Updating remote

Got h264 parsing working. Got testing utilities for this. Working on modifying code to be more robust, with mpegts. Adding pcr and pts

packets/MpegTs.go

@@ -28,7 +28,7 @@ LICENSE
 
 package packets
 
-import _"fmt"
+import _ "fmt"
 
 // Length of some fields in bits
 const (
@@ -40,7 +40,7 @@ const (
 	tscLength      = 2
 	afcLength      = 2
 	ccLength       = 4
-	packetLength = 188
+	packetLength   = 188
 )
 
 // Index of the fields
@@ -57,27 +57,42 @@ const (
 )
 
 type MpegTsPacket struct {
-	SyncByte byte
-	TEI      bool // Transport Error Indicator
-	PUSI     bool // Payload Unit Start Indicator
-	Priority bool
-	PID      uint16
-	TSC      byte   // Transport Scrambling Control
-	AFC      byte   // Adaption Field Control
-	CC       byte    // Continuity Counter
-	AF       []byte // Adaption Field
-	Payload  []byte
+	// syncByte byte // (octet:0 bit:0 - octet:0 bit:7)
+	TEI       bool   // (octet:1 bit:0) 									Transport Error Indicator
+	PUSI      bool   // (octet:1 bit:1) 									Payload Unit Start Indicator
+	Priority  bool   // (octet:1 bit:2) 									Tranposrt priority indicator
+	PID       uint16 // (octet:1 bit:3 - octect:3 bit:7)	Packet identifier
+	TSC       byte   // (octet:4 bit:0 - octect:4 bit:1) 	Transport Scrambling Control
+	AFC       byte   // (octet:4 bit:2 - octect:4 bit:3) 	Adaption Field Control
+	CC        byte   // (octet:4 bit:4 - octect:4 bit:7) 	Continuity Counter
+	AFL       byte   // (octet:5 bit:0 - octect:5 bit:7) 	Adaptation field length
+	DI        bool   // (octet:6 bit:0) 									Discontinouty indicator
+	RAI       bool   // (octet:6 bit:1) 									random access indicator
+	ESPI      bool   // (octet:6 bit:2) 									Elementary stream priority indicator
+	PCRF      bool   // (octet:6 bit:3) 									pcr flag
+	OPCRF     bool   // (octet:6 bit:4) 									opcr flag
+	SPF       bool   // (octet:6 bit:5) 									splicing point flag
+	TPDF      bool   // (octet:6 bit:6) 									transport private data flag
+	AFEF      bool   // (octet:6 bit:7) 									adaptation field extension flag
+	PCR       uint64 // (optional 48 bits) 								program clock reference
+	OPCR      uint64 // (optional 48 bits) 								Original program clock reference
+	SC        byte   // (optional 8 bits) 								splice countdown
+	TPDL      byte   // (optional 8 bits) 								tranposrt private data length
+	TPD       []byte // (optional variable length) 				private data
+	Extension []byte // (optional variable length) 				adaptation field extension
+	Stuffing  []byte // (optional variable length) 				stuffing bytes
+	Payload   []byte // (optional variable length)				mpeg ts payload
 }
 
 func (p *MpegTsPacket) ToByteSlice() (output []byte) {
-	output = make([]byte,188)
-	output[0] = p.SyncByte
-	output[1] = ( boolToByte(p.TEI) << (7-teiIndex%8) ) |
-							( boolToByte(p.PUSI) << (7-pusiIndex%8) ) |
-							( boolToByte(p.Priority) << (7-priorityIndex%8) ) |
-							byte(( p.PID & 0xFF00 ) >> 8)
+	output = make([]byte, 188)
+	output[0] = 0x47 // sync byte always the same
+	output[1] = (boolToByte(p.TEI) << (7 - teiIndex%8)) |
+		(boolToByte(p.PUSI) << (7 - pusiIndex%8)) |
+		(boolToByte(p.Priority) << (7 - priorityIndex%8)) |
+		byte((p.PID&0xFF00)>>8)
 	output[2] = byte(p.PID & 0x00FF)
-	output[3] = ( p.TSC << 6 ) | ( p.AFC << 4 ) | p.CC
+	output[3] = (p.TSC << 6) | (p.AFC << 4) | p.CC
 	for ii := 4; ii-4 < len(p.AF); ii++ {
 		output[ii] = p.AF[ii-4]
 	}

