ref: 64ab658728b7dd967598fbe89f4e1d7082bad8f4
dir: /common/mp4v2/mp4track.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 - 2004. All Rights Reserved.
*
* 3GPP features implementation is based on 3GPP's TS26.234-v5.60,
* and was contributed by Ximpo Group Ltd.
*
* Portions created by Ximpo Group Ltd. are
* Copyright (C) Ximpo Group Ltd. 2003, 2004. All Rights Reserved.
*
* Contributor(s):
* Dave Mackie dmackie@cisco.com
* Alix Marchandise-Franquet alix@cisco.com
* Ximpo Group Ltd. mp4v2@ximpo.com
*/
#include "mp4common.h"
#define AMR_UNINITIALIZED -1
#define AMR_TRUE 0
#define AMR_FALSE 1
MP4Track::MP4Track(MP4File* pFile, MP4Atom* pTrakAtom)
{
m_pFile = pFile;
m_pTrakAtom = pTrakAtom;
m_lastStsdIndex = 0;
m_lastSampleFile = NULL;
m_cachedReadSampleId = MP4_INVALID_SAMPLE_ID;
m_pCachedReadSample = NULL;
m_cachedReadSampleSize = 0;
m_writeSampleId = 1;
m_fixedSampleDuration = 0;
m_pChunkBuffer = NULL;
m_chunkBufferSize = 0;
m_chunkSamples = 0;
m_chunkDuration = 0;
m_samplesPerChunk = 0;
m_durationPerChunk = 0;
m_isAmr = AMR_UNINITIALIZED;
m_curMode = 0;
bool success = true;
MP4Integer32Property* pTrackIdProperty;
success &= m_pTrakAtom->FindProperty(
"trak.tkhd.trackId",
(MP4Property**)&pTrackIdProperty);
if (success) {
m_trackId = pTrackIdProperty->GetValue();
}
success &= m_pTrakAtom->FindProperty(
"trak.mdia.mdhd.timeScale",
(MP4Property**)&m_pTimeScaleProperty);
if (success) {
// default chunking is 1 second of samples
m_durationPerChunk = m_pTimeScaleProperty->GetValue();
}
success &= m_pTrakAtom->FindProperty(
"trak.tkhd.duration",
(MP4Property**)&m_pTrackDurationProperty);
success &= m_pTrakAtom->FindProperty(
"trak.mdia.mdhd.duration",
(MP4Property**)&m_pMediaDurationProperty);
success &= m_pTrakAtom->FindProperty(
"trak.tkhd.modificationTime",
(MP4Property**)&m_pTrackModificationProperty);
success &= m_pTrakAtom->FindProperty(
"trak.mdia.mdhd.modificationTime",
(MP4Property**)&m_pMediaModificationProperty);
success &= m_pTrakAtom->FindProperty(
"trak.mdia.hdlr.handlerType",
(MP4Property**)&m_pTypeProperty);
// get handles on sample size information
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stsz.sampleSize",
(MP4Property**)&m_pStszFixedSampleSizeProperty);
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stsz.sampleCount",
(MP4Property**)&m_pStszSampleCountProperty);
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stsz.entries.sampleSize",
(MP4Property**)&m_pStszSampleSizeProperty);
// get handles on information needed to map sample id's to file offsets
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stsc.entryCount",
(MP4Property**)&m_pStscCountProperty);
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stsc.entries.firstChunk",
(MP4Property**)&m_pStscFirstChunkProperty);
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stsc.entries.samplesPerChunk",
(MP4Property**)&m_pStscSamplesPerChunkProperty);
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stsc.entries.sampleDescriptionIndex",
(MP4Property**)&m_pStscSampleDescrIndexProperty);
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stsc.entries.firstSample",
(MP4Property**)&m_pStscFirstSampleProperty);
bool haveStco = m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stco.entryCount",
(MP4Property**)&m_pChunkCountProperty);
if (haveStco) {
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stco.entries.chunkOffset",
(MP4Property**)&m_pChunkOffsetProperty);
} else {
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.co64.entryCount",
(MP4Property**)&m_pChunkCountProperty);
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.co64.entries.chunkOffset",
(MP4Property**)&m_pChunkOffsetProperty);
}
// get handles on sample timing info
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stts.entryCount",
(MP4Property**)&m_pSttsCountProperty);
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stts.entries.sampleCount",
(MP4Property**)&m_pSttsSampleCountProperty);
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stts.entries.sampleDelta",
(MP4Property**)&m_pSttsSampleDeltaProperty);
// get handles on rendering offset info if it exists
m_pCttsCountProperty = NULL;
m_pCttsSampleCountProperty = NULL;
m_pCttsSampleOffsetProperty = NULL;
bool haveCtts = m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.ctts.entryCount",
(MP4Property**)&m_pCttsCountProperty);
if (haveCtts) {
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.ctts.entries.sampleCount",
(MP4Property**)&m_pCttsSampleCountProperty);
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.ctts.entries.sampleOffset",
(MP4Property**)&m_pCttsSampleOffsetProperty);
}
// get handles on sync sample info if it exists
m_pStssCountProperty = NULL;
m_pStssSampleProperty = NULL;
bool haveStss = m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stss.entryCount",
(MP4Property**)&m_pStssCountProperty);
if (haveStss) {
success &= m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stss.entries.sampleNumber",
(MP4Property**)&m_pStssSampleProperty);
}
// edit list
InitEditListProperties();
// was everything found?
