generator: clean up MPEG-TS encoding

This deletes or marks unused cruft, removes internal chans and makes
interface chans single item long to make way for removal.

generator/mpegts_generator.go

@@ -6,6 +6,7 @@ DESCRIPTION
   See Readme.md
 
 AUTHOR
+  Dan Kortschak <dan@ausocean.org>
   Saxon Nelson-Milton <saxon@ausocean.org>
 
 LICENSE
@@ -22,8 +23,9 @@ LICENSE
  for more details.
 
   You should have received a copy of the GNU General Public License
-  along with revid in gpl.txt.  If not, see http://www.gnu.org/licenses.
+  along with revid in gpl.txt. If not, see http://www.gnu.org/licenses.
 */
+
 package generator
 
 import (
@@ -39,47 +41,60 @@ var (
 	pmtTable = []byte{0, 2, 176, 18, 0, 1, 193, 0, 0, 0xE1, 0x00, 0xF0, 0, 0x1B, 0xE1, 0, 0xF0, 0, 0x15, 0xBD, 0x4D, 0x56}
 )
 
-// genPatAndPmt generates the rest of the pat and pmt tables i.e. fills them
+func init() {
-// with 0xFFs - because it looks ugly to hardcode above. This is called through
-// NewMpegtsgenerator
-func genPatAndPmt() {
 	for len(patTable) < psiPacketSize {
-		patTable = append(patTable, 255)
+		patTable = append(patTable, 0xff)
 	}
 	for len(pmtTable) < psiPacketSize {
-		pmtTable = append(pmtTable, 255)
+		pmtTable = append(pmtTable, 0xff)
 	}
 }
 
 const (
-	SdtPid              = 17
+	SdtPid    = 17
-	PatPid              = 0
+	PatPid    = 0
-	pmtPid              = 4096
+	pmtPid    = 4096
-	videoPid            = 256
+	videoPid  = 256
-	streamID            = 0xE0
+	streamID  = 0xe0
-	outputChanSize      = 100
+	ptsOffset = 0.7
-	inputChanSize       = 10000
+	maxCC     = 0xf
-	pesPktChanSize      = 1000
-	payloadByteChanSize = 200000
-	ptsOffset           = .7
-	maxCC               = 15
 )
 
 // tsGenerator encapsulates properties of an mpegts generator.
 type tsGenerator struct {
-	outputChan      chan []byte
+	outputChan     chan []byte
-	nalInputChan    chan []byte
+	nalInputChan   chan []byte
-	currentTsPacket *mpegts.MpegTsPacket
+	currentPtsTime float64
-	payloadByteChan chan byte
+	currentPcrTime float64
-	currentCC       byte
+	fps            float64
-	currentPtsTime  float64
+	continuity     map[int]byte
-	currentPcrTime  float64
+	isGenerating   bool
-	fps             uint
-	pesPktChan      chan []byte
-	ccMap           map[int]int
-	isGenerating    bool
 }
 
+// NewTsGenerator returns an instance of the tsGenerator struct
+func NewTsGenerator(fps float64) (g *tsGenerator) {
+	return &tsGenerator{
+		outputChan:     make(chan []byte, 1),
+		nalInputChan:   make(chan []byte, 1),
+		fps:            fps,
+		currentPtsTime: ptsOffset,
+		continuity: map[int]byte{
+			SdtPid:   0, // FIXME(kortschak): This is not used.
+			PatPid:   0,
+			pmtPid:   0,
+			videoPid: 0,
+		},
+	}
+}
+
+// Start is called when we would like generation to begin, i.e. we would like
+// the generator to start taking input data and creating mpegts packets
+func (g *tsGenerator) Start() {
+	go g.generate()
+}
+
+func (g *tsGenerator) Stop() {}
+
 // InputChan returns a handle to the nalInputChan (inputChan) so that nal units
 // can be passed to the generator and processed
 func (g *tsGenerator) InputChan() chan []byte {
@@ -92,117 +107,79 @@ func (g *tsGenerator) OutputChan() <-chan []byte {
 	return g.outputChan
 }
 
