shithub: aacdec

ref: a78f38542dd5f4774ed651eb26218f53001fc6d4
dir: /common/mp4v2/mp4file.cpp/

/*
 * The contents of this file are subject to the Mozilla Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/MPL/
 * 
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 * 
 * The Original Code is MPEG4IP.
 * 
 * The Initial Developer of the Original Code is Cisco Systems Inc.
 * Portions created by Cisco Systems Inc. are
 * Copyright (C) Cisco Systems Inc. 2001.  All Rights Reserved.
 * 
 * Contributor(s): 
 *		Dave Mackie		[email protected]
 */

#include "mp4common.h"

MP4File::MP4File(u_int32_t verbosity)
{
	m_fileName = NULL;
	m_pFile = NULL;
	m_orgFileSize = 0;
	m_fileSize = 0;
	m_pRootAtom = NULL;
	m_odTrackId = MP4_INVALID_TRACK_ID;

	m_verbosity = verbosity;
	m_mode = 0;
	m_use64bits = false;
	m_useIsma = false;

	m_pModificationProperty = NULL;
	m_pTimeScaleProperty = NULL;
	m_pDurationProperty = NULL;

	m_memoryBuffer = NULL;
	m_memoryBufferSize = 0;
	m_memoryBufferPosition = 0;

	m_numReadBits = 0;
	m_bufReadBits = 0;
	m_numWriteBits = 0;
	m_bufWriteBits = 0;
}

MP4File::~MP4File()
{
	MP4Free(m_fileName);
	delete m_pRootAtom;
	for (u_int32_t i = 0; i < m_pTracks.Size(); i++) {
		delete m_pTracks[i];
	}
	MP4Free(m_memoryBuffer);	// just in case
}

void MP4File::Read(const char* fileName)
{
	m_fileName = MP4Stralloc(fileName);
	m_mode = 'r';

	Open("rb");

	ReadFromFile();

	CacheProperties();
}

void MP4File::Create(const char* fileName, bool use64bits)
{
	m_fileName = MP4Stralloc(fileName);
	m_mode = 'w';
	m_use64bits = use64bits;

	Open("wb+");

	// generate a skeletal atom tree
	m_pRootAtom = MP4Atom::CreateAtom(NULL);
	m_pRootAtom->SetFile(this);
	m_pRootAtom->Generate();

	CacheProperties();

	// create mdat, and insert it after ftyp, and before moov
	InsertChildAtom(m_pRootAtom, "mdat", 1);

	// start writing
	m_pRootAtom->BeginWrite();
}

void MP4File::Modify(const char* fileName)
{
	m_fileName = MP4Stralloc(fileName);
	m_mode = 'r';

	Open("rb+");
	ReadFromFile();

	m_mode = 'w';

	// find the moov atom
	MP4Atom* pMoovAtom = m_pRootAtom->FindAtom("moov");
	u_int32_t numAtoms;

	if (pMoovAtom == NULL) {
		// there isn't one, odd but we can still proceed
		pMoovAtom = AddChildAtom(m_pRootAtom, "moov");
	} else {
		numAtoms = m_pRootAtom->GetNumberOfChildAtoms();

		// work backwards thru the top level atoms
		int32_t i;
		bool lastAtomIsMoov = true;
		MP4Atom* pLastAtom = NULL;

		for (i = numAtoms - 1; i >= 0; i--) {
			MP4Atom* pAtom = m_pRootAtom->GetChildAtom(i);
			const char* type = pAtom->GetType();
			
			// get rid of any trailing free or skips
			if (!strcmp(type, "free") || !strcmp(type, "skip")) {
				m_pRootAtom->DeleteChildAtom(pAtom);
				continue;
			}

			if (strcmp(type, "moov")) {
				if (pLastAtom == NULL) {
					pLastAtom = pAtom;
					lastAtomIsMoov = false;
				}
				continue;
			}

			// now at moov atom

			// multiple moov atoms?!?
			if (pAtom != pMoovAtom) {
				throw new MP4Error(
					"Badly formed mp4 file, multiple moov atoms", 
					"MP4Modify");
			}

			if (lastAtomIsMoov) {
				// position to start of moov atom,
				// effectively truncating file 
				// prior to adding new mdat
				SetPosition(pMoovAtom->GetStart());

			} else { // last atom isn't moov
				// need to place a free atom 
				MP4Atom* pFreeAtom = MP4Atom::CreateAtom("free");

				// in existing position of the moov atom
				m_pRootAtom->InsertChildAtom(pFreeAtom, i);
				m_pRootAtom->DeleteChildAtom(pMoovAtom);
				m_pRootAtom->AddChildAtom(pMoovAtom);

				// write free atom to disk
				SetPosition(pMoovAtom->GetStart());
				pFreeAtom->SetSize(pMoovAtom->GetSize());
				pFreeAtom->Write();

				// finally set our file position to the end of the last atom
				SetPosition(pLastAtom->GetEnd());
			}

			break;
		}
		ASSERT(i != -1);
	}

	CacheProperties();	// of moov atom

	numAtoms = m_pRootAtom->GetNumberOfChildAtoms();

	// insert another mdat prior to moov atom (the last atom)
	MP4Atom* pMdatAtom = InsertChildAtom(m_pRootAtom, "mdat", numAtoms - 1);

	// start writing new mdat
	pMdatAtom->BeginWrite();
}

void MP4File::Optimize(const char* orgFileName, const char* newFileName)
{
	m_fileName = MP4Stralloc(orgFileName);
	m_mode = 'r';

	// first load meta-info into memory
	Open("rb");
	ReadFromFile();

	CacheProperties();	// of moov atom

	// now switch over to writing the new file
	MP4Free(m_fileName);
	m_fileName = MP4Stralloc(newFileName);
	FILE* pReadFile = m_pFile;
	m_pFile = NULL;
	m_mode = 'w';

	Open("wb");

	SetIntegerProperty("moov.mvhd.modificationTime", 
		MP4GetAbsTimestamp());

	// writing meta info in the optimal order
	((MP4RootAtom*)m_pRootAtom)->BeginOptimalWrite();

	// write data in optimal order
	RewriteMdat(pReadFile, m_pFile);

	// finish writing
	((MP4RootAtom*)m_pRootAtom)->FinishOptimalWrite();

	// cleanup
	fclose(m_pFile);
	m_pFile = NULL;
	fclose(pReadFile);
}

void MP4File::RewriteMdat(FILE* pReadFile, FILE* pWriteFile)
{
	u_int32_t numTracks = m_pTracks.Size();

	MP4ChunkId* chunkIds = new MP4ChunkId[numTracks];
	MP4ChunkId* maxChunkIds = new MP4ChunkId[numTracks];
	MP4Timestamp* nextChunkTimes = new MP4Timestamp[numTracks];

	for (u_int32_t i = 0; i < numTracks; i++) {
		chunkIds[i] = 1;
		maxChunkIds[i] = m_pTracks[i]->GetNumberOfChunks();
		nextChunkTimes[i] = MP4_INVALID_TIMESTAMP;
	}

	while (true) {
		u_int32_t nextTrackIndex = (u_int32_t)-1;
		MP4Timestamp nextTime = MP4_INVALID_TIMESTAMP;

		for (u_int32_t i = 0; i < numTracks; i++) {
			if (chunkIds[i] > maxChunkIds[i]) {
				continue;
			}

			if (nextChunkTimes[i] == MP4_INVALID_TIMESTAMP) {
				MP4Timestamp chunkTime =
					m_pTracks[i]->GetChunkTime(chunkIds[i]);

				nextChunkTimes[i] = MP4ConvertTime(chunkTime,
					m_pTracks[i]->GetTimeScale(), GetTimeScale());
			}

			// time is not earliest so far
			if (nextChunkTimes[i] > nextTime) {
				continue;
			}

			// prefer hint tracks to media tracks if times are equal
			if (nextChunkTimes[i] == nextTime 
			  && strcmp(m_pTracks[i]->GetType(), MP4_HINT_TRACK_TYPE)) {
				continue;
			}

