use projectm_pcm_get_max_samples to set buffer size

cmd/root.go

@@ -117,7 +117,7 @@ func update(m *milkDropWindow) (bool, error) {
 		}
 	}
 
-	audioData := make([]int16, 2048)
+	audioData := make([]int16, maxSamples(2, 2))
 
 	err := binary.Read(os.Stdin, binary.LittleEndian, audioData)
 	if err == io.ErrUnexpectedEOF {

cmd/window.go

@@ -31,6 +31,18 @@ import (
 	"github.com/veandco/go-sdl2/sdl"
 )
 
+/*
+ * maxSamples returns the maximum number of audio samples stored by projectm
+ * when passing it audio data, given the number of bytes in one sample and the
+ * number of channels.
+ */
+func maxSamples(bytesPerSample uint, numChannels uint) uint {
+	// NOTE: not 100% sure about this, but I think
+	// projectm_pcm_get_max_samples assumes 4 bytes per sample, so we
+	// multiply by 4/bytesPerSample to convert
+	return 4 / bytesPerSample * numChannels * uint(C.projectm_pcm_get_max_samples())
+}
+
 // milkDropWindow represents the window projectm will render visualizations in.
 type milkDropWindow struct {
 	window  *sdl.Window