packets/helpers.go

@@ -31,6 +31,7 @@ package packets
 import (
 	_"os"
 	_"fmt"
+	"reflect"
 )
 
 func boolToByte(in bool) (out uint8) {
@@ -52,28 +53,26 @@ func getEndBit(p *RtpPacket) byte {
 	return (p.Payload[1] & 0x40) >> 6
 }
 
-func ParseRawH264(buffer []byte, outputChan chan<- []byte) {
+func ParseH264Buffer(buffer []byte, outputChan chan<- []byte) {
+	startCode1 := []byte{0x00,0x00,0x01}
+	startCode2 := []byte{0x00,0x00,0x00,0x01}
 	for i := 0; i < len(buffer); i++ {
-		i, start := func() (int,bool) {
+		var start bool
+		i, start = func() (int,bool) {
 			switch{
-			case buffer[i:i+3] == []byte{0x00,0x00,0x01}:
-				return 3, true
-			case buffer[i:i+4] == []byte{0x00,0x00,0x00,0x01}:
-				return 4, true
-			default:
-				return 4, false
-			}
-		}
-		if start {
-			nalHeader := buffer[i]
-			nalType := nalHeader & 0x1F
-			if nalType == 1 || nalType == 5 {
-				for ; i < len(buffer) && buffer[i+1:i+4] != []byte{0x00,0x00,0x01} &&
-					buffer[i+1:i+5] != []byte{0x00,0x00,0x00,0x01}; i++ {}
-				outputChan<-append(append([]byte{0x00,0x00,0x01},[]byte{0x09,0xF0}...),buffer[0:i]...)
-				buffer = buffer[i+1:]
-				i=0
+			case reflect.DeepEqual(buffer[i:i+3],startCode1):
+				return i+3, true
+			case reflect.DeepEqual(buffer[i:i+4],startCode2):
+				return i+4, true
 			}
+				return i, false
+		}()
+		if nalType := buffer[i] & 0x1F; start && ( nalType == 1 || nalType == 5) {
+			for ; i < len(buffer) && !(i+3 < len(buffer) && ( reflect.DeepEqual(buffer[i:i+3],startCode1) ||
+				reflect.DeepEqual(buffer[i:i+4],startCode2))); i++ {}
+			outputChan<-append(append(startCode1,[]byte{0x09,0xF0}...),buffer[:i]...)
+			buffer = buffer[i:]
+			i=0
 		}
 	}
 }

packets/packets_test.go

@@ -37,7 +37,7 @@ import (
 	"reflect"
 	"testing"
 	"time"
-	"math/rand"
+	_"math/rand"
 
 	"github.com/beatgammit/rtsp"
 )
@@ -540,25 +540,24 @@ func TestH264Parsing(t *testing.T) {
 		4,34,2,3,2,0,0,1,1,3,4,5,5,76,4,234,78,65,34,34,43,45,
 	}
 	nalAccess1 := []byte{
-		0,0,1,7,59,100,45,82,93,0,0,1,8,23,78,65,0,0,1,6,45,34,23,3,2,0,0,1,5,3,4,5,
+		0,0,1,9,240,0,0,1,7,59,100,45,82,93,0,0,1,8,23,78,65,0,0,1,6,45,34,23,3,2,0,0,1,5,3,4,5,
 		56,76,4,234,78,65,34,34,43,
 	}
 	nalAccess2 := []byte{
-		0,0,1,7,67,10,45,8,93,0,0,1,8,23,7,5,0,0,1,6,
+		0,0,1,9,240,0,0,1,7,67,10,45,8,93,0,0,1,8,23,7,5,0,0,1,6,
 		4,34,2,3,2,0,0,1,1,3,4,5,5,76,4,234,78,65,34,34,43,45,
 	}
-
 	aChannel := make(chan []byte, 10)
 	var nalAccessChan chan<- []byte
 	nalAccessChan = aChannel
-	go parseH264Buffer(someData,nalAccessChan)
-	anAccessUnit := <-nalAccessChan
+	go ParseH264Buffer(someData,nalAccessChan)
+	anAccessUnit := <-aChannel
 	for i := range anAccessUnit {
 		if anAccessUnit[i] != nalAccess1[i] {
 			t.Errorf("Should have been equal!")
 		}
 	}
-	anAccessUnit = <-nalAccessChan
+	anAccessUnit = <-aChannel
 	for i := range anAccessUnit {
 		if anAccessUnit[i] != nalAccess2[i] {
 			t.Errorf("Should have been equal!")

