/********** 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 2.1 of the License, or (at your option) any later version. (See .) 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) 1996-2015 Live Networks, Inc. All rights reserved. // A filter that passes through (unchanged) chunks that contain an integral number // of MPEG-2 Transport Stream packets, but returning (in "fDurationInMicroseconds") // an updated estimate of the time gap between chunks. // Implementation #include "MPEG2TransportStreamFramer.hh" #include // for "gettimeofday()" #define TRANSPORT_PACKET_SIZE 188 ////////// Definitions of constants that control the behavior of this code ///////// #if !defined(NEW_DURATION_WEIGHT) #define NEW_DURATION_WEIGHT 0.5 // How much weight to give to the latest duration measurement (must be <= 1) #endif #if !defined(TIME_ADJUSTMENT_FACTOR) #define TIME_ADJUSTMENT_FACTOR 0.8 // A factor by which to adjust the duration estimate to ensure that the overall // packet transmission times remains matched with the PCR times (which will be the // times that we expect receivers to play the incoming packets). // (must be <= 1) #endif #if !defined(MAX_PLAYOUT_BUFFER_DURATION) #define MAX_PLAYOUT_BUFFER_DURATION 0.1 // (seconds) #endif #if !defined(PCR_PERIOD_VARIATION_RATIO) #define PCR_PERIOD_VARIATION_RATIO 0.5 #endif ////////// PIDStatus ////////// class PIDStatus { public: PIDStatus(double _firstClock, double _firstRealTime) : firstClock(_firstClock), lastClock(_firstClock), firstRealTime(_firstRealTime), lastRealTime(_firstRealTime), lastPacketNum(0) { } double firstClock, lastClock, firstRealTime, lastRealTime; u_int64_t lastPacketNum; }; ////////// MPEG2TransportStreamFramer ////////// MPEG2TransportStreamFramer* MPEG2TransportStreamFramer ::createNew(UsageEnvironment& env, FramedSource* inputSource) { return new MPEG2TransportStreamFramer(env, inputSource); } MPEG2TransportStreamFramer ::MPEG2TransportStreamFramer(UsageEnvironment& env, FramedSource* inputSource) : FramedFilter(env, inputSource), fTSPacketCount(0), fTSPacketDurationEstimate(0.0), fTSPCRCount(0), fLimitNumTSPacketsToStream(False), fNumTSPacketsToStream(0), fLimitTSPacketsToStreamByPCR(False), fPCRLimit(0.0) { fPIDStatusTable = HashTable::create(ONE_WORD_HASH_KEYS); } MPEG2TransportStreamFramer::~MPEG2TransportStreamFramer() { clearPIDStatusTable(); delete fPIDStatusTable; } void MPEG2TransportStreamFramer::clearPIDStatusTable() { PIDStatus* pidStatus; while ((pidStatus = (PIDStatus*)fPIDStatusTable->RemoveNext()) != NULL) { delete pidStatus; } } void MPEG2TransportStreamFramer::setNumTSPacketsToStream(unsigned long numTSRecordsToStream) { fNumTSPacketsToStream = numTSRecordsToStream; fLimitNumTSPacketsToStream = numTSRecordsToStream > 0; } void MPEG2TransportStreamFramer::setPCRLimit(float pcrLimit) { fPCRLimit = pcrLimit; fLimitTSPacketsToStreamByPCR = pcrLimit != 0.0; } void MPEG2TransportStreamFramer::doGetNextFrame() { if (fLimitNumTSPacketsToStream) { if (fNumTSPacketsToStream == 0) { handleClosure(); return; } if (fNumTSPacketsToStream*TRANSPORT_PACKET_SIZE < fMaxSize) { fMaxSize = fNumTSPacketsToStream*TRANSPORT_PACKET_SIZE; } } // Read directly from our input source into our client's buffer: fFrameSize = 