lkm/rtmp/rtmp_transtream.go

package rtmp

import (
	"github.com/yangjiechina/avformat/libflv"
	"github.com/yangjiechina/avformat/librtmp"
	"github.com/yangjiechina/avformat/utils"
	"github.com/yangjiechina/live-server/stream"
)

type TransStream struct {
	stream.TransStreamImpl
	chunkSize  int
	header     []byte //音视频头chunk
	headerSize int
	muxer      *libflv.Muxer

	audioChunk librtmp.Chunk
	videoChunk librtmp.Chunk

	memoryPool  stream.MemoryPool
	transBuffer stream.StreamBuffer
}

func (t *TransStream) Input(packet utils.AVPacket) {
	utils.Assert(t.TransStreamImpl.Completed)
	var data []byte
	var chunk *librtmp.Chunk
	var videoPkt bool

	if utils.AVMediaTypeAudio == packet.MediaType() {
		data = packet.Data()
		chunk = &t.audioChunk
	} else if utils.AVMediaTypeVideo == packet.MediaType() {
		videoPkt = true
		data = packet.AVCCPacketData()
		chunk = &t.videoChunk
	}

	length := len(data)
	//rtmp chunk消息体的数据大小
	payloadSize := 5 + length
	payloadSize += payloadSize / t.chunkSize

	//分配内存
	t.memoryPool.Mark()
	allocate := t.memoryPool.Allocate(12 + payloadSize)

	//写chunk头
	chunk.Length = payloadSize
	chunk.Timestamp = uint32(packet.Dts())
	n := chunk.ToBytes(allocate)
	utils.Assert(n == 12)

	//写flv
	ct := packet.Pts() - packet.Dts()
	if videoPkt {
		n += t.muxer.WriteVideoData(allocate, uint32(ct), packet.KeyFrame(), false)
	} else {
		n += t.muxer.WriteAudioData(allocate, false)
	}

	for length > 0 {
		min := utils.MinInt(length, t.chunkSize)
		copy(allocate[n:], data[:min])
		n += min

		length -= min
		data = data[min:]

		//写一个ChunkType3用作分割
		if length > 0 {
			if videoPkt {
				allocate[n] = (0x3 << 6) | byte(librtmp.ChunkStreamIdVideo)
			} else {
				allocate[n] = (0x3 << 6) | byte(librtmp.ChunkStreamIdAudio)
			}
			n++
		}
	}

	rtmpData := t.memoryPool.Fetch()
	ret := t.transBuffer.AddPacket(rtmpData, packet.KeyFrame() && utils.AVMediaTypeVideo == packet.MediaType(), packet.Dts())
	if ret {
		//发送给sink

		for _, sink := range t.Sinks {
			sink.Input(rtmpData)
		}
	}

}

func (t *TransStream) AddSink(sink stream.ISink) {
	t.TransStreamImpl.AddSink(sink)

	t.transBuffer.Peek(func(packet interface{}) {
		sink.Input(packet.([]byte))
	})
}

func (t *TransStream) onDiscardPacket(pkt interface{}) {
	bytes := pkt.([]byte)
	t.memoryPool.FreeHead(len(bytes))
}

func (t *TransStream) WriteHeader() error {
	utils.Assert(t.Tracks != nil)
	utils.Assert(!t.TransStreamImpl.Completed)

	var audioStream utils.AVStream
	var videoStream utils.AVStream
	var audioCodecId utils.AVCodecID
	var videoCodecId utils.AVCodecID

	for _, track := range t.Tracks {
		if utils.AVMediaTypeAudio == track.Type() {
			audioStream = track
			audioCodecId = audioStream.CodecId()
			t.audioChunk = librtmp.NewAudioChunk()
		} else if utils.AVMediaTypeAudio == track.Type() {
			videoStream = track
			videoCodecId = videoStream.CodecId()
			t.videoChunk = librtmp.NewVideoChunk()
		}
	}

	utils.Assert(audioStream != nil || videoStream != nil)

	//初始化
	t.header = make([]byte, 1024)
	t.muxer = libflv.NewMuxer(audioCodecId, videoCodecId, 0, 0, 0)
	t.memoryPool = stream.NewMemoryPool(1024 * 1024 * 2)
	t.transBuffer = stream.NewStreamBuffer(2000)
	t.transBuffer.SetDiscardHandler(t.onDiscardPacket)

	var n int
	if audioStream != nil {
		n += t.muxer.WriteAudioData(t.header, true)
		extra := audioStream.Extra()
		copy(t.header[n:], extra)
		n += len(extra)
	}

	if videoStream != nil {
		n += t.muxer.WriteAudioData(t.header[n:], true)
		extra := videoStream.Extra()
		copy(t.header[n:], extra)
		n += len(extra)
	}

	t.headerSize = n
	return nil
}

func NewTransStream(chunkSize int) stream.ITransStream {
	transStream := &TransStream{chunkSize: chunkSize}
	return transStream
}