revid/H264ParseTesting.go

@@ -1,11 +0,0 @@
-package main
-
-import "../packets"
-const (
-  fileName = "out.h264"
-)
-
-func main(){
-  converter := packets.NewRtpToTsConverter()
-  packets.ParseRawH264(fileName,&converter.NalInputChan)
-}

revid/mpegtsCompare.go

@@ -0,0 +1,592 @@
+/*
+NAME
+  revid - a testbed for re-muxing and re-directing video streams as MPEG-TS over various protocols.
+
+DESCRIPTION
+  See Readme.md
+
+AUTHOR
+  Alan Noble <anoble@gmail.com>
+
+LICENSE
+  revid is Copyright (C) 2017 Alan Noble.
+
+  It is free software: you can redistribute it and/or modify them
+  under the terms of the GNU General Public License as published by the
+  Free Software Foundation, either version 3 of the License, or (at your
+  option) any later version.
+
+  It is distributed in the hope that it will be useful, but WITHOUT
+  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public 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 [GNU licenses](http://www.gnu.org/licenses).
+*/
+
+// revid is a testbed for re-muxing and re-directing video streams as MPEG-TS over various protocols.
+package main
+
+import (
+	"bufio"
+	"bytes"
+	"crypto/md5"
+	"encoding/binary"
+	"encoding/hex"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"math/rand"
+	"net"
+	"net/http"
+	"runtime"
+	"strconv"
+	"strings"
+	"time"
+	"os"
+
+	"../packets"
+
+	"bitbucket.org/ausocean/av/ringbuffer"
+
+	"github.com/Comcast/gots/packet"
+	"github.com/Comcast/gots/packet/adaptationfield"
+	"github.com/Comcast/gots/psi"
+)
+
+// defaults and networking consts
+const (
+	clipDuration       = 1 // s
+	defaultPID         = 256
+	defaultFrameRate   = 25
+	defaultHTTPOutput  = "http://localhost:8080?"
+	defaultUDPOutput   = "udp://0.0.0.0:16384"
+	defaultRTPOutput   = "rtp://0.0.0.0:16384"
+	mp2tPacketSize     = 188                 // MPEG-TS packet size
+	mp2tMaxPackets     = 2016 * clipDuration // # first multiple of 7 and 8 greater than 2000
+	udpPackets         = 7                   // # of UDP packets per ethernet frame (8 is the max)
+	rtpPackets         = 7                   // # of RTP packets per ethernet frame (7 is the max)
+	rtpHeaderSize      = 12
+	rtpSSRC            = 1 // any value will do
+	bufferSize         = 1000 / clipDuration
+	bitrateOutputDelay = 60 // s
+	httpTimeOut        = 5  // s
+	motionThreshold    = "0.0025"
+	qscale             = "3"
+	rtpPort = 17300
+  rtcpPort = 17319
+  rtspUrl = "rtsp://192.168.0.50:8554/CH002.sdp"
+  rtpUrl = "rtsp://192.168.0.50:8554/CH002.sdp/track1"
+	inputFileName = "testInput.h264"
+)
+
+// flag values
+const (
+	filterFixPTS        = 0x0001
+	filterDropAudio     = 0x0002
+	filterScale640      = 0x0004
+	filterScale320      = 0x0008
+	filterFixContinuity = 0x0010
+	filterEdgeDetection = 0x0020
+	filterMotionDetect  = 0x0040
+	filterRepacket = 0x0080
+	dumpProgramInfo     = 0x0100 // 256
+	dumpPacketStats     = 0x0200 // 512
