av/packets/RtpToTsConverter.go

/*
NAME
  RtpToTsConverter.go - provides utilities for the conversion of Rtp packets
  to equivalent MpegTs packets.

DESCRIPTION
  See Readme.md

AUTHOR
  Saxon Nelson-Milton <saxon.milton@gmail.com>

LICENSE
  RtpToTsConverter.go is Copyright (C) 2017 the Australian Ocean Lab (AusOcean)

  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).
*/

package packets

import (
  _"fmt"
  "os"
)

type RtpToTsConverter interface {
  Convert()
}

type rtpToTsConverter struct {
  TsChan <-chan *MpegTsPacket
  tsChan chan<- *MpegTsPacket
  InputChan chan<- RtpPacket
  inputChan <-chan RtpPacket
  currentTsPacket *MpegTsPacket
  payloadByteChan chan byte
  currentCC byte
}

func NewRtpToTsConverter() (c *rtpToTsConverter) {
  c = new(rtpToTsConverter)
  tsChan := make(chan *MpegTsPacket,100)
  c.TsChan = tsChan
  c.tsChan = tsChan
  inputChan := make(chan RtpPacket,100)
  c.InputChan = inputChan
  c.inputChan = inputChan
  c.currentCC = 0
  return
}

func getOctectType(p *RtpPacket) byte {
  return p.Payload[0] & 0x1F
}

func getStartBit(p *RtpPacket) byte {
  return (p.Payload[1] & 0x80)>>7
}

func getEndBit(p *RtpPacket) byte {
  return (p.Payload[1] & 0x40)>>6
}
func (c* rtpToTsConverter) Convert() {
  file,_ := os.Create("video")
  pesPktChan := make(chan []byte, 10)
  pesDataChan := make(chan byte, 50000)
  nalAccessChan := make(chan []byte, 10)
  payloadByteChan := make(chan byte, 100000)
  // grab sps pps and sei
  var sps []byte
  var pps []byte
  var sei []byte

