commit 3733fdedcc81d8d4ce9cfc51b2fa63306a759119
Author: nareix <hi.nareix@gmail.com>
Date:   Wed Jun 15 07:53:28 2016 +0800

    first blood

diff --git a/flv.go b/flv.go
new file mode 100644
index 0000000..f562da0
--- /dev/null
+++ b/flv.go
@@ -0,0 +1,475 @@
+package flv
+
+import (
+	"fmt"
+	"github.com/nareix/av"
+	"github.com/nareix/bits"
+	"io"
+)
+
+const (
+	TAG_AUDIO      = 8
+	TAG_VIDEO      = 9
+	TAG_SCRIPTDATA = 18
+)
+
+type Tag interface {
+	Type() uint8
+	Len() int
+	Marshal(*Writer) error
+	Unmarshal(*Reader) error
+}
+
+type Scriptdata struct {
+	Data []byte
+}
+
+func (self Scriptdata) Type() uint8 {
+	return TAG_SCRIPTDATA
+}
+
+func (self Scriptdata) Marshal(w *Writer) (err error) {
+	if _, err = w.Write(self.Data); err != nil {
+		return
+	}
+	return
+}
+
+func (self Scriptdata) Len() int {
+	return len(self.Data)
+}
+
+func (self *Scriptdata) Unmarshal(r *Reader) (err error) {
+	self.Data = make([]byte, r.N())
+	if _, err = io.ReadFull(r, self.Data); err != nil {
+		return
+	}
+	return
+}
+
+const (
+	SOUND_AAC = 10
+
+	SOUND_5_5Khz = 0
+	SOUND_11Khz  = 1
+	SOUND_22Khz  = 2
+	SOUND_44Khz  = 3
+
+	SOUND_8BIT  = 0
+	SOUND_16BIT = 1
+
+	SOUND_MONO   = 0
+	SOUND_STEREO = 1
+
+	AAC_SEQHDR = 0
+	AAC_RAW    = 0
+)
+
+type Audiodata struct {
+	/*
+		SoundFormat: UB[4]
+		0 = Linear PCM, platform endian
+		1 = ADPCM
+		2 = MP3
+		3 = Linear PCM, little endian
+		4 = Nellymoser 16-kHz mono
+		5 = Nellymoser 8-kHz mono
+		6 = Nellymoser
+		7 = G.711 A-law logarithmic PCM 8 = G.711 mu-law logarithmic PCM 9 = reserved
+		10 = AAC
+		11 = Speex
+		14 = MP3 8-Khz
+		15 = Device-specific sound
+		Formats 7, 8, 14, and 15 are reserved for internal use
+		AAC is supported in Flash Player 9,0,115,0 and higher.
+		Speex is supported in Flash Player 10 and higher.
+	*/
+	SoundFormat uint8
+
+	/*
+		SoundRate: UB[2]
+		Sampling rate
+		0 = 5.5-kHz For AAC: always 3
+		1 = 11-kHz
+		2 = 22-kHz
+		3 = 44-kHz
+	*/
+	SoundRate uint8
+
+	/*
+		SoundSize: UB[1]
+		0 = snd8Bit
+		1 = snd16Bit
+		Size of each sample.
+		This parameter only pertains to uncompressed formats.