			// this is our current choice of tracks
			nextTime = nextChunkTimes[i];
			nextTrackIndex = i;
		}

		if (nextTrackIndex == (u_int32_t)-1) {
			break;
		}

		// point into original mp4 file for read chunk call
		m_pFile = pReadFile;
		m_mode = 'r';

		u_int8_t* pChunk;
		u_int32_t chunkSize;

		m_pTracks[nextTrackIndex]->
			ReadChunk(chunkIds[nextTrackIndex], &pChunk, &chunkSize);

		// point back at the new mp4 file for write chunk
		m_pFile = pWriteFile;
		m_mode = 'w';

		m_pTracks[nextTrackIndex]->
			RewriteChunk(chunkIds[nextTrackIndex], pChunk, chunkSize);

		MP4Free(pChunk);

		chunkIds[nextTrackIndex]++;
		nextChunkTimes[nextTrackIndex] = MP4_INVALID_TIMESTAMP;
	}

	delete [] chunkIds;
	delete [] maxChunkIds;
	delete [] nextChunkTimes;
}

void MP4File::Open(const char* fmode)
{
	ASSERT(m_pFile == NULL);
	m_pFile = fopen(m_fileName, fmode);
	if (m_pFile == NULL) {
		throw new MP4Error(errno, "failed", "MP4Open");
	}

	if (m_mode == 'r') {
		struct stat s;
		if (fstat(fileno(m_pFile), &s) < 0) {
			throw new MP4Error(errno, "stat failed", "MP4Open");
		}
		m_orgFileSize = m_fileSize = s.st_size;
	} else {
		m_orgFileSize = m_fileSize = 0;
	}
}

void MP4File::ReadFromFile()
{
	// ensure we start at beginning of file
	SetPosition(0);

	// create a new root atom
	ASSERT(m_pRootAtom == NULL);
	m_pRootAtom = MP4Atom::CreateAtom(NULL);

	u_int64_t fileSize = GetSize();

	m_pRootAtom->SetFile(this);
	m_pRootAtom->SetStart(0);
	m_pRootAtom->SetSize(fileSize);
	m_pRootAtom->SetEnd(fileSize);

	m_pRootAtom->Read();

	// create MP4Track's for any tracks in the file
	GenerateTracks();
}

void MP4File::GenerateTracks()
{
	u_int32_t trackIndex = 0;

	while (true) {
		char trackName[32];
		snprintf(trackName, sizeof(trackName), "moov.trak[%u]", trackIndex);

		// find next trak atom
		MP4Atom* pTrakAtom = m_pRootAtom->FindAtom(trackName);

		// done, no more trak atoms
		if (pTrakAtom == NULL) {
			break;
		}

		// find track id property
		MP4Integer32Property* pTrackIdProperty = NULL;
		pTrakAtom->FindProperty(
			"trak.tkhd.trackId",
			(MP4Property**)&pTrackIdProperty);

		// find track type property
		MP4StringProperty* pTypeProperty = NULL;
		pTrakAtom->FindProperty(
			"trak.mdia.hdlr.handlerType",
			(MP4Property**)&pTypeProperty);

		// ensure we have the basics properties
		if (pTrackIdProperty && pTypeProperty) {

			m_trakIds.Add(pTrackIdProperty->GetValue());

			MP4Track* pTrack = NULL;
			try {
				if (!strcmp(pTypeProperty->GetValue(), MP4_HINT_TRACK_TYPE)) {
					pTrack = new MP4RtpHintTrack(this, pTrakAtom);
				} else {
					pTrack = new MP4Track(this, pTrakAtom);
				}
				m_pTracks.Add(pTrack);
			}
			catch (MP4Error* e) {
				VERBOSE_ERROR(m_verbosity, e->Print());
				delete e;
			}

			// remember when we encounter the OD track
			if (pTrack && !strcmp(pTrack->GetType(), MP4_OD_TRACK_TYPE)) {
				if (m_odTrackId == MP4_INVALID_TRACK_ID) {
					m_odTrackId = pTrackIdProperty->GetValue();
				} else {
					VERBOSE_READ(GetVerbosity(),
						printf("Warning: multiple OD tracks present\n"));
				}
			}
		} else {
			m_trakIds.Add(0);
		}

		trackIndex++;
	}
}

void MP4File::CacheProperties()
{
	FindIntegerProperty("moov.mvhd.modificationTime", 
		(MP4Property**)&m_pModificationProperty);

	FindIntegerProperty("moov.mvhd.timeScale", 
		(MP4Property**)&m_pTimeScaleProperty);

	FindIntegerProperty("moov.mvhd.duration", 
		(MP4Property**)&m_pDurationProperty);
}

void MP4File::BeginWrite()
{
	m_pRootAtom->BeginWrite();
}

void MP4File::FinishWrite()
{
	// for all tracks, flush chunking buffers
	for (u_int32_t i = 0; i < m_pTracks.Size(); i++) {
		ASSERT(m_pTracks[i]);
		m_pTracks[i]->FinishWrite();
	}

	// ask root atom to write
	m_pRootAtom->FinishWrite();

	// check if file shrunk, e.g. we deleted a track
	if (GetSize() < m_orgFileSize) {
		// just use a free atom to mark unused space
		// MP4Optimize() should be used to clean up this space
		MP4Atom* pFreeAtom = MP4Atom::CreateAtom("free");
		ASSERT(pFreeAtom);
		pFreeAtom->SetFile(this);
		pFreeAtom->SetSize(MAX(m_orgFileSize - (m_fileSize + 8), 0));
		pFreeAtom->Write();
		delete pFreeAtom;
	}
}

MP4Duration MP4File::UpdateDuration(MP4Duration duration)
{
	MP4Duration currentDuration = GetDuration();
	if (duration > currentDuration) {
		SetDuration(duration);
		return duration;
	}
	return currentDuration;
}

void MP4File::Dump(FILE* pDumpFile, bool dumpImplicits)
{
	if (pDumpFile == NULL) {
		pDumpFile = stdout;
	}

	fprintf(pDumpFile, "Dumping %s meta-information...\n", m_fileName);
	m_pRootAtom->Dump(pDumpFile, 0, dumpImplicits);
}

void MP4File::Close()
{
	if (m_mode == 'w') {
		SetIntegerProperty("moov.mvhd.modificationTime", 
			MP4GetAbsTimestamp());

		FinishWrite();
	}

	fclose(m_pFile);
	m_pFile = NULL;
}

void MP4File::ProtectWriteOperation(char* where)
{
	if (m_mode == 'r') {
		throw new MP4Error("operation not permitted in read mode", where);
	}
}

MP4Track* MP4File::GetTrack(MP4TrackId trackId)
{
	return m_pTracks[FindTrackIndex(trackId)];
}

MP4Atom* MP4File::FindAtom(const char* name)
{
	MP4Atom* pAtom = NULL;
	if (!name || !strcmp(name, "")) {
		pAtom = m_pRootAtom;
	} else {
		pAtom = m_pRootAtom->FindAtom(name);
	}
	return pAtom;
}

MP4Atom* MP4File::AddChildAtom(
	const char* parentName, 
	const char* childName)
{
	return AddChildAtom(FindAtom(parentName), childName);
}

MP4Atom* MP4File::AddChildAtom(
	MP4Atom* pParentAtom, 
	const char* childName)
{
	return InsertChildAtom(pParentAtom, childName, 
		pParentAtom->GetNumberOfChildAtoms());
}

MP4Atom* MP4File::InsertChildAtom(
	const char* parentName, 
	const char* childName, 
	u_int32_t index)
{
	return InsertChildAtom(FindAtom(parentName), childName, index); 
}

MP4Atom* MP4File::InsertChildAtom(
	MP4Atom* pParentAtom, 
	const char* childName, 
	u_int32_t index)
{
	MP4Atom* pChildAtom = MP4Atom::CreateAtom(childName);