  // Frist find sps
  for {
   rtpPacket := <-c.inputChan
   fragmentType := rtpPacket.Payload[0] & 0x1F
   if fragmentType == 7 {
     sps = make([]byte,len(rtpPacket.Payload))
     for i := range rtpPacket.Payload {
       sps[i] = rtpPacket.Payload[i]
     }
     break
   }
  }
  // now find pps
  for {
   rtpPacket := <-c.inputChan
   fragmentType := rtpPacket.Payload[0] & 0x1F
   if fragmentType == 8 {
     pps = make([]byte,len(rtpPacket.Payload))
     for i := range rtpPacket.Payload {
       pps[i] = rtpPacket.Payload[i]
     }
     break
   }
  }
  // now find sei
  for {
   rtpPacket := <-c.inputChan
   fragmentType := rtpPacket.Payload[0] & 0x1F
   if fragmentType == 6 {
     sei = make([]byte,len(rtpPacket.Payload))
     for i := range rtpPacket.Payload {
       sei[i] = rtpPacket.Payload[i]
     }
     break
   }
  }
  for {
    select {
    default:
    case rtpPacket := <-c.inputChan:
      if getOctectType(&rtpPacket) == 28 {
        if getStartBit(&rtpPacket) == 1 {
          var buffer []byte
          // au delimiter
          buffer = append(buffer, []byte{0x00,0x00,0x01}...)
          buffer = append(buffer, []byte{0x09,0x10}...)
          buffer = append(buffer, []byte{0x00,0x00,0x01}...)
          buffer = append(buffer, sps...)
          buffer = append(buffer, []byte{0x00,0x00,0x01}...)
          buffer = append(buffer, pps...)
          buffer = append(buffer, []byte{0x00,0x00,0x01}...)
          buffer = append(buffer, sei...)
          buffer = append(buffer, []byte{0x00,0x00,0x01}...)
          buffer = append(buffer, rtpPacket.Payload[0] & 0xE0 | rtpPacket.Payload[1] & 0x1F )
          buffer = append(buffer, rtpPacket.Payload[2:]...)
          for {
            rtpPacket := <-c.inputChan
            if getOctectType(&rtpPacket) != 28 || getStartBit(&rtpPacket) == 1 {
              nalAccessChan<-buffer
              file.Write(buffer)
              break
            }
            buffer = append(buffer, rtpPacket.Payload[2:]...)
            if getEndBit(&rtpPacket) == 1 {
              nalAccessChan<-buffer
              file.Write(buffer)
              break
            }
          }
        }
      } else {
        if getOctectType(&rtpPacket) == 1 {
          var buffer []byte
          buffer = append(buffer, []byte{0x00,0x00,0x01}...)
          buffer = append(buffer, []byte{0x09,0x10}...)
          buffer = append(buffer, []byte{0x00,0x00,0x01}...)
          buffer = append(buffer, sps...)
          buffer = append(buffer, []byte{0x00,0x00,0x01}...)
          buffer = append(buffer, pps...)
          buffer = append(buffer, []byte{0x00,0x00,0x01}...)
          buffer = append(buffer, sei...)
          buffer = append(buffer, []byte{0x00,0x00,0x01}...)
          buffer = append(buffer, rtpPacket.Payload...)
          nalAccessChan<-buffer
          file.Write(buffer)
        }
      }
    case nalUnit := <-nalAccessChan:
      for ii := range nalUnit {
        pesDataChan<-nalUnit[ii]
      }
      pesDataChanLen := len(nalUnit)
      pesPkt := new(PESPacket)
      pesPkt.StreamID = 0xE0
      pesPkt.Length = uint16( 3 + pesDataChanLen )
      pesPkt.ScramblingControl = 0
      pesPkt.Priority = true
      pesPkt.DAI = false
      pesPkt.Copyright = false
      pesPkt.Original = true
      pesPkt.PDI = 0
      pesPkt.ESCR = false
      pesPkt.ESRate = false
      pesPkt.DSMTrickMode = false
      pesPkt.ACI = false
      pesPkt.CRC = false
      pesPkt.Ext = false
      pesPkt.HeaderLength = 0
      pesPkt.Data = make([]byte,pesDataChanLen)
      for ii:=0; ii<pesDataChanLen; ii++ {
        pesPkt.Data[ii] = <-pesDataChan
      }
      pesPktChan<-pesPkt.ToByteSlice()
    case pesPkt := <-pesPktChan:
      for ii:=range pesPkt {
        payloadByteChan<-pesPkt[ii]
      }
      firstPacket:=true
      for len(payloadByteChan) > 0 {
        lengthOfByteChan := len(payloadByteChan)
        c.currentTsPacket = new(MpegTsPacket)
        c.currentTsPacket.SyncByte = 0x47
        c.currentTsPacket.TEI = false
        c.currentTsPacket.PUSI = false
        if firstPacket  { // if it's the start of the payload
          c.currentTsPacket.PUSI = true
          firstPacket = false
        }
        c.currentTsPacket.Priority = false
        c.currentTsPacket.PID = 256
        c.currentTsPacket.TSC = 0
        c.currentTsPacket.CC = c.currentCC
        if c.currentCC++; c.currentCC > 15 { c.currentCC = 0 }
        payloadLength := 182
        if lengthOfByteChan < 182 {
          payloadLength = lengthOfByteChan
        }
        c.currentTsPacket.AFC = 3
        stuffingLength := 182-payloadLength
        c.currentTsPacket.AF = make([]byte,2 + stuffingLength) // adaptationfield flag length = 16
        c.currentTsPacket.AF[0] = byte(1 + stuffingLength)
        c.currentTsPacket.AF[1] = 0
        if c.currentTsPacket.PUSI {
          c.currentTsPacket.AF[1] = 0x00
        }
        for ii := 0; ii < stuffingLength; ii++ {
          c.currentTsPacket.AF[2+ii] = 0xFF
        }
        c.currentTsPacket.Payload = make([]byte, payloadLength)
        for ii:=0; ii < payloadLength; ii++ {
          c.currentTsPacket.Payload[ii] = <-payloadByteChan
        }
        c.tsChan<-c.currentTsPacket
      }
    }
  }
}