hls: send PCR once, at the beginning of every TS segment

internal/hls/muxer.go

@@ -34,7 +34,6 @@ type Muxer struct {
 	h264SPS       []byte
 	h264PPS       []byte
 	aacConfig     rtpaac.MPEG4AudioConfig
-	startPCR      time.Time
 	videoDTSEst   *h264.DTSEstimator
 	audioAUCount  int
 	tsCurrent     *tsFile
@@ -42,6 +41,7 @@ type Muxer struct {
 	tsByName      map[string]*tsFile
 	tsDeleteCount int
 	mutex         sync.RWMutex
+	startPCR      time.Time
 	startPTS      time.Duration
 }
 
@@ -82,7 +82,6 @@ func NewMuxer(
 		h264SPS:            h264SPS,
 		h264PPS:            h264PPS,
 		aacConfig:          aacConfig,
-		startPCR:           time.Now(),
 		videoDTSEst:        h264.NewDTSEstimator(),
 		tsCurrent:          newTSFile(videoTrack, audioTrack),
 		tsByName:           make(map[string]*tsFile),
@@ -122,11 +121,10 @@ func (m *Muxer) WriteH264(pts time.Duration, nalus [][]byte) error {
 	if idrPresent &&
 		m.tsCurrent.firstPacketWritten &&
 		m.tsCurrent.duration() >= m.hlsSegmentDuration {
-		if m.tsCurrent != nil {
-			m.tsCurrent.close()
-		}
+		m.tsCurrent.close()
 
 		m.tsCurrent = newTSFile(m.videoTrack, m.audioTrack)
+		m.tsCurrent.setStartPCR(m.startPCR)
 
 		m.tsByName[m.tsCurrent.name] = m.tsCurrent
 		m.tsQueue = append(m.tsQueue, m.tsCurrent)
@@ -136,11 +134,12 @@ func (m *Muxer) WriteH264(pts time.Duration, nalus [][]byte) error {
 			m.tsDeleteCount++
 		}
 	} else if !m.tsCurrent.firstPacketWritten {
+		m.startPCR = time.Now()
 		m.startPTS = pts
+		m.tsCurrent.setStartPCR(m.startPCR)
 	}
 
 	pts = pts + ptsOffset - m.startPTS
-	m.tsCurrent.setPCR(time.Since(m.startPCR))
 	err := m.tsCurrent.writeH264(
 		m.h264SPS,
 		m.h264PPS,
@@ -164,13 +163,13 @@ func (m *Muxer) WriteAAC(pts time.Duration, aus [][]byte) error {
 		if m.audioAUCount >= segmentMinAUCount &&
 			m.tsCurrent.firstPacketWritten &&
 			m.tsCurrent.duration() >= m.hlsSegmentDuration {
-
-			if m.tsCurrent != nil {
-				m.tsCurrent.close()
-			}
+			m.tsCurrent.close()
 
 			m.audioAUCount = 0
+
 			m.tsCurrent = newTSFile(m.videoTrack, m.audioTrack)
+			m.tsCurrent.setStartPCR(m.startPCR)
+
 			m.tsByName[m.tsCurrent.name] = m.tsCurrent
 			m.tsQueue = append(m.tsQueue, m.tsCurrent)
 			if len(m.tsQueue) > m.hlsSegmentCount {
@@ -179,7 +178,9 @@ func (m *Muxer) WriteAAC(pts time.Duration, aus [][]byte) error {
 				m.tsDeleteCount++
 			}
 		} else if !m.tsCurrent.firstPacketWritten {
+			m.startPCR = time.Now()
 			m.startPTS = pts
+			m.tsCurrent.setStartPCR(m.startPCR)
 		}
 	} else {
 		if !m.tsCurrent.firstPacketWritten {
@@ -192,8 +193,6 @@ func (m *Muxer) WriteAAC(pts time.Duration, aus [][]byte) error {
 	for i, au := range aus {
 		auPTS := pts + time.Duration(i)*1000*time.Second/time.Duration(m.aacConfig.SampleRate)
 
