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fix large mdat #40

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fix large mdat #40

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b12d77f
fix large mdat
Nov 23, 2015
060d33d
fix large mdat
Sep 23, 2016
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59 changes: 56 additions & 3 deletions Source/C++/Core/Ap4FileWriter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,8 @@
#include "Ap4DataBuffer.h"
#include "Ap4FtypAtom.h"
#include "Ap4SampleTable.h"
#include "Ap4StcoAtom.h"
#include "Ap4Co64Atom.h"

/*----------------------------------------------------------------------
| AP4_FileWriter::Write
Expand Down Expand Up @@ -76,6 +78,52 @@ AP4_FileWriter::Write(AP4_File& file, AP4_ByteStream& stream, Interleaving /* in
unsigned int t=0;
AP4_Result result = AP4_SUCCESS;
AP4_UI64 mdat_size = AP4_ATOM_HEADER_SIZE;
// compute mdat_size
for (AP4_List<AP4_Track>::Item* track_item = movie->GetTracks().FirstItem();
track_item; track_item = track_item->GetNext()) {
AP4_Track* track = track_item->GetData();
AP4_Cardinal sample_count = track->GetSampleCount();
AP4_SampleTable* sample_table = track->GetSampleTable();
AP4_Sample sample;
for (AP4_Ordinal i=0; i<sample_count; i++) {
sample_table->GetSample(i, sample);
mdat_size += sample.GetSize();
}
}

// replace stco with co64
if (mdat_size >> 32) {
for (AP4_List<AP4_Track>::Item* track_item = movie->GetTracks().FirstItem();
track_item; track_item = track_item->GetNext()) {
AP4_Track* track = track_item->GetData();
AP4_TrakAtom* trak = const_cast<AP4_TrakAtom*>(track->GetTrakAtom());
AP4_StcoAtom* stco = AP4_DYNAMIC_CAST(AP4_StcoAtom, trak->FindChild("mdia/minf/stbl/stco"));
if (stco) {
AP4_Cardinal chunk_count = stco->GetChunkCount();
AP4_UI64* chunk_offsets = new AP4_UI64[chunk_count];
AP4_UI32* chunk_offsets_32 = stco->GetChunkOffsets();
for (unsigned int i=0; i<chunk_count; i++) {
chunk_offsets[i] = chunk_offsets_32[i];
}

AP4_Co64Atom* co64 = new AP4_Co64Atom(chunk_offsets, chunk_count);
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chunk_offsets gets copied into AP4_Co64Atom. So, that needs to be deleted to prevent a leak.

delete[] chunk_offsets;
stco->Detach();
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The Detach() function only detach it from the parent. As far as I can tell, you will need to delete stco to prevent a leak.

delete stco;

AP4_ContainerAtom* stbl = AP4_DYNAMIC_CAST(AP4_ContainerAtom, trak->FindChild("mdia/minf/stbl"));
if (stbl == NULL) {
delete co64;
return AP4_ERROR_INTERNAL;
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I saw the FIXME comment also and saw this pull request. You will be leaking co64 here when you return.

}
stbl->AddChild(co64, -1);
}
}
mdat_size = AP4_ATOM_HEADER_SIZE_64;
} else {
mdat_size = AP4_ATOM_HEADER_SIZE;
}

AP4_UI64 mdat_position = position+movie->GetMoovAtom()->GetSize();
AP4_Array<AP4_Array<AP4_UI64>*> trak_chunk_offsets_backup;
AP4_Array<AP4_UI64> chunk_offsets;
Expand Down Expand Up @@ -117,9 +165,14 @@ AP4_FileWriter::Write(AP4_File& file, AP4_ByteStream& stream, Interleaving /* in
movie->GetMoovAtom()->Write(stream);

// create and write the media data (mdat)
// FIXME: this only supports 32-bit mdat size
stream.WriteUI32((AP4_UI32)mdat_size);
stream.WriteUI32(AP4_ATOM_TYPE_MDAT);
if ((mdat_size >> 32) == 0) {
stream.WriteUI32((AP4_UI32)mdat_size);
stream.WriteUI32(AP4_ATOM_TYPE_MDAT);
} else {
stream.WriteUI32(1);
stream.WriteUI32(AP4_ATOM_TYPE_MDAT);
stream.WriteUI64(mdat_size);
}

// write all tracks and restore the chunk offsets to their backed-up values
for (AP4_List<AP4_Track>::Item* track_item = movie->GetTracks().FirstItem();
Expand Down
1 change: 1 addition & 0 deletions Source/C++/Core/Ap4Processor.cpp
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Expand Up @@ -308,6 +308,7 @@ AP4_Processor::ProcessFragments(AP4_MoovAtom* moov,
AP4_ASSERT(mdat_out_end-mdat_out_start == mdat_size);
#endif
output.Seek(mdat_out_start);
AP4_ASSERT(mdat_size <= 0xFFFFFFFF);
output.WriteUI32((AP4_UI32)mdat_size);
output.Seek(mdat_out_end);

Expand Down
1 change: 1 addition & 0 deletions Source/C++/Core/Ap4TrakAtom.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -372,6 +372,7 @@ AP4_TrakAtom::SetChunkOffsets(const AP4_Array<AP4_UI64>& chunk_offsets)
return AP4_ERROR_OUT_OF_RANGE;
}
for (unsigned int i=0; i<stco_chunk_count; i++) {
AP4_ASSERT(!(chunk_offsets[i] >> 32));
stco_chunk_offsets[i] = (AP4_UI32)chunk_offsets[i];
}
return AP4_SUCCESS;
Expand Down