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Fix for negative MP4 CTS offsets (turns them into positive DTS/PTS offsets)

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This commit is contained in:
Thulinma 2022-11-29 19:34:05 +01:00
parent 4dd6f0676c
commit c0f4bfdd5f
1 changed files with 49 additions and 3 deletions
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52
src/input/input_mp4.cpp
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@ -249,6 +249,42 @@ namespace Mist{
std::deque<MP4::TRAK> trak = ((MP4::MOOV*)&moovBox)->getChildren<MP4::TRAK>();
HIGH_MSG("Obtained %zu trak Boxes", trak.size());
uint64_t globalTimeOffset = 0;
for (std::deque<MP4::TRAK>::iterator trakIt = trak.begin(); trakIt != trak.end(); trakIt++){
MP4::MDIA mdiaBox = trakIt->getChild<MP4::MDIA>();
std::string hdlrType = mdiaBox.getChild<MP4::HDLR>().getHandlerType();
if (hdlrType != "vide" && hdlrType != "soun" && hdlrType != "sbtl"){
INFO_MSG("Unsupported handler: %s", hdlrType.c_str());
continue;
}
MP4::STBL stblBox = mdiaBox.getChild<MP4::MINF>().getChild<MP4::STBL>();
MP4::STSD stsdBox = stblBox.getChild<MP4::STSD>();
MP4::Box sEntryBox = stsdBox.getEntry(0);
std::string sType = sEntryBox.getType();
if (!(sType == "avc1" || sType == "h264" || sType == "mp4v" || sType == "hev1" || sType == "hvc1" || sType == "mp4a" || sType == "aac " || sType == "ac-3" || sType == "tx3g")){
INFO_MSG("Unsupported track type: %s", sType.c_str());
continue;
}
MP4::CTTS cttsBox = stblBox.getChild<MP4::CTTS>(); // optional ctts box
MP4::MDHD mdhdBox = mdiaBox.getChild<MP4::MDHD>();
uint64_t timescale = mdhdBox.getTimeScale();
int64_t DTS_CTS_offset = 0; ///< Difference between composition time and decode time. Always positive.
if (cttsBox.isType("ctts")){
uint32_t cttsCount = cttsBox.getEntryCount();
for (uint32_t i = 0; i < cttsCount; ++i){
MP4::CTTSEntry e = cttsBox.getCTTSEntry(i);
int64_t o = (-e.sampleOffset * 1000) / (int64_t)timescale;
if (o > DTS_CTS_offset){DTS_CTS_offset = o;}
}
if (DTS_CTS_offset > globalTimeOffset){globalTimeOffset = DTS_CTS_offset;}
}
}
for (std::deque<MP4::TRAK>::iterator trakIt = trak.begin(); trakIt != trak.end(); trakIt++){
MP4::MDIA mdiaBox = trakIt->getChild<MP4::MDIA>();
@ -388,6 +424,16 @@ namespace Mist{
bool stco64 = co64Box.isType("co64");
bool hasCTTS = cttsBox.isType("ctts");
int64_t DTS_CTS_offset = 0; ///< Difference between composition time and decode time. Always positive.
if (hasCTTS){
uint32_t cttsCount = cttsBox.getEntryCount();
for (uint32_t i = 0; i < cttsCount; ++i){
MP4::CTTSEntry e = cttsBox.getCTTSEntry(i);
int64_t o = (-e.sampleOffset * 1000) / (int64_t)timescale;
if (o > DTS_CTS_offset){DTS_CTS_offset = o;}
}
}
INFO_MSG("Calculated DTS/CTS offset for track %zu: %" PRId64, tNumber, DTS_CTS_offset);
uint64_t totaldur = 0; ///\todo note: set this to begin time
uint64_t totalExtraDur = 0;
@ -465,7 +511,7 @@ namespace Mist{
++cttsIndex;
cttsEntryRead = 0;
}
BsetPart.timeOffset = (cttsEntry.sampleOffset * 1000) / timescale;
BsetPart.timeOffset = (cttsEntry.sampleOffset * 1000) / (int64_t)timescale;
}else{
BsetPart.timeOffset = 0;
}
@ -477,11 +523,11 @@ namespace Mist{
long long packSendSize = 0;
packSendSize = 24 + (BsetPart.timeOffset ? 17 : 0) + (BsetPart.bpos ? 15 : 0) + 19 +
stszBox.getEntrySize(stszIndex) + 11 - 2 + 19;
meta.update(BsetPart.time, BsetPart.timeOffset, tNumber,
meta.update(BsetPart.time - DTS_CTS_offset + globalTimeOffset, BsetPart.timeOffset + DTS_CTS_offset, tNumber,
stszBox.getEntrySize(stszIndex) - 2, BsetPart.bpos+2, true, packSendSize);
}
}else{
meta.update(BsetPart.time, BsetPart.timeOffset, tNumber,
meta.update(BsetPart.time - DTS_CTS_offset + globalTimeOffset, BsetPart.timeOffset + DTS_CTS_offset, tNumber,
stszBox.getEntrySize(stszIndex), BsetPart.bpos, BsetPart.keyframe);
}
}