if (!success) {
throw new MP4Error("invalid track", "MP4Track::MP4Track");
}
}
MP4Track::~MP4Track()
{
MP4Free(m_pCachedReadSample);
MP4Free(m_pChunkBuffer);
}
const char* MP4Track::GetType()
{
return m_pTypeProperty->GetValue();
}
void MP4Track::SetType(const char* type)
{
m_pTypeProperty->SetValue(NormalizeTrackType(type));
}
void MP4Track::ReadSample(
MP4SampleId sampleId,
u_int8_t** ppBytes,
u_int32_t* pNumBytes,
MP4Timestamp* pStartTime,
MP4Duration* pDuration,
MP4Duration* pRenderingOffset,
bool* pIsSyncSample)
{
if (sampleId == MP4_INVALID_SAMPLE_ID) {
throw new MP4Error("sample id can't be zero",
"MP4Track::ReadSample");
}
// handle unusual case of wanting to read a sample
// that is still sitting in the write chunk buffer
if (m_pChunkBuffer && sampleId >= m_writeSampleId - m_chunkSamples) {
WriteChunkBuffer();
}
FILE* pFile = GetSampleFile(sampleId);
if (pFile == (FILE*)-1) {
throw new MP4Error("sample is located in an inaccessible file",
"MP4Track::ReadSample");
}
u_int64_t fileOffset = GetSampleFileOffset(sampleId);
u_int32_t sampleSize = GetSampleSize(sampleId);
if (*ppBytes != NULL && *pNumBytes < sampleSize) {
throw new MP4Error("sample buffer is too small",
"MP4Track::ReadSample");
}
*pNumBytes = sampleSize;
VERBOSE_READ_SAMPLE(m_pFile->GetVerbosity(),
printf("ReadSample: track %u id %u offset 0x"X64" size %u (0x%x)\n",
m_trackId, sampleId, fileOffset, *pNumBytes, *pNumBytes));
bool bufferMalloc = false;
if (*ppBytes == NULL) {
*ppBytes = (u_int8_t*)MP4Malloc(*pNumBytes);
bufferMalloc = true;
}
u_int64_t oldPos = m_pFile->GetPosition(pFile); // only used in mode == 'w'
try {
m_pFile->SetPosition(fileOffset, pFile);
m_pFile->ReadBytes(*ppBytes, *pNumBytes, pFile);
if (pStartTime || pDuration) {
GetSampleTimes(sampleId, pStartTime, pDuration);
VERBOSE_READ_SAMPLE(m_pFile->GetVerbosity(),
printf("ReadSample: start "U64" duration "D64"\n",
(pStartTime ? *pStartTime : 0),
(pDuration ? *pDuration : 0)));
}
if (pRenderingOffset) {
*pRenderingOffset = GetSampleRenderingOffset(sampleId);
VERBOSE_READ_SAMPLE(m_pFile->GetVerbosity(),
printf("ReadSample: renderingOffset "D64"\n",
*pRenderingOffset));
}
if (pIsSyncSample) {
*pIsSyncSample = IsSyncSample(sampleId);
VERBOSE_READ_SAMPLE(m_pFile->GetVerbosity(),
printf("ReadSample: isSyncSample %u\n",
*pIsSyncSample));
}
}
catch (MP4Error* e) {
if (bufferMalloc) {
// let's not leak memory
MP4Free(*ppBytes);
*ppBytes = NULL;
}
if (m_pFile->GetMode() == 'w') {
m_pFile->SetPosition(oldPos, pFile);
}
throw e;
}
if (m_pFile->GetMode() == 'w') {
m_pFile->SetPosition(oldPos, pFile);
}
}
void MP4Track::ReadSampleFragment(
MP4SampleId sampleId,
u_int32_t sampleOffset,
u_int16_t sampleLength,
u_int8_t* pDest)
{
if (sampleId == MP4_INVALID_SAMPLE_ID) {
throw new MP4Error("invalid sample id",
"MP4Track::ReadSampleFragment");
}
if (sampleId != m_cachedReadSampleId) {
MP4Free(m_pCachedReadSample);
m_pCachedReadSample = NULL;
m_cachedReadSampleSize = 0;
m_cachedReadSampleId = MP4_INVALID_SAMPLE_ID;
ReadSample(
sampleId,
&m_pCachedReadSample,
&m_cachedReadSampleSize);
m_cachedReadSampleId = sampleId;
}
if (sampleOffset + sampleLength > m_cachedReadSampleSize) {
throw new MP4Error("offset and/or length are too large",
"MP4Track::ReadSampleFragment");
}
memcpy(pDest, &m_pCachedReadSample[sampleOffset], sampleLength);
}
void MP4Track::WriteSample(
const u_int8_t* pBytes,
u_int32_t numBytes,
MP4Duration duration,
MP4Duration renderingOffset,
bool isSyncSample)
{
u_int8_t curMode = 0;
VERBOSE_WRITE_SAMPLE(m_pFile->GetVerbosity(),
printf("WriteSample: track %u id %u size %u (0x%x) ",
m_trackId, m_writeSampleId, numBytes, numBytes));
if (pBytes == NULL && numBytes > 0) {
throw new MP4Error("no sample data", "MP4WriteSample");
}
if (m_isAmr == AMR_UNINITIALIZED ) {
// figure out if this is an AMR audio track
if (m_pTrakAtom->FindAtom("trak.mdia.minf.stbl.stsd.samr") ||
m_pTrakAtom->FindAtom("trak.mdia.minf.stbl.stsd.sawb")) {
m_isAmr = AMR_TRUE;
m_curMode = (pBytes[0] >> 3) & 0x000F;
} else {
m_isAmr = AMR_FALSE;
}
}
if (m_isAmr == AMR_TRUE) {
curMode = (pBytes[0] >> 3) &0x000F; // The mode is in the first byte
}
if (duration == MP4_INVALID_DURATION) {
duration = GetFixedSampleDuration();
}
VERBOSE_WRITE_SAMPLE(m_pFile->GetVerbosity(),
printf("duration "U64"\n", duration));
if ((m_isAmr == AMR_TRUE) &&
(m_curMode != curMode)) {
WriteChunkBuffer();
m_curMode = curMode;
}
// append sample bytes to chunk buffer
m_pChunkBuffer = (u_int8_t*)MP4Realloc(m_pChunkBuffer,
m_chunkBufferSize + numBytes);
memcpy(&m_pChunkBuffer[m_chunkBufferSize], pBytes, numBytes);
m_chunkBufferSize += numBytes;
m_chunkSamples++;
m_chunkDuration += duration;
UpdateSampleSizes(m_writeSampleId, numBytes);
UpdateSampleTimes(duration);
UpdateRenderingOffsets(m_writeSampleId, renderingOffset);
UpdateSyncSamples(m_writeSampleId, isSyncSample);
if ((m_isAmr == AMR_FALSE) &&
IsChunkFull(m_writeSampleId)) {
WriteChunkBuffer();
m_curMode = curMode;
}
UpdateDurations(duration);
UpdateModificationTimes();
m_writeSampleId++;
}
void MP4Track::WriteChunkBuffer()
{
if (m_chunkBufferSize == 0) {
return;
}
u_int64_t chunkOffset = m_pFile->GetPosition();
// write chunk buffer
m_pFile->WriteBytes(m_pChunkBuffer, m_chunkBufferSize);
VERBOSE_WRITE_SAMPLE(m_pFile->GetVerbosity(),
printf("WriteChunk: track %u offset 0x"X64" size %u (0x%x) numSamples %u\n",
