// https://stackoverflow.com/questions/36081740/uwp-async-read-file-into-byte
public static async Task <WaveData> LoadWave(StorageFile file)
{
byte[] wav;
using (Stream stream = await file.OpenStreamForReadAsync())
{
using (var memoryStream = new MemoryStream())
{
stream.CopyTo(memoryStream);
wav = memoryStream.ToArray();
}
}
int channels = wav[22];
int sampleRate = wav[24] + wav[25] * 256;
int bitsPerSample = wav[34];
int pos = 12;
while (!(wav[pos] == 100 && wav[pos + 1] == 97 && wav[pos + 2] == 116 && wav[pos + 3] == 97))
{
pos += 4;
int chunkSize = wav[pos] + wav[pos + 1] * 256 + wav[pos + 2] * 65536 + wav[pos + 3] * 16777216;
pos += 4 + chunkSize;
}
pos += 8;
// Pos is now positioned to start of actual sound data
int samples = (wav.Length - pos) / 2; // 2 bytes per sample (16 bit sound mono)
if (channels == 2)
{
samples /= 2; // 4 bytes per sample (16 bit stereo)
}
// Allocate memory (right will be null if only mono sound)
var result = new WaveData
{
BitsPerSample = bitsPerSample,
SampleRate = sampleRate,
LeftChannel = new double[samples],
RightChannel = channels == 2 ? new double[samples] : null
};
int i = 0;
while (pos < wav.Length)
{
result.LeftChannel[i] = WaveUtils.BytesToDouble(wav[pos], wav[pos + 1]);
pos += 2;
if (channels == 2)
{
result.RightChannel[i] = WaveUtils.BytesToDouble(wav[pos], wav[pos + 1]);
pos += 2;
}
i++;
}
return(result);
}
public async Task LoadWave(string filePath)
{
var picker = new Windows.Storage.Pickers.FileOpenPicker();
picker.FileTypeFilter.Add(".wav");
var file = await picker.PickSingleFileAsync();
var filename = file.Name;
this.filenameTextBlock.Text = filename;
this.Editor.WaveData = await WaveUtils.LoadWave(file);
this.sampleRateTextBlock.Text = $"{this.Editor.WaveData.SampleRate.ToString()} Hz";
this.formatTextBlock.Text = $"{this.Editor.WaveData.BitsPerSample.ToString()}-bit";
}
// https://stackoverflow.com/questions/39605118/how-to-draw-an-audio-waveform-to-a-bitmap
private void canvas_Draw(CanvasControl sender, CanvasDrawEventArgs args)
{
if (Editor.WaveData.LeftChannel == null)
{
return;
}
const int FONT_SIZE = 14;
args.DrawingSession.Clear(sender.ClearColor);
args.DrawingSession.Antialiasing = Microsoft.Graphics.Canvas.CanvasAntialiasing.Aliased;
var textFormat = new CanvasTextFormat {
FontSize = FONT_SIZE, Direction = CanvasTextDirection.TopToBottomThenLeftToRight
};
var negTextFormat = new CanvasTextFormat {
FontSize = FONT_SIZE, Direction = CanvasTextDirection.BottomToTopThenLeftToRight
};
var scale = Editor.Scale;
var size = Editor.WaveData.LeftChannel.Length;
var height = sender.ActualHeight;
var width = sender.ActualWidth * scale;
float previousX = 0;
float previousY = (float)(height / 2);
for (int x = 0; x < width / scale; x++)
{
int start = (int)(x * (size / width));
int end = (int)((x + 1) * (size / width));
if (end > size)
{
end = size;
}
if (start == end)
{
// Blank pixel
continue;
}
WaveUtils.averages(Editor.WaveData.LeftChannel, start, end, out double posAvg, out double negAvg);
float yMax = (float)(height - ((posAvg + 1) * .5f * height));
float yMin = (float)(height - ((negAvg + 1) * .5f * height));
args.DrawingSession.DrawLine(x, yMax, x, yMin, Colors.Red);
if (posAvg > 0)
{
args.DrawingSession.DrawText(posAvg.ToString(), x - FONT_SIZE / 2, yMin, Colors.Blue, textFormat);
args.DrawingSession.DrawLine(previousX, previousY, x, yMax, Colors.Silver);
previousY = yMax;
}
else if (negAvg < 0)
{
args.DrawingSession.DrawText(negAvg.ToString(), x - FONT_SIZE / 2, yMax, Colors.Blue, negTextFormat);
args.DrawingSession.DrawLine(previousX, previousY, x, yMin, Colors.Silver);
previousY = yMin;
}
else
{
args.DrawingSession.DrawText("0", x - FONT_SIZE / 2, yMin, Colors.Blue, textFormat);
previousY = (float)(height / 2);
}
previousX = x;
}
// Selection
if (this.Editor.PointerX1 > 0)
{
args.DrawingSession.DrawLine((float)this.Editor.PointerX1, 0f, (float)this.Editor.PointerX1, (float)height, Colors.Blue);
}
if (this.Editor.PointerX2 > 0)
{
args.DrawingSession.DrawLine((float)this.Editor.PointerX2, 0f, (float)this.Editor.PointerX2, (float)height, Colors.Blue);
}
if (this.Editor.IsPointerPressed)
{
var brush = new CanvasSolidColorBrush(canvas, Colors.LightSkyBlue);
brush.Opacity = 0.4f;
args.DrawingSession.FillRectangle((float)this.Editor.PointerX1, 0f, (float)(this.Editor.PointerX2 - this.Editor.PointerX1), (float)height, brush);
}
}
