int CaptureStreamT::Read(unsigned char* Buffer, unsigned int Size)
{
const unsigned int MAX_WRITE_SAMPLES=Size/BytesPerSample(m_FORMAT);
// If this is the first read after initialization or a rewind, start capturing now.
// When capturing has been stopped before and is restarted here, GetNumCaptureSamples() should return 0,
// just as if it had been started for the first time. See Rewind() for more information.
if (!m_IsCapturing)
{
alcCaptureStart(m_CaptureDevice);
m_IsCapturing=true;
}
// std::cout << "\n" << __FUNCTION__ << "():\n" << " "; PrintDebug();
// If there are not enough "live" capture samples available, fill-in zeros until
// the buffer is half full. This gives the device the chance to capture more data.
if (GetNumCaptureSamples() < m_MAX_CAPTURE_BUFFER_SAMPLES/8)
{
m_ZeroSamples=m_MAX_CAPTURE_BUFFER_SAMPLES/2-GetNumCaptureSamples();
// std::cout << " + ... "; PrintDebug();
}
// If the capture buffer is too full, we have probably lost data already.
// In order to prevent this from happening over and over again, reduce it to half its size.
if (m_ZeroSamples+GetNumCaptureSamples() >= m_MAX_CAPTURE_BUFFER_SAMPLES)
{
m_ZeroSamples=0;
ReduceSamplesTo(m_MAX_CAPTURE_BUFFER_SAMPLES/2 + MAX_WRITE_SAMPLES);
// std::cout << " - ... "; PrintDebug();
}
// Write the leading zero samples.
unsigned int SamplesWritten=std::min(m_ZeroSamples, MAX_WRITE_SAMPLES);
memset(Buffer, 0, SamplesWritten*BytesPerSample(m_FORMAT));
m_ZeroSamples-=SamplesWritten;
// Write the samples with real, live, captured data.
if (GetNumCaptureSamples()>0 && SamplesWritten<MAX_WRITE_SAMPLES)
{
const unsigned int NumLive=std::min(GetNumCaptureSamples(), MAX_WRITE_SAMPLES-SamplesWritten);
alcCaptureSamples(m_CaptureDevice, &Buffer[SamplesWritten*BytesPerSample(m_FORMAT)], NumLive);
SamplesWritten+=NumLive;
}
// std::cout << " " << SamplesWritten << " samples written,\n" << " = "; PrintDebug();
return SamplesWritten*BytesPerSample(m_FORMAT);
}
void Resize(int channels, int bits)
{
m_bits = bits;
m_channels = channels;
m_sizeMax = ((m_sample_rate * kBufferMilliSecs) / 1000) * BytesPerSample();
resize(0);
}
void CaptureStreamT::ReduceSamplesTo(unsigned int NumLeft)
{
const unsigned int NumNow=GetNumCaptureSamples();
if (NumNow>NumLeft)
{
ArrayT<unsigned char> Discard;
Discard.PushBackEmpty((NumNow-NumLeft)*BytesPerSample(m_FORMAT));
alcCaptureSamples(m_CaptureDevice, &Discard[0], NumNow-NumLeft);
}
}
inline unsigned Bytes2Samples(unsigned bytes) const
{
return (m_channels && m_bits) ? bytes / BytesPerSample() : 0;
}
const int16_t* Data16(const range_t &avail) const
{
unsigned start = MS2Samples(avail.first - m_tcFirst);
return reinterpret_cast< const int16_t* >(constData() + start * BytesPerSample());
}
