rename mpegtsencoder into mpegtsmuxer

examples/client-read-h264-save-to-disk/mpegtsmuxer.go

@@ -0,0 +1,171 @@
+package main
+
+import (
+	"bufio"
+	"context"
+	"log"
+	"os"
+	"time"
+
+	"github.com/aler9/gortsplib/pkg/h264"
+	"github.com/asticode/go-astits"
+)
+
+// mpegtsMuxer allows to save a H264 stream into a MPEG-TS file.
+type mpegtsMuxer struct {
+	sps []byte
+	pps []byte
+
+	f                *os.File
+	b                *bufio.Writer
+	mux              *astits.Muxer
+	dtsExtractor     *h264.DTSExtractor
+	firstIDRReceived bool
+	startDTS         time.Duration
+}
+
+// newMPEGTSMuxer allocates a mpegtsMuxer.
+func newMPEGTSMuxer(sps []byte, pps []byte) (*mpegtsMuxer, error) {
+	f, err := os.Create("mystream.ts")
+	if err != nil {
+		return nil, err
+	}
+	b := bufio.NewWriter(f)
+
+	mux := astits.NewMuxer(context.Background(), b)
+	mux.AddElementaryStream(astits.PMTElementaryStream{
+		ElementaryPID: 256,
+		StreamType:    astits.StreamTypeH264Video,
+	})
+	mux.SetPCRPID(256)
+
+	return &mpegtsMuxer{
+		sps: sps,
+		pps: pps,
+		f:   f,
+		b:   b,
+		mux: mux,
+	}, nil
+}
+
+// close closes all the mpegtsMuxer resources.
+func (e *mpegtsMuxer) close() {
+	e.b.Flush()
+	e.f.Close()
+}
+
+// encode encodes H264 NALUs into MPEG-TS.
+func (e *mpegtsMuxer) encode(nalus [][]byte, pts time.Duration) error {
+	// prepend an AUD. This is required by some players
+	filteredNALUs := [][]byte{
+		{byte(h264.NALUTypeAccessUnitDelimiter), 240},
+	}
+
+	nonIDRPresent := false
+	idrPresent := false
+
+	for _, nalu := range nalus {
+		typ := h264.NALUType(nalu[0] & 0x1F)
+		switch typ {
+		case h264.NALUTypeSPS:
+			e.sps = append([]byte(nil), nalu...)
+			continue
+
+		case h264.NALUTypePPS:
+			e.pps = append([]byte(nil), nalu...)
+			continue
+
+		case h264.NALUTypeAccessUnitDelimiter:
+			continue
+
+		case h264.NALUTypeIDR:
+			idrPresent = true
+
+			// add SPS and PPS before every IDR
+			if e.sps != nil && e.pps != nil {
+				filteredNALUs = append(filteredNALUs, e.sps, e.pps)
+			}
+
+		case h264.NALUTypeNonIDR:
+			nonIDRPresent = true
+		}
+
+		filteredNALUs = append(filteredNALUs, nalu)
+	}
+
+	if !nonIDRPresent && !idrPresent {
+		return nil
+	}
+
+	var dts time.Duration
+
+	if !e.firstIDRReceived {
+		// skip samples silently until we find one with a IDR
+		if !idrPresent {
+			return nil
+		}
+
+		e.firstIDRReceived = true
+		e.dtsExtractor = h264.NewDTSExtractor()
+
+		var err error
+		dts, err = e.dtsExtractor.Extract(filteredNALUs, pts)
+		if err != nil {
+			return err
+		}
+
+		e.startDTS = dts
+		dts = 0
+		pts -= e.startDTS
+
+	} else {
+		var err error
+		dts, err = e.dtsExtractor.Extract(filteredNALUs, pts)
+		if err != nil {
+			return err
+		}
+
+		dts -= e.startDTS
+		pts -= e.startDTS
+	}
+
+	oh := &astits.PESOptionalHeader{
+		MarkerBits: 2,
+	}
+
+	if dts == pts {
+		oh.PTSDTSIndicator = astits.PTSDTSIndicatorOnlyPTS
+		oh.PTS = &astits.ClockReference{Base: int64(pts.Seconds() * 90000)}
+	} else {
+		oh.PTSDTSIndicator = astits.PTSDTSIndicatorBothPresent
+		oh.DTS = &astits.ClockReference{Base: int64(dts.Seconds() * 90000)}
+		oh.PTS = &astits.ClockReference{Base: int64(pts.Seconds() * 90000)}
+	}
+
+	// encode into Annex-B
+	annexb, err := h264.AnnexBMarshal(filteredNALUs)
+	if err != nil {
+		return err
+	}
+
+	// write TS packet
+	_, err = e.mux.WriteData(&astits.MuxerData{
+		PID: 256,
+		AdaptationField: &astits.PacketAdaptationField{
+			RandomAccessIndicator: idrPresent,
+		},
+		PES: &astits.PESData{
+			Header: &astits.PESHeader{
+				OptionalHeader: oh,
+				StreamID:       224, // video
+			},
+			Data: annexb,
+		},
+	})
+	if err != nil {
+		return err
+	}
+
+	log.Println("wrote TS packet")
+	return nil
+}