Better default window function

CHANGELOG.md

@@ -1,5 +1,8 @@
 # CHANGELOG
 
+## version 10.4.2 - 2020-01-22
+Better sinc resampling.
+
 ## version 10.4.1 - 2020-01-21
 Faster sinc resampling.
 

lib/resampler/interpolator.js

@@ -90,7 +90,7 @@ export class Interpolator {
      * The sinc kernel.
      * @type {Function}
      */
-    this.kernel_ = sincKernel_(details.sincWindow || gaussianWindow_);
+    this.kernel_ = sincKernel_(details.sincWindow || window_);
   }
 
   /**
@@ -187,8 +187,8 @@ export class Interpolator {
  * @return {number}
  * @private
  */
-function gaussianWindow_(x) {
-  return Math.exp(-x * x);
+function window_(x) {
+  return Math.exp(-x / 2 * x / 2);
 }
 
 /**

package.json

@@ -1,6 +1,6 @@
 {
   "name": "wavefile",
-  "version": "10.4.1",
+  "version": "10.4.2",
   "description": "Create, read and write wav files according to the specs.",
   "homepage": "https://github.com/rochars/wavefile",
   "author": "Rafael da Silva Rocha <[email protected]>",
@@ -73,7 +73,7 @@
     "test-sr-point": "node ./node_modules/mocha/bin/_mocha test/resampler-full/point.js -R dot --timeout=1600000",
     "test-sr-linear": "node ./node_modules/mocha/bin/_mocha test/resampler-full/linear.js -R dot --timeout=1600000",
     "test-sr-cubic": "node ./node_modules/mocha/bin/_mocha test/resampler-full/cubic.js -R dot --timeout=1600000",
-    "test-sr-sinc": "node ./node_modules/mocha/bin/_mocha test/resampler-full/sinc.js test/resampler-full/sinc-IIR.js -R dot --timeout=1600000",
+    "test-sr-sinc": "node ./node_modules/mocha/bin/_mocha test/resampler-full/sinc.js test/resampler-full/sinc-IIR.js test/resampler-full/sinc-no-lpf.js -R dot --timeout=1600000",
     "test-umd": "node ./node_modules/mocha/bin/_mocha test/resampler test/dist test/src --umd --recursive -R dot --timeout=240000",
     "test-tsc": "tsc ./test/TypeScript/index.ts && node -r esm ./test/TypeScript/index.js",
     "test-cli": "wavefile ./test/files/M1F1-int12WE-AFsp.wav --tag=ICMT",