	ASSERT(pParentAtom);
	pParentAtom->InsertChildAtom(pChildAtom, index);

	pChildAtom->Generate();

	return pChildAtom;
}

MP4Atom* MP4File::AddDescendantAtoms(
	const char* ancestorName, 
	const char* descendantNames)
{
	return AddDescendantAtoms(FindAtom(ancestorName), descendantNames);
}

MP4Atom* MP4File::AddDescendantAtoms(
	MP4Atom* pAncestorAtom, const char* descendantNames)
{
	ASSERT(pAncestorAtom);

	MP4Atom* pParentAtom = pAncestorAtom;
	MP4Atom* pChildAtom = NULL;

	while (true) {
		char* childName = MP4NameFirst(descendantNames);

		if (childName == NULL) {
			break;
		}

		descendantNames = MP4NameAfterFirst(descendantNames);

		pChildAtom = pParentAtom->FindChildAtom(childName);

		if (pChildAtom == NULL) {
			pChildAtom = AddChildAtom(pParentAtom, childName);
		}

		pParentAtom = pChildAtom;

		MP4Free(childName);
	}

	return pChildAtom;
}

bool MP4File::FindProperty(const char* name, 
	MP4Property** ppProperty, u_int32_t* pIndex)
{
	if (pIndex) {
		*pIndex = 0;	// set the default answer for index
	}

	return m_pRootAtom->FindProperty(name, ppProperty, pIndex);
}

void MP4File::FindIntegerProperty(const char* name, 
	MP4Property** ppProperty, u_int32_t* pIndex)
{
	if (!FindProperty(name, ppProperty, pIndex)) {
		throw new MP4Error("no such property", "MP4File::FindIntegerProperty");
	}

	switch ((*ppProperty)->GetType()) {
	case Integer8Property:
	case Integer16Property:
	case Integer24Property:
	case Integer32Property:
	case Integer64Property:
		break;
	default:
		throw new MP4Error("type mismatch", "MP4File::FindIntegerProperty");
	}
}

u_int64_t MP4File::GetIntegerProperty(const char* name)
{
	MP4Property* pProperty;
	u_int32_t index;

	FindIntegerProperty(name, &pProperty, &index);

	return ((MP4IntegerProperty*)pProperty)->GetValue(index);
}

void MP4File::SetIntegerProperty(const char* name, u_int64_t value)
{
	ProtectWriteOperation("SetIntegerProperty");

	MP4Property* pProperty = NULL;
	u_int32_t index = 0;

	FindIntegerProperty(name, &pProperty, &index);

	((MP4IntegerProperty*)pProperty)->SetValue(value, index);
}

void MP4File::FindFloatProperty(const char* name, 
	MP4Property** ppProperty, u_int32_t* pIndex)
{
	if (!FindProperty(name, ppProperty, pIndex)) {
		throw new MP4Error("no such property", "MP4File::FindFloatProperty");
	}
	if ((*ppProperty)->GetType() != Float32Property) {
		throw new MP4Error("type mismatch", "MP4File::FindFloatProperty");
	}
}

float MP4File::GetFloatProperty(const char* name)
{
	MP4Property* pProperty;
	u_int32_t index;

	FindFloatProperty(name, &pProperty, &index);

	return ((MP4Float32Property*)pProperty)->GetValue(index);
}

void MP4File::SetFloatProperty(const char* name, float value)
{
	ProtectWriteOperation("SetFloatProperty");

	MP4Property* pProperty;
	u_int32_t index;

	FindFloatProperty(name, &pProperty, &index);

	((MP4Float32Property*)pProperty)->SetValue(value, index);
}

void MP4File::FindStringProperty(const char* name, 
	MP4Property** ppProperty, u_int32_t* pIndex)
{
	if (!FindProperty(name, ppProperty, pIndex)) {
		throw new MP4Error("no such property", "MP4File::FindStringProperty");
	}
	if ((*ppProperty)->GetType() != StringProperty) {
		throw new MP4Error("type mismatch", "MP4File::FindStringProperty");
	}
}

const char* MP4File::GetStringProperty(const char* name)
{
	MP4Property* pProperty;
	u_int32_t index;

	FindStringProperty(name, &pProperty, &index);

	return ((MP4StringProperty*)pProperty)->GetValue(index);
}

void MP4File::SetStringProperty(const char* name, const char* value)
{
	ProtectWriteOperation("SetStringProperty");

	MP4Property* pProperty;
	u_int32_t index;

	FindStringProperty(name, &pProperty, &index);

	((MP4StringProperty*)pProperty)->SetValue(value, index);
}

void MP4File::FindBytesProperty(const char* name, 
	MP4Property** ppProperty, u_int32_t* pIndex)
{
	if (!FindProperty(name, ppProperty, pIndex)) {
		throw new MP4Error("no such property", "MP4File::FindBytesProperty");
	}
	if ((*ppProperty)->GetType() != BytesProperty) {
		throw new MP4Error("type mismatch", "MP4File::FindBytesProperty");
	}
}

void MP4File::GetBytesProperty(const char* name, 
	u_int8_t** ppValue, u_int32_t* pValueSize)
{
	MP4Property* pProperty;
	u_int32_t index;

	FindBytesProperty(name, &pProperty, &index);

	((MP4BytesProperty*)pProperty)->GetValue(ppValue, pValueSize, index);
}

void MP4File::SetBytesProperty(const char* name, 
	const u_int8_t* pValue, u_int32_t valueSize)
{
	ProtectWriteOperation("SetBytesProperty");

	MP4Property* pProperty;
	u_int32_t index;

	FindBytesProperty(name, &pProperty, &index);

	((MP4BytesProperty*)pProperty)->SetValue(pValue, valueSize, index);
}


// track functions

MP4TrackId MP4File::AddTrack(const char* type, u_int32_t timeScale)
{
	ProtectWriteOperation("AddTrack");

	// create and add new trak atom
	MP4Atom* pTrakAtom = AddChildAtom("moov", "trak");

	// allocate a new track id
	MP4TrackId trackId = AllocTrackId();

	m_trakIds.Add(trackId);

	// set track id
	MP4Integer32Property* pInteger32Property = NULL;
	pTrakAtom->FindProperty(
		"trak.tkhd.trackId", (MP4Property**)&pInteger32Property);
	ASSERT(pInteger32Property);
	pInteger32Property->SetValue(trackId);

	// set track type
	const char* normType = MP4Track::NormalizeTrackType(type);

	MP4StringProperty* pStringProperty = NULL;
	pTrakAtom->FindProperty(
		"trak.mdia.hdlr.handlerType", (MP4Property**)&pStringProperty);
	ASSERT(pStringProperty);
	pStringProperty->SetValue(normType);

	// set track time scale
	pInteger32Property = NULL;
	pTrakAtom->FindProperty(
		"trak.mdia.mdhd.timeScale", (MP4Property**)&pInteger32Property);
	ASSERT(pInteger32Property);
	pInteger32Property->SetValue(timeScale ? timeScale : 1);

	// now have enough to create MP4Track object
	MP4Track* pTrack = NULL;
	if (!strcmp(normType, MP4_HINT_TRACK_TYPE)) {
		pTrack = new MP4RtpHintTrack(this, pTrakAtom);
	} else {
		pTrack = new MP4Track(this, pTrakAtom);
	}
	m_pTracks.Add(pTrack);

	// mark non-hint tracks as enabled
	if (strcmp(normType, MP4_HINT_TRACK_TYPE)) {
		SetTrackIntegerProperty(trackId, "tkhd.flags", 1);
	}

	// mark track as contained in this file
	// LATER will provide option for external data references
	AddDataReference(trackId, NULL);

	return trackId;
}

void MP4File::AddTrackToIod(MP4TrackId trackId)
{
	MP4DescriptorProperty* pDescriptorProperty = NULL;
	m_pRootAtom->FindProperty("moov.iods.esIds", 
		(MP4Property**)&pDescriptorProperty);
	ASSERT(pDescriptorProperty);