+	dumpPacketHeader    = 0x0400 // 1024
+	dumpPacketPayload   = 0x0800 // 2048
+)
+
+// globals
+var (
+	sendClip        = sendClipToRTP
+	packetsPerFrame = rtpPackets
+	clipCount       int
+	expectCC        int
+	dumpCC          int
+	dumpPCRBase     uint64
+	rtpSequenceNum  uint16
+	conn            net.Conn
+	ffmpegPath      string
+	tempDir         string
+	inputErrChan    chan error
+	outputErrChan   chan error
+	ringBuffer      ringbuffer.RingBuffer
+)
+
+// command-line flags
+var (
+	inputURL    = flag.String("i", "", "Input RTSP URL")
+	outputURL   = flag.String("o", "", "Output URL (HTTP, UDP or RTP)")
+	mode        = flag.String("m", "r", "Mode: one of f,h,u,r or d")
+	flags       = flag.Int("f", 0, "Flags: see readme for explanation")
+	frameRate   = flag.Int("r", defaultFrameRate, "Input video frame rate (25fps by default)")
+	selectedPID = flag.Int("p", defaultPID, "Select packets with this packet ID (PID)")
+)
+
+func main() {
+	setUpDirs()
+	flag.Parse()
+
+	if *inputURL == "" {
+		log.Fatal("Input (-i) required\n")
+	}
+
+	switch *mode {
+	case "f":
+		sendClip = sendClipToFile
+	case "h":
+		sendClip = sendClipToHTTP
+		if *outputURL == "" {
+			*outputURL = defaultHTTPOutput
+		}
+	case "u":
+		sendClip = sendClipToUDP
+		packetsPerFrame = udpPackets
+		if *outputURL == "" {
+			*outputURL = defaultUDPOutput
+		}
+	case "r":
+		sendClip = sendClipToRTP
+		packetsPerFrame = rtpPackets
+		if *outputURL == "" {
+			*outputURL = defaultRTPOutput
+		}
+	case "d":
+		//sendClip = sendClipToStdout
+	default:
+		log.Fatalf("Invalid mode %s\n", *mode)
+	}
+
+	if *flags&filterFixContinuity != 0 && *flags&dumpProgramInfo != 0 {
+		log.Fatal("Cannot combine filterFixContinuity and dumpProgramInfo flags\n")
+	}
+
+	ringBuffer = ringbuffer.NewRingBuffer(bufferSize, mp2tPacketSize*mp2tMaxPackets)
+	inputErrChan = make(chan error, 10)
+	outputErrChan = make(chan error, 10)
+
+	go input(*inputURL, *outputURL)
+	go output(*outputURL)
+
+	for {
+		select {
+		default:
+		case err := <-inputErrChan:
+			fmt.Fprintln(os.Stderr, err)
+			fmt.Fprintln(os.Stderr, "Trying again in 10s")
+			time.Sleep(10 * time.Second)
+			go input(*inputURL, *outputURL)
+		case err := <-outputErrChan:
+			fmt.Fprintln(os.Stderr, err)
+			fmt.Fprintln(os.Stderr, "Attempting to write again!")
+		}
+	}
+}
+
+// setUpDirs sets directories based on the OS that Revid is running on
+func setUpDirs() {
+	switch runtime.GOOS {
+	case "windows":
+		ffmpegPath = "C:/ffmpeg/ffmpeg"
+		tempDir = "tmp/"
+	case "darwin":
+		ffmpegPath = "/usr/local/bin/ffmpeg"
+		tempDir = "/tmp/"
+	default:
+		ffmpegPath = "/home/$USER/bin/ffmpeg"
+		tempDir = "/output/"
+	}
+}
+
+// input handles the reading from the specified input
+func input(input string, output string) {
+	fmt.Printf("Reading video from %s\n", input)
+	// (re)initialize globals
+	clipCount = 0
+	expectCC = -1
+	dumpCC = -1
+	dumpPCRBase = 0
