自学教程：C++ GetDuration函数代码示例

//--------------------------------------------------------------------------------------// Name: ReadSampleRaw()// Desc: Reads data from the audio file. No endianness conversion is performed.//--------------------------------------------------------------------------------------HRESULT WaveFile::ReadSampleRaw( DWORD dwPosition, VOID* pBuffer,                              DWORD dwBufferSize, DWORD* pdwRead ) const{    // Don't read past the end of the data chunk    DWORD dwDuration;    GetDuration( &dwDuration );    if( dwPosition + dwBufferSize > dwDuration )        dwBufferSize = dwDuration - dwPosition;    HRESULT hr = S_OK;    if( dwBufferSize )        hr = m_DataChunk.ReadData( ( LONG )dwPosition, pBuffer, dwBufferSize, NULL );    if( pdwRead )        *pdwRead = dwBufferSize;    return hr;}

DurationTimeline::GetNaturalDuration (Clock *clock){	Duration* d = GetDuration ();	if (*d == Duration::Automatic) {//  		printf ("automatic duration, we need to calculate it/n");		Duration cd = GetNaturalDurationCore (clock);// 		if (cd.HasTimeSpan ())//  			printf (" + duration (%" G_GINT64_FORMAT " timespan)/n", cd.GetTimeSpan ());// 		else if (cd == Duration::Automatic)// 			printf (" + automatic/n");// 		else if (cd == Duration::Forever)// 			printf (" + forever/n");		return cd;	}	else {		return *d;	}}

double DoubleAnimation::GetCurrentValue(){    if (_isEndOf)    {        return 0;    }    double dDiff = (_dTo - _dFrom) * GetSpeedRatio() / GetDuration();    if (_bReverse)    {        _dCurrent -= dDiff;        if ((dDiff > 0 && _dCurrent <= _dFrom)             || (dDiff < 0 && _dCurrent >= _dFrom))        {            _dCurrent = _dFrom;            _isEndOf = true;        }    }    else    {        _dCurrent += dDiff;        if ((dDiff > 0 && _dCurrent >= _dTo)             || (dDiff < 0 && _dCurrent <= _dTo))        {            _dCurrent = _dTo;            if (GetAutoReverse())            {                _bReverse = true;            }            else            {                _isEndOf = true;            }        }    }    return _dCurrent;}

bool EffectDtmf::ProcessInitialize(sampleCount WXUNUSED(totalLen), ChannelNames WXUNUSED(chanMap)){   double duration = GetDuration();   // all dtmf sequence durations in samples from seconds   // MJS: Note that mDuration is in seconds but will have been quantised to the units of the TTC.   // If this was 'samples' and the project rate was lower than the track rate,   // extra samples may get created as mDuration may now be > mT1 - mT0;   // However we are making our best efforts at creating what was asked for.   auto nT0 = (sampleCount)floor(mT0 * mSampleRate + 0.5);   auto nT1 = (sampleCount)floor((mT0 + duration) * mSampleRate + 0.5);   numSamplesSequence = nT1 - nT0;  // needs to be exact number of samples selected   //make under-estimates if anything, and then redistribute the few remaining samples   numSamplesTone = sampleCount( floor(dtmfTone * mSampleRate) );   numSamplesSilence = sampleCount( floor(dtmfSilence * mSampleRate) );   // recalculate the sum, and spread the difference - due to approximations.   // Since diff should be in the order of "some" samples, a division (resulting in zero)   // is not sufficient, so we add the additional remaining samples in each tone/silence block,   // at least until available.   diff = numSamplesSequence - (dtmfNTones*numSamplesTone) - (dtmfNTones-1)*numSamplesSilence;   while (diff > 2*dtmfNTones - 1) {   // more than one per thingToBeGenerated      // in this case, both numSamplesTone and numSamplesSilence would change, so it makes sense      //  to recalculate diff here, otherwise just keep the value we already have      // should always be the case that dtmfNTones>1, as if 0, we don't even start processing,      // and with 1 there is no difference to spread (no silence slot)...      wxASSERT(dtmfNTones > 1);      numSamplesTone += (diff/(dtmfNTones));      numSamplesSilence += (diff/(dtmfNTones-1));      diff = numSamplesSequence - (dtmfNTones*numSamplesTone) - (dtmfNTones-1)*numSamplesSilence;   }   wxASSERT(diff >= 0);  // should never be negative   curSeqPos = -1; // pointer to string in dtmfSequence   isTone = false;   numRemaining = 0;   return true;}