m_trackId, chunkOffset, m_chunkBufferSize,
m_chunkBufferSize, m_chunkSamples));
UpdateSampleToChunk(m_writeSampleId,
m_pChunkCountProperty->GetValue() + 1,
m_chunkSamples);
UpdateChunkOffsets(chunkOffset);
// clean up chunk buffer
MP4Free(m_pChunkBuffer);
m_pChunkBuffer = NULL;
m_chunkBufferSize = 0;
m_chunkSamples = 0;
m_chunkDuration = 0;
}
void MP4Track::FinishWrite()
{
// write out any remaining samples in chunk buffer
WriteChunkBuffer();
// record buffer size and bitrates
MP4BitfieldProperty* pBufferSizeProperty;
if (m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stsd.*.esds.decConfigDescr.bufferSizeDB",
(MP4Property**)&pBufferSizeProperty)) {
pBufferSizeProperty->SetValue(GetMaxSampleSize());
}
MP4Integer32Property* pBitrateProperty;
if (m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stsd.*.esds.decConfigDescr.maxBitrate",
(MP4Property**)&pBitrateProperty)) {
pBitrateProperty->SetValue(GetMaxBitrate());
}
if (m_pTrakAtom->FindProperty(
"trak.mdia.minf.stbl.stsd.*.esds.decConfigDescr.avgBitrate",
(MP4Property**)&pBitrateProperty)) {
pBitrateProperty->SetValue(GetAvgBitrate());
}
}
bool MP4Track::IsChunkFull(MP4SampleId sampleId)
{
if (m_samplesPerChunk) {
return m_chunkSamples >= m_samplesPerChunk;
}
ASSERT(m_durationPerChunk);
return m_chunkDuration >= m_durationPerChunk;
}
u_int32_t MP4Track::GetNumberOfSamples()
{
return m_pStszSampleCountProperty->GetValue();
}
u_int32_t MP4Track::GetSampleSize(MP4SampleId sampleId)
{
u_int32_t fixedSampleSize =
m_pStszFixedSampleSizeProperty->GetValue();
if (fixedSampleSize != 0) {
return fixedSampleSize;
}
return m_pStszSampleSizeProperty->GetValue(sampleId - 1);
}
u_int32_t MP4Track::GetMaxSampleSize()
{
u_int32_t fixedSampleSize =
m_pStszFixedSampleSizeProperty->GetValue();
if (fixedSampleSize != 0) {
return fixedSampleSize;
}
u_int32_t maxSampleSize = 0;
u_int32_t numSamples = m_pStszSampleSizeProperty->GetCount();
for (MP4SampleId sid = 1; sid <= numSamples; sid++) {
u_int32_t sampleSize =
m_pStszSampleSizeProperty->GetValue(sid - 1);
if (sampleSize > maxSampleSize) {
maxSampleSize = sampleSize;
}
}
return maxSampleSize;
}
u_int64_t MP4Track::GetTotalOfSampleSizes()
{
u_int32_t fixedSampleSize =
m_pStszFixedSampleSizeProperty->GetValue();
// if fixed sample size, just need to multiply by number of samples
if (fixedSampleSize != 0) {
return fixedSampleSize * GetNumberOfSamples();
}
// else non-fixed sample size, sum them
u_int64_t totalSampleSizes = 0;
u_int32_t numSamples = m_pStszSampleSizeProperty->GetCount();
for (MP4SampleId sid = 1; sid <= numSamples; sid++) {
u_int32_t sampleSize =
m_pStszSampleSizeProperty->GetValue(sid - 1);
totalSampleSizes += sampleSize;
}
return totalSampleSizes;
}
void MP4Track::UpdateSampleSizes(MP4SampleId sampleId, u_int32_t numBytes)
{
// for first sample
if (sampleId == 1) {
if (numBytes > 0) {
// presume sample size is fixed
m_pStszFixedSampleSizeProperty->SetValue(numBytes);
} else {
// special case of first sample is zero bytes in length
// leave m_pStszFixedSampleSizeProperty at 0
// start recording variable sample sizes
m_pStszSampleSizeProperty->AddValue(0);
}
} else { // sampleId > 1
u_int32_t fixedSampleSize =
m_pStszFixedSampleSizeProperty->GetValue();
if (fixedSampleSize == 0 || numBytes != fixedSampleSize) {
// sample size is not fixed
if (fixedSampleSize) {
// need to clear fixed sample size
m_pStszFixedSampleSizeProperty->SetValue(0);
// and create sizes for all previous samples
for (MP4SampleId sid = 1; sid < sampleId; sid++) {
m_pStszSampleSizeProperty->AddValue(fixedSampleSize);
}
}
// add size value for this sample
m_pStszSampleSizeProperty->AddValue(numBytes);
}
}
m_pStszSampleCountProperty->IncrementValue();
}
u_int32_t MP4Track::GetAvgBitrate()
{
if (GetDuration() == 0) {
return 0;
}
u_int64_t durationSecs =
MP4ConvertTime(GetDuration(), GetTimeScale(), MP4_SECS_TIME_SCALE);
if (GetDuration() % GetTimeScale() != 0) {
durationSecs++;
}
return (GetTotalOfSampleSizes() * 8) / durationSecs;
}
u_int32_t MP4Track::GetMaxBitrate()
{
u_int32_t timeScale = GetTimeScale();
MP4SampleId numSamples = GetNumberOfSamples();
u_int32_t maxBytesPerSec = 0;
u_int32_t bytesThisSec = 0;
MP4Timestamp thisSec = 0;
for (MP4SampleId sid = 1; sid <= numSamples; sid++) {
u_int32_t sampleSize;
MP4Timestamp sampleTime;
sampleSize = GetSampleSize(sid);
GetSampleTimes(sid, &sampleTime, NULL);
// sample counts for current second
if (sampleTime < thisSec + timeScale) {
bytesThisSec += sampleSize;
} else { // sample is in a future second
if (bytesThisSec > maxBytesPerSec) {
maxBytesPerSec = bytesThisSec;
}
thisSec = sampleTime - (sampleTime % timeScale);
bytesThisSec = sampleSize;
}
}
// last second (or partial second)
if (bytesThisSec > maxBytesPerSec) {
maxBytesPerSec = bytesThisSec;
}
return maxBytesPerSec * 8;
}
u_int32_t MP4Track::GetSampleStscIndex(MP4SampleId sampleId)
{
u_int32_t stscIndex;
u_int32_t numStscs = m_pStscCountProperty->GetValue();
if (numStscs == 0) {
throw new MP4Error("No data chunks exist", "GetSampleStscIndex");
}
for (stscIndex = 0; stscIndex < numStscs; stscIndex++) {
if (sampleId < m_pStscFirstSampleProperty->GetValue(stscIndex)) {
ASSERT(stscIndex != 0);
stscIndex -= 1;
break;
}
}
if (stscIndex == numStscs) {
ASSERT(stscIndex != 0);
stscIndex -= 1;
}
return stscIndex;
}
