Added a DisplayWaveform method on a frame, to help debug audio issues. It uses ImageMagick to draw each channel and all samples in each channel.

src/Frame.cpp

@@ -121,6 +121,77 @@ void Frame::Display()
 	image->display();
 }
 
+// Display the wave form
+void Frame::DisplayWaveform(bool resize)
+{
+	// Create black image
+	int width = audio->getNumSamples();
+	int height = 200 * audio->getNumChannels();
+	int height_padding = 20 * (audio->getNumChannels() - 1);
+	int total_height = height + height_padding;
+	Magick::Image wave_image(Magick::Geometry(width, total_height), Magick::Color("#000000"));
+
+	// Init a list of lines
+	list<Magick::Drawable> lines;
+	lines.push_back(Magick::DrawableFillColor("#0070ff"));
+	lines.push_back(Magick::DrawablePointSize(16));
+
+	// Loop through each audio channel
+	int Y = 100;
+	for (int channel = 0; channel < audio->getNumChannels(); channel++)
+	{
+		// Get audio for this channel
+		float *samples = audio->getSampleData(channel);
+
+		for (int sample = 0; sample < audio->getNumSamples(); sample++)
+		{
+			// Sample value (scaled to -100 to 100)
+			float value = samples[sample] * 100;
+
+			if (value > 100 || value < -100)
+				cout << "TOO BIG!!! " << value << endl;
+
+			// Append a line segment for each sample
+			if (value != 0.0)
+			{
+				// LINE
+				lines.push_back(Magick::DrawableStrokeColor("#0070ff"));
+				lines.push_back(Magick::DrawableStrokeWidth(1));
+				lines.push_back(Magick::DrawableLine(sample,Y, sample,Y-value)); // sample=X coordinate, Y=100 is the middle
+			}
+			else
+			{
+				// DOT
+				lines.push_back(Magick::DrawableFillColor("#0070ff"));
+				lines.push_back(Magick::DrawableStrokeWidth(1));
+				lines.push_back(Magick::DrawablePoint(sample,Y));
+			}
+		}
+
+		// Add Channel Label
+		stringstream label;
+		label << "Channel " << channel;
+		lines.push_back(Magick::DrawableStrokeColor("#ffffff"));
+		lines.push_back(Magick::DrawableFillColor("#ffffff"));
+		lines.push_back(Magick::DrawableStrokeWidth(0.1));
+		lines.push_back(Magick::DrawableText(5, Y - 5, label.str()));
+
+		// Increment Y
+		Y += (200 + height_padding);
+	}
+
+	// Draw the waveform
+	wave_image.draw(lines);
+
+	// Resize Image (if requested)
+	if (resize)
+		// Resize to 60%
+		wave_image.resize(Magick::Geometry(width * 0.6, total_height * 0.6));
+
+	// Display Image
+	wave_image.display();
+}
+
 // Get pixel data (as packets)
 const Magick::PixelPacket* Frame::GetPixels()
 {