void CMMAMMFPlayerBase::GetMediaTime(TInt64* aMediaTime){    LOG(EJavaMMAPI, EInfo, "CMMAMMFPlayerBase::GetMediaTime +");    TTimeIntervalMicroSeconds position(0);    if (iMediaTime == KTimeUnknown || iState == EStarted)    {        // The controller must be in the PRIMED or PLAYING state        TInt error(iController.GetPosition(position));        if (error == KErrNone)        {            TInt64 newTime = position.Int64();            LOG1(EJavaMMAPI, EInfo, "CMMAMMFPlayerBase::GetMediaTime iController.GetPosition : %d", newTime);            // Sanity check for media time going backwards or beyond the            // duration.            // Some native controls may return zero media time for            // a few moments just before playback will complete.            if (newTime < iMediaTime ||                    (iDuration > 0 && newTime > iDuration))            {                LOG(EJavaMMAPI, EInfo, "CMMAMMFPlayerBase::GetMediaTime.GetDuration ");                GetDuration(&iMediaTime);            }            else            {                LOG(EJavaMMAPI, EInfo, "CMMAMMFPlayerBase::GetMediaTime.else ");                // set return value                iMediaTime = newTime;            }        }        else        {            LOG1(EJavaMMAPI, EInfo, "CMMAMMFPlayerBase::GetMediaTime: error=%d, returning TIME_UNKNOWN", error);            // cannot get media time            iMediaTime = KTimeUnknown;        }    }    *aMediaTime = iMediaTime;    LOG1(EJavaMMAPI, EInfo, "CMMAMMFPlayerBase::GetMediaTime - %d", *aMediaTime);}

void CAVISplitter::GetSeekingParams(REFERENCE_TIME* ptStart, REFERENCE_TIME* ptStop, double* pdRate){	if (ptStart != NULL)	{		*ptStart = m_tStart;	}	if (ptStop != NULL)	{		if (m_tStop == MAX_TIME)		{			m_tStop = GetDuration();		}		*ptStop = m_tStop;	}	if (pdRate != NULL)	{		*pdRate = m_dRate;	}}

HRESULT CAVISplitter::Seek(REFERENCE_TIME tStart, REFERENCE_TIME tStop, double dRate){	// We must stop the pushing thread before we change	// the seek parameters -- especially for VBR seeking, 	// where we might re-seek based on the incoming data.		CAutoLock lock(&m_csSeeking);	if (tStop == 0 || tStop < tStart)		tStop = GetDuration();	bool bShouldRestart = Suspend();	m_tStart = tStart;	m_tStop = tStop;	m_dRate = dRate;	m_scanner.Seek(m_tStart);	if (bShouldRestart)		Resume();		return S_OK;}

STDMETHODIMP IKGSTAudioPlayer::SetPosition(STREAM_TIME pos)//0-100{    if(!pipeline)        return E_FAIL;    gint64 time;    GstElement *p = pipeline;    gint64 Glength = GetDuration(), Gstart = 0;    if (Glength)    {        time = Glength;        time *= (double)pos/100;        time += Gstart;        bool b = gst_element_seek(p, 1.0, GST_FORMAT_TIME, GST_SEEK_FLAG_FLUSH, GST_SEEK_TYPE_SET, time, GST_SEEK_TYPE_SET, Gstart + Glength);        return b ? S_OK : E_FAIL;    }    else        return  E_FAIL;}

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