-		m.audioAUCount++
-		m.tsCurrent.setPCR(time.Since(m.startPCR))
 		err := m.tsCurrent.writeAAC(
 			m.aacConfig.SampleRate,
 			m.aacConfig.ChannelCount,
@@ -202,6 +201,8 @@ func (m *Muxer) WriteAAC(pts time.Duration, aus [][]byte) error {
 		if err != nil {
 			return err
 		}
+
+		m.audioAUCount++
 	}
 
 	return nil

internal/hls/tsfile.go

@@ -18,10 +18,10 @@ type tsFile struct {
 	name               string
 	buf                *multiAccessBuffer
 	mux                *astits.Muxer
-	pcr                time.Duration
 	firstPacketWritten bool
 	minPTS             time.Duration
 	maxPTS             time.Duration
+	startPCR           time.Time
 }
 
 func newTSFile(videoTrack *gortsplib.Track, audioTrack *gortsplib.Track) *tsFile {
@@ -69,8 +69,8 @@ func (t *tsFile) duration() time.Duration {
 	return t.maxPTS - t.minPTS
 }
 
-func (t *tsFile) setPCR(pcr time.Duration) {
-	t.pcr = pcr
+func (t *tsFile) setStartPCR(startPCR time.Time) {
+	t.startPCR = startPCR
 }
 
 func (t *tsFile) newReader() io.Reader {
@@ -81,7 +81,6 @@ func (t *tsFile) writeH264(
 	h264SPS []byte, h264PPS []byte,
 	dts time.Duration, pts time.Duration, isIDR bool, nalus [][]byte) error {
 	if !t.firstPacketWritten {
-		t.firstPacketWritten = true
 		t.minPTS = pts
 		t.maxPTS = pts
 	} else {
@@ -115,17 +114,30 @@ func (t *tsFile) writeH264(
 		filteredNALUs = append(filteredNALUs, nalu)
 	}
 
+	var af *astits.PacketAdaptationField
+
+	if isIDR {
+		if af == nil {
+			af = &astits.PacketAdaptationField{}
+		}
+		af.RandomAccessIndicator = true
+	}
+
+	if !t.firstPacketWritten {
+		t.firstPacketWritten = true
+		if af == nil {
+			af = &astits.PacketAdaptationField{}
+		}
+		af.HasPCR = true
+		pcr := time.Since(t.startPCR)
+		af.PCR = &astits.ClockReference{Base: int64(pcr.Seconds() * 90000)}
+	}
+
 	enc, err := h264.EncodeAnnexB(filteredNALUs)
 	if err != nil {
 		return err
 	}
 
-	af := &astits.PacketAdaptationField{
-		RandomAccessIndicator: isIDR,
-		HasPCR:                true,
-		PCR:                   &astits.ClockReference{Base: int64(t.pcr.Seconds() * 90000)},
-	}
-
 	_, err = t.mux.WriteData(&astits.MuxerData{
 		PID:             256,
 		AdaptationField: af,
@@ -148,7 +160,6 @@ func (t *tsFile) writeH264(
 func (t *tsFile) writeAAC(sampleRate int, channelCount int, pts time.Duration, au []byte) error {
 	if t.videoTrack == nil {
 		if !t.firstPacketWritten {
-			t.firstPacketWritten = true
 			t.minPTS = pts
 			t.maxPTS = pts
 		} else {
@@ -176,9 +187,11 @@ func (t *tsFile) writeAAC(sampleRate int, channelCount int, pts time.Duration, a
 		RandomAccessIndicator: true,
 	}
 
-	if t.videoTrack == nil {
+	if t.videoTrack == nil && !t.firstPacketWritten {
+		t.firstPacketWritten = true
 		af.HasPCR = true
-		af.PCR = &astits.ClockReference{Base: int64(t.pcr.Seconds() * 90000)}
+		pcr := time.Since(t.startPCR)
+		af.PCR = &astits.ClockReference{Base: int64(pcr.Seconds() * 90000)}
 	}
 
 	_, err = t.mux.WriteData(&astits.MuxerData{