+		Compressed formats always decode to 16 bits internally
+	*/
+	SoundSize uint8
+
+	/*
+		SoundType: UB[1]
+		0 = sndMono
+		1 = sndStereo
+		Mono or stereo sound For Nellymoser: always 0
+		For AAC: always 1
+	*/
+	SoundType uint8
+
+	/*
+		0: AAC sequence header
+		1: AAC raw
+	*/
+	AACPacketType uint8
+
+	Data []byte
+}
+
+func (self Audiodata) Type() uint8 {
+	return TAG_AUDIO
+}
+
+func (self Audiodata) Len() int {
+	return 2 + len(self.Data)
+}
+
+func (self Audiodata) Marshal(w *Writer) (err error) {
+	var flags uint8
+	flags |= self.SoundFormat << 4
+	flags |= self.SoundRate << 2
+	flags |= self.SoundSize << 1
+	flags |= self.SoundType
+	if err = w.WriteUInt8(flags); err != nil {
+		return
+	}
+	if self.SoundFormat == SOUND_AAC {
+		if err = w.WriteUInt8(self.AACPacketType); err != nil {
+			return
+		}
+		if _, err = w.Write(self.Data); err != nil {
+			return
+		}
+	} else {
+		err = fmt.Errorf("flv: Audiodata.Marshal: unsupported SoundFormat=%d", self.SoundFormat)
+		return
+	}
+	return
+}
+
+func (self *Audiodata) Unmarshal(r *Reader) (err error) {
+	var flags uint8
+	if flags, err = r.ReadUInt8(); err != nil {
+		return
+	}
+	self.SoundFormat = flags >> 4
+	self.SoundRate = (flags >> 2) & 0x3
+	self.SoundSize = (flags >> 1) & 0x1
+	self.SoundType = flags & 0x1
+	if self.SoundFormat == SOUND_AAC {
+		if self.AACPacketType, err = r.ReadUInt8(); err != nil {
+			return
+		}
+		self.Data = make([]byte, r.N())
+		if _, err = io.ReadFull(r, self.Data); err != nil {
+			return
+		}
+	} else {
+		err = fmt.Errorf("flv: Audiodata.Unmarshal: unsupported SoundFormat=%d", self.SoundFormat)
+		return
+	}
+	return
+}
+
+const (
+	AVC_SEQHDR = 0
+	AVC_NALU   = 1
+	AVC_EOS    = 2
+
+	FRAME_KEY   = 1
+	FRAME_INTER = 2
+
+	CODEC_AAC = 7
+)
+
+type Videodata struct {
+	/*
+		1: keyframe (for AVC, a seekable frame)
+		2: inter frame (for AVC, a non- seekable frame)
+		3: disposable inter frame (H.263 only)
+		4: generated keyframe (reserved for server use only)
+		5: video info/command frame
+	*/
+	FrameType uint8
+
+	/*
+		1: JPEG (currently unused)
+		2: Sorenson H.263
+		3: Screen video
+		4: On2 VP6
+		5: On2 VP6 with alpha channel
+		6: Screen video version 2
+		7: AVC
+	*/
+	CodecID uint8
+
+	/*
+		0: AVC sequence header
+		1: AVC NALU
+		2: AVC end of sequence (lower level NALU sequence ender is not required or supported)
+	*/
+	AVCPacketType uint8
+
+	Data            []byte
+	CompositionTime int32
+}
+
+func (self Videodata) Type() uint8 {
+	return TAG_VIDEO
+}
+
+func (self Videodata) Len() int {
+	return 5 + len(self.Data)
+}
+
+func (self *Videodata) Unmarshal(r *Reader) (err error) {
+	var flags uint8
+	if flags, err = r.ReadUInt8(); err != nil {
+		return
+	}
+	self.FrameType = flags >> 4
+	self.CodecID = flags & 0xff
+	if self.AVCPacketType, err = r.ReadUInt8(); err != nil {
+		return
+	}
+	if self.CompositionTime, err = r.ReadInt24BE(); err != nil {
+		return
+	}
+	switch self.AVCPacketType {
+	case AVC_SEQHDR, AVC_NALU:
+		self.Data = make([]byte, r.N())
+		if _, err = io.ReadFull(r, self.Data); err != nil {
+			return
+		}
+	}
+	return
+}
+
+func (self Videodata) Marshal(w *Writer) (err error) {
+	flags := self.FrameType<<4 | self.CodecID
+	if err = w.WriteUInt8(flags); err != nil {
+		return
+	}
+	if err = w.WriteUInt8(self.AVCPacketType); err != nil {
+		return
+	}
+	if err = w.WriteInt24BE(self.CompositionTime); err != nil {
+		return
+	}
+	switch self.AVCPacketType {
+	case AVC_SEQHDR, AVC_NALU:
+		if _, err = w.Write(self.Data); err != nil {
+			return
+		}
+	}
+	return
+}
+
+type Reader struct {
+	bits.IntReader
+}
+
+func NewReader(r io.Reader) *Reader {
+	return &Reader{IntReader: bits.NewIntReader(r)}
+}
+
+func (self *Reader) NewLimitedReader(n int) *Reader {
+	nr := *self
