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, 1000)
  pesDataChan := make(chan byte, 50000)
  nalAccessChan := make(chan []byte, 10000)
  payloadByteChan := make(chan byte, 100000)
  var rtpBuffer [](*RtpPacket)
  for {
    select {
    default:
    case rtpPacket := <-c.inputChan:
      rtpBuffer = append(rtpBuffer,&rtpPacket)
      if len(rtpBuffer) > 2 {
        // if there's something weird going on with sequence numbers then sort
        if rtpPacket.SequenceNumber < rtpBuffer[len(rtpBuffer)-2].SequenceNumber {
          for i := 1; i < len(rtpBuffer); i++ {
            for j := i; j > 0 && rtpBuffer[j].SequenceNumber < rtpBuffer[j - 1].SequenceNumber; j-- {
              temp := rtpBuffer[j]
              rtpBuffer[j] = rtpBuffer[j-1]
              rtpBuffer[j-1] = temp
            }
          }
        }
      }
      if len(rtpBuffer) > 200 {
        // Discard everything before a type 7
        for GetOctectType(rtpBuffer[0]) != 7 {
          rtpBuffer = rtpBuffer[1:]
        }
        // get sps
        sps := make([]byte,len(rtpBuffer[0].Payload))
        copy(sps[:],rtpBuffer[0].Payload[:])
        rtpBuffer = rtpBuffer[1:]
        // get pps
        pps := make([]byte,len(rtpBuffer[0].Payload))
        copy(pps[:],rtpBuffer[0].Payload[:])
        rtpBuffer = rtpBuffer[1:]
        // get sei
        sei := make([]byte, len(rtpBuffer[0].Payload))
        copy(sei[:],rtpBuffer[0].Payload[:])
        rtpBuffer = rtpBuffer[1:]
        // while we haven't reached the next sps in the buffer
        for GetOctectType(rtpBuffer[0]) != 7 {
          switch(GetOctectType(rtpBuffer[0])){
          case 28:
            if GetStartBit(rtpBuffer[0]) == 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, rtpBuffer[0].Payload[0] & 0xE0 | rtpBuffer[0].Payload[1] & 0x1F )
              buffer = append(buffer, rtpBuffer[0].Payload[2:]...)
              rtpBuffer = rtpBuffer[1:]
              for {
                buffer = append(buffer, rtpBuffer[0].Payload[2:]...)
                if getEndBit(rtpBuffer[0]) == 1 {
                  rtpBuffer = rtpBuffer[1:]
                  nalAccessChan<-buffer
                  file.Write(buffer)
                  break
                }
                rtpBuffer = rtpBuffer[1:]
              }
            }
          case 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, rtpBuffer[0].Payload[0] & 0xE0 | rtpBuffer[0].Payload[1] & 0x1F )
            buffer = append(buffer, rtpBuffer[0].Payload[2:]...)
            rtpBuffer = rtpBuffer[1:]
            nalAccessChan<-buffer
            file.Write(buffer)
          default:
          }

        }
      }
    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
      }
    }
  }
}