+	rtpSequenceNum = uint16(rand.Intn(1 << 15))
+
+	// for UDP and RTP only dial once
+	var err error
+	if strings.HasPrefix(output, "udp://") || strings.HasPrefix(output, "rtp://") {
+		conn, err = net.Dial("udp", output[6:])
+		if err != nil {
+			inputErrChan <- err
+			return
+		}
+	}
+	converter := packets.NewRtpToTsConverter()
+	// Open the h264 file
+	file, err := os.Open(inputFileName)
+	if err != nil {
+		panic("Could not open file!")
+		return
+	}
+	stats, err := file.Stat()
+	if err != nil {
+		panic("Could not get file stats!")
+	}
+	buffer := make([]byte, stats.Size())
+	_, err = file.Read(buffer)
+	if err != nil {
+		panic("Could not read file!")
+	}
+
+	// Start parsing the h264 file and send nal access units to the converter
+	go packets.ParseH264Buffer(buffer,converter.NalInputChan)
+	go converter.Convert()
+	clipSize := 0
+	packetCount := 0
+	now := time.Now()
+	prevTime := now
+	fmt.Printf("Looping\n")
+
+	startPackets := [][]byte{
+		{71,64,17,16,0,66,240,65,0,1,193,0,0,255,1,255,0,1,252,128,48,72,46,1,6,70,70,109,112,101,103,37,115,116,114,101,97,109,101,100,32,98,121,32,116,104,101,32,71,101,111,86,105,115,105,111,110,32,82,116,115,112,32,83,101,114,118,101,114,99,176,214,195,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255},
+		{71,64,0,16,0,0,176,13,0,1,193,0,0,0,1,240,0,42,177,4,178,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255},
+		/*PMT*/{71,80,0,16,
+		/*Start of payload*/
+		0,2,176,18,0,1,193,0,0,255,255,240,0,27,225,0,240,0,193,91,65,224,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255},
+	}
+
+	donePSI := false
+
+	for {
+		if clip, err := ringBuffer.Get(); err != nil {
+			inputErrChan <- err
+			return
+		} else {
+			ii := 0
+			for {
+				upperBound := clipSize + mp2tPacketSize
+
+				if ii < 3 && !donePSI {
+					packetByteSlice := startPackets[ii]
+					copy(clip[clipSize:upperBound],packetByteSlice)
+					ii++
+				} else {
+					donePSI = true
+					packet := <-converter.TsChan
+					packetByteSlice := packet.ToByteSlice()
+					copy(clip[clipSize:upperBound],packetByteSlice)
+				}
+				//fmt.Println(clip[clipSize:upperBound])
+				packetCount++
+				clipSize += mp2tPacketSize
+				// send if (1) our buffer is full or (2) 1 second has elapsed and we have % packetsPerFrame
+				now = time.Now()
+				if (packetCount == mp2tMaxPackets) ||
+					(now.Sub(prevTime) > clipDuration*time.Second && packetCount%packetsPerFrame == 0) {
+					clipCount++
+					if err := ringBuffer.DoneWriting(clipSize); err != nil {
+						inputErrChan <- err
+						return
+					}
+					clipSize = 0
+					packetCount = 0
+					prevTime = now
+					break
+				}
+			}
+		}
+	}
+}
+
+// output handles the writing to specified output
+func output(output string) {
+	file, err := os.Create("output/saxonOut.ts")
+	if err != nil {
+		panic("Can't create output file!")
+	}
+	for {
+		if clip, err := ringBuffer.Read(); err == nil {
