnDeadline    = time.Second * 3
 	ProbeTimeout    = time.Second * 3

pkg/flv/client.go

@@ -12,9 +12,9 @@ import (
 )
 
 type Client struct {
-	URL string
+	Transport
 
-	rd io.Reader
+	URL string
 
 	medias    []*core.Media
 	receivers []*core.Receiver
@@ -22,15 +22,15 @@ type Client struct {
 	recv int
 }
 
-func NewClient(rd io.Reader) *Client {
+func NewClient(rd io.Reader) (*Client, error) {
-	return &Client{rd: rd}
+	tr, err := NewTransport(rd)
+	if err != nil {
+		return nil, err
+	}
+	return &Client{Transport: tr}, nil
 }
 
 func (c *Client) Describe() error {
-	if err := c.ReadHeader(); err != nil {
-		return err
-	}
-
 	// Normal software sends:
 	// 1. Video/audio flag in header
 	// 2. MetaData as first tag (with video/audio codec info)
@@ -45,7 +45,7 @@ func (c *Client) Describe() error {
 	timeout := time.Now().Add(core.ProbeTimeout)
 
 	for (waitVideo || waitAudio) && time.Now().Before(timeout) {
-		tagType, _, b, err := c.ReadTag()
+		tagType, _, b, err := c.Transport.ReadTag()
 		if err != nil {
 			return err
 		}
@@ -123,7 +123,7 @@ func (c *Client) Play() error {
 	video, audio := core.VA(c.receivers)
 
 	for {
-		tagType, timeMS, b, err := c.ReadTag()
+		tagType, timeMS, b, err := c.Transport.ReadTag()
 		if err != nil {
 			return err
 		}

pkg/flv/flv.go

@@ -15,28 +15,25 @@ const (
 	CodecAVC = 7
 )
 
-func (c *Client) ReadHeader() error {
+// Transport - it is recommended to implement io.Closer
-	b := make([]byte, 9)
+type Transport interface {
-	if _, err := io.ReadFull(c.rd, b); err != nil {
+	ReadTag() (byte, uint32, []byte, error)
-		return err
-	}
-
-	if string(b[:3]) != "FLV" {
-		return errors.New("flv: wrong header")
-	}
-
-	_ = b[4] // flags (skip because unsupported by Reolink cameras)
-
-	if skip := binary.BigEndian.Uint32(b[5:]) - 9; skip > 0 {
-		if _, err := io.ReadFull(c.rd, make([]byte, skip)); err != nil {
-			return err
-		}
-	}
-
-	return nil
 }
 
-func (c *Client) ReadTag() (byte, uint32, []byte, error) {
+// NewTransport - it is recommended to use bufio.Reader
+func NewTransport(rd io.Reader) (Transport, error) {
+	c := &flv{rd: rd}
+	if err := c.readHeader(); err != nil {
+		return nil, err
+	}
+	return c, nil
+}
+
+type flv struct {
+	rd io.Reader
+}
+
+func (c *flv) ReadTag() (byte, uint32, []byte, error) {
 	// https://rtmp.veriskope.com/pdf/video_file_format_spec_v10.pdf
 	b := make([]byte, 4+11)
 	if _, err := io.ReadFull(c.rd, b); err != nil {
@@ -57,6 +54,34 @@ func (c *Client) ReadTag() (byte, uint32, []byte, error) {
 	return tagType, timeMS, b, nil
 }
 
