liveMedia/include/MPEG2TransportStreamMultiplexor.hh

/**********
This library is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the
Free Software Foundation; either version 3 of the License, or (at your
option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)

This library 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 Lesser General Public License for
more details.

You should have received a copy of the GNU Lesser General Public License
along with this library; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
**********/
// "liveMedia"
// Copyright (c) 1996-2020 Live Networks, Inc.  All rights reserved.
// A class for generating MPEG-2 Transport Stream from one or more input
// Elementary Stream data sources
// C++ header

#ifndef _MPEG2_TRANSPORT_STREAM_MULTIPLEXOR_HH
#define _MPEG2_TRANSPORT_STREAM_MULTIPLEXOR_HH

#ifndef _FRAMED_SOURCE_HH
#include "FramedSource.hh"
#endif
#ifndef _MPEG_1OR2_DEMUX_HH
#include "MPEG1or2Demux.hh" // for SCR
#endif

#define PID_TABLE_SIZE 0x2000 // 2^13

class MPEG2TransportStreamMultiplexor: public FramedSource {
public:
  typedef void (onEndOfSegmentFunc)(void* clientData, double segmentDuration);
  void setTimedSegmentation(unsigned segmentationDuration,
			    onEndOfSegmentFunc* onEndOfSegmentFunc = NULL,
			    void* onEndOfSegmentClientData = NULL);
      // Specifies that PAT and PMT packets should be output every "segmentationDuration" seconds.
      // (If "segmentationDuration" is 0 (the default value), then PAT and PMT packets are output
      // at a preset frequency.)
      // The optional function "onEndOfSegmentFunc" is called after each segment is output.
  double currentSegmentDuration() const { return fCurrentSegmentDuration; }
      // Valid only if "setTimedSegmentation()" was previously called with "segmentationDuration" > 0

  Boolean canDeliverNewFrameImmediately() const { return fInputBufferBytesUsed < fInputBufferSize; }
      // Can be used by a downstream reader to test whether the next call to "doGetNextFrame()"
      // will deliver data immediately).

protected:
  MPEG2TransportStreamMultiplexor(UsageEnvironment& env);
  virtual ~MPEG2TransportStreamMultiplexor();

  virtual void awaitNewBuffer(unsigned char* oldBuffer) = 0;
      // implemented by subclasses

  void handleNewBuffer(unsigned char* buffer, unsigned bufferSize,
		       int mpegVersion, MPEG1or2Demux::SCR scr, int16_t PID = -1);
      // called by "awaitNewBuffer()"
      // Note: For MPEG-4 video, set "mpegVersion" to 4; for H.264 video, set "mpegVersion" to 5;
      //     for H.265 video, set "mpegVersion" to 6.
      //     For Opus audio, set "mpegVersion" to 3.
      // The buffer is assumed to be a PES packet, with a proper PES header.
      // If "PID" is not -1, then it (currently, only the low 8 bits) is used as the stream's PID,
      // otherwise the "stream_id" in the PES header is reused to be the stream's PID.

private:
  // Redefined virtual functions:
  virtual Boolean isMPEG2TransportStreamMultiplexor() const;
  virtual void doGetNextFrame();

private:
  void deliverDataToClient(u_int16_t pid, unsigned char* buffer, unsigned bufferSize,
			   unsigned& startPositionInBuffer);

  void deliverPATPacket();
  void deliverPMTPacket(Boolean hasChanged);

  void setProgramStreamMap(unsigned frameSize);

protected:
  Boolean fHaveVideoStreams;

private:
  unsigned fOutgoingPacketCounter;
  unsigned fProgramMapVersion;
  u_int8_t fPreviousInputProgramMapVersion, fCurrentInputProgramMapVersion;
      // These two fields are used if we see "program_stream_map"s in the input.
  struct {
    unsigned counter;
    u_int8_t streamType; // for use in Program Maps
  } fPIDState[PID_TABLE_SIZE];
  u_int16_t fPCR_PID, fCurrentPID; // only the low 13 bits are used
  MPEG1or2Demux::SCR fPCR;
  unsigned char* fInputBuffer;
  unsigned fInputBufferSize, fInputBufferBytesUsed;
  Boolean fIsFirstAdaptationField;
  unsigned fSegmentationDuration;
      // if nonzero, this is the number of seconds between successive 'segments'.  Each 'segment'
      // begins with a PAT, followed by a PMT.
      // if zero (the default value), then the frequency of PATs and PMTs depends on the constants
      // PAT_PERIOD_IF_UNTIMED and PMT_PERIOD_IF_UNTIMED, defined in the .cpp file.
  Boolean segmentationIsTimed() const { return fSegmentationDuration > 0; }
  u_int8_t fSegmentationIndication;
      // used only if fSegmentationDuration > 0:
      // 1 if a segment has just ended and the next packet is to be a PAT
      // 2 if a segment has just ended and the following PAT has been sent; a PMT is next
      // 0 otherwise
  double fCurrentSegmentDuration, fPreviousPTS; // used only if fSegmentationDuration > 0
  onEndOfSegmentFunc* fOnEndOfSegmentFunc; // used only if fSegmentationDuration > 0
  void* fOnEndOfSegmentClientData; // ditto
};


// The CRC calculation function that Transport Streams use.  We make this function public
// here in case it's useful elsewhere:
u_int32_t calculateCRC(u_int8_t const* data, unsigned dataLength, u_int32_t initialValue = 0xFFFFFFFF);

#endif