+			file.Write(clip)
+			/*
+			for err = sendClip(clip, output, conn); err != nil; {
+				outputErrChan <- err
+				//err = sendClip(clip, output, conn)
+				// TODO: figure out how to write to single file
+
+			}
+			*/
+			if err := ringBuffer.DoneReading(); err != nil {
+				outputErrChan <- err
+			}
+		}
+	}
+}
+
+// sendClipToFile writes a video clip to a /tmp file.
+func sendClipToFile(clip []byte, _ string, _ net.Conn) error {
+	filename := fmt.Sprintf(tempDir+"vid%03d.ts", clipCount)
+	fmt.Printf("Writing %s (%d bytes)\n", filename, len(clip))
+	err := ioutil.WriteFile(filename, clip, 0644)
+	if err != nil {
+		return fmt.Errorf("Error writing file %s: %s", filename, err)
+	}
+	return nil
+}
+
+// sendClipToHTPP posts a video clip via HTTP, using a new TCP connection each time.
+func sendClipToHTTP(clip []byte, output string, _ net.Conn) error {
+	timeout := time.Duration(httpTimeOut * time.Second)
+	client := http.Client{
+		Timeout: timeout,
+	}
+	hash := md5.Sum(clip)
+	url := output + strconv.Itoa(len(clip)) + "." + hex.EncodeToString(hash[:]) // NB: append size.digest to output
+	fmt.Printf("Posting %s (%d bytes)\n", url, len(clip))
+	resp, err := client.Post(url, "video/mp2t", bytes.NewReader(clip)) // lighter than NewBuffer
+	if err != nil {
+		return fmt.Errorf("Error posting to %s: %s", output, err)
+	}
+	defer resp.Body.Close()
+	body, err := ioutil.ReadAll(resp.Body)
+	if err == nil {
+		fmt.Printf("%s\n", body)
+	}
+	return err
+}
+
+// sendClipToUDP sends a video clip over UDP.
+func sendClipToUDP(clip []byte, _ string, conn net.Conn) error {
+	size := udpPackets * mp2tPacketSize
+	fmt.Printf("Sending %d UDP packets of size %d (%d bytes)\n", len(clip)/size, size, len(clip))
+	for offset := 0; offset < len(clip); offset += size {
+		pkt := clip[offset : offset+size]
+		_, err := conn.Write(pkt)
+		if err != nil {
+			return fmt.Errorf("UDP write error %s. Is your player listening?", err)
+		}
+	}
+	return nil
+}
+
+// sendClipToRTP sends a video clip over RTP.
+func sendClipToRTP(clip []byte, _ string, conn net.Conn) error {
+	size := rtpPackets * mp2tPacketSize
+	fmt.Printf("Sending %d RTP packets of size %d (%d bytes)\n",
+		len(clip)/size, size+rtpHeaderSize, len(clip))
+	pkt := make([]byte, rtpHeaderSize+rtpPackets*mp2tPacketSize)
+	for offset := 0; offset < len(clip); offset += size {
+		rtpEncapsulate(clip[offset:offset+size], pkt)
+		_, err := conn.Write(pkt)
+		if err != nil {
+			return fmt.Errorf("RTP write error %s. Is your player listening?", err)
+		}
+	}
+	return nil
+}
+
+// checkContinuityCounts checks that the continuity of the clip is correct
+func checkContinuityCounts(clip []byte) error {
+	for offset := 0; offset < len(clip); offset += mp2tPacketSize {
+		dumpCC = -1
+		pkt := clip[offset : offset+mp2tPacketSize]
+		cc := int(pkt[3] & 0xf)
+		if dumpCC != -1 && cc != dumpCC {