+func (c *flv) Close() error {
+	if closer, ok := c.rd.(io.Closer); ok {
+		return closer.Close()
+	}
+	return nil
+}
+
+func (c *flv) readHeader() error {
+	b := make([]byte, 9)
+	if _, err := io.ReadFull(c.rd, b); err != nil {
+		return err
+	}
+
+	if string(b[:3]) != "FLV" {
+		return errors.New("flv: wrong header")
+	}
+
+	_ = b[4] // flags (skip because unsupported by Reolink cameras)
+
+	if skip := binary.BigEndian.Uint32(b[5:]) - 9; skip > 0 {
+		if _, err := io.ReadFull(c.rd, make([]byte, skip)); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
 func TimeToRTP(timeMS uint32, clockRate uint32) uint32 {
 	return timeMS * clockRate / 1000
 }

pkg/flv/producer.go

@@ -27,7 +27,7 @@ func (c *Client) Start() error {
 }
 
 func (c *Client) Stop() error {
-	if closer, ok := c.rd.(io.Closer); ok {
+	if closer, ok := c.Transport.(io.Closer); ok {
 		return closer.Close()
 	}
 	return nil

pkg/rtmp/client.go

@@ -1,156 +1,50 @@
 package rtmp
 
 import (
-	"encoding/base64"
+	"bufio"
-	"encoding/hex"
+	"net"
-	"fmt"
+	"net/url"
+	"strings"
+
 	"github.com/AlexxIT/go2rtc/pkg/core"
-	"github.com/AlexxIT/go2rtc/pkg/httpflv"
+	"github.com/AlexxIT/go2rtc/pkg/flv"
-	"github.com/deepch/vdk/av"
-	"github.com/deepch/vdk/codec/aacparser"
-	"github.com/deepch/vdk/codec/h264parser"
-	"github.com/deepch/vdk/format/rtmp"
-	"github.com/pion/rtp"
-	"net/http"
-	"time"
 )
 
-// Conn for RTMP and RTMPT (flv over HTTP)
+func Dial(rawURL string) (*flv.Client, error) {
-type Conn interface {
+	u, err := url.Parse(rawURL)
-	Streams() (streams []av.CodecData, err error)
-	ReadPacket() (pkt av.Packet, err error)
-	Close() (err error)
-}
-
-type Client struct {
-	core.Listener
-
-	URI string
-
-	medias    []*core.Media
-	receivers []*core.Receiver
-
-	conn   Conn
-	closed bool
-
-	recv int
-}
-
-func NewClient(uri string) *Client {
-	return &Client{URI: uri}
-}
-
-func (c *Client) Dial() (err error) {
-	c.conn, err = rtmp.Dial(c.URI)
-	return
-}
-
-// Accept - convert http.Response to Client
-func Accept(res *http.Response) (*Client, error) {
-	conn, err := httpflv.Accept(res)
 	if err != nil {
 		return nil, err
 	}
-	return &Client{URI: res.Request.URL.String(), conn: conn}, nil
-}
 
-func (c *Client) Describe() (err error) {
+	host := u.Host
-	// important to get SPS/PPS
+	if strings.IndexByte(host, ':') < 0 {
-	streams, err := c.conn.Streams()
+		host += ":1935"
+	}
+
+	conn, err := net.DialTimeout("tcp", host, core.ConnDialTimeout)
 	if err != nil {
-		return
+		return nil, err
 	}
 
-	for _, stream := range streams {
+	tr := &rtmp{
-		switch stream.Type() {
+		url:  rawURL,
-		case av.H264:
+		conn: conn,
-			info := stream.(h264parser.CodecData).RecordInfo
+		rd:   bufio.NewReaderSize(conn, core.BufferSize),
-
-			fmtp := fmt.Sprintf(
-				"profile-level-id=%02X%02X%02X;sprop-parameter-sets=%s,%s",
-				info.AVCProfileIndication, info.ProfileCompatibility, info.AVCLevelIndication,
-				base64.StdEncoding.EncodeToString(info.SPS[0]),
-				base64.StdEncoding.EncodeToString(info.PPS[0]),
-			)
-
-			codec := &core.Codec{
-				Name:        core.CodecH264,
-				ClockRate:   90000,
-				FmtpLine:    fmtp,
-				PayloadType: core.PayloadTypeRAW,
 	}
 
