Muxer: increase Continuity Counter of PAT and PMT (#29)

Countinuity counter of PAT and PMT must be increased after every
delivery in order to avoid errors when playing TS files with VLC
or hls.js.

PAT and PMT buffers are reused in order to save RAM.

Author: aler9

muxer.go

@@ -34,6 +34,8 @@ type Muxer struct {
 	nextPID    uint16
 	patVersion wrappingCounter
 	pmtVersion wrappingCounter
+	patCC      wrappingCounter
+	pmtCC      wrappingCounter
 
 	patBytes bytes.Buffer
 	pmtBytes bytes.Buffer
@@ -83,6 +85,9 @@ func NewMuxer(ctx context.Context, w io.Writer, opts ...func(*Muxer)) *Muxer {
 		patVersion: newWrappingCounter(0b11111),
 		pmtVersion: newWrappingCounter(0b11111),
 
+		patCC: newWrappingCounter(0b1111),
+		pmtCC: newWrappingCounter(0b1111),
+
 		esContexts: map[uint16]*esContext{},
 	}
 
@@ -285,16 +290,12 @@ func (m *Muxer) retransmitTables(force bool) (int, error) {
 func (m *Muxer) WriteTables() (int, error) {
 	bytesWritten := 0
 
-	if m.patBytes.Len() != m.packetSize {
-		if err := m.generatePAT(); err != nil {
-			return bytesWritten, err
-		}
+	if err := m.generatePAT(); err != nil {
+		return bytesWritten, err
 	}
 
-	if m.pmtBytes.Len() != m.packetSize {
-		if err := m.generatePMT(); err != nil {
-			return bytesWritten, err
-		}
+	if err := m.generatePMT(); err != nil {
+		return bytesWritten, err
 	}
 
 	n, err := m.w.Write(m.patBytes.Bytes())
@@ -351,6 +352,7 @@ func (m *Muxer) generatePAT() error {
 			HasPayload:                true,
 			PayloadUnitStartIndicator: true,
 			PID:                       PIDPAT,
+			ContinuityCounter:         uint8(m.patCC.get()),
 		},
 		Payload: m.buf.Bytes(),
 	}
@@ -411,6 +413,7 @@ func (m *Muxer) generatePMT() error {
 			HasPayload:                true,
 			PayloadUnitStartIndicator: true,
 			PID:                       pmtStartPID, // FIXME multiple programs support
+			ContinuityCounter:         uint8(m.pmtCC.get()),
 		},
 		Payload: m.buf.Bytes(),
 	}

muxer_test.go

@@ -8,14 +8,14 @@ import (
 	"testing"
 )
 
-func patExpectedBytes(versionNumber uint8) []byte {
+func patExpectedBytes(versionNumber uint8, cc uint8) []byte {
 	buf := bytes.Buffer{}
 	w := astikit.NewBitsWriter(astikit.BitsWriterOptions{Writer: &buf})
 	w.Write(uint8(syncByte))
 	w.Write("010") // no transport error, payload start, no priority
 	w.WriteN(PIDPAT, 13)
 	w.Write("0001") // no scrambling, no AF, payload present
-	w.Write("0000") // CC
+	w.WriteN(cc, 4)
 
 	w.Write(uint16(0))       // Table ID
 	w.Write("1011")          // Syntax section indicator, private bit, reserved
@@ -50,13 +50,13 @@ func TestMuxer_generatePAT(t *testing.T) {
 	err := muxer.generatePAT()
 	assert.NoError(t, err)
 	assert.Equal(t, MpegTsPacketSize, muxer.patBytes.Len())
-	assert.Equal(t, patExpectedBytes(0), muxer.patBytes.Bytes())
+	assert.Equal(t, patExpectedBytes(0, 0), muxer.patBytes.Bytes())
 
 	// to check version number increment
 	err = muxer.generatePAT()
 	assert.NoError(t, err)
 	assert.Equal(t, MpegTsPacketSize, muxer.patBytes.Len())
-	assert.Equal(t, patExpectedBytes(1), muxer.patBytes.Bytes())
+	assert.Equal(t, patExpectedBytes(1, 1), muxer.patBytes.Bytes())
 }
 
 func pmtExpectedBytesVideoOnly(versionNumber uint8) []byte {
@@ -99,14 +99,14 @@ func pmtExpectedBytesVideoOnly(versionNumber uint8) []byte {
 	return buf.Bytes()
 }
 
-func pmtExpectedBytesVideoAndAudio(versionNumber uint8) []byte {
+func pmtExpectedBytesVideoAndAudio(versionNumber uint8, cc uint8) []byte {
 	buf := bytes.Buffer{}
 	w := astikit.NewBitsWriter(astikit.BitsWriterOptions{Writer: &buf})
 	w.Write(uint8(syncByte))
 	w.Write("010") // no transport error, payload start, no priority
 	w.WriteN(pmtStartPID, 13)
 	w.Write("0001") // no scrambling, no AF, payload present
-	w.Write("0000") // CC
+	w.WriteN(cc, 4)
 
 	w.Write(uint16(PSITableIDPMT)) // Table ID
 	w.Write("1011")                // Syntax section indicator, private bit, reserved
@@ -172,7 +172,7 @@ func TestMuxer_generatePMT(t *testing.T) {
 	err = muxer.generatePMT()
 	assert.NoError(t, err)
 	assert.Equal(t, MpegTsPacketSize, muxer.pmtBytes.Len())
-	assert.Equal(t, pmtExpectedBytesVideoAndAudio(1), muxer.pmtBytes.Bytes())
+	assert.Equal(t, pmtExpectedBytesVideoAndAudio(1, 1), muxer.pmtBytes.Bytes())
 }
 
 func TestMuxer_WriteTables(t *testing.T) {
@@ -190,7 +190,7 @@ func TestMuxer_WriteTables(t *testing.T) {
 	assert.Equal(t, 2*MpegTsPacketSize, n)
 	assert.Equal(t, n, buf.Len())
 
-	expectedBytes := append(patExpectedBytes(0), pmtExpectedBytesVideoOnly(0)...)
+	expectedBytes := append(patExpectedBytes(0, 0), pmtExpectedBytesVideoOnly(0)...)
 	assert.Equal(t, expectedBytes, buf.Bytes())
 }
 
@@ -316,6 +316,6 @@ func TestMuxer_WritePayload(t *testing.T) {
 	assert.Equal(t, 0, buf.Len()%MpegTsPacketSize)
 
 	bs := buf.Bytes()
-	assert.Equal(t, patExpectedBytes(0), bs[:MpegTsPacketSize])
-	assert.Equal(t, pmtExpectedBytesVideoAndAudio(0), bs[MpegTsPacketSize:MpegTsPacketSize*2])
+	assert.Equal(t, patExpectedBytes(0, 0), bs[:MpegTsPacketSize])
+	assert.Equal(t, pmtExpectedBytesVideoAndAudio(0, 0), bs[MpegTsPacketSize:MpegTsPacketSize*2])
 }