+			return fmt.Errorf("Continuity count out of order. Expected %v, Got: %v.", dumpCC, cc)
+		}
+		dumpCC = (cc + 1) % 16
+	}
+	return nil
+}
+
+// sendClipToStdout dumps video stats to stdout.
+func sendClipToStdout(clip []byte) error {
+	fmt.Printf("Dumping clip (%d bytes)\n", len(clip))
+	/*
+	if *flags&dumpProgramInfo != 0 {
+		return mp2tDumpProgram(clip)
+	}
+	*/
+
+	packetCount := 0
+	discontinuities := 0
+	var cc int
+
+	for offset := 0; offset < len(clip); offset += mp2tPacketSize {
+		packetCount++
+		pkt := clip[offset : offset+mp2tPacketSize]
+
+		pktPID, err := packet.Pid(pkt)
+		if err != nil {
+			return err
+		}
+		if pktPID != uint16(*selectedPID) {
+			continue
+		}
+
+		if *flags&(dumpPacketHeader|dumpPacketPayload) != 0 {
+			fmt.Printf("Packet #%d.%d\n", clipCount, packetCount)
+		}
+
+		hasPayload := pkt[3]&0x10 != 0
+		if !hasPayload {
+			continue // nothing to do
+		}
+
+		// extract interesting info from header
+		tei := pkt[1] & 0x80 >> 7
+		pusi := pkt[1] & 0x40 >> 6
+		tp := pkt[1] & 0x20 >> 5
+		tcs := pkt[3] & 0xc0 >> 6
+		afc := pkt[3] & 0x30 >> 4
+		cc = int(pkt[3] & 0xf)
+		di := pkt[5] & 0x80
+
+		if dumpCC != -1 && cc != dumpCC {
+			discontinuities++
+			fmt.Printf("Warning: Packet #%d.%d continuity counter out of order! Got %d, expected %d.\n",
+				clipCount, packetCount, cc, dumpCC)
+		}
+		dumpCC = (cc + 1) % 16
+
+		//if *flags&dumpPacketHeader != 0 {
+			fmt.Printf("\t\tTEI=%d, PUSI=%d, TP=%d, TSC=%d, AFC=%d, CC=%d\n", tei, pusi, tp, tcs, afc, cc)
+		//}
+
+		if afc == 3 {
+			// adaptation field, followed by payload
+			afl := adaptationfield.Length(pkt)
+			if adaptationfield.HasPCR(pkt) {
+				pcrBase, pcrExt, _ := mp2tGetPCR(pkt)
+				if *flags&dumpPacketHeader != 0 {
+					fmt.Printf("\t\tAFL=%d, PCRbase=%d, PCRext=%d, DI=%v\n", afl, pcrBase, pcrExt, di)
+				}
+				if pcrBase < dumpPCRBase {
+					fmt.Printf("Warning: PCRbase went backwards!\n")
+				}
+				dumpPCRBase = pcrBase
+			} else if *flags&dumpPacketHeader != 0 {
+				fmt.Printf("\t\tAFL=%d, DI=%v\n", afl, di)
+			}
+		}
+		if *flags&dumpPacketPayload != 0 {
+			fmt.Printf("\t\tPayload=%x\n", pkt)
+		}
+
+	}
+	if *flags&dumpPacketStats != 0 {
+		fmt.Printf("%d packets of size %d bytes (%d bytes, %d discontinuites)\n",
+			packetCount, packet.PacketSize, packetCount*packet.PacketSize, discontinuities)
+	}
+	return nil
+}
+
+// mp2tDumpProgram dumps MPEG-TS Program Association Table (PAT) and Program Map Tables (PMT).
+func mp2tDumpProgram(clip []byte) error {
+	// NB: Comcast API requires a buffered reader
+	reader := bufio.NewReader(bytes.NewReader(clip))
+
+	_, err := packet.Sync(reader)
+	if err != nil {
+		return fmt.Errorf("Error reading sync byte: %s", err)
+	}
+	pat, err := psi.ReadPAT(reader)
+	if err != nil {
+		return fmt.Errorf("Error reading PAT: %s", err)
+	}
+	mp2tDumpPat(pat)
+
+	var pmts []psi.PMT
+	pm := pat.ProgramMap()
+	for pn, pid := range pm {