-			media := &core.Media{
+	if args := strings.Split(u.Path, "/"); len(args) >= 2 {
-				Kind:      core.KindVideo,
+		tr.app = args[1]
-				Direction: core.DirectionRecvonly,
+		if len(args) >= 3 {
-				Codecs:    []*core.Codec{codec},
+			tr.stream = args[2]
+			if u.RawQuery != "" {
+				tr.stream += "?" + u.RawQuery
 			}
-			c.medias = append(c.medias, media)
-
-			track := core.NewReceiver(media, codec)
-			c.receivers = append(c.receivers, track)
-
-		case av.AAC:
-			// TODO: fix support
-			cd := stream.(aacparser.CodecData)
-
-			codec := &core.Codec{
-				Name:      core.CodecAAC,
-				ClockRate: uint32(cd.Config.SampleRate),
-				Channels:  uint16(cd.Config.ChannelConfig),
-				//  a=fmtp:97 streamtype=5;profile-level-id=1;mode=AAC-hbr;sizelength=13;indexlength=3;indexdeltalength=3;config=1588
-				FmtpLine:    "streamtype=5;profile-level-id=1;mode=AAC-hbr;sizelength=13;indexlength=3;indexdeltalength=3;config=" + hex.EncodeToString(cd.ConfigBytes),
-				PayloadType: core.PayloadTypeRAW,
-			}
-
-			media := &core.Media{
-				Kind:      core.KindAudio,
-				Direction: core.DirectionRecvonly,
-				Codecs:    []*core.Codec{codec},
-			}
-			c.medias = append(c.medias, media)
-
-			track := core.NewReceiver(media, codec)
-			c.receivers = append(c.receivers, track)
-
-		default:
-			fmt.Printf("[rtmp] unsupported codec %+v\n", stream)
 		}
 	}
 
-	return
+	if err = tr.init(); err != nil {
-}
+		return nil, err
-
+	}
-func (c *Client) Handle() (err error) {
+
-	for {
+	return &flv.Client{Transport: tr, URL: rawURL}, nil
-		var pkt av.Packet
-		pkt, err = c.conn.ReadPacket()
-		if err != nil {
-			if c.closed {
-				return nil
-			}
-			return
-		}
-
-		c.recv += len(pkt.Data)
-
-		track := c.receivers[int(pkt.Idx)]
-
-		// convert seconds to RTP timestamp
-		timestamp := uint32(pkt.Time * time.Duration(track.Codec.ClockRate) / time.Second)
-
-		packet := &rtp.Packet{
-			Header:  rtp.Header{Timestamp: timestamp},
-			Payload: pkt.Data,
-		}
-		track.WriteRTP(packet)
-	}
-}
-
-func (c *Client) Close() error {
-	if c.conn == nil {
-		return nil
-	}
-	c.closed = true
-	return c.conn.Close()
 }

pkg/rtmp/producer.go

@@ -1,41 +0,0 @@
-package rtmp
-
-import (
-	"encoding/json"
-	"github.com/AlexxIT/go2rtc/pkg/core"
-)
-
-func (c *Client) GetMedias() []*core.Media {
-	return c.medias
-}
-
-func (c *Client) GetTrack(media *core.Media, codec *core.Codec) (*core.Receiver, error) {
-	for _, track := range c.receivers {
-		if track.Codec == codec {
-			return track, nil
-		}
-	}
-	return nil, core.ErrCantGetTrack
-}
-
-func (c *Client) Start() error {
-	return c.Handle()
-}
-
-func (c *Client) Stop() error {
-	for _, receiver := range c.receivers {
-		receiver.Close()
-	}
-	return c.Close()
-}
-
-func (c *Client) MarshalJSON() ([]byte, error) {
-	info := &core.Info{
-		Type:      "RTMP active producer",
-		URL:       c.URI,
-		Medias:    c.medias,
-		Receivers: c.receivers,
-		Recv:      c.recv,
-	}
-	return json.Marshal(info)
-}