test/resampler-full/sinc-no-lpf.js

@@ -0,0 +1,165 @@
+/**
+* WaveFile: https://github.com/rochars/wavefile
+* Copyright (c) 2017-2018 Rafael da Silva Rocha. MIT License.
+*
+* Tests for sample rate conversion, sinc method.
+* 
+*/
+
+const assert = require('assert');
+const fs = require("fs");
+const WaveFile = require("../../test/loader.js");
+const path = "./test/files/";
+
+console.log('sinc, no LPF');
+
+let hrstart = process.hrtime();
+
+// Chirps, FP
+
+describe('Downsample a 32-bit 44.1kHz log sine sweep', function() {
+  // Read a 8kHz wav 
+  let wav = new WaveFile(
+    fs.readFileSync(path + "32fp-44100Hz-mono-chirp-1-22050-log.wav"));
+
+  // Convert to another sample rate
+  wav.toSampleRate(16000, {method: 'sinc', LPF: false});
+
+  // Write the file
+  fs.writeFileSync(
+    path + "/out/to-sample-rate/sinc-no-LPF-32fp-16000Hz-mono-chirp-1-22050-log.wav",
+    wav.toBuffer());
+});
+
+describe('Upsample a 32-bit 44.1kHz log sine sweep', function() {
+  // Read a 8kHz wav 
+  let wav = new WaveFile(
+    fs.readFileSync(path + "32fp-44100Hz-mono-chirp-1-22050-log.wav"));
+
+  // Convert to another sample rate
+  wav.toSampleRate(96000, {method: 'sinc', LPF: false});
+
+  // Write the file
+  fs.writeFileSync(
+    path + "/out/to-sample-rate/sinc-no-LPF-32fp-96000Hz-mono-chirp-1-22050-log.wav",
+    wav.toBuffer());
+});
+
+describe('Downsample a 32-bit 44.1kHz linear sine sweep', function() {
+  // Read a 8kHz wav 
+  let wav = new WaveFile(
+    fs.readFileSync(path + "32fp-44100Hz-mono-chirp-1-22050-linear.wav"));
+
+  // Convert to another sample rate
+  wav.toSampleRate(16000, {method: 'sinc', LPF: false});
+
+  // Write the file
+  fs.writeFileSync(
+    path + "/out/to-sample-rate/sinc-no-LPF-32fp-16000Hz-mono-chirp-1-22050-linear.wav",
+    wav.toBuffer());
+});
+
+describe('Upsample a 32-bit 44.1kHz linear sine sweep', function() {
+  // Read a 8kHz wav 
+  let wav = new WaveFile(
+    fs.readFileSync(path + "32fp-44100Hz-mono-chirp-1-22050-linear.wav"));
+
+  // Convert to another sample rate
+  wav.toSampleRate(96000, {method: 'sinc', LPF: false});
+
+  // Write the file
+  fs.writeFileSync(
+    path + "/out/to-sample-rate/sinc-no-LPF-32fp-96000Hz-mono-chirp-1-22050-linear.wav",
+    wav.toBuffer());
+});
+
+// Chirps, int
+
+describe('Downsample a 16-bit 44.1kHz log sine sweep', function() {
+  // Read a 8kHz wav 
+  let wav = new WaveFile(
+    fs.readFileSync(path + "16bit-44100Hz-mono-chirp-1-22050-log.wav"));
+
+  // Convert to another sample rate
+  wav.toSampleRate(16000, {method: 'sinc', LPF: false});
+
+  // Write the file
+  fs.writeFileSync(
+    path + "/out/to-sample-rate/sinc-no-LPF-16bit-16000Hz-mono-chirp-1-22050-log.wav",
+    wav.toBuffer());
+});
+
+describe('Upsample a 16-bit 44.1kHz log sine sweep', function() {
+  // Read a 8kHz wav 
+  let wav = new WaveFile(
+    fs.readFileSync(path + "16bit-44100Hz-mono-chirp-1-22050-log.wav"));
+
+  // Convert to another sample rate
+  wav.toSampleRate(96000, {method: 'sinc', LPF: false});
+
+  // Write the file
+  fs.writeFileSync(
+    path + "/out/to-sample-rate/sinc-no-LPF-16bit-96000Hz-mono-chirp-1-22050-log.wav",
+    wav.toBuffer());
+});
+
+describe('Downsample a 16-bit 44.1kHz linear sine sweep', function() {
+  // Read a 8kHz wav 
+  let wav = new WaveFile(
+    fs.readFileSync(path + "16bit-44100Hz-mono-chirp-1-22050-linear.wav"));
+
+  // Convert to another sample rate
+  wav.toSampleRate(16000, {method: 'sinc', LPF: false});
+
+  // Write the file
+  fs.writeFileSync(
+    path + "/out/to-sample-rate/sinc-no-LPF-16bit-16000Hz-mono-chirp-1-22050-linear.wav",
+    wav.toBuffer());
+});
+
+describe('Upsample a 16-bit 44.1kHz linear sine sweep', function() {
+  // Read a 8kHz wav 
+  let wav = new WaveFile(
+    fs.readFileSync(path + "16bit-44100Hz-mono-chirp-1-22050-linear.wav"));
+
+  // Convert to another sample rate
+  wav.toSampleRate(96000, {method: 'sinc', LPF: false});
+
+  // Write the file
+  fs.writeFileSync(
+    path + "/out/to-sample-rate/sinc-no-LPF-16bit-96000Hz-mono-chirp-1-22050-linear.wav",
+    wav.toBuffer());
+});
+
+// Songs
+
+describe('Downsample a 16bit 44.1kHz file', function() {
+  // Read a 8kHz wav 
+  let wav = new WaveFile(
+    fs.readFileSync(path + "song1.wav"));
+
+  // Convert to another sample rate
+  wav.toSampleRate(16000, {method: 'sinc', LPF: false});
+
+  // Write the file
+  fs.writeFileSync(
+    path + "/out/to-sample-rate/sinc-no-LPF-song1-16kHz.wav",
+    wav.toBuffer());
+});
+
+describe('Upsample a 16bit 44.1kHz file', function() {
+  // Read a 8kHz wav 
+  let wav = new WaveFile(
+    fs.readFileSync(path + "song1.wav"));
+
+  // Convert to another sample rate
+  wav.toSampleRate(96000, {method: 'sinc', LPF: false});
+
+  // Write the file
+  fs.writeFileSync(
+    path + "/out/to-sample-rate/sinc-no-LPF-song1-96kHz.wav",
+    wav.toBuffer());
+});
+
+hrend = process.hrtime(hrstart);
+console.info('%ds %dms', hrend[0], hrend[1] / 1000000);