FILE* MP4Track::GetSampleFile(MP4SampleId sampleId)
{
u_int32_t stscIndex =
GetSampleStscIndex(sampleId);
u_int32_t stsdIndex =
m_pStscSampleDescrIndexProperty->GetValue(stscIndex);
// check if the answer will be the same as last time
if (m_lastStsdIndex && stsdIndex == m_lastStsdIndex) {
return m_lastSampleFile;
}
MP4Atom* pStsdAtom =
m_pTrakAtom->FindAtom("trak.mdia.minf.stbl.stsd");
ASSERT(pStsdAtom);
MP4Atom* pStsdEntryAtom =
pStsdAtom->GetChildAtom(stsdIndex - 1);
ASSERT(pStsdEntryAtom);
MP4Integer16Property* pDrefIndexProperty = NULL;
pStsdEntryAtom->FindProperty(
"*.dataReferenceIndex",
(MP4Property**)&pDrefIndexProperty);
if (pDrefIndexProperty == NULL) {
throw new MP4Error("invalid stsd entry", "GetSampleFile");
}
u_int32_t drefIndex =
pDrefIndexProperty->GetValue();
MP4Atom* pDrefAtom =
m_pTrakAtom->FindAtom("trak.mdia.minf.dinf.dref");
ASSERT(pDrefAtom);
MP4Atom* pUrlAtom =
pDrefAtom->GetChildAtom(drefIndex - 1);
ASSERT(pUrlAtom);
FILE* pFile;
if (pUrlAtom->GetFlags() & 1) {
pFile = NULL; // self-contained
} else {
MP4StringProperty* pLocationProperty = NULL;
pUrlAtom->FindProperty(
"*.location",
(MP4Property**)&pLocationProperty);
ASSERT(pLocationProperty);
const char* url = pLocationProperty->GetValue();
VERBOSE_READ_SAMPLE(m_pFile->GetVerbosity(),
printf("dref url = %s\n", url));
pFile = (FILE*)-1;
// attempt to open url if it's a file url
// currently this is the only thing we understand
if (!strncmp(url, "file:", 5)) {
const char* fileName = url + 5;
if (!strncmp(fileName, "//", 2)) {
fileName = strchr(fileName + 2, '/');
}
if (fileName) {
pFile = fopen(fileName, "rb");
if (!pFile) {
pFile = (FILE*)-1;
}
}
}
}
if (m_lastSampleFile) {
fclose(m_lastSampleFile);
}
// cache the answer
m_lastStsdIndex = stsdIndex;
m_lastSampleFile = pFile;
return pFile;
}
u_int64_t MP4Track::GetSampleFileOffset(MP4SampleId sampleId)
{
u_int32_t stscIndex =
GetSampleStscIndex(sampleId);
u_int32_t firstChunk =
m_pStscFirstChunkProperty->GetValue(stscIndex);
MP4SampleId firstSample =
m_pStscFirstSampleProperty->GetValue(stscIndex);
u_int32_t samplesPerChunk =
m_pStscSamplesPerChunkProperty->GetValue(stscIndex);
MP4ChunkId chunkId = firstChunk +
((sampleId - firstSample) / samplesPerChunk);
u_int64_t chunkOffset = m_pChunkOffsetProperty->GetValue(chunkId - 1);
MP4SampleId firstSampleInChunk =
sampleId - ((sampleId - firstSample) % samplesPerChunk);
// need cumulative samples sizes from firstSample to sampleId - 1
u_int32_t sampleOffset = 0;
for (MP4SampleId i = firstSampleInChunk; i < sampleId; i++) {
sampleOffset += GetSampleSize(i);
}
return chunkOffset + sampleOffset;
}
void MP4Track::UpdateSampleToChunk(MP4SampleId sampleId,
MP4ChunkId chunkId, u_int32_t samplesPerChunk)
{
u_int32_t numStsc = m_pStscCountProperty->GetValue();
// if samplesPerChunk == samplesPerChunk of last entry
if (numStsc && samplesPerChunk ==
m_pStscSamplesPerChunkProperty->GetValue(numStsc-1)) {
// nothing to do
} else {
// add stsc entry
m_pStscFirstChunkProperty->AddValue(chunkId);
m_pStscSamplesPerChunkProperty->AddValue(samplesPerChunk);
m_pStscSampleDescrIndexProperty->AddValue(1);
m_pStscFirstSampleProperty->AddValue(sampleId - samplesPerChunk + 1);
m_pStscCountProperty->IncrementValue();
}
}
void MP4Track::UpdateChunkOffsets(u_int64_t chunkOffset)
{
if (m_pChunkOffsetProperty->GetType() == Integer32Property) {
((MP4Integer32Property*)m_pChunkOffsetProperty)->AddValue(chunkOffset);
} else {
((MP4Integer64Property*)m_pChunkOffsetProperty)->AddValue(chunkOffset);
}
m_pChunkCountProperty->IncrementValue();
}
MP4Duration MP4Track::GetFixedSampleDuration()
{
u_int32_t numStts = m_pSttsCountProperty->GetValue();
if (numStts == 0) {
return m_fixedSampleDuration;
}
if (numStts != 1) {
return MP4_INVALID_DURATION; // sample duration is not fixed
}
return m_pSttsSampleDeltaProperty->GetValue(0);
}
bool MP4Track::SetFixedSampleDuration(MP4Duration duration)
{
u_int32_t numStts = m_pSttsCountProperty->GetValue();
// setting this is only allowed before samples have been written
if (numStts != 0) {
return false;
}
m_fixedSampleDuration = duration;
return true;
}
void MP4Track::GetSampleTimes(MP4SampleId sampleId,
MP4Timestamp* pStartTime, MP4Duration* pDuration)
{
u_int32_t numStts = m_pSttsCountProperty->GetValue();
MP4SampleId sid = 1;
MP4Duration elapsed = 0;
for (u_int32_t sttsIndex = 0; sttsIndex < numStts; sttsIndex++) {
u_int32_t sampleCount =
m_pSttsSampleCountProperty->GetValue(sttsIndex);
u_int32_t sampleDelta =
m_pSttsSampleDeltaProperty->GetValue(sttsIndex);
if (sampleId <= sid + sampleCount - 1) {
if (pStartTime) {
*pStartTime = (sampleId - sid);
*pStartTime *= sampleDelta;
*pStartTime += elapsed;
}
if (pDuration) {
*pDuration = sampleDelta;
}
return;
}
sid += sampleCount;
elapsed += sampleCount * sampleDelta;
}
throw new MP4Error("sample id out of range",
"MP4Track::GetSampleTimes");
}
MP4SampleId MP4Track::GetSampleIdFromTime(
MP4Timestamp when,
bool wantSyncSample)
{
u_int32_t numStts = m_pSttsCountProperty->GetValue();
MP4SampleId sid = 1;
MP4Duration elapsed = 0;
for (u_int32_t sttsIndex = 0; sttsIndex < numStts; sttsIndex++) {
u_int32_t sampleCount =
m_pSttsSampleCountProperty->GetValue(sttsIndex);
u_int32_t sampleDelta =
m_pSttsSampleDeltaProperty->GetValue(sttsIndex);
if (sampleDelta == 0 && sttsIndex < numStts - 1) {