pkg/rtmp/rtmp.go

@@ -0,0 +1,408 @@
+package rtmp
+
+import (
+	"encoding/binary"
+	"errors"
+	"io"
+	"net"
+
+	"github.com/AlexxIT/go2rtc/pkg/flv/amf"
+)
+
+const (
+	MsgSetPacketSize   = 1
+	MsgServerBandwidth = 5
+	MsgClientBandwidth = 6
+	MsgCommand         = 20
+
+	//MsgAck         = 3
+	//MsgControl     = 4
+	//MsgAudioPacket = 8
+	//MsgVideoPacket = 9
+	//MsgDataExt     = 15
+	//MsgCommandExt  = 17
+	//MsgData        = 18
+)
+
+var ErrResponse = errors.New("rtmp: wrong response")
+
+// rtmp - implements flv.Transport
+type rtmp struct {
+	url     string
+	app     string
+	stream  string
+	pktSize uint32
+
+	headers map[uint32]*header
+
+	conn net.Conn
+	rd   io.Reader
+}
+
+type header struct {
+	msgTime uint32
+	msgSize uint32
+	msgType byte
+}
+
+func (c *rtmp) ReadTag() (byte, uint32, []byte, error) {
+	hdrType, sid, err := c.readHeader()
+	if err != nil {
+		return 0, 0, nil, err
+	}
+
+	// storing header information for support header type 3
+	hdr, ok := c.headers[sid]
+	if !ok {
+		hdr = &header{}
+		c.headers[sid] = hdr
+	}
+
+	var b []byte
+
+	// https://en.wikipedia.org/wiki/Real-Time_Messaging_Protocol#Packet_structure
+	switch hdrType {
+	case 0: // 12 byte header (full header)
+		if b, err = c.readSize(11); err != nil {
+			return 0, 0, nil, err
+		}
+		_ = b[7]
+		hdr.msgTime = Uint24(b)            // timestamp
+		hdr.msgSize = Uint24(b[3:])        // msgdatalen
+		hdr.msgType = b[6]                 // msgtypeid
+		_ = binary.BigEndian.Uint32(b[7:]) // msgsid
+
+	case 1: // 8 bytes - like type b00, not including message ID (4 last bytes)
+		if b, err = c.readSize(7); err != nil {
+			return 0, 0, nil, err
+		}
+		_ = b[6]
+		hdr.msgTime = Uint24(b)     // timestamp
+		hdr.msgSize = Uint24(b[3:]) // msgdatalen
+		hdr.msgType = b[6]          // msgtypeid
+
+	case 2: // 4 bytes - Basic Header and timestamp (3 bytes) are included
+		if b, err = c.readSize(3); err != nil {
+			return 0, 0, nil, err
+		}
+		hdr.msgTime = Uint24(b) // timestamp
+
+	case 3: // 1 byte - only the Basic Header is included
+		// use here hdr from previous msg with same session ID (sid)
+	}
+
+	timeMS := hdr.msgTime
+	if timeMS == 0xFFFFFF {
+		if b, err = c.readSize(4); err != nil {
+			return 0, 0, nil, err
+		}
+		timeMS = binary.BigEndian.Uint32(b)
+	}
+
+	//log.Printf("[rtmp] hdrType=%d sid=%d msdTime=%d msgSize=%d msgType=%d", hdrType, sid, hdr.msgTime, hdr.msgSize, hdr.msgType)
+
+	// 1. Response zero size
+	if hdr.msgSize == 0 {
+		return hdr.msgType, timeMS, nil, nil
+	}
+
+	b = make([]byte, hdr.msgSize)
+
+	// 2. Response small packet
+	if c.pktSize == 0 || hdr.msgSize < c.pktSize {
+		if _, err = io.ReadFull(c.rd, b); err != nil {
+			return 0, 0, nil, err
+		}
+		return hdr.msgType, timeMS, b, nil
+	}
+
+	// 3. Response big packet
+	var i0 uint32