+		pmt, err := psi.ReadPMT(reader, pid)
+		if err != nil {
+			return fmt.Errorf("Error reading PMT: %s", err)
+		}
+		pmts = append(pmts, pmt)
+		mp2tDumpPmt(pn, pmt)
+	}
+	return nil
+}
+
+func mp2tDumpPat(pat psi.PAT) {
+	fmt.Printf("Pat\n")
+	fmt.Printf("\tPMT PIDs %v\n", pat.ProgramMap())
+	fmt.Printf("\tNumber of Programs %v\n", pat.NumPrograms())
+}
+
+func mp2tDumpPmt(pn uint16, pmt psi.PMT) {
+	// pn = program number
+	fmt.Printf("Program #%v PMT\n", pn)
+	fmt.Printf("\tPIDs %v\n", pmt.Pids())
+	fmt.Printf("\tElementary Streams")
+	for _, es := range pmt.ElementaryStreams() {
+		fmt.Printf("\t\tPID %v : StreamType %v\n", es.ElementaryPid(), es.StreamType())
+		for _, d := range es.Descriptors() {
+			fmt.Printf("\t\t\t%+v\n", d)
+		}
+	}
+}
+
+// Mp2tFixContinuity fixes discontinous MPEG-TS continuity counts (CC)
+func mp2tFixContinuity(pkt []byte, pid uint16) bool {
+
+	hasPayload, err := packet.ContainsPayload(pkt)
+	if err != nil {
+		fmt.Printf("Warning: Packet bad.\n")
+		return false
+	}
+	if !hasPayload {
+		return false
+	}
+	if pktPID, _ := packet.Pid(pkt); pktPID != pid {
+		return false
+	}
+	fixed := false
+	// extract continuity counter from 2nd nibble of 4th byte of header
+	cc := int(pkt[3] & 0xf)
+	if expectCC == -1 {
+		expectCC = cc
+	} else if cc != expectCC {
+		fmt.Println("Have to fix")
+		pkt[3] = pkt[3]&0xf0 | byte(expectCC&0xf)
+		fixed = true
+	}
+	expectCC = (expectCC + 1) % 16
+	return fixed
+}
+
+// Mp2tGetPCR extracts the Program Clock Reference (PCR) from an MPEG-TS packet (if any)
+func mp2tGetPCR(pkt []byte) (uint64, uint32, bool) {
+	if !adaptationfield.HasPCR(pkt) {
+		return 0, 0, false
+	}
+	pcrBytes, _ := adaptationfield.PCR(pkt) // 6 bytes
+	// first 33 bits are PCR base, next 6 bits are reserved, final 9 bits are PCR extension.
+	pcrBase := uint64(binary.BigEndian.Uint32(pcrBytes[:4]))<<1 | uint64(pcrBytes[4]&0x80>>7)
+	pcrExt := uint32(pcrBytes[4]&0x01)<<1 | uint32(pcrBytes[5])
+	return pcrBase, pcrExt, true
+}
+
+// rtpEncapsulate encapsulates MPEG-TS packets within an RTP header,
+// setting the payload type accordingly (to 33) and incrementing the RTP sequence number.
+func rtpEncapsulate(mp2tPacket []byte, pkt []byte) {
+	// RTP packet encapsulates the MP2T
+	// first 12 bytes is the header
+	// byte 0: version=2, padding=0, extension=0, cc=0
+	pkt[0] = 0x80 // version (2)
+	// byte 1: marker=0, pt = 33 (MP2T)
+	pkt[1] = 33
+	// bytes 2 & 3: sequence number
+	binary.BigEndian.PutUint16(pkt[2:4], rtpSequenceNum)
+	if rtpSequenceNum == ^uint16(0) {
+		rtpSequenceNum = 0
+	} else {
+		rtpSequenceNum++
+	}
+	// bytes 4,5,6&7: timestamp
+	timestamp := uint32(time.Now().UnixNano() / 1e6) // ms timestamp
+	binary.BigEndian.PutUint32(pkt[4:8], timestamp)
+	// bytes 8,9,10&11: SSRC
+	binary.BigEndian.PutUint32(pkt[8:12], rtpSSRC)
+
+	// payload follows
+	copy(pkt[rtpHeaderSize:rtpHeaderSize+rtpPackets*mp2tPacketSize], mp2tPacket)
+}