	MP4Descriptor* pDescriptor = 
		pDescriptorProperty->AddDescriptor(MP4ESIDIncDescrTag);
	ASSERT(pDescriptor);

	MP4Integer32Property* pIdProperty = NULL;
	pDescriptor->FindProperty("id", 
		(MP4Property**)&pIdProperty);
	ASSERT(pIdProperty);

	pIdProperty->SetValue(trackId);
}

void MP4File::RemoveTrackFromIod(MP4TrackId trackId)
{
	MP4DescriptorProperty* pDescriptorProperty = NULL;
	m_pRootAtom->FindProperty("moov.iods.esIds",
		(MP4Property**)&pDescriptorProperty);
	ASSERT(pDescriptorProperty);

	for (u_int32_t i = 0; i < pDescriptorProperty->GetCount(); i++) {
		static char name[32];
		snprintf(name, sizeof(name), "esIds[%u].id", i);

		MP4Integer32Property* pIdProperty = NULL;
		pDescriptorProperty->FindProperty(name, 
			(MP4Property**)&pIdProperty);
		ASSERT(pIdProperty);

		if (pIdProperty->GetValue() == trackId) {
			pDescriptorProperty->DeleteDescriptor(i);
			break;
		}
	}
}

void MP4File::AddTrackToOd(MP4TrackId trackId)
{
	if (!m_odTrackId) {
		return;
	}

	AddTrackReference(MakeTrackName(m_odTrackId, "tref.mpod"), trackId);
}

void MP4File::RemoveTrackFromOd(MP4TrackId trackId)
{
	if (!m_odTrackId) {
		return;
	}

	RemoveTrackReference(MakeTrackName(m_odTrackId, "tref.mpod"), trackId);
}

void MP4File::GetTrackReferenceProperties(const char* trefName,
	MP4Property** ppCountProperty, MP4Property** ppTrackIdProperty)
{
	char propName[1024];

	snprintf(propName, sizeof(propName), "%s.%s", trefName, "entryCount");
	m_pRootAtom->FindProperty(propName, ppCountProperty);
	ASSERT(*ppCountProperty);

	snprintf(propName, sizeof(propName), "%s.%s", trefName, "entries.trackId");
	m_pRootAtom->FindProperty(propName, ppTrackIdProperty);
	ASSERT(*ppTrackIdProperty);
}

void MP4File::AddTrackReference(const char* trefName, MP4TrackId refTrackId)
{
	MP4Integer32Property* pCountProperty = NULL;
	MP4Integer32Property* pTrackIdProperty = NULL;

	GetTrackReferenceProperties(trefName,
		(MP4Property**)&pCountProperty, 
		(MP4Property**)&pTrackIdProperty);

	pTrackIdProperty->AddValue(refTrackId);
	pCountProperty->IncrementValue();
}

u_int32_t MP4File::FindTrackReference(const char* trefName, 
	MP4TrackId refTrackId)
{
	MP4Integer32Property* pCountProperty = NULL;
	MP4Integer32Property* pTrackIdProperty = NULL;

	GetTrackReferenceProperties(trefName, 
		(MP4Property**)&pCountProperty, 
		(MP4Property**)&pTrackIdProperty);

	for (u_int32_t i = 0; i < pCountProperty->GetValue(); i++) {
		if (refTrackId == pTrackIdProperty->GetValue(i)) {
			return i + 1;	// N.B. 1 not 0 based index
		}
	}
	return 0;
}

void MP4File::RemoveTrackReference(const char* trefName, MP4TrackId refTrackId)
{
	MP4Integer32Property* pCountProperty = NULL;
	MP4Integer32Property* pTrackIdProperty = NULL;

	GetTrackReferenceProperties(trefName,
		(MP4Property**)&pCountProperty, 
		(MP4Property**)&pTrackIdProperty);

	for (u_int32_t i = 0; i < pCountProperty->GetValue(); i++) {
		if (refTrackId == pTrackIdProperty->GetValue(i)) {
			pTrackIdProperty->DeleteValue(i);
			pCountProperty->SetValue(pCountProperty->GetValue() - 1);
		}
	}
}

void MP4File::AddDataReference(MP4TrackId trackId, const char* url)
{
	MP4Atom* pDrefAtom = 
		FindAtom(MakeTrackName(trackId, "mdia.minf.dinf.dref"));
	ASSERT(pDrefAtom);

	MP4Integer32Property* pCountProperty = NULL;
	pDrefAtom->FindProperty("dref.entryCount", 
		(MP4Property**)&pCountProperty);
	ASSERT(pCountProperty);
	pCountProperty->IncrementValue();

	MP4Atom* pUrlAtom = AddChildAtom(pDrefAtom, "url ");

	if (url && url[0] != '\0') {
		pUrlAtom->SetFlags(pUrlAtom->GetFlags() & 0xFFFFFE);

		MP4StringProperty* pUrlProperty = NULL;
		pUrlAtom->FindProperty("url .location",
			(MP4Property**)&pUrlProperty);
		ASSERT(pUrlProperty);
		pUrlProperty->SetValue(url);
	} else {
		pUrlAtom->SetFlags(pUrlAtom->GetFlags() | 1);
	}
}

MP4TrackId MP4File::AddSystemsTrack(const char* type)
{
	const char* normType = MP4Track::NormalizeTrackType(type); 

	MP4TrackId trackId = AddTrack(type, MP4_MSECS_TIME_SCALE);

	InsertChildAtom(MakeTrackName(trackId, "mdia.minf"), "nmhd", 0);

	AddChildAtom(MakeTrackName(trackId, "mdia.minf.stbl.stsd"), "mp4s");

	// stsd is a unique beast in that it has a count of the number 
	// of child atoms that needs to be incremented after we add the mp4s atom
	MP4Integer32Property* pStsdCountProperty;
	FindIntegerProperty(
		MakeTrackName(trackId, "mdia.minf.stbl.stsd.entryCount"),
		(MP4Property**)&pStsdCountProperty);
	pStsdCountProperty->IncrementValue();

	SetTrackIntegerProperty(trackId, 
		"mdia.minf.stbl.stsd.mp4s.esds.ESID", trackId);

	SetTrackIntegerProperty(trackId, 
		"mdia.minf.stbl.stsd.mp4s.esds.decConfigDescr.objectTypeId", 
		MP4SystemsV1ObjectType);

	SetTrackIntegerProperty(trackId, 
		"mdia.minf.stbl.stsd.mp4s.esds.decConfigDescr.streamType", 
		ConvertTrackTypeToStreamType(normType));

	return trackId;
}

MP4TrackId MP4File::AddODTrack()
{
	// until a demonstrated need emerges
	// we limit ourselves to one object description track
	if (m_odTrackId != MP4_INVALID_TRACK_ID) {
		throw new MP4Error("object description track already exists",
			"AddObjectDescriptionTrack");
	}

	m_odTrackId = AddSystemsTrack(MP4_OD_TRACK_TYPE);

	AddTrackToIod(m_odTrackId);

	AddDescendantAtoms(MakeTrackName(m_odTrackId, NULL), "tref.mpod");

	return m_odTrackId;
}

MP4TrackId MP4File::AddSceneTrack()
{
	MP4TrackId trackId = AddSystemsTrack(MP4_SCENE_TRACK_TYPE);

	AddTrackToIod(trackId);
	AddTrackToOd(trackId);

	return trackId;
}

MP4TrackId MP4File::AddAudioTrack(u_int32_t timeScale, 
	u_int32_t sampleDuration, u_int8_t audioType)
{
	MP4TrackId trackId = AddTrack(MP4_AUDIO_TRACK_TYPE, timeScale);

	AddTrackToOd(trackId);

	SetTrackFloatProperty(trackId, "tkhd.volume", 1.0);

