container/mts: add constructors for standard PAT and PMT PSI tables in psi package and have MTS encoder use these.

container/mts/encoder.go

@@ -106,44 +106,6 @@ const (
 	defaultMediaPID  = PIDVideo
 )
 
-// Some common manifestations of PSI.
-var (
-	// StandardPAT is a minimal PAT.
-	StandardPAT = psi.PSI{
-		Pf:  0x00,
-		Tid: 0x00,
-		Ssi: true,
-		Pb:  false,
-		Sl:  0x0d,
-		Tss: &psi.TSS{
-			Tide: 0x01,
-			V:    0,
-			Cni:  true,
-			Sn:   0,
-			Lsn:  0,
-			Sd: &psi.PAT{
-				Pn:    0x01,
-				Pmpid: 0x1000,
-			},
-		},
-	}
-
-	// Base PMT is a minimal PMT without specific data.
-	BasePMT = psi.PSI{
-		Pf:  0x00,
-		Tid: 0x02,
-		Ssi: true,
-		Sl:  0x12,
-		Tss: &psi.TSS{
-			Tide: 0x01,
-			V:    0,
-			Cni:  true,
-			Sn:   0,
-			Lsn:  0,
-		},
-	}
-)
-
 // Meta allows addition of metadata to encoded mts from outside of this pkg.
 // See meta pkg for usage.
 //
@@ -153,11 +115,6 @@ var Meta *meta.Data
 // This will help us obtain a realtime for timestamp meta encoding.
 var RealTime = realtime.NewRealTime()
 
-var (
-	patTable = StandardPAT.Bytes()
-	pmtTable []byte
-)
-
 type logger interface {
 	Debug(string, ...interface{})
 	Info(string, ...interface{})
@@ -188,6 +145,9 @@ type Encoder struct {
 	mediaPID     uint16
 	streamID     byte
 
+	pmt                *psi.PSI
+	patBytes, pmtBytes []byte
+
 	// log is a function that will be used through the encoder code for logging.
 	log logger
 }
@@ -205,6 +165,8 @@ func NewEncoder(dst io.WriteCloser, log logger, options ...func(*Encoder) error)
 		streamID:    defaultStreamID,
 		continuity:  map[uint16]byte{PatPid: 0, PmtPid: 0, defaultMediaPID: 0},
 		log:         log,
+		patBytes:    psi.NewPATPSI().Bytes(),
+		pmt:         psi.NewPMTPSI(),
 	}
 
 	for _, option := range options {
@@ -215,17 +177,9 @@ func NewEncoder(dst io.WriteCloser, log logger, options ...func(*Encoder) error)
 	}
 	log.Debug("encoder options applied")
 
-	pmt := BasePMT
-	pmt.Tss.Sd = &psi.PMT{
-		Pcrpid: 0x0100,
-		Pil:    0,
-		Essd: &psi.ESSD{
-			St:   byte(e.streamID),
-			Epid: e.mediaPID,
-			Esil: 0x00,
-		},
-	}
-	pmtTable = pmt.Bytes()
+	e.pmt.Tss.Sd.(*psi.PMT).Essd.St = e.streamID
+	e.pmt.Tss.Sd.(*psi.PMT).Essd.Epid = e.mediaPID
+	e.pmtBytes = e.pmt.Bytes()
 
 	return e, nil
 }
@@ -324,7 +278,7 @@ func (e *Encoder) writePSI() error {
 		PID:     PatPid,
 		CC:      e.ccFor(PatPid),
 		AFC:     hasPayload,
-		Payload: psi.AddPadding(patTable),
+		Payload: psi.AddPadding(e.patBytes),
 	}
 	_, err := e.dst.Write(patPkt.Bytes(e.tsSpace[:PacketSize]))
 	if err != nil {
@@ -332,7 +286,7 @@ func (e *Encoder) writePSI() error {
 	}
 	e.pktCount++
 
