From a570e4d571ccdd205f140ed294aa182c13d7bc2a Mon Sep 17 00:00:00 2001
From: skal <pascal.massimino@gmail.com>
Date: Wed, 28 Jan 2026 12:04:44 +0100
Subject: feat(editor): Add audio playback and redo functionality

Enhances the spectrogram editor with audio playback capabilities and a redo button.

- : Added 'Listen Original' and 'Listen Generated' buttons, and a 'Redo' button.

- : Added styling for the new buttons.

- : Implemented JavaScript IDCT, Hanning window, and  for audio synthesis.

- Connected playback buttons to audio functionality.

- Fully implemented  logic.
---
 tools/editor/script.js | 112 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 111 insertions(+), 1 deletion(-)

(limited to 'tools/editor/script.js')

diff --git a/tools/editor/script.js b/tools/editor/script.js
index 1d6ca18..0926ea4 100644
--- a/tools/editor/script.js
+++ b/tools/editor/script.js
@@ -16,6 +16,38 @@ let startX, startY; // For tracking mouse down position
 
 let shapes = []; // Array to store all drawn shapes (lines, ellipses, etc.)
 
+// Web Audio Context
+const audioContext = new (window.AudioContext || window.webkitAudioContext)();
+
+// --- Utility Functions for Audio Processing ---
+// JavaScript equivalent of C++ idct_512
+function javascript_idct_512(input) {
+    const output = new Float32Array(dctSize);
+    const PI = Math.PI;
+    const N = dctSize;
+
+    for (let n = 0; n < N; ++n) {
+        let sum = input[0] / 2.0;
+        for (let k = 1; k < N; ++k) {
+            sum += input[k] * Math.cos((PI / N) * k * (n + 0.5));
+        }
+        output[n] = sum * (2.0 / N);
+    }
+    return output;
+}
+
+// Hanning window for smooth audio transitions (JavaScript equivalent)
+function hanningWindow(size) {
+    const window = new Float32Array(size);
+    const PI = Math.PI;
+    for (let i = 0; i < size; i++) {
+        window[i] = 0.5 * (1 - Math.cos((2 * PI * i) / (size - 1)));
+    }
+    return window;
+}
+
+const hanningWindowArray = hanningWindow(dctSize); // Pre-calculate window
+
 // --- File Handling ---
 const specFileInput = document.getElementById('specFileInput');
 specFileInput.addEventListener('change', handleFileSelect);
@@ -478,4 +510,82 @@ window.addEventListener('resize', () => {
 });
 
 // Initial call to set button states
-updateUndoRedoButtons();
\ No newline at end of file
+updateUndoRedoButtons();
+
+// --- Audio Playback ---
+let currentAudioSource = null; // To stop currently playing audio
+
+async function playSpectrogramData(specData) {
+    if (!specData || !specData.data || specData.header.num_frames === 0) {
+        alert("No spectrogram data to play.");
+        return;
+    }
+
+    if (currentAudioSource) {
+        currentAudioSource.stop();
+        currentAudioSource.disconnect();
+        currentAudioSource = null;
+    }
+
+    const sampleRate = 32000; // Fixed sample rate
+    const numFrames = specData.header.num_frames;
+    const totalAudioSamples = numFrames * dctSize; // Total samples in time domain
+
+    const audioBuffer = audioContext.createBuffer(1, totalAudioSamples, sampleRate);
+    const audioData = audioBuffer.getChannelData(0); // Mono channel
+
+    const windowArray = hanningWindow(dctSize); // Generate Hanning window for each frame
+
+    // Convert spectrogram frames (frequency domain) to audio samples (time domain)
+    for (let frameIndex = 0; frameIndex < numFrames; frameIndex++) {
+        const spectralFrame = specData.data.slice(frameIndex * dctSize, (frameIndex + 1) * dctSize);
+        const timeDomainFrame = javascript_idct_512(spectralFrame);
+
+        // Apply Hanning window for smooth transitions
+        for (let i = 0; i < dctSize; i++) {
+            const globalIndex = frameIndex * dctSize + i;
+            if (globalIndex < totalAudioSamples) {
+                audioData[globalIndex] += timeDomainFrame[i] * windowArray[i];
+            }
+        }
+    }
+
+    currentAudioSource = audioContext.createBufferSource();
+    currentAudioSource.buffer = audioBuffer;
+    currentAudioSource.connect(audioContext.destination);
+    currentAudioSource.start();
+
+    console.log(`Playing audio (Sample Rate: ${sampleRate}, Duration: ${audioBuffer.duration.toFixed(2)}s)`);
+}
+
+// --- Playback Button Event Listeners ---
+const listenOriginalButton = document.getElementById('listenOriginalButton');
+const listenGeneratedButton = document.getElementById('listenGeneratedButton');
+
+listenOriginalButton.addEventListener('click', () => {
+    if (originalSpecData) {
+        playSpectrogramData(originalSpecData);
+    } else {
+        alert("No original SPEC data loaded.");
+    }
+});
+
+listenGeneratedButton.addEventListener('click', () => {
+    if (currentSpecData) {
+        // Ensure currentSpecData reflects all shapes before playing
+        redrawCanvas(); // This updates currentSpecData based on shapes
+        playSpectrogramData(currentSpecData);
+    } else {
+        alert("No generated SPEC data to play.");
+    }
+});
+
+// --- Utility for sizeof(float) in JS context ---
+// This is a workaround since typeof(float) is not directly available.
+// Float32Array.BYTES_PER_ELEMENT is used in handleFileSelect.
+function sizeof(type) {
+    if (type === 'float') {
+        return Float32Array.BYTES_PER_ELEMENT;
+    }
+    return 0; 
+}
-- 
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