spek

commit 2e8355ee84a298472c081759f5503832af432fa2
parent 4e186744ad2c4d8f595e662885c6705c0a8f672f
Author: Alexander Kojevnikov <alexander@kojevnikov.com>
Date:   Sat,  3 Jul 2010 22:43:40 +1000

Apply Hamming window function

Diffstat:
M
src/spek-pipeline.vala
 | 
9
++++++---
M
src/spek-spectrogram.vala
 | 
4
++--

2 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/src/spek-pipeline.vala b/src/spek-pipeline.vala
@@ -39,8 +39,8 @@ namespace Spek {
 		private uint8[] buffer;
 		private Fft.Plan fft;
 		private int nfft;
-		float[] input;
-		float[] output;
+		private float[] input;
+		private float[] output;
 
 		public Pipeline (string file_name, int bands, int samples, int threshold, Callback cb) {
 			this.cx = new Audio.Context (file_name);
@@ -113,7 +113,10 @@ namespace Spek {
 						acc_error < cx.error_base && frames == cx.frames_per_interval ||
 						acc_error >= cx.error_base && frames == 1 + cx.frames_per_interval) {
 						for (int i = 0; i < nfft; i++) {
-							fft.input[i] = input[(pos + i) % nfft];
+							double val = input[(pos + i) % nfft];
+							// Hamming window.
+							val *= 0.53836 - 0.46164 * Math.cos (2.0 * Math.PI * i / nfft);
+							fft.input[i] = (float) val;
 						}
 						fft.execute ();
 						num_fft++;
diff --git a/src/spek-spectrogram.vala b/src/spek-spectrogram.vala
@@ -27,7 +27,7 @@ namespace Spek {
 		public string file_name { get; private set; }
 		private Pipeline pipeline;
 		private string info;
-		private const int THRESHOLD = -86;
+		private const int THRESHOLD = -92;
 		private const int NFFT = 2048;
 		private const int BANDS = NFFT / 2 + 1;
 
@@ -103,7 +103,7 @@ namespace Spek {
 		}
 
 		private void data_cb (int sample, float[] values) {
-			for (int y = 0; y < values.length; y++) {
+			for (int y = 0; y < BANDS; y++) {
 				var level = double.min (
 					1.0, Math.log10 (1.0 - THRESHOLD + values[y]) / Math.log10 (-THRESHOLD));
 				put_pixel (image, sample, y, get_color (level));