+	for i1 := c.pktSize; i1 < hdr.msgSize; i1 += c.pktSize {
+		if _, err = io.ReadFull(c.rd, b[i0:i1]); err != nil {
+			return 0, 0, nil, err
+		}
+
+		if _, _, err = c.readHeader(); err != nil {
+			return 0, 0, nil, err
+		}
+
+		if hdr.msgTime == 0xFFFFFF {
+			if _, err = c.readSize(4); err != nil {
+				return 0, 0, nil, err
+			}
+		}
+
+		i0 = i1
+	}
+
+	if _, err = io.ReadFull(c.rd, b[i0:]); err != nil {
+		return 0, 0, nil, err
+	}
+
+	return hdr.msgType, timeMS, b, nil
+}
+
+func (c *rtmp) Close() error {
+	return c.conn.Close()
+}
+
+func (c *rtmp) init() error {
+	if err := c.handshake(); err != nil {
+		return err
+	}
+	if err := c.sendConfig(); err != nil {
+		return err
+	}
+
+	c.headers = map[uint32]*header{}
+
+	if err := c.sendConnect(); err != nil {
+		return err
+	}
+	if err := c.sendPlay(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (c *rtmp) handshake() error {
+	// simple handshake without real random and check response
+	const randomSize = 4 + 4 + 1528
+
+	b := make([]byte, 1+randomSize)
+	b[0] = 0x03
+	if _, err := c.conn.Write(b); err != nil {
+		return err
+	}
+
+	if _, err := io.ReadFull(c.rd, b); err != nil {
+		return err
+	}
+
+	if b[0] != 3 {
+		return errors.New("rtmp: wrong handshake")
+	}
+
+	if _, err := c.conn.Write(b[1:]); err != nil {
+		return err
+	}
+
+	if _, err := io.ReadFull(c.rd, b[1:]); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (c *rtmp) sendConfig() error {
+	b := make([]byte, 5)
+	binary.BigEndian.PutUint32(b, 65536)
+	if err := c.sendRequest(MsgSetPacketSize, 0, b[:4]); err != nil {
+		return err
+	}
+
+	binary.BigEndian.PutUint32(b, 2500000)
+	if err := c.sendRequest(MsgServerBandwidth, 0, b[:4]); err != nil {
+		return err
+	}
+
+	binary.BigEndian.PutUint32(b, 10000000) // ack size
+	b[4] = 2                                // limit type
+	if err := c.sendRequest(MsgClientBandwidth, 0, b); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (c *rtmp) sendConnect() error {
+	msg := amf.AMF{}
+	msg.WriteString("connect")
+	msg.WriteNumber(1)
+	msg.WriteObject(map[string]any{
+		"app":           c.app,
+		"flashVer":      "MAC 32,0,0,0",
+		"tcUrl":         c.url,
+		"fpad":          false, // ?
+		"capabilities":  15,    // ?
+		"audioCodecs":   4071,  // ?
+		"videoCodecs":   252,   // ?
+		"videoFunction": 1,     // ?
+	})
+
+	if err := c.sendRequest(MsgCommand, 0, msg.Bytes()); err != nil {
+		return err
+	}
+
+	s, err := c.waitCode()
+	if err != nil {
+		return err
+	}
+
+	if s != "NetConnection.Connect.Success" {
+		return errors.New("rtmp: wrong code: " + s)
+	}
+
+	return nil
+}
+
+func (c *rtmp) sendPlay() error {
+	msg := amf.NewWriter()
+	msg.WriteString("createStream")
+	msg.WriteNumber(2)
+	msg.WriteNull()
+
+	if err := c.sendRequest(MsgCommand, 0, msg.Bytes()); err != nil {
+		return err
+	}
+