	InsertChildAtom(MakeTrackName(trackId, "mdia.minf"), "smhd", 0);

	AddChildAtom(MakeTrackName(trackId, "mdia.minf.stbl.stsd"), "mp4a");

	// stsd is a unique beast in that it has a count of the number 
	// of child atoms that needs to be incremented after we add the mp4a atom
	MP4Integer32Property* pStsdCountProperty;
	FindIntegerProperty(
		MakeTrackName(trackId, "mdia.minf.stbl.stsd.entryCount"),
		(MP4Property**)&pStsdCountProperty);
	pStsdCountProperty->IncrementValue();

	SetTrackIntegerProperty(trackId, 
		"mdia.minf.stbl.stsd.mp4a.timeScale", timeScale);

	SetTrackIntegerProperty(trackId, 
		"mdia.minf.stbl.stsd.mp4a.esds.ESID", trackId);

	SetTrackIntegerProperty(trackId, 
		"mdia.minf.stbl.stsd.mp4a.esds.decConfigDescr.objectTypeId", 
		audioType);

	SetTrackIntegerProperty(trackId, 
		"mdia.minf.stbl.stsd.mp4a.esds.decConfigDescr.streamType", 
		MP4AudioStreamType);

	m_pTracks[FindTrackIndex(trackId)]->
		SetFixedSampleDuration(sampleDuration);

	return trackId;
}

MP4TrackId MP4File::AddVideoTrack(
	u_int32_t timeScale, u_int32_t sampleDuration, 
	u_int16_t width, u_int16_t height, u_int8_t videoType)
{
	MP4TrackId trackId = AddTrack(MP4_VIDEO_TRACK_TYPE, timeScale);

	AddTrackToOd(trackId);

	SetTrackFloatProperty(trackId, "tkhd.width", width);
	SetTrackFloatProperty(trackId, "tkhd.height", height);

	InsertChildAtom(MakeTrackName(trackId, "mdia.minf"), "vmhd", 0);

	AddChildAtom(MakeTrackName(trackId, "mdia.minf.stbl.stsd"), "mp4v");

	// stsd is a unique beast in that it has a count of the number 
	// of child atoms that needs to be incremented after we add the mp4v atom
	MP4Integer32Property* pStsdCountProperty;
	FindIntegerProperty(
		MakeTrackName(trackId, "mdia.minf.stbl.stsd.entryCount"),
		(MP4Property**)&pStsdCountProperty);
	pStsdCountProperty->IncrementValue();

	SetTrackIntegerProperty(trackId, 
		"mdia.minf.stbl.stsd.mp4v.width", width);
	SetTrackIntegerProperty(trackId, 
		"mdia.minf.stbl.stsd.mp4v.height", height);

	SetTrackIntegerProperty(trackId, 
		"mdia.minf.stbl.stsd.mp4v.esds.ESID", trackId);

	SetTrackIntegerProperty(trackId, 
		"mdia.minf.stbl.stsd.mp4v.esds.decConfigDescr.objectTypeId", 
		videoType);

	SetTrackIntegerProperty(trackId, 
		"mdia.minf.stbl.stsd.mp4v.esds.decConfigDescr.streamType", 
		MP4VisualStreamType);

	SetTrackIntegerProperty(trackId, 
		"mdia.minf.stbl.stsz.sampleSize", sampleDuration);

	m_pTracks[FindTrackIndex(trackId)]->
		SetFixedSampleDuration(sampleDuration);

	return trackId;
}

MP4TrackId MP4File::AddHintTrack(MP4TrackId refTrackId)
{
	// validate reference track id
	FindTrackIndex(refTrackId);

	MP4TrackId trackId = 
		AddTrack(MP4_HINT_TRACK_TYPE, GetTrackTimeScale(refTrackId));

	InsertChildAtom(MakeTrackName(trackId, "mdia.minf"), "hmhd", 0);

	AddChildAtom(MakeTrackName(trackId, "mdia.minf.stbl.stsd"), "rtp ");

	// stsd is a unique beast in that it has a count of the number 
	// of child atoms that needs to be incremented after we add the rtp atom
	MP4Integer32Property* pStsdCountProperty;
	FindIntegerProperty(
		MakeTrackName(trackId, "mdia.minf.stbl.stsd.entryCount"),
		(MP4Property**)&pStsdCountProperty);
	pStsdCountProperty->IncrementValue();

	SetTrackIntegerProperty(trackId, 
		"mdia.minf.stbl.stsd.rtp .tims.timeScale", 
		GetTrackTimeScale(trackId));

	AddDescendantAtoms(MakeTrackName(trackId, NULL), "tref.hint");

	AddTrackReference(MakeTrackName(trackId, "tref.hint"), refTrackId);

	AddDescendantAtoms(MakeTrackName(trackId, NULL), "udta.hnti.sdp ");

	AddDescendantAtoms(MakeTrackName(trackId, NULL), "udta.hinf");

	return trackId;
}

void MP4File::DeleteTrack(MP4TrackId trackId)
{
	ProtectWriteOperation("MP4DeleteTrack");

	u_int32_t trakIndex = FindTrakAtomIndex(trackId);
	u_int16_t trackIndex = FindTrackIndex(trackId);
	MP4Track* pTrack = m_pTracks[trackIndex];

	MP4Atom* pTrakAtom = pTrack->GetTrakAtom();
	ASSERT(pTrakAtom);

	MP4Atom* pMoovAtom = FindAtom("moov");
	ASSERT(pMoovAtom);

	RemoveTrackFromIod(trackId);
	RemoveTrackFromOd(trackId);

	if (trackId == m_odTrackId) {
		m_odTrackId = 0;
	}

	pMoovAtom->DeleteChildAtom(pTrakAtom);

	m_trakIds.Delete(trakIndex);

	m_pTracks.Delete(trackIndex);

	delete pTrack;
	delete pTrakAtom;
}

u_int32_t MP4File::GetNumberOfTracks(const char* type)
{
	if (type == NULL) {
		return m_pTracks.Size();
	} else {
		u_int16_t typeSeen = 0;
		const char* normType = MP4Track::NormalizeTrackType(type);

		for (u_int16_t i = 0; i < m_pTracks.Size(); i++) {
			if (!strcmp(normType, m_pTracks[i]->GetType())) {
				typeSeen++;
			}
		}
		return typeSeen;
	}
}

MP4TrackId MP4File::AllocTrackId()
{
	MP4TrackId trackId = GetIntegerProperty("moov.mvhd.nextTrackId");

	if (trackId <= 0xFFFF) {
		SetIntegerProperty("moov.mvhd.nextTrackId", trackId + 1);
	} else {
		// extremely rare case where we need to search for a track id
		for (u_int16_t i = 1; i <= 0xFFFF; i++) {
			try {
				FindTrackIndex(i);
			}
			catch (MP4Error* e) {
				trackId = i;
				delete e;
			}
		}
		// even more extreme case where mp4 file has 2^16 tracks in it
		if (trackId > 0xFFFF) {
			throw new MP4Error("too many exising tracks", "AddTrack");
		}
	}

	return trackId;
}

MP4TrackId MP4File::FindTrackId(u_int16_t trackIndex, const char* type)
{
	if (type == NULL) {
		return m_pTracks[trackIndex]->GetId();
	} else {
		u_int16_t typeSeen = 0;
		const char* normType = MP4Track::NormalizeTrackType(type);

		for (u_int16_t i = 0; i < m_pTracks.Size(); i++) {
			if (!strcmp(normType, m_pTracks[i]->GetType())) {
				if (trackIndex == typeSeen) {
					return m_pTracks[i]->GetId();
				}
				typeSeen++;
			}
		}
		throw new MP4Error("Track index doesn't exist", "FindTrackId"); 
		return MP4_INVALID_TRACK_ID; // satisfy MS compiler
	}
}

u_int16_t MP4File::FindTrackIndex(MP4TrackId trackId)
{
	for (u_int16_t i = 0; i < m_pTracks.Size(); i++) {
		if (m_pTracks[i]->GetId() == trackId) {
			return i;
		}
	}
	
	throw new MP4Error("Track id doesn't exist", "FindTrackIndex"); 
	return (u_int16_t)-1; // satisfy MS compiler
}

u_int16_t MP4File::FindTrakAtomIndex(MP4TrackId trackId)
{
	if (trackId) {
		for (u_int32_t i = 0; i < m_trakIds.Size(); i++) {
			if (m_trakIds[i] == trackId) {
				return i;
			}
		}
	}

	throw new MP4Error("Track id doesn't exist", "FindTrakAtomIndex"); 
	return (u_int16_t)-1; // satisfy MS compiler
}

u_int32_t MP4File::GetSampleSize(MP4TrackId trackId, MP4SampleId sampleId)
{
	return m_pTracks[FindTrackIndex(trackId)]->GetSampleSize(sampleId);
}

u_int32_t MP4File::GetTrackMaxSampleSize(MP4TrackId trackId)
{
	return m_pTracks[FindTrackIndex(trackId)]->GetMaxSampleSize();
}