-// NewTsGenerator returns an instance of the tsGenerator struct
-func NewTsGenerator(fps uint) (g *tsGenerator) {
-	g = new(tsGenerator)
-	g.outputChan = make(chan []byte, outputChanSize)
-	g.nalInputChan = make(chan []byte, inputChanSize)
-	g.currentCC = 0
-	g.fps = fps
-	g.currentPcrTime = 0.0
-	g.currentPtsTime = ptsOffset
-	g.pesPktChan = make(chan []byte, pesPktChanSize)
-	g.payloadByteChan = make(chan byte, payloadByteChanSize)
-	g.ccMap = make(map[int]int, 4)
-	g.ccMap[SdtPid] = 0
-	g.ccMap[PatPid] = 0
-	g.ccMap[pmtPid] = 0
-	g.ccMap[videoPid] = 0
-	genPatAndPmt()
-	g.isGenerating = false
-	return
-}
-
-// getPts retuns the next presentation timestamp for the tsGenerator t.
-func (g *tsGenerator) genPts() (pts uint64) {
-	pts = uint64(g.currentPtsTime * float64(90000))
-	g.currentPtsTime += 1.0 / float64(g.fps)
-	return
-}
-
-// genPcr returns the next program clock reference for the tsGenerator g
-func (g *tsGenerator) genPcr() (pcr uint64) {
-	pcr = uint64(g.currentPcrTime * float64(90000))
-	g.currentPcrTime += 1.0 / float64(g.fps)
-	return
-}
-
-// Start is called when we would like generation to begin, i.e. we would like
-// the generator to start taking input data and creating mpegts packets
-func (g *tsGenerator) Start() {
-	g.isGenerating = true
-	go g.generate()
-}
-
-func (g *tsGenerator) Stop() {
-	g.isGenerating = false
-}
-
-// getCC returns the next continuity counter for a particular pid
-func (g *tsGenerator) getCC(pid int) int {
-	temp := g.ccMap[pid]
-	if g.ccMap[pid]++; g.ccMap[pid] > maxCC {
-		g.ccMap[pid] = 0
-	}
-	return temp
-}
-
 // generate handles the incoming data and generates equivalent mpegts packets -
 // sending them to the output channel
 func (g *tsGenerator) generate() {
 	for {
-		select {
+		nalu := <-g.nalInputChan
-		case nalUnit := <-g.nalInputChan:
+		pesPkt := pes.Packet{
-			pesPkt := pes.PESPacket{
+			StreamID:     streamID,
-				StreamID:     streamID,
+			PDI:          2,
-				PDI:          byte(2),
+			PTS:          g.pts(),
-				PTS:          g.genPts(),
+			Data:         nalu,
-				Data:         nalUnit,
+			HeaderLength: 5,
-				HeaderLength: 5,
+		}
-			}
+		buf := pesPkt.Bytes()
-			pesPktSlice := pesPkt.ToByteSlice()
 
-			for ii := range pesPktSlice {
+		pusi := true
-				g.payloadByteChan <- pesPktSlice[ii]
+		for len(buf) != 0 {
+			pkt := mpegts.Packet{
+				PUSI: pusi,
+				PID:  videoPid,
+				RAI:  pusi,
+				CC:   g.ccFor(videoPid),
+				AFC:  3,
+				PCRF: pusi,
 			}
-			pusi := true
+			n := pkt.FillPayload(buf)
-			for len(g.payloadByteChan) > 0 {
+			buf = buf[n:]
-				pkt := mpegts.MpegTsPacket{
-					PUSI: pusi,
-					PID:  videoPid,
-					RAI:  pusi,
-					CC:   byte(g.getCC(videoPid)),
-					AFC:  byte(3),
-					PCRF: pusi,
-				}
-				pkt.FillPayload(g.payloadByteChan)
 
-				// TODO: create consts for AFC parameters
+			// TODO: create consts for AFC parameters
-				if pusi {
+			if pusi {
-					// Create pat table
+				// Create pat table
-					patPkt := mpegts.MpegTsPacket{
+				patPkt := mpegts.Packet{
-						PUSI:    pusi,
+					PUSI:    pusi,
-						PID:     PatPid,
+					PID:     PatPid,
-						CC:      byte(g.getCC(PatPid)),
+					CC:      g.ccFor(PatPid),
-						AFC:     1,
+					AFC:     1,
-						Payload: patTable,
+					Payload: patTable,
-					}
-					g.outputChan <- patPkt.ToByteSlice()
-					// Create pmt table
-					pmtPkt := mpegts.MpegTsPacket{
-						PUSI:    pusi,
-						PID:     pmtPid,
-						CC:      byte(g.getCC(pmtPid)),
-						AFC:     1,
-						Payload: pmtTable,
-					}
-					g.outputChan <- pmtPkt.ToByteSlice()
-					// If pusi then we need to gen a pcr
-					pkt.PCR = g.genPcr()
-					pusi = false
 				}
-				g.outputChan <- pkt.ToByteSlice()
+				g.outputChan <- patPkt.Bytes()
+				// Create pmt table
+				pmtPkt := mpegts.Packet{
+					PUSI:    pusi,
+					PID:     pmtPid,
+					CC:      g.ccFor(pmtPid),
+					AFC:     1,
+					Payload: pmtTable,
+				}
+				g.outputChan <- pmtPkt.Bytes()
+				// If pusi then we need to gen a pcr
+				pkt.PCR = g.pcr()
+				pusi = false
 			}
+			g.outputChan <- pkt.Bytes()
 		}
 	}
 }
+
+// pts retuns the next presentation timestamp.
+func (g *tsGenerator) pts() uint64 {
+	pts := uint64(g.currentPtsTime * 90000) // FIXME(kortschak): Name this magic number.
+	g.currentPtsTime += 1 / g.fps
+	return pts
+}
+
+// pcr returns the next program clock reference.
+func (g *tsGenerator) pcr() uint64 {
+	pcr := uint64(g.currentPcrTime * 90000) // FIXME(kortschak): Name this magic number.
+	g.currentPcrTime += 1 / g.fps
+	return pcr
+}
+
+// ccFor returns the next continuity counter for pid.
+func (g *tsGenerator) ccFor(pid int) byte {
+	cc := g.continuity[pid]
+	g.continuity[pid] = (cc + 1) & maxCC
+	return cc
+}