VERBOSE_READ(m_pFile->GetVerbosity(),
printf("Warning: Zero sample duration, stts entry %u\n",
sttsIndex));
}
MP4Duration d = when - elapsed;
if (d <= sampleCount * sampleDelta) {
MP4SampleId sampleId = sid;
if (sampleDelta) {
sampleId += (d / sampleDelta);
}
if (wantSyncSample) {
return GetNextSyncSample(sampleId);
}
return sampleId;
}
sid += sampleCount;
elapsed += sampleCount * sampleDelta;
}
throw new MP4Error("time out of range",
"MP4Track::GetSampleIdFromTime");
return 0; // satisfy MS compiler
}
void MP4Track::UpdateSampleTimes(MP4Duration duration)
{
u_int32_t numStts = m_pSttsCountProperty->GetValue();
// if duration == duration of last entry
if (numStts
&& duration == m_pSttsSampleDeltaProperty->GetValue(numStts-1)) {
// increment last entry sampleCount
m_pSttsSampleCountProperty->IncrementValue(1, numStts-1);
} else {
// add stts entry, sampleCount = 1, sampleDuration = duration
m_pSttsSampleCountProperty->AddValue(1);
m_pSttsSampleDeltaProperty->AddValue(duration);
m_pSttsCountProperty->IncrementValue();;
}
}
u_int32_t MP4Track::GetSampleCttsIndex(MP4SampleId sampleId,
MP4SampleId* pFirstSampleId)
{
u_int32_t numCtts = m_pCttsCountProperty->GetValue();
MP4SampleId sid = 1;
for (u_int32_t cttsIndex = 0; cttsIndex < numCtts; cttsIndex++) {
u_int32_t sampleCount =
m_pCttsSampleCountProperty->GetValue(cttsIndex);
if (sampleId <= sid + sampleCount - 1) {
if (pFirstSampleId) {
*pFirstSampleId = sid;
}
return cttsIndex;
}
sid += sampleCount;
}
throw new MP4Error("sample id out of range",
"MP4Track::GetSampleCttsIndex");
return 0; // satisfy MS compiler
}
MP4Duration MP4Track::GetSampleRenderingOffset(MP4SampleId sampleId)
{
if (m_pCttsCountProperty == NULL) {
return 0;
}
if (m_pCttsCountProperty->GetValue() == 0) {
return 0;
}
u_int32_t cttsIndex = GetSampleCttsIndex(sampleId);
return m_pCttsSampleOffsetProperty->GetValue(cttsIndex);
}
void MP4Track::UpdateRenderingOffsets(MP4SampleId sampleId,
MP4Duration renderingOffset)
{
// if ctts atom doesn't exist
if (m_pCttsCountProperty == NULL) {
// no rendering offset, so nothing to do
if (renderingOffset == 0) {
return;
}
// else create a ctts atom
MP4Atom* pCttsAtom = AddAtom("trak.mdia.minf.stbl", "ctts");
// and get handles on the properties
pCttsAtom->FindProperty(
"ctts.entryCount",
(MP4Property**)&m_pCttsCountProperty);
pCttsAtom->FindProperty(
"ctts.entries.sampleCount",
(MP4Property**)&m_pCttsSampleCountProperty);
pCttsAtom->FindProperty(
"ctts.entries.sampleOffset",
(MP4Property**)&m_pCttsSampleOffsetProperty);
// if this is not the first sample
if (sampleId > 1) {
// add a ctts entry for all previous samples
// with rendering offset equal to zero
m_pCttsSampleCountProperty->AddValue(sampleId - 1);
m_pCttsSampleOffsetProperty->AddValue(0);
m_pCttsCountProperty->IncrementValue();;
}
}
// ctts atom exists (now)
u_int32_t numCtts = m_pCttsCountProperty->GetValue();
// if renderingOffset == renderingOffset of last entry
if (numCtts && renderingOffset
== m_pCttsSampleOffsetProperty->GetValue(numCtts-1)) {
// increment last entry sampleCount
m_pCttsSampleCountProperty->IncrementValue(1, numCtts-1);
} else {
// add ctts entry, sampleCount = 1, sampleOffset = renderingOffset
m_pCttsSampleCountProperty->AddValue(1);
m_pCttsSampleOffsetProperty->AddValue(renderingOffset);
m_pCttsCountProperty->IncrementValue();
}
}
void MP4Track::SetSampleRenderingOffset(MP4SampleId sampleId,
MP4Duration renderingOffset)
{
// check if any ctts entries exist
if (m_pCttsCountProperty == NULL
|| m_pCttsCountProperty->GetValue() == 0) {
// if not then Update routine can be used
// to create a ctts entry for samples before this one
// and a ctts entry for this sample
UpdateRenderingOffsets(sampleId, renderingOffset);
// but we also need a ctts entry
// for all samples after this one
u_int32_t afterSamples = GetNumberOfSamples() - sampleId;
if (afterSamples) {
m_pCttsSampleCountProperty->AddValue(afterSamples);
m_pCttsSampleOffsetProperty->AddValue(0);
m_pCttsCountProperty->IncrementValue();;
}
return;
}
MP4SampleId firstSampleId;
u_int32_t cttsIndex = GetSampleCttsIndex(sampleId, &firstSampleId);
// do nothing in the degenerate case
if (renderingOffset ==
m_pCttsSampleOffsetProperty->GetValue(cttsIndex)) {
return;
}
u_int32_t sampleCount =
m_pCttsSampleCountProperty->GetValue(cttsIndex);
// if this sample has it's own ctts entry
if (sampleCount == 1) {
// then just set the value,
// note we don't attempt to collapse entries
m_pCttsSampleOffsetProperty->SetValue(renderingOffset, cttsIndex);
return;
}
MP4SampleId lastSampleId = firstSampleId + sampleCount - 1;
// else we share this entry with other samples
// we need to insert our own entry
if (sampleId == firstSampleId) {
// our sample is the first one
m_pCttsSampleCountProperty->
InsertValue(1, cttsIndex);
m_pCttsSampleOffsetProperty->
InsertValue(renderingOffset, cttsIndex);
m_pCttsSampleCountProperty->
SetValue(sampleCount - 1, cttsIndex + 1);
m_pCttsCountProperty->IncrementValue();
} else if (sampleId == lastSampleId) {
// our sample is the last one
m_pCttsSampleCountProperty->
InsertValue(1, cttsIndex + 1);
m_pCttsSampleOffsetProperty->
InsertValue(renderingOffset, cttsIndex + 1);
m_pCttsSampleCountProperty->
SetValue(sampleCount - 1, cttsIndex);
m_pCttsCountProperty->IncrementValue();
} else {
// our sample is in the middle, UGH!