+	args, err := c.waitResponse()
+	if err != nil {
+		return err
+	}
+
+	if len(args) < 4 {
+		return ErrResponse
+	}
+
+	sid, _ := args[3].(float64)
+
+	msg = amf.NewWriter()
+	msg.WriteString("play")
+	msg.WriteNumber(3)
+	msg.WriteNull()
+	msg.WriteString(c.stream)
+
+	if err = c.sendRequest(MsgCommand, uint32(sid), msg.Bytes()); err != nil {
+		return err
+	}
+
+	s, err := c.waitCode()
+	if err != nil {
+		return err
+	}
+
+	switch s {
+	case "NetStream.Play.Start", "NetStream.Play.Reset":
+		return nil
+	}
+
+	return errors.New("rtmp: wrong code: " + s)
+}
+
+func (c *rtmp) sendRequest(msgType byte, streamID uint32, payload []byte) error {
+	n := len(payload)
+	b := make([]byte, 12+n)
+	_ = b[12]
+
+	switch msgType {
+	case MsgSetPacketSize, MsgServerBandwidth, MsgClientBandwidth:
+		b[0] = 0x02 // chunk ID
+	case MsgCommand:
+		if streamID == 0 {
+			b[0] = 0x03 // chunk ID
+		} else {
+			b[0] = 0x08 // chunk ID
+		}
+	}
+
+	//PutUint24(b[1:], 0)                  // timestamp
+	PutUint24(b[4:], uint32(n))                 // payload size
+	b[7] = msgType                              // message type
+	binary.BigEndian.PutUint32(b[8:], streamID) // message stream ID
+	copy(b[12:], payload)
+
+	if _, err := c.conn.Write(b); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (c *rtmp) readHeader() (byte, uint32, error) {
+	b, err := c.readSize(1)
+	if err != nil {
+		return 0, 0, err
+	}
+
+	hdrType := b[0] >> 6
+	sid := uint32(b[0] & 0b111111)
+
+	switch sid {
+	case 0:
+		if b, err = c.readSize(1); err != nil {
+			return 0, 0, err
+		}
+		sid = 64 + uint32(b[0])
+	case 1:
+		if b, err = c.readSize(2); err != nil {
+			return 0, 0, err
+		}
+		sid = 64 + uint32(binary.BigEndian.Uint16(b))
+	}
+
+	return hdrType, sid, nil
+}
+
+func (c *rtmp) readSize(n uint32) ([]byte, error) {
+	b := make([]byte, n)
+	if _, err := io.ReadAtLeast(c.rd, b, int(n)); err != nil {
+		return nil, err
+	}
+	return b, nil
+}
+
+func (c *rtmp) waitResponse() ([]any, error) {
+	for {
+		msgType, _, b, err := c.ReadTag()
+		if err != nil {
+			return nil, err
+		}
+
+		switch msgType {
+		case MsgSetPacketSize:
+			c.pktSize = binary.BigEndian.Uint32(b)
+
+		case MsgCommand:
+			return amf.NewReader(b).ReadItems()
+		}
+	}
+}
+
+func (c *rtmp) waitCode() (string, error) {
+	args, err := c.waitResponse()
+	if err != nil {
+		return "", err
+	}
+
+	if len(args) < 4 {
+		return "", ErrResponse
+	}
+
+	m, _ := args[3].(map[string]any)
+	if m == nil {
+		return "", ErrResponse
+	}
+
+	v, _ := m["code"]
+	if v == nil {
+		return "", ErrResponse
+	}
+
+	s, _ := v.(string)
+	return s, nil
+}
+
+func PutUint24(b []byte, v uint32) {
+	_ = b[2]
+	b[0] = byte(v >> 16)
+	b[1] = byte(v >> 8)
+	b[2] = byte(v)
+}
+
+func Uint24(b []byte) uint32 {
+	_ = b[2]
+	return uint32(b[0])<<16 | uint32(b[1])<<8 | uint32(b[2])
+}