mpegts/MpegTs.go

@@ -28,8 +28,6 @@ LICENSE
 
 package mpegts
 
-import "bitbucket.org/ausocean/av/tools"
-
 const (
 	mpegTsSize        = 188
 	mpegtsPayloadSize = 176
@@ -100,7 +98,7 @@ the formatting of an MPEG-TS packet for reference!
 | -        | ...                                                           |
 ----------------------------------------------------------------------------
 */
-type MpegTsPacket struct {
+type Packet struct {
 	TEI      bool   // Transport Error Indicator
 	PUSI     bool   // Payload Unit Start Indicator
 	Priority bool   // Tranposrt priority indicator
@@ -127,27 +125,32 @@ type MpegTsPacket struct {
 
 // FillPayload takes a channel and fills the packets Payload field until the
 // channel is empty or we've the packet reaches capacity
-func (p *MpegTsPacket) FillPayload(channel chan byte) {
+func (p *Packet) FillPayload(data []byte) int {
-	p.Payload = make([]byte, 0, mpegtsPayloadSize)
+	currentPktLength := 6 + asInt(p.PCRF)*6 + asInt(p.OPCRF)*6 +
-	currentPktLength := 6 + int(toByte(p.PCRF))*6 + int(toByte(p.OPCRF))*6 +
+		asInt(p.SPF)*1 + asInt(p.TPDF)*1 + len(p.TPD)
-		int(toByte(p.SPF))*1 + int(toByte(p.TPDF))*1 + len(p.TPD)
+	p.Payload = make([]byte, mpegtsPayloadSize-currentPktLength)
-	// While we're within the mpegts packet size and we still have data we can use
+	return copy(p.Payload, data)
-	for (currentPktLength+len(p.Payload)) < mpegTsSize && len(channel) > 0 {
-		p.Payload = append(p.Payload, <-channel)
-	}
 }
 
-// toByte is a simple wrapper function for tools.BoolToByte which takes a bool
+func asInt(b bool) int {
-// and returns an equivalent byte
+	if b {
-func toByte(b bool) byte {
+		return 1
-	return tools.BoolToByte(b)
+	}
+	return 0
+}
+
+func asByte(b bool) byte {
+	if b {
+		return 1
+	}
+	return 0
 }
 
 // ToByteSlice interprets the fields of the ts packet instance and outputs a
 // corresponding byte slice
-func (p *MpegTsPacket) ToByteSlice() (output []byte) {
+func (p *Packet) Bytes() []byte {
-	stuffingLength := 182 - len(p.Payload) - len(p.TPD) - int(toByte(p.PCRF))*6 -
+	stuffingLength := 182 - len(p.Payload) - len(p.TPD) - asInt(p.PCRF)*6 -
-		int(toByte(p.OPCRF))*6 - int(toByte(p.SPF))
+		asInt(p.OPCRF)*6 - asInt(p.SPF)
 	var stuffing []byte
 	if stuffingLength > 0 {
 		stuffing = make([]byte, stuffingLength)
@@ -155,36 +158,36 @@ func (p *MpegTsPacket) ToByteSlice() (output []byte) {
 	for i := range stuffing {
 		stuffing[i] = 0xFF
 	}
-	afl := 1 + int(toByte(p.PCRF))*6 + int(toByte(p.OPCRF))*6 + int(toByte(p.SPF)) + int(toByte(p.TPDF)) + len(p.TPD) + len(stuffing)
+	afl := 1 + asInt(p.PCRF)*6 + asInt(p.OPCRF)*6 + asInt(p.SPF) + asInt(p.TPDF) + len(p.TPD) + len(stuffing)
-	output = make([]byte, 0, mpegTsSize)
+	buf := make([]byte, 0, mpegTsSize)
-	output = append(output, []byte{
+	buf = append(buf, []byte{
 		0x47,
-		(toByte(p.TEI)<<7 | toByte(p.PUSI)<<6 | toByte(p.Priority)<<5 | byte((p.PID&0xFF00)>>8)),
+		(asByte(p.TEI)<<7 | asByte(p.PUSI)<<6 | asByte(p.Priority)<<5 | byte((p.PID&0xFF00)>>8)),
 		byte(p.PID & 0x00FF),
 		(p.TSC<<6 | p.AFC<<4 | p.CC),
 	}...)
 