MP4SampleId MP4File::GetSampleIdFromTime(MP4TrackId trackId, 
	MP4Timestamp when, bool wantSyncSample)
{
	return m_pTracks[FindTrackIndex(trackId)]->
		GetSampleIdFromTime(when, wantSyncSample);
}

MP4Timestamp MP4File::GetSampleTime(
	MP4TrackId trackId, MP4SampleId sampleId)
{
	MP4Timestamp timestamp;
	m_pTracks[FindTrackIndex(trackId)]->
		GetSampleTimes(sampleId, &timestamp, NULL);
	return timestamp;
}

MP4Duration MP4File::GetSampleDuration(
	MP4TrackId trackId, MP4SampleId sampleId)
{
	MP4Duration duration;
	m_pTracks[FindTrackIndex(trackId)]->
		GetSampleTimes(sampleId, NULL, &duration);
	return duration; 
}

MP4Duration MP4File::GetSampleRenderingOffset(
	MP4TrackId trackId, MP4SampleId sampleId)
{
	return m_pTracks[FindTrackIndex(trackId)]->
		GetSampleRenderingOffset(sampleId);
}

bool MP4File::GetSampleSync(MP4TrackId trackId, MP4SampleId sampleId)
{
	return m_pTracks[FindTrackIndex(trackId)]->IsSyncSample(sampleId);
}

void MP4File::ReadSample(MP4TrackId trackId, MP4SampleId sampleId,
		u_int8_t** ppBytes, u_int32_t* pNumBytes, 
		MP4Timestamp* pStartTime, MP4Duration* pDuration,
		MP4Duration* pRenderingOffset, bool* pIsSyncSample)
{
	m_pTracks[FindTrackIndex(trackId)]->
		ReadSample(sampleId, ppBytes, pNumBytes, 
			pStartTime, pDuration, pRenderingOffset, pIsSyncSample);
}

void MP4File::WriteSample(MP4TrackId trackId,
		u_int8_t* pBytes, u_int32_t numBytes,
		MP4Duration duration, MP4Duration renderingOffset, bool isSyncSample)
{
	ProtectWriteOperation("MP4WriteSample");

	m_pTracks[FindTrackIndex(trackId)]->
		WriteSample(pBytes, numBytes, duration, renderingOffset, isSyncSample);

	m_pModificationProperty->SetValue(MP4GetAbsTimestamp());
}

void MP4File::SetSampleRenderingOffset(MP4TrackId trackId, 
	MP4SampleId sampleId, MP4Duration renderingOffset)
{
	ProtectWriteOperation("MP4SetSampleRenderingOffset");

	m_pTracks[FindTrackIndex(trackId)]->
		SetSampleRenderingOffset(sampleId, renderingOffset);

	m_pModificationProperty->SetValue(MP4GetAbsTimestamp());
}

char* MP4File::MakeTrackName(MP4TrackId trackId, const char* name)
{
	u_int16_t trakIndex = FindTrakAtomIndex(trackId);

	static char trakName[1024];
	if (name == NULL || name[0] == '\0') {
		snprintf(trakName, sizeof(trakName), 
			"moov.trak[%u]", trakIndex);
	} else {
		snprintf(trakName, sizeof(trakName), 
			"moov.trak[%u].%s", trakIndex, name);
	}
	return trakName;
}

u_int64_t MP4File::GetTrackIntegerProperty(MP4TrackId trackId, const char* name)
{
	return GetIntegerProperty(MakeTrackName(trackId, name));
}

void MP4File::SetTrackIntegerProperty(MP4TrackId trackId, const char* name, 
	int64_t value)
{
	SetIntegerProperty(MakeTrackName(trackId, name), value);
}

float MP4File::GetTrackFloatProperty(MP4TrackId trackId, const char* name)
{
	return GetFloatProperty(MakeTrackName(trackId, name));
}

void MP4File::SetTrackFloatProperty(MP4TrackId trackId, const char* name, 
	float value)
{
	SetFloatProperty(MakeTrackName(trackId, name), value);
}

const char* MP4File::GetTrackStringProperty(MP4TrackId trackId, const char* name)
{
	return GetStringProperty(MakeTrackName(trackId, name));
}

void MP4File::SetTrackStringProperty(MP4TrackId trackId, const char* name,
	const char* value)
{
	SetStringProperty(MakeTrackName(trackId, name), value);
}

void MP4File::GetTrackBytesProperty(MP4TrackId trackId, const char* name, 
	u_int8_t** ppValue, u_int32_t* pValueSize)
{
	GetBytesProperty(MakeTrackName(trackId, name), ppValue, pValueSize);
}

void MP4File::SetTrackBytesProperty(MP4TrackId trackId, const char* name, 
	const u_int8_t* pValue, u_int32_t valueSize)
{
	SetBytesProperty(MakeTrackName(trackId, name), pValue, valueSize);
}


// file level convenience functions

MP4Duration MP4File::GetDuration()
{
	return m_pDurationProperty->GetValue();
}

void MP4File::SetDuration(MP4Duration value)
{
	m_pDurationProperty->SetValue(value);
}

u_int32_t MP4File::GetTimeScale()
{
	return m_pTimeScaleProperty->GetValue();
}

void MP4File::SetTimeScale(u_int32_t value)
{
	if (value == 0) {
		throw new MP4Error("invalid value", "SetTimeScale");
	}
	m_pTimeScaleProperty->SetValue(value);
}

u_int8_t MP4File::GetODProfileLevel()
{
	return GetIntegerProperty("moov.iods.ODProfileLevelId");
}

void MP4File::SetODProfileLevel(u_int8_t value)
{
	SetIntegerProperty("moov.iods.ODProfileLevelId", value);
}
 
u_int8_t MP4File::GetSceneProfileLevel()
{
	return GetIntegerProperty("moov.iods.sceneProfileLevelId");
}

void MP4File::SetSceneProfileLevel(u_int8_t value)
{
	SetIntegerProperty("moov.iods.sceneProfileLevelId", value);
}
 
u_int8_t MP4File::GetVideoProfileLevel()
{
	return GetIntegerProperty("moov.iods.visualProfileLevelId");
}

void MP4File::SetVideoProfileLevel(u_int8_t value)
{
	SetIntegerProperty("moov.iods.visualProfileLevelId", value);
}
 
u_int8_t MP4File::GetAudioProfileLevel()
{
	return GetIntegerProperty("moov.iods.audioProfileLevelId");
}

void MP4File::SetAudioProfileLevel(u_int8_t value)
{
	SetIntegerProperty("moov.iods.audioProfileLevelId", value);
}
 
u_int8_t MP4File::GetGraphicsProfileLevel()
{
	return GetIntegerProperty("moov.iods.graphicsProfileLevelId");
}

void MP4File::SetGraphicsProfileLevel(u_int8_t value)
{
	SetIntegerProperty("moov.iods.graphicsProfileLevelId", value);
}
 
const char* MP4File::GetSessionSdp()
{
	return GetStringProperty("moov.udta.hnti.rtp .sdpText");
}

void MP4File::SetSessionSdp(const char* sdpString)
{
	AddDescendantAtoms("moov", "udta.hnti.rtp ");

