BOOL CMpcAudioRenderer::ScheduleSample(IMediaSample *pMediaSample)
{
REFERENCE_TIME StartSample;
REFERENCE_TIME EndSample;
// Is someone pulling our leg
if (pMediaSample == NULL) {
return FALSE;
}
// Get the next sample due up for rendering. If there aren't any ready
// then GetNextSampleTimes returns an error. If there is one to be done
// then it succeeds and yields the sample times. If it is due now then
// it returns S_OK other if it's to be done when due it returns S_FALSE
HRESULT hr = GetSampleTimes(pMediaSample, &StartSample, &EndSample);
if (FAILED(hr)) {
return FALSE;
}
// If we don't have a reference clock then we cannot set up the advise
// time so we simply set the event indicating an image to render. This
// will cause us to run flat out without any timing or synchronisation
if (hr == S_OK) {
EXECUTE_ASSERT(SetEvent((HANDLE) m_RenderEvent));
return TRUE;
}
if (m_dRate <= 1.1) {
ASSERT(m_dwAdvise == 0);
ASSERT(m_pClock);
WaitForSingleObject((HANDLE)m_RenderEvent,0);
hr = m_pClock->AdviseTime( (REFERENCE_TIME) m_tStart, StartSample, (HEVENT)(HANDLE) m_RenderEvent, &m_dwAdvise);
if (SUCCEEDED(hr)) {
return TRUE;
}
} else {
hr = DoRenderSample (pMediaSample);
}
// We could not schedule the next sample for rendering despite the fact
// we have a valid sample here. This is a fair indication that either
// the system clock is wrong or the time stamp for the sample is duff
ASSERT(m_dwAdvise == 0);
return FALSE;
}
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::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;
}
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"LLX" 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 "LLU" duration "LLD"\n",
(pStartTime ? *pStartTime : 0),
(pDuration ? *pDuration : 0)));
}
if (pRenderingOffset) {
*pRenderingOffset = GetSampleRenderingOffset(sampleId);
VERBOSE_READ_SAMPLE(m_pFile->GetVerbosity(),
printf("ReadSample: renderingOffset "LLD"\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);
}
}
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 %llu "
"sampleId %u start %llu duration %lld\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;
}