 	if p.AFC == 3 || p.AFC == 2 {
-		output = append(output, []byte{
+		buf = append(buf, []byte{
-			byte(afl), (toByte(p.DI)<<7 | toByte(p.RAI)<<6 | toByte(p.ESPI)<<5 |
+			byte(afl), (asByte(p.DI)<<7 | asByte(p.RAI)<<6 | asByte(p.ESPI)<<5 |
-				toByte(p.PCRF)<<4 | toByte(p.OPCRF)<<3 | toByte(p.SPF)<<2 |
+				asByte(p.PCRF)<<4 | asByte(p.OPCRF)<<3 | asByte(p.SPF)<<2 |
-				toByte(p.TPDF)<<1 | toByte(p.AFEF)),
+				asByte(p.TPDF)<<1 | asByte(p.AFEF)),
 		}...)
 		for i := 40; p.PCRF && i >= 0; i -= 8 {
-			output = append(output, byte((p.PCR<<15)>>uint(i)))
+			buf = append(buf, byte((p.PCR<<15)>>uint(i)))
 		}
 		for i := 40; p.OPCRF && i >= 0; i -= 8 {
-			output = append(output, byte(p.OPCR>>uint(i)))
+			buf = append(buf, byte(p.OPCR>>uint(i)))
 		}
 		if p.SPF {
-			output = append(output, p.SC)
+			buf = append(buf, p.SC)
 		}
 		if p.TPDF {
-			output = append(output, append([]byte{p.TPDL}, p.TPD...)...)
+			buf = append(buf, append([]byte{p.TPDL}, p.TPD...)...)
 		}
-		output = append(output, p.Ext...)
+		buf = append(buf, p.Ext...)
-		output = append(output, stuffing...)
+		buf = append(buf, stuffing...)
 	}
-	output = append(output, p.Payload...)
+	buf = append(buf, p.Payload...)
-	return
+	return buf
 }

pes/pes.go

@@ -70,7 +70,7 @@ the formatting of a PES packet for reference!
 ----------------------------------------------------------------------------
 */
 // TODO: add DSMTM, ACI, CRC, Ext fields
-type PESPacket struct {
+type Packet struct {
 	StreamID     byte   // Type of stream
 	Length       uint16 // Pes packet length in bytes after this field
 	SC           byte   // Scrambling control
@@ -94,9 +94,9 @@ type PESPacket struct {
 	Data         []byte // Pes packet data
 }
 
-func (p *PESPacket) ToByteSlice() (output []byte) {
+func (p *Packet) Bytes() []byte {
-	output = make([]byte, 0, maxPesSize)
+	buf := make([]byte, 0, maxPesSize)
-	output = append(output, []byte{
+	buf = append(buf, []byte{
 		0x00, 0x00, 0x01,
 		p.StreamID,
 		byte((p.Length & 0xFF00) >> 8),
@@ -110,7 +110,7 @@ func (p *PESPacket) ToByteSlice() (output []byte) {
 	if p.PDI == byte(2) {
 		pts := 0x2100010001 | (p.PTS&0x1C0000000)<<3 | (p.PTS&0x3FFF8000)<<2 |
 			(p.PTS&0x7FFF)<<1
-		output = append(output, []byte{
+		buf = append(buf, []byte{
 			byte((pts & 0xFF00000000) >> 32),
 			byte((pts & 0x00FF000000) >> 24),
 			byte((pts & 0x0000FF0000) >> 16),
@@ -118,6 +118,6 @@ func (p *PESPacket) ToByteSlice() (output []byte) {
 			byte(pts & 0x00000000FF),
 		}...)
 	}
-	output = append(output, append(p.Stuff, p.Data...)...)
+	buf = append(buf, append(p.Stuff, p.Data...)...)
-	return
+	return buf
 }

revid/revid.go

@@ -209,7 +209,7 @@ func (r *Revid) reset(config Config) error {
 	case Mpegts:
 		r.Log(Info, "Using MPEGTS packetisation")
 		frameRate, _ := strconv.Atoi(r.config.FrameRate)
-		r.generator = generator.NewTsGenerator(uint(frameRate))
+		r.generator = generator.NewTsGenerator(float64(frameRate))
 	case Flv:
 		r.Log(Info, "Using FLV packetisation")
 		frameRate, _ := strconv.Atoi(r.config.FrameRate)