	SetStringProperty("moov.udta.hnti.rtp .sdpText", sdpString);
}

void MP4File::AppendSessionSdp(const char* sdpFragment)
{
	const char* oldSdpString = NULL;
	try {
		oldSdpString = GetSessionSdp();
	}
	catch (MP4Error* e) {
		delete e;
		SetSessionSdp(sdpFragment);
		return;
	}

	char* newSdpString =
		(char*)MP4Malloc(strlen(oldSdpString) + strlen(sdpFragment) + 1);
	strcpy(newSdpString, oldSdpString);
	strcat(newSdpString, sdpFragment);
	SetSessionSdp(newSdpString);
	MP4Free(newSdpString);
}


// track level convenience functions

MP4SampleId MP4File::GetTrackNumberOfSamples(MP4TrackId trackId)
{
	return m_pTracks[FindTrackIndex(trackId)]->GetNumberOfSamples();
}

const char* MP4File::GetTrackType(MP4TrackId trackId)
{
	return m_pTracks[FindTrackIndex(trackId)]->GetType();
}

u_int32_t MP4File::GetTrackTimeScale(MP4TrackId trackId)
{
	return m_pTracks[FindTrackIndex(trackId)]->GetTimeScale();
}

void MP4File::SetTrackTimeScale(MP4TrackId trackId, u_int32_t value)
{
	if (value == 0) {
		throw new MP4Error("invalid value", "SetTrackTimeScale");
	}
	SetTrackIntegerProperty(trackId, "mdia.mdhd.timeScale", value);
}

MP4Duration MP4File::GetTrackDuration(MP4TrackId trackId)
{
	return GetTrackIntegerProperty(trackId, "mdia.mdhd.duration");
}

u_int8_t MP4File::GetTrackAudioType(MP4TrackId trackId)
{
	return GetTrackIntegerProperty(trackId, 
		"mdia.minf.stbl.stsd.mp4a.esds.decConfigDescr.objectTypeId");
}

u_int8_t MP4File::GetTrackVideoType(MP4TrackId trackId)
{
	return GetTrackIntegerProperty(trackId, 
		"mdia.minf.stbl.stsd.mp4v.esds.decConfigDescr.objectTypeId");
}

MP4Duration MP4File::GetTrackFixedSampleDuration(MP4TrackId trackId)
{
	return m_pTracks[FindTrackIndex(trackId)]->GetFixedSampleDuration();
}

void MP4File::GetTrackESConfiguration(MP4TrackId trackId, 
	u_int8_t** ppConfig, u_int32_t* pConfigSize)
{
	GetTrackBytesProperty(trackId, 
		"mdia.minf.stbl.stsd.*[0].esds.decConfigDescr.decSpecificInfo[0].info",
		ppConfig, pConfigSize);
}

void MP4File::SetTrackESConfiguration(MP4TrackId trackId, 
	const u_int8_t* pConfig, u_int32_t configSize)
{
	// get a handle on the track decoder config descriptor 
	MP4DescriptorProperty* pConfigDescrProperty = NULL;
	FindProperty(MakeTrackName(trackId, 
		"mdia.minf.stbl.stsd.*[0].esds.decConfigDescr.decSpecificInfo"),
		(MP4Property**)&pConfigDescrProperty);

	if (pConfigDescrProperty == NULL) {
		// probably trackId refers to a hint track
		throw new MP4Error("no such property", "MP4SetTrackESConfiguration");
	}

	// lookup the property to store the configuration
	MP4BytesProperty* pInfoProperty = NULL;
	pConfigDescrProperty->FindProperty("decSpecificInfo[0].info",
		(MP4Property**)&pInfoProperty);

	// configuration being set for the first time
	if (pInfoProperty == NULL) {
		// need to create a new descriptor to hold it
		MP4Descriptor* pConfigDescr =
			pConfigDescrProperty->AddDescriptor(MP4DecSpecificDescrTag);
		pConfigDescr->Generate();

		pConfigDescrProperty->FindProperty(
			"decSpecificInfo[0].info",
			(MP4Property**)&pInfoProperty);
		ASSERT(pInfoProperty);
	}

	// set the value
	pInfoProperty->SetValue(pConfig, configSize);
}

const char* MP4File::GetHintTrackSdp(MP4TrackId hintTrackId)
{
	return GetTrackStringProperty(hintTrackId, "udta.hnti.sdp .sdpText");
}

void MP4File::SetHintTrackSdp(MP4TrackId hintTrackId, const char* sdpString)
{
	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", 
			"MP4SetHintTrackSdp");
	}

	AddDescendantAtoms(
		MakeTrackName(hintTrackId, NULL), "udta.hnti.sdp ");

	SetTrackStringProperty(hintTrackId, "udta.hnti.sdp .sdpText", sdpString);
}

void MP4File::AppendHintTrackSdp(MP4TrackId hintTrackId, 
	const char* sdpFragment)
{
	const char* oldSdpString = NULL;
	try {
		oldSdpString = GetHintTrackSdp(hintTrackId);
	}
	catch (MP4Error* e) {
		delete e;
		SetHintTrackSdp(hintTrackId, sdpFragment);
		return;
	}

	char* newSdpString =
		(char*)MP4Malloc(strlen(oldSdpString) + strlen(sdpFragment) + 1);
	strcpy(newSdpString, oldSdpString);
	strcat(newSdpString, sdpFragment);
	SetHintTrackSdp(hintTrackId, newSdpString);
	MP4Free(newSdpString);
}

void MP4File::GetHintTrackRtpPayload(
	MP4TrackId hintTrackId,
	char** ppPayloadName,
	u_int8_t* pPayloadNumber,
	u_int16_t* pMaxPayloadSize)
{
	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", 
			"MP4GetHintTrackRtpPayload");
	}

	((MP4RtpHintTrack*)pTrack)->GetPayload(
		ppPayloadName, pPayloadNumber, pMaxPayloadSize);
}

void MP4File::SetHintTrackRtpPayload(MP4TrackId hintTrackId,
	const char* payloadName, u_int8_t* pPayloadNumber, u_int16_t maxPayloadSize)
{
	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", 
			"MP4SetHintTrackRtpPayload");
	}

	u_int8_t payloadNumber;
	if (pPayloadNumber && *pPayloadNumber != 0) {
		payloadNumber = *pPayloadNumber;
	} else {
		payloadNumber = AllocRtpPayloadNumber();
		if (pPayloadNumber) {
			*pPayloadNumber = payloadNumber;
		}
	}

	((MP4RtpHintTrack*)pTrack)->SetPayload(
		payloadName, payloadNumber, maxPayloadSize);
}

u_int8_t MP4File::AllocRtpPayloadNumber()
{
	MP4Integer32Array usedPayloads;
	u_int32_t i;

	// collect rtp payload numbers in use by existing tracks
	for (i = 0; i < m_pTracks.Size(); i++) {
		MP4Atom* pTrakAtom = m_pTracks[i]->GetTrakAtom();

		MP4Integer32Property* pPayloadProperty = NULL;
		pTrakAtom->FindProperty("trak.udta.hinf.payt.payloadNumber",
			(MP4Property**)&pPayloadProperty);

		if (pPayloadProperty) {
			usedPayloads.Add(pPayloadProperty->GetValue());
		}
	}

	// search dynamic payload range for an available slot
	u_int8_t payload;
	for (payload = 96; payload < 128; payload++) {
		for (i = 0; i < usedPayloads.Size(); i++) {
			if (payload == usedPayloads[i]) {
				break;
			}
		}
		if (i == usedPayloads.Size()) {
			break;
		}
	}

	if (payload >= 128) {
		throw new MP4Error("no more available rtp payload numbers",
			"AllocRtpPayloadNumber");
	}

	return payload;
}

MP4TrackId MP4File::GetHintTrackReferenceTrackId(
	MP4TrackId hintTrackId)
{
	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", 
			"MP4GetHintTrackReferenceTrackId");
	}