0; fInputSource->getNextFrame(fTo, fMaxSize, afterGettingFrame, this, FramedSource::handleClosure, this); } void MPEG2TransportStreamFramer::doStopGettingFrames() { FramedFilter::doStopGettingFrames(); fTSPacketCount = 0; fTSPCRCount = 0; clearPIDStatusTable(); } void MPEG2TransportStreamFramer ::afterGettingFrame(void* clientData, unsigned frameSize, unsigned /*numTruncatedBytes*/, struct timeval presentationTime, unsigned /*durationInMicroseconds*/) { MPEG2TransportStreamFramer* framer = (MPEG2TransportStreamFramer*)clientData; framer->afterGettingFrame1(frameSize, presentationTime); } #define TRANSPORT_SYNC_BYTE 0x47 void MPEG2TransportStreamFramer::afterGettingFrame1(unsigned frameSize, struct timeval presentationTime) { fFrameSize += frameSize; unsigned const numTSPackets = fFrameSize/TRANSPORT_PACKET_SIZE; fNumTSPacketsToStream -= numTSPackets; fFrameSize = numTSPackets*TRANSPORT_PACKET_SIZE; // an integral # of TS packets if (fFrameSize == 0) { // We didn't read a complete TS packet; assume that the input source has closed. handleClosure(); return; } // Make sure the data begins with a sync byte: unsigned syncBytePosition; for (syncBytePosition = 0; syncBytePosition < fFrameSize; ++syncBytePosition) { if (fTo[syncBytePosition] == TRANSPORT_SYNC_BYTE) break; } if (syncBytePosition == fFrameSize) { envir() << "No Transport Stream sync byte in data."; handleClosure(); return; } else if (syncBytePosition > 0) { // There's a sync byte, but not at the start of the data. Move the good data // to the start of the buffer, then read more to fill it up again: memmove(fTo, &fTo[syncBytePosition], fFrameSize - syncBytePosition); fFrameSize -= syncBytePosition; fInputSource->getNextFrame(&fTo[fFrameSize], syncBytePosition, afterGettingFrame, this, FramedSource::handleClosure, this); return; } // else normal case: the data begins with a sync byte fPresentationTime = presentationTime; // Scan through the TS packets that we read, and update our estimate of // the duration of each packet: struct timeval tvNow; gettimeofday(&tvNow, NULL); double timeNow = tvNow.tv_sec + tvNow.tv_usec/1000000.0; for (unsigned i = 0; i < numTSPackets; ++i) { if (!updateTSPacketDurationEstimate(&fTo[i*TRANSPORT_PACKET_SIZE], timeNow)) { // We hit a preset limit (based on PCR) within the stream. Handle this as if the input source has closed: handleClosure(); return; } } fDurationInMicroseconds = numTSPackets * (unsigned)(fTSPacketDurationEstimate*1000000); // Complete the delivery to our client: afterGetting(this); } Boolean MPEG2TransportStreamFramer::updateTSPacketDurationEstimate(unsigned char* pkt, double timeNow) { // Sanity check: Make sure we start with the sync byte: if (pkt[0] != TRANSPORT_SYNC_BYTE) { envir() << "Missing sync byte!\n"; return True; } ++fTSPacketCount; // If this packet doesn't contain a PCR, then we're not interested in it: u_int8_t const adaptation_field_control = (pkt[3]&0x30)>>4; if (adaptation_field_control != 2 && adaptation_field_control != 3) return True; // there's no adaptation_field u_int8_t const adaptation_field_length = pkt[4]; if (adaptation_field_length == 0) return True; u_int8_t const discontinuity_indicator = pkt[5]&0x80; u_int8_t const pcrFlag = pkt[5]&0x10; if (pcrFlag == 0) return True; // no PCR // There's