// insert our new entry
m_pCttsSampleCountProperty->
InsertValue(1, cttsIndex + 1);
m_pCttsSampleOffsetProperty->
InsertValue(renderingOffset, cttsIndex + 1);
// adjust count of previous entry
m_pCttsSampleCountProperty->
SetValue(sampleId - firstSampleId, cttsIndex);
// insert new entry for those samples beyond our sample
m_pCttsSampleCountProperty->
InsertValue(lastSampleId - sampleId, cttsIndex + 2);
u_int32_t oldRenderingOffset =
m_pCttsSampleOffsetProperty->GetValue(cttsIndex);
m_pCttsSampleOffsetProperty->
InsertValue(oldRenderingOffset, cttsIndex + 2);
m_pCttsCountProperty->IncrementValue(2);
}
}
bool MP4Track::IsSyncSample(MP4SampleId sampleId)
{
if (m_pStssCountProperty == NULL) {
return true;
}
u_int32_t numStss = m_pStssCountProperty->GetValue();
for (u_int32_t stssIndex = 0; stssIndex < numStss; stssIndex++) {
MP4SampleId syncSampleId =
m_pStssSampleProperty->GetValue(stssIndex);
if (sampleId == syncSampleId) {
return true;
}
if (sampleId < syncSampleId) {
break;
}
}
return false;
}
// N.B. "next" is inclusive of this sample id
MP4SampleId MP4Track::GetNextSyncSample(MP4SampleId sampleId)
{
if (m_pStssCountProperty == NULL) {
return sampleId;
}
u_int32_t numStss = m_pStssCountProperty->GetValue();
for (u_int32_t stssIndex = 0; stssIndex < numStss; stssIndex++) {
MP4SampleId syncSampleId =
m_pStssSampleProperty->GetValue(stssIndex);
if (sampleId > syncSampleId) {
continue;
}
return syncSampleId;
}
// LATER check stsh for alternate sample
return MP4_INVALID_SAMPLE_ID;
}
void MP4Track::UpdateSyncSamples(MP4SampleId sampleId, bool isSyncSample)
{
if (isSyncSample) {
// if stss atom exists, add entry
if (m_pStssCountProperty) {
m_pStssSampleProperty->AddValue(sampleId);
m_pStssCountProperty->IncrementValue();
} // else nothing to do (yet)
} else { // !isSyncSample
// if stss atom doesn't exist, create one
if (m_pStssCountProperty == NULL) {
MP4Atom* pStssAtom = AddAtom("trak.mdia.minf.stbl", "stss");
pStssAtom->FindProperty(
"stss.entryCount",
(MP4Property**)&m_pStssCountProperty);
pStssAtom->FindProperty(
"stss.entries.sampleNumber",
(MP4Property**)&m_pStssSampleProperty);
// set values for all samples that came before this one
for (MP4SampleId sid = 1; sid < sampleId; sid++) {
m_pStssSampleProperty->AddValue(sid);
m_pStssCountProperty->IncrementValue();
}
} // else nothing to do
}
}
MP4Atom* MP4Track::AddAtom(char* parentName, char* childName)
{
MP4Atom* pChildAtom = MP4Atom::CreateAtom(childName);
MP4Atom* pParentAtom = m_pTrakAtom->FindAtom(parentName);
ASSERT(pParentAtom);
pParentAtom->AddChildAtom(pChildAtom);
pChildAtom->Generate();
return pChildAtom;
}
u_int64_t MP4Track::GetDuration()
{
return m_pMediaDurationProperty->GetValue();
}
u_int32_t MP4Track::GetTimeScale()
{
return m_pTimeScaleProperty->GetValue();
}
void MP4Track::UpdateDurations(MP4Duration duration)
{
// update media, track, and movie durations
m_pMediaDurationProperty->SetValue(
m_pMediaDurationProperty->GetValue() + duration);
MP4Duration movieDuration = ToMovieDuration(duration);
m_pTrackDurationProperty->SetValue(
m_pTrackDurationProperty->GetValue() + movieDuration);
m_pFile->UpdateDuration(m_pTrackDurationProperty->GetValue());
}
MP4Duration MP4Track::ToMovieDuration(MP4Duration trackDuration)
{
return (trackDuration * m_pFile->GetTimeScale())
/ m_pTimeScaleProperty->GetValue();
}
void MP4Track::UpdateModificationTimes()
{
// update media and track modification times
MP4Timestamp now = MP4GetAbsTimestamp();
m_pMediaModificationProperty->SetValue(now);
m_pTrackModificationProperty->SetValue(now);
}
u_int32_t MP4Track::GetNumberOfChunks()
{
return m_pChunkOffsetProperty->GetCount();
}
u_int32_t MP4Track::GetChunkStscIndex(MP4ChunkId chunkId)
{
u_int32_t stscIndex;
u_int32_t numStscs = m_pStscCountProperty->GetValue();
ASSERT(chunkId);
ASSERT(numStscs > 0);
for (stscIndex = 0; stscIndex < numStscs; stscIndex++) {
if (chunkId < m_pStscFirstChunkProperty->GetValue(stscIndex)) {
ASSERT(stscIndex != 0);
break;
}
}
return stscIndex - 1;
}
MP4Timestamp MP4Track::GetChunkTime(MP4ChunkId chunkId)
{
u_int32_t stscIndex = GetChunkStscIndex(chunkId);
MP4ChunkId firstChunkId =
m_pStscFirstChunkProperty->GetValue(stscIndex);
MP4SampleId firstSample =
m_pStscFirstSampleProperty->GetValue(stscIndex);
u_int32_t samplesPerChunk =
m_pStscSamplesPerChunkProperty->GetValue(stscIndex);
MP4SampleId firstSampleInChunk =
firstSample + ((chunkId - firstChunkId) * samplesPerChunk);