	MP4Track* pRefTrack = ((MP4RtpHintTrack*)pTrack)->GetRefTrack();

	if (pRefTrack == NULL) {
		return MP4_INVALID_TRACK_ID;
	}
	return pRefTrack->GetId();
}

void MP4File::ReadRtpHint(
	MP4TrackId hintTrackId,
	MP4SampleId hintSampleId,
	u_int16_t* pNumPackets)
{
	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", "MP4ReadRtpHint");
	}
	((MP4RtpHintTrack*)pTrack)->
		ReadHint(hintSampleId, pNumPackets);
}

u_int16_t MP4File::GetRtpHintNumberOfPackets(
	MP4TrackId hintTrackId)
{
	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", 
			"MP4GetRtpHintNumberOfPackets");
	}
	return ((MP4RtpHintTrack*)pTrack)->GetHintNumberOfPackets();
}

int8_t MP4File::GetRtpPacketBFrame(
	MP4TrackId hintTrackId,
	u_int16_t packetIndex)
{
	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", 
			"MP4GetRtpHintBFrame");
	}
	return ((MP4RtpHintTrack*)pTrack)->GetPacketBFrame(packetIndex);
}

int32_t MP4File::GetRtpPacketTransmitOffset(
	MP4TrackId hintTrackId,
	u_int16_t packetIndex)
{
	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", 
			"MP4GetRtpPacketTransmitOffset");
	}
	return ((MP4RtpHintTrack*)pTrack)->GetPacketTransmitOffset(packetIndex);
}

void MP4File::ReadRtpPacket(
	MP4TrackId hintTrackId,
	u_int16_t packetIndex,
	u_int8_t** ppBytes, 
	u_int32_t* pNumBytes,
	u_int32_t ssrc,
	bool includeHeader,
	bool includePayload)
{
	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", "MP4ReadPacket");
	}
	((MP4RtpHintTrack*)pTrack)->ReadPacket(
		packetIndex, ppBytes, pNumBytes,
		ssrc, includeHeader, includePayload);
}

MP4Timestamp MP4File::GetRtpTimestampStart(
	MP4TrackId hintTrackId)
{
	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", 
			"MP4GetRtpTimestampStart");
	}
	return ((MP4RtpHintTrack*)pTrack)->GetRtpTimestampStart();
}

void MP4File::SetRtpTimestampStart(
	MP4TrackId hintTrackId,
	MP4Timestamp rtpStart)
{
	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", 
			"MP4SetRtpTimestampStart");
	}
	((MP4RtpHintTrack*)pTrack)->SetRtpTimestampStart(rtpStart);
}

void MP4File::AddRtpHint(MP4TrackId hintTrackId, 
	bool isBframe, u_int32_t timestampOffset)
{
	ProtectWriteOperation("MP4AddRtpHint");

	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", "MP4AddRtpHint");
	}
	((MP4RtpHintTrack*)pTrack)->AddHint(isBframe, timestampOffset);
}

void MP4File::AddRtpPacket(
	MP4TrackId hintTrackId, bool setMbit, int32_t transmitOffset)
{
	ProtectWriteOperation("MP4AddRtpPacket");

	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", "MP4AddRtpPacket");
	}
	((MP4RtpHintTrack*)pTrack)->AddPacket(setMbit, transmitOffset);
}

void MP4File::AddRtpImmediateData(MP4TrackId hintTrackId, 
	const u_int8_t* pBytes, u_int32_t numBytes)
{
	ProtectWriteOperation("MP4AddRtpImmediateData");

	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", 
			"MP4AddRtpImmediateData");
	}
	((MP4RtpHintTrack*)pTrack)->AddImmediateData(pBytes, numBytes);
}

void MP4File::AddRtpSampleData(MP4TrackId hintTrackId, 
	MP4SampleId sampleId, u_int32_t dataOffset, u_int32_t dataLength)
{
	ProtectWriteOperation("MP4AddRtpSampleData");

	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", 
			"MP4AddRtpSampleData");
	}
	((MP4RtpHintTrack*)pTrack)->AddSampleData(
		sampleId, dataOffset, dataLength);
}

void MP4File::AddRtpESConfigurationPacket(MP4TrackId hintTrackId)
{
	ProtectWriteOperation("MP4AddRtpESConfigurationPacket");

	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", 
			"MP4AddRtpESConfigurationPacket");
	}
	((MP4RtpHintTrack*)pTrack)->AddESConfigurationPacket();
}

void MP4File::WriteRtpHint(MP4TrackId hintTrackId,
	MP4Duration duration, bool isSyncSample)
{
	ProtectWriteOperation("MP4WriteRtpHint");

	MP4Track* pTrack = m_pTracks[FindTrackIndex(hintTrackId)];

	if (strcmp(pTrack->GetType(), MP4_HINT_TRACK_TYPE)) {
		throw new MP4Error("track is not a hint track", 
			"MP4WriteRtpHint");
	}
	((MP4RtpHintTrack*)pTrack)->WriteHint(duration, isSyncSample);
}

u_int64_t MP4File::ConvertFromMovieDuration(
	MP4Duration duration,
	u_int32_t timeScale)
{
	return MP4ConvertTime((u_int64_t)duration, 
		GetTimeScale(), timeScale);
}

u_int64_t MP4File::ConvertFromTrackTimestamp(
	MP4TrackId trackId, 
	MP4Timestamp timeStamp,
	u_int32_t timeScale)
{
	return MP4ConvertTime((u_int64_t)timeStamp, 
		GetTrackTimeScale(trackId), timeScale);
}

MP4Timestamp MP4File::ConvertToTrackTimestamp(
	MP4TrackId trackId, 
	u_int64_t timeStamp,
	u_int32_t timeScale)
{
	return (MP4Timestamp)MP4ConvertTime(timeStamp, 
		timeScale, GetTrackTimeScale(trackId));
}

u_int64_t MP4File::ConvertFromTrackDuration(
	MP4TrackId trackId, 
	MP4Duration duration,
	u_int32_t timeScale)
{
	return MP4ConvertTime((u_int64_t)duration, 
		GetTrackTimeScale(trackId), timeScale);
}

MP4Duration MP4File::ConvertToTrackDuration(
	MP4TrackId trackId, 
	u_int64_t duration,
	u_int32_t timeScale)
{
	return (MP4Duration)MP4ConvertTime(duration, 
		timeScale, GetTrackTimeScale(trackId));
}

u_int8_t MP4File::ConvertTrackTypeToStreamType(const char* trackType)
{
	u_int8_t streamType;

	if (!strcmp(trackType, MP4_OD_TRACK_TYPE)) {
		streamType = MP4ObjectDescriptionStreamType;
	} else if (!strcmp(trackType, MP4_SCENE_TRACK_TYPE)) {
		streamType = MP4SceneDescriptionStreamType;
	} else if (!strcmp(trackType, MP4_CLOCK_TRACK_TYPE)) {
		streamType = MP4ClockReferenceStreamType;
	} else if (!strcmp(trackType, MP4_MPEG7_TRACK_TYPE)) {
		streamType = MP4Mpeg7StreamType;
	} else if (!strcmp(trackType, MP4_OCI_TRACK_TYPE)) {
		streamType = MP4OCIStreamType;
	} else if (!strcmp(trackType, MP4_IPMP_TRACK_TYPE)) {
		streamType = MP4IPMPStreamType;
	} else if (!strcmp(trackType, MP4_MPEGJ_TRACK_TYPE)) {
		streamType = MP4MPEGJStreamType;
	} else {
		streamType = MP4UserPrivateStreamType;
	}

	return streamType;
}