-	pmtTable, err = updateMeta(pmtTable, e.log)
+	e.pmtBytes, err = updateMeta(e.pmtBytes, e.log)
 
 	if err != nil {
 		return err
@@ -344,7 +298,7 @@ func (e *Encoder) writePSI() error {
 		PID:     PmtPid,
 		CC:      e.ccFor(PmtPid),
 		AFC:     hasPayload,
-		Payload: psi.AddPadding(pmtTable),
+		Payload: psi.AddPadding(e.pmtBytes),
 	}
 	_, err = e.dst.Write(pmtPkt.Bytes(e.tsSpace[:PacketSize]))
 	if err != nil {

container/mts/mpegts_test.go

@@ -98,13 +98,15 @@ func TestGetPTSRange1(t *testing.T) {
 
 // writePSI is a helper function write the PSI found at the start of a clip.
 func writePSI(b *bytes.Buffer) error {
+	patBytes := psi.NewPATPSI().Bytes()
+	pmtBytes := psi.NewPMTPSI().Bytes()
 	// Write PAT.
 	pat := Packet{
 		PUSI:    true,
 		PID:     PatPid,
 		CC:      0,
 		AFC:     HasPayload,
-		Payload: psi.AddPadding(patTable),
+		Payload: psi.AddPadding(patBytes),
 	}
 	_, err := b.Write(pat.Bytes(nil))
 	if err != nil {
@@ -117,7 +119,7 @@ func writePSI(b *bytes.Buffer) error {
 		PID:     PmtPid,
 		CC:      0,
 		AFC:     HasPayload,
-		Payload: psi.AddPadding(pmtTable),
+		Payload: psi.AddPadding(pmtBytes),
 	}
 	_, err = b.Write(pmt.Bytes(nil))
 	if err != nil {

container/mts/payload_test.go

@@ -137,13 +137,15 @@ func TestExtract(t *testing.T) {
 
 // writePSIWithMeta writes PSI to b with updated metadata.
 func writePSIWithMeta(b *bytes.Buffer, t *testing.T) error {
+	patBytes := psi.NewPATPSI().Bytes()
+	pmtBytes := psi.NewPMTPSI().Bytes()
 	// Write PAT.
 	pat := Packet{
 		PUSI:    true,
 		PID:     PatPid,
 		CC:      0,
 		AFC:     HasPayload,
-		Payload: psi.AddPadding(patTable),
+		Payload: psi.AddPadding(patBytes),
 	}
 	_, err := b.Write(pat.Bytes(nil))
 	if err != nil {
@@ -151,7 +153,7 @@ func writePSIWithMeta(b *bytes.Buffer, t *testing.T) error {
 	}
 
 	// Update the meta in the pmt table.
-	pmtTable, err = updateMeta(pmtTable, (*testLogger)(t))
+	pmtBytes, err = updateMeta(pmtBytes, (*testLogger)(t))
 	if err != nil {
 		return err
 	}
@@ -162,7 +164,7 @@ func writePSIWithMeta(b *bytes.Buffer, t *testing.T) error {
 		PID:     PmtPid,
 		CC:      0,
 		AFC:     HasPayload,
-		Payload: psi.AddPadding(pmtTable),
+		Payload: psi.AddPadding(pmtBytes),
 	}
 	_, err = b.Write(pmt.Bytes(nil))
 	if err != nil {

container/mts/psi/psi.go

@@ -96,6 +96,57 @@ const DescriptorsIdx = ProgramInfoLenIdx2 + 1
 // MetadataTag is the descriptor tag used for metadata.
 const MetadataTag = 0x26
 
+// NewPATPSI will provide a standard program specific information (PSI) table
+// with a program association table (PAT) specific data field.
+func NewPATPSI() *PSI {
+	return &PSI{
+		Pf:  0x00,
+		Tid: 0x00,
+		Ssi: true,
+		Pb:  false,
+		Sl:  0x0d,
+		Tss: &TSS{
+			Tide: 0x01,
+			V:    0,
+			Cni:  true,
+			Sn:   0,
+			Lsn:  0,
+			Sd: &PAT{
+				Pn:    0x01,
+				Pmpid: 0x1000,
+			},
+		},
+	}
+}
+
+// NewPMTPSI will provide a standard program specific information (PSI) table
+// with a program mapping table specific data field.
+// NOTE: Media PID and stream ID are default to 0.
+func NewPMTPSI() *PSI {
+	return &PSI{
+		Pf:  0x00,
+		Tid: 0x02,
+		Ssi: true,
+		Sl:  0x12,
+		Tss: &TSS{
+			Tide: 0x01,
+			V:    0,
+			Cni:  true,
+			Sn:   0,
+			Lsn:  0,
+			Sd: &PMT{
+				Pcrpid: 0x0100,
+				Pil:    0,
+				Essd: &ESSD{
+					St:   0,
+					Epid: 0,
+					Esil: 0x00,
+				},
+			},
+		},
+	}
+}
+
 // TODO: get rid of these - not a good idea.
 type (
 	PSIBytes   []byte