MP4Timestamp chunkTime;
GetSampleTimes(firstSampleInChunk, &chunkTime, NULL);
return chunkTime;
}
u_int32_t MP4Track::GetChunkSize(MP4ChunkId chunkId)
{
u_int32_t stscIndex = GetChunkStscIndex(chunkId);
MP4ChunkId firstChunkId =
m_pStscFirstChunkProperty->GetValue(stscIndex);
MP4SampleId firstSample =
m_pStscFirstSampleProperty->GetValue(stscIndex);
u_int32_t samplesPerChunk =
m_pStscSamplesPerChunkProperty->GetValue(stscIndex);
MP4SampleId firstSampleInChunk =
firstSample + ((chunkId - firstChunkId) * samplesPerChunk);
// need cumulative sizes of samples in chunk
u_int32_t chunkSize = 0;
for (u_int32_t i = 0; i < samplesPerChunk; i++) {
chunkSize += GetSampleSize(firstSampleInChunk + i);
}
return chunkSize;
}
void MP4Track::ReadChunk(MP4ChunkId chunkId,
u_int8_t** ppChunk, u_int32_t* pChunkSize)
{
ASSERT(chunkId);
ASSERT(ppChunk);
ASSERT(pChunkSize);
u_int64_t chunkOffset =
m_pChunkOffsetProperty->GetValue(chunkId - 1);
*pChunkSize = GetChunkSize(chunkId);
*ppChunk = (u_int8_t*)MP4Malloc(*pChunkSize);
VERBOSE_READ_SAMPLE(m_pFile->GetVerbosity(),
printf("ReadChunk: track %u id %u offset 0x"X64" size %u (0x%x)\n",
m_trackId, chunkId, chunkOffset, *pChunkSize, *pChunkSize));
u_int64_t oldPos = m_pFile->GetPosition(); // only used in mode == 'w'
try {
m_pFile->SetPosition(chunkOffset);
m_pFile->ReadBytes(*ppChunk, *pChunkSize);
}
catch (MP4Error* e) {
// let's not leak memory
MP4Free(*ppChunk);
*ppChunk = NULL;
if (m_pFile->GetMode() == 'w') {
m_pFile->SetPosition(oldPos);
}
throw e;
}
if (m_pFile->GetMode() == 'w') {
m_pFile->SetPosition(oldPos);
}
}
void MP4Track::RewriteChunk(MP4ChunkId chunkId,
u_int8_t* pChunk, u_int32_t chunkSize)
{
u_int64_t chunkOffset = m_pFile->GetPosition();
m_pFile->WriteBytes(pChunk, chunkSize);
m_pChunkOffsetProperty->SetValue(chunkOffset, chunkId - 1);
VERBOSE_WRITE_SAMPLE(m_pFile->GetVerbosity(),
printf("RewriteChunk: track %u id %u offset 0x"X64" size %u (0x%x)\n",
m_trackId, chunkId, chunkOffset, chunkSize, chunkSize));
}
// map track type name aliases to official names
const char* MP4Track::NormalizeTrackType(const char* type)
{
if (!strcasecmp(type, "vide")
|| !strcasecmp(type, "video")
|| !strcasecmp(type, "mp4v")
|| !strcasecmp(type, "s263") // 3GPP H.263
|| !strcasecmp(type, "encv")) {
return MP4_VIDEO_TRACK_TYPE;
}
if (!strcasecmp(type, "soun")
|| !strcasecmp(type, "sound")
|| !strcasecmp(type, "audio")
|| !strcasecmp(type, "enca")
|| !strcasecmp(type, "samr") // 3GPP AMR
|| !strcasecmp(type, "sawb") // 3GPP AMR/WB
|| !strcasecmp(type, "mp4a")) {
return MP4_AUDIO_TRACK_TYPE;
}
if (!strcasecmp(type, "sdsm")
|| !strcasecmp(type, "scene")
|| !strcasecmp(type, "bifs")) {
return MP4_SCENE_TRACK_TYPE;
}
if (!strcasecmp(type, "odsm")
|| !strcasecmp(type, "od")) {
return MP4_OD_TRACK_TYPE;
}
return type;
}
bool MP4Track::InitEditListProperties()
{
m_pElstCountProperty = NULL;
m_pElstMediaTimeProperty = NULL;
m_pElstDurationProperty = NULL;
m_pElstRateProperty = NULL;
m_pElstReservedProperty = NULL;
MP4Atom* pElstAtom =
m_pTrakAtom->FindAtom("trak.edts.elst");
if (!pElstAtom) {
return false;
}
pElstAtom->FindProperty(
"elst.entryCount",
(MP4Property**)&m_pElstCountProperty);
pElstAtom->FindProperty(
"elst.entries.mediaTime",
(MP4Property**)&m_pElstMediaTimeProperty);
pElstAtom->FindProperty(
"elst.entries.segmentDuration",
(MP4Property**)&m_pElstDurationProperty);
pElstAtom->FindProperty(
"elst.entries.mediaRate",
(MP4Property**)&m_pElstRateProperty);
pElstAtom->FindProperty(
"elst.entries.reserved",
(MP4Property**)&m_pElstReservedProperty);
return m_pElstCountProperty
&& m_pElstMediaTimeProperty
&& m_pElstDurationProperty
&& m_pElstRateProperty
&& m_pElstReservedProperty;
}
MP4EditId MP4Track::AddEdit(MP4EditId editId)
{
if (!m_pElstCountProperty) {
m_pFile->AddDescendantAtoms(m_pTrakAtom, "edts.elst");
InitEditListProperties();
}
if (editId == MP4_INVALID_EDIT_ID) {
editId = m_pElstCountProperty->GetValue() + 1;
}
m_pElstMediaTimeProperty->InsertValue(0, editId - 1);
m_pElstDurationProperty->InsertValue(0, editId - 1);
m_pElstRateProperty->InsertValue(1, editId - 1);
m_pElstReservedProperty->InsertValue(0, editId - 1);
m_pElstCountProperty->IncrementValue();
return editId;
}
void MP4Track::DeleteEdit(MP4EditId editId)
{
if (editId == MP4_INVALID_EDIT_ID) {
throw new MP4Error("edit id can't be zero",
"MP4Track::DeleteEdit");
}
if (!m_pElstCountProperty
|| m_pElstCountProperty->GetValue() == 0) {
