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Merge branch 'experimental-draw-waveform' into 'experimental-draw-waveform' 

Waveform optimization: split into RMS of chunks instead of drawing every point

See merge request samplehive/sample-hive!8
This commit is contained in:
Apoorv 2021-09-07 22:31:00 +00:00
parent 0eaf78923c 86a5c218ac
commit 28cff9a8fe
1 changed files with 41 additions and 20 deletions
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61
src/WaveformViewer.cpp
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@ -186,35 +186,47 @@ void WaveformViewer::UpdateWaveformBitmap()
std::vector<float> waveform;
// TODO, FIXME: Don't reload file on every window resize
snd_file.read(&sample.at(0), frames * channels);
float display_width = this->GetSize().GetWidth();
float display_height = this->GetSize().GetHeight();
double max_value;
snd_file.command(SFC_CALC_NORM_SIGNAL_MAX, &max_value, sizeof(max_value));
wxLogDebug("Calculating Waveform bars RMS..");
float normalized_value = max_value > 1.0f ? 1.0f : 1.0f / max_value;
float chunk_size = (float)(frames) / (float)display_width;
int number_chunks = static_cast<int>(static_cast<float>(frames) / chunk_size);
float samples_per_pixel = static_cast<float>(frames) / (float)display_width;
// Start with low non-zero value
float normalize = 0.00001;
if (channels == 2)
{
for (int i = 0, j = 0 ; i < frames; i++)
{
float sum = (((sample[j] + sample[j + 1]) * 0.5f) * normalized_value) * float(display_height / 2.0f);
waveform.push_back(sum);
j += 2;
for (int i=0; i<number_chunks; i++) {
double sum = 0, mono = 0;
int start_point = static_cast<int>(i*chunk_size*channels);
// Iterate on the chunk, get the square of sum of monos
for (int j=0; j<chunk_size; j++) {
if (channels == 2) {
mono = 0.5f * (sample[start_point+(2*j)] + sample[start_point+(2*j)+1]);
} else {
mono = sample[start_point+j];
}
sum += mono * mono; // Square
}
sum /= chunk_size; // Mean
sum = pow(sum, 0.5); // Root
// We might bleed a bit on the end and get some near infs, dunno
// what is causing astronomically big numbers from sample[]
if ((sum < 200.0) && (sum > normalize)) {
normalize = sum;
}
waveform.push_back(sum);
}
else
{
waveform.resize(frames);
for (int i = 0; i < frames; i++)
{
waveform[i] = (sample[i] * normalized_value) * float(display_height / 2.0f);
}
// Actually normalize
for (int i=0; i<waveform.size(); i++) {
waveform[i] /= normalize;
}
// Draw code
@ -231,8 +243,17 @@ void WaveformViewer::UpdateWaveformBitmap()
for (int i = 0; i < waveform.size() - 1; i++)
{
mdc.DrawLine((display_width * i) / waveform.size(), waveform[i] + display_height / 2.0f,
(display_width * i) / waveform.size(), (waveform[i] / samples_per_pixel) + display_height / 2.0f);
float half_vertical = static_cast<float>(display_height) / 2.0f;
// X is percentage of i relative to waveform.size() multiplied by
// the width, Y is the half height times the value up or down
float X = display_width * ((float)i / waveform.size());
float Y = waveform[i] * half_vertical;
mdc.DrawLine(
X, half_vertical + Y,
X, half_vertical - Y
);
}
wxLogDebug("Done drawing bitmap..");