int AudioOpenAL::music_stream (ALuint buffer) {
size_t size = music_decoder->read (music_data, setting.buffer);
if (size > 0) {
alBufferData (buffer, music_decoder->get_format (), music_data, size,
music_decoder->get_frequency ());
}
return size;
}
void AudioItem::createWaveform(bool left, bool right)
{
if ((left == true || right == true) && m_audio->getAudioDecoder() != NULL)
{
AudioDecoder *ad = m_audio->getAudioDecoder();
AudioParameters ap = ad->audioParameters();
// 1- find out how many samples have to be represented on a single pixel on a 1:1 time scale
int sampleSize = ap.sampleSize();
int channels = ap.channels();
int oneSecondSamples = ap.sampleRate() * channels;
int onePixelSamples = oneSecondSamples / 50;
//qint32 maxValue = qPow(0xFF, sampleSize);
qint32 maxValue = 0;
if (left == true && right == true)
maxValue = 0x7F << (8 * (sampleSize - 1));
else
maxValue = 0x3F << (8 * (sampleSize - 1));
quint32 defaultDataLen = onePixelSamples * sampleSize;
// 2- decode the whole file and fill a QPixmap with a sample block RMS value for each pixel
qint64 dataRead = 1;
unsigned char audioData[defaultDataLen * 4];
quint32 audioDataOffset = 0;
m_preview = new QPixmap((50 * m_audio->totalDuration()) / 1000, 76);
m_preview->fill(Qt::transparent);
QPainter p(m_preview);
int xpos = 0;
qDebug() << "Audio duration: " << m_audio->totalDuration() <<
", pixmap width: " << ((50 * m_audio->totalDuration()) / 1000) <<
", maxValue: " << maxValue;
qDebug() << "Samples per second: " << oneSecondSamples << ", for one pixel: " << onePixelSamples;
while (dataRead)
{
quint32 tmpExceedData = 0;
if (audioDataOffset < defaultDataLen)
{
dataRead = ad->read((char *)audioData + audioDataOffset, defaultDataLen * 2);
if (dataRead > 0)
{
if(dataRead + audioDataOffset >= defaultDataLen)
{
tmpExceedData = dataRead + audioDataOffset - defaultDataLen;
dataRead = defaultDataLen;
}
else
{
audioDataOffset = dataRead;
continue;
}
}
}
else
{
dataRead = defaultDataLen;
tmpExceedData = audioDataOffset - defaultDataLen;
}
if (dataRead > 0)
{
quint32 i = 0;
// calculate the RMS value (peak) for this data block
double rmsLeft = 0;
double rmsRight = 0;
bool done = false;
while (!done)
{
if (left == true)
{
qint32 sampleVal = getSample(audioData, &i, sampleSize);
rmsLeft += (sampleVal * sampleVal);
}
if (channels == 2)
{
if (right == true)
{
qint32 sampleVal = getSample(audioData, &i, sampleSize);
rmsRight += (sampleVal * sampleVal);
}
else
getSample(audioData, &i, sampleSize); // got to read it anyway and discard data
}
if (i >= dataRead / sampleSize)
done = true;
}
quint32 divisor = (dataRead / sampleSize) / channels;
if (left == true)
rmsLeft = sqrt(rmsLeft / divisor);
if (right == true)
rmsRight = sqrt(rmsRight / divisor);
// 3- Draw the actual waveform
unsigned short lineHeightLeft = 0, lineHeightRight = 0;
if (left == true)
lineHeightLeft = (76 * rmsLeft) / maxValue;
if (right == true)
lineHeightRight = (76 * rmsRight) / maxValue;
if (left == true && right == true)
{
if (lineHeightLeft > 1)
p.drawLine(xpos, 19 - (lineHeightLeft / 2), xpos, 19 + (lineHeightLeft / 2));
else
p.drawLine(xpos, 19, xpos + 1, 19);
if (lineHeightRight > 1)
p.drawLine(xpos, 51 - (lineHeightRight / 2), xpos, 51 + (lineHeightRight / 2));
else
p.drawLine(xpos, 51, xpos + 1, 51);
}
else
{
unsigned short lineHeight = 0;
if (left == true)
lineHeight = lineHeightLeft;
else
lineHeight = lineHeightRight;
if (lineHeight > 1)
p.drawLine(xpos, 38 - (lineHeight / 2), xpos, 38 + (lineHeight / 2));
else
p.drawLine(xpos, 38, xpos + 1, 38);
//qDebug() << "Data read: " << dataRead << ", rms: " << rms << ", line height: " << lineHeight << ", xpos = " << xpos;
}
xpos++;
if (tmpExceedData > 0)
{
//qDebug() << "Exceed data found: " << tmpExceedData;
memmove(audioData, audioData + defaultDataLen, tmpExceedData);
audioDataOffset = tmpExceedData;
}
else
audioDataOffset = 0;
}
}
//qDebug() << "Iterations done: " << xpos;
ad->seek(0);
}
else // no preview selected. Delete pixmap
{
delete m_preview;
m_preview = NULL;
}
update();
}