throw new MP4Error("no edits exist",
"MP4Track::DeleteEdit");
}
m_pElstMediaTimeProperty->DeleteValue(editId - 1);
m_pElstDurationProperty->DeleteValue(editId - 1);
m_pElstRateProperty->DeleteValue(editId - 1);
m_pElstReservedProperty->DeleteValue(editId - 1);
m_pElstCountProperty->IncrementValue(-1);
// clean up if last edit is deleted
if (m_pElstCountProperty->GetValue() == 0) {
m_pElstCountProperty = NULL;
m_pElstMediaTimeProperty = NULL;
m_pElstDurationProperty = NULL;
m_pElstRateProperty = NULL;
m_pElstReservedProperty = NULL;
m_pTrakAtom->DeleteChildAtom(
m_pTrakAtom->FindAtom("trak.edts"));
}
}
MP4Timestamp MP4Track::GetEditStart(
MP4EditId editId)
{
if (editId == MP4_INVALID_EDIT_ID) {
return MP4_INVALID_TIMESTAMP;
} else if (editId == 1) {
return 0;
}
return (MP4Timestamp)GetEditTotalDuration(editId - 1);
}
MP4Duration MP4Track::GetEditTotalDuration(
MP4EditId editId)
{
u_int32_t numEdits = 0;
if (m_pElstCountProperty) {
numEdits = m_pElstCountProperty->GetValue();
}
if (editId == MP4_INVALID_EDIT_ID) {
editId = numEdits;
}
if (numEdits == 0 || editId > numEdits) {
return MP4_INVALID_DURATION;
}
MP4Duration totalDuration = 0;
for (MP4EditId eid = 1; eid <= editId; eid++) {
totalDuration +=
m_pElstDurationProperty->GetValue(eid - 1);
}
return totalDuration;
}
MP4SampleId MP4Track::GetSampleIdFromEditTime(
MP4Timestamp editWhen,
MP4Timestamp* pStartTime,
MP4Duration* pDuration)
{
MP4SampleId sampleId = MP4_INVALID_SAMPLE_ID;
u_int32_t numEdits = 0;
if (m_pElstCountProperty) {
numEdits = m_pElstCountProperty->GetValue();
}
if (numEdits) {
MP4Duration editElapsedDuration = 0;
for (MP4EditId editId = 1; editId <= numEdits; editId++) {
// remember edit segment's start time (in edit timeline)
MP4Timestamp editStartTime =
(MP4Timestamp)editElapsedDuration;
// accumulate edit segment's duration
editElapsedDuration +=
m_pElstDurationProperty->GetValue(editId - 1);
// calculate difference between the specified edit time
// and the end of this edit segment
if (editElapsedDuration - editWhen <= 0) {
// the specified time has not yet been reached
continue;
}
// 'editWhen' is within this edit segment
// calculate the specified edit time
// relative to just this edit segment
MP4Duration editOffset =
editWhen - editStartTime;
// calculate the media (track) time that corresponds
// to the specified edit time based on the edit list
MP4Timestamp mediaWhen =
m_pElstMediaTimeProperty->GetValue(editId - 1)
+ editOffset;
// lookup the sample id for the media time
sampleId = GetSampleIdFromTime(mediaWhen, false);
// lookup the sample's media start time and duration
MP4Timestamp sampleStartTime;
MP4Duration sampleDuration;
GetSampleTimes(sampleId, &sampleStartTime, &sampleDuration);
// calculate the difference if any between when the sample
// would naturally start and when it starts in the edit timeline
MP4Duration sampleStartOffset =
mediaWhen - sampleStartTime;
// calculate the start time for the sample in the edit time line
MP4Timestamp editSampleStartTime =
editWhen - MIN(editOffset, sampleStartOffset);
MP4Duration editSampleDuration = 0;
// calculate how long this sample lasts in the edit list timeline
if (m_pElstRateProperty->GetValue(editId - 1) == 0) {
// edit segment is a "dwell"
// so sample duration is that of the edit segment
editSampleDuration =
m_pElstDurationProperty->GetValue(editId - 1);
} else {
// begin with the natural sample duration
editSampleDuration = sampleDuration;
// now shorten that if the edit segment starts
// after the sample would naturally start
if (editOffset < sampleStartOffset) {
editSampleDuration -= sampleStartOffset - editOffset;
}
// now shorten that if the edit segment ends
// before the sample would naturally end
if (editElapsedDuration
< editSampleStartTime + sampleDuration) {
editSampleDuration -= (editSampleStartTime + sampleDuration)
- editElapsedDuration;
}
}
if (pStartTime) {
*pStartTime = editSampleStartTime;
}
if (pDuration) {
*pDuration = editSampleDuration;
}
VERBOSE_EDIT(m_pFile->GetVerbosity(),
printf("GetSampleIdFromEditTime: when "U64" "
"sampleId %u start "U64" duration "D64"\n",
editWhen, sampleId,
editSampleStartTime, editSampleDuration));
return sampleId;
}
throw new MP4Error("time out of range",
"MP4Track::GetSampleIdFromEditTime");
} else { // no edit list
sampleId = GetSampleIdFromTime(editWhen, false);
if (pStartTime || pDuration) {
GetSampleTimes(sampleId, pStartTime, pDuration);
}
}
return sampleId;
}