+	nr.IntReader.R = &io.LimitedReader{R: nr.IntReader.R, N: int64(n)}
+	return &nr
+}
+
+func (self Reader) N() int {
+	return int(self.IntReader.R.(*io.LimitedReader).N)
+}
+
+func (self *Reader) ReadHeader() (err error) {
+	var cc3 uint32
+	if cc3, err = self.ReadUInt24BE(); err != nil {
+		return
+	}
+	if cc3 != 0x464c56 { // 'FLV'
+		err = fmt.Errorf("flv: file header cc3 invalid")
+		return
+	}
+
+	// version
+	if _, err = self.ReadInt8(); err != nil {
+		return
+	}
+
+	// flags
+	if _, err = self.ReadInt8(); err != nil {
+		return
+	}
+
+	var dataoffset uint
+	if dataoffset, err = self.ReadUInt32BE(); err != nil {
+		return
+	}
+	dataoffset -= 9
+
+	// skip header and first `tagsize`
+	if err = self.Skip(int(dataoffset + 4)); err != nil {
+		return
+	}
+
+	return
+}
+
+func (self *Reader) ReadTag() (tag Tag, timestamp int32, err error) {
+	var tagtype uint8
+	if tagtype, err = self.ReadUInt8(); err != nil {
+		return
+	}
+
+	switch tagtype {
+	case TAG_AUDIO:
+		tag = &Audiodata{}
+
+	case TAG_VIDEO:
+		tag = &Videodata{}
+
+	case TAG_SCRIPTDATA:
+		tag = &Scriptdata{}
+
+	default:
+		err = fmt.Errorf("flv: ReadTag tagtype=%d invalid", tagtype)
+		return
+	}
+
+	var datasize uint32
+	if datasize, err = self.ReadUInt24BE(); err != nil {
+		return
+	}
+
+	var tslo uint32
+	var tshi uint8
+	if tslo, err = self.ReadUInt24BE(); err != nil {
+		return
+	}
+	if tshi, err = self.ReadUInt8(); err != nil {
+		return
+	}
+	timestamp = int32(tslo|uint32(tshi)<<24)
+
+	if _, err = self.ReadInt24BE(); err != nil {
+		return
+	}
+
+	if err = tag.Unmarshal(self.NewLimitedReader(int(datasize))); err != nil {
+		return
+	}
+
+	if _, err = self.ReadInt32BE(); err != nil {
+		return
+	}
+
+	return
+}
+
+type Writer struct {
+	bits.IntWriter
+}
+
+func NewWriter(w io.Writer) *Writer {
+	return &Writer{IntWriter: bits.NewIntWriter(w)}
+}
+
+func (self *Writer) WriteTag(tag Tag, timestamp int32) (err error) {
+	if err = self.WriteUInt8(tag.Type()); err != nil {
+		return
+	}
+	datasize := tag.Len()
+	if err = self.WriteUInt24BE(uint32(datasize)); err != nil {
+		return
+	}
+	if err = self.WriteUInt24BE(uint32(timestamp & 0xffffff)); err != nil {
+		return
+	}
+	if err = self.WriteUInt8(uint8(timestamp >> 24)); err != nil {
+		return
+	}
+	if err = self.WriteInt24BE(0); err != nil {
+		return
+	}
+	if err = tag.Marshal(self); err != nil {
+		return
+	}
+	if err = self.WriteUInt32BE(uint32(datasize) + 11); err != nil {
+		return
+	}
+	return
+}
+
+func (self *Writer) WriteHeader(hasVideo bool, hasAudio bool) (err error) {
+	// 'FLV', version 1
+	if err = self.WriteInt32BE(0x464c5601); err != nil {
+		return
+	}
+
+	// TypeFlagsReserved UB[5]
+	// TypeFlagsAudio    UB[1] Audio tags are present
+	// TypeFlagsReserved UB[1] Must be 0
+	// TypeFlagsVideo    UB[1] Video tags are present
+	var flags uint8
+	if hasAudio {
+		flags |= 1 << 2
+	}
+	if hasVideo {
+		flags |= 1
+	}
+	if err = self.WriteUInt8(flags); err != nil {
+		return
+	}
+
+	// DataOffset: UI32 Offset in bytes from start of file to start of body (that is, size of header)
+	// The DataOffset field usually has a value of 9 for FLV version 1.
+	if err = self.WriteUInt32BE(9); err != nil {
+		return
+	}
+
+	// PreviousTagSize0: UI32 Always 0
+	if err = self.WriteUInt32BE(0); err != nil {
+		return
+	}
+
+	return
+}
+
+type Muxer struct {
+	fw *Writer
+}
+
+func NewMuxer(w io.Writer) *Muxer {
+	self := &Muxer{}
+	self.fw = NewWriter(w)
+	return self
+}
+
+func (self *Muxer) WriteHeader(streams []av.CodecData) (err error) {
+	hasVideo := false
+	hasAudio := false
+	for _, stream := range streams {
+		if stream.IsVideo() {
+			hasVideo = true
+		} else if stream.IsAudio() {
+			hasAudio = true
+		}
+	}
+
+	if err = self.fw.WriteHeader(hasVideo, hasAudio); err != nil {
+		return
+	}
+
+	return
+}
+