a PCR. Get it, and the PID: ++fTSPCRCount; u_int32_t pcrBaseHigh = (pkt[6]<<24)|(pkt[7]<<16)|(pkt[8]<<8)|pkt[9]; double clock = pcrBaseHigh/45000.0; if ((pkt[10]&0x80) != 0) clock += 1/90000.0; // add in low-bit (if set) unsigned short pcrExt = ((pkt[10]&0x01)<<8) | pkt[11]; clock += pcrExt/27000000.0; if (fLimitTSPacketsToStreamByPCR) { if (clock > fPCRLimit) { // We've hit a preset limit within the stream: return False; } } unsigned pid = ((pkt[1]&0x1F)<<8) | pkt[2]; // Check whether we already have a record of a PCR for this PID: PIDStatus* pidStatus = (PIDStatus*)(fPIDStatusTable->Lookup((char*)pid)); if (pidStatus == NULL) { // We're seeing this PID's PCR for the first time: pidStatus = new PIDStatus(clock, timeNow); fPIDStatusTable->Add((char*)pid, pidStatus); #ifdef DEBUG_PCR fprintf(stderr, "PID 0x%x, FIRST PCR 0x%08x+%d:%03x == %f @ %f, pkt #%lu\n", pid, pcrBaseHigh, pkt[10]>>7, pcrExt, clock, timeNow, fTSPacketCount); #endif } else { // We've seen this PID's PCR before; update our per-packet duration estimate: int64_t packetsSinceLast = (int64_t)(fTSPacketCount - pidStatus->lastPacketNum); // it's "int64_t" because some compilers can't convert "u_int64_t" -> "double" double durationPerPacket = (clock - pidStatus->lastClock)/packetsSinceLast; // Hack (suggested by "Romain"): Don't update our estimate if this PCR appeared unusually quickly. // (This can produce more accurate estimates for wildly VBR streams.) double meanPCRPeriod = 0.0; if (fTSPCRCount > 0) { double tsPacketCount = (double)(int64_t)fTSPacketCount; double tsPCRCount = (double)(int64_t)fTSPCRCount; meanPCRPeriod = tsPacketCount/tsPCRCount; if (packetsSinceLast < meanPCRPeriod*PCR_PERIOD_VARIATION_RATIO) return True; } if (fTSPacketDurationEstimate == 0.0) { // we've just started fTSPacketDurationEstimate = durationPerPacket; } else if (discontinuity_indicator == 0 && durationPerPacket >= 0.0) { fTSPacketDurationEstimate = durationPerPacket*NEW_DURATION_WEIGHT + fTSPacketDurationEstimate*(1-NEW_DURATION_WEIGHT); // Also adjust the duration estimate to try to ensure that the transmission // rate matches the playout rate: double transmitDuration = timeNow - pidStatus->firstRealTime; double playoutDuration = clock - pidStatus->firstClock; if (transmitDuration > playoutDuration) { fTSPacketDurationEstimate *= TIME_ADJUSTMENT_FACTOR; // reduce estimate } else if (transmitDuration + MAX_PLAYOUT_BUFFER_DURATION < playoutDuration) { fTSPacketDurationEstimate /= TIME_ADJUSTMENT_FACTOR; // increase estimate } } else { // the PCR has a discontinuity from its previous value; don't use it now, // but reset our PCR and real-time values to compensate: pidStatus->firstClock = clock; pidStatus->firstRealTime = timeNow; } #ifdef DEBUG_PCR fprintf(stderr, "PID 0x%x, PCR 0x%08x+%d:%03x == %f @ %f (diffs %f @ %f), pkt #%lu, discon %d => this duration %f, new estimate %f, mean PCR period=%f\n", pid, pcrBaseHigh, pkt[10]>>7, pcrExt, clock, timeNow, clock - pidStatus->firstClock, timeNow - pidStatus->firstRealTime, fTSPacketCount, discontinuity_indicator != 0, durationPerPacket, fTSPacketDurationEstimate, meanPCRPeriod ); #endif } pidStatus->lastClock = clock; pidStatus->lastRealTime = timeNow; pidStatus->lastPacketNum = fTSPacketCount; return True; }