liveMedia/MPEG2TransportStreamAccumulator.cpp

/**********
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.
// Collects a stream of incoming MPEG Transport Stream packets into
//  a chunk sufficiently large to send in a single outgoing (RTP or UDP) packet.
// Implementation

#include "MPEG2TransportStreamAccumulator.hh"

MPEG2TransportStreamAccumulator*
MPEG2TransportStreamAccumulator::createNew(UsageEnvironment& env,
					   FramedSource* inputSource, unsigned maxPacketSize) {
  return new MPEG2TransportStreamAccumulator(env, inputSource, maxPacketSize);
}

#ifndef TRANSPORT_PACKET_SIZE
#define TRANSPORT_PACKET_SIZE 188
#endif

MPEG2TransportStreamAccumulator
::MPEG2TransportStreamAccumulator(UsageEnvironment& env,
				  FramedSource* inputSource, unsigned maxPacketSize)
  : FramedFilter(env, inputSource),
    fDesiredPacketSize(maxPacketSize < TRANSPORT_PACKET_SIZE ? TRANSPORT_PACKET_SIZE : (maxPacketSize/TRANSPORT_PACKET_SIZE)),
    fNumBytesGathered(0) {
}

MPEG2TransportStreamAccumulator::~MPEG2TransportStreamAccumulator() {
}

void MPEG2TransportStreamAccumulator::doGetNextFrame() {
  if (fNumBytesGathered >= fDesiredPacketSize) {
    // Complete the delivery to the client:
    fFrameSize = fNumBytesGathered;
    fNumBytesGathered = 0;
    afterGetting(this);
  } else {
    // Ask for more data (delivered directly to the client's buffer);
    fInputSource->getNextFrame(fTo, fMaxSize, afterGettingFrame, this,
			       FramedSource::handleClosure, this);
  }
}

void MPEG2TransportStreamAccumulator
::afterGettingFrame(void* clientData, unsigned frameSize,
		    unsigned numTruncatedBytes,
		    struct timeval presentationTime,
		    unsigned durationInMicroseconds) {
  MPEG2TransportStreamAccumulator* accumulator
    = (MPEG2TransportStreamAccumulator*)clientData;
  accumulator->afterGettingFrame1(frameSize, numTruncatedBytes,
				  presentationTime, durationInMicroseconds);
}

void MPEG2TransportStreamAccumulator
::afterGettingFrame1(unsigned frameSize,
		     unsigned numTruncatedBytes,
		     struct timeval presentationTime,
		     unsigned durationInMicroseconds) {
  if (fNumBytesGathered == 0) { // this is the first frame of the new chunk
    fPresentationTime = presentationTime;
    fDurationInMicroseconds = 0;
  }
  fNumBytesGathered += frameSize;
  fTo += frameSize;
  fMaxSize -= frameSize;
  fDurationInMicroseconds += durationInMicroseconds;

  // Try again to complete delivery:
  doGetNextFrame();
}