Smarter asset loading. Better audio rendering.

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

packages/wolf_3d_synth/lib/src/imf_renderer.dart

@@ -5,75 +5,89 @@ import 'package:wolf_3d_data_types/wolf_3d_data_types.dart';
 import 'opl2_emulator.dart';
 
 class ImfRenderer {
-  /// Renders an ImfMusic track into raw 16-bit PCM samples
+  /// Renders music in Stereo with a 10ms Haas widening effect.
   static Int16List render(ImfMusic music) {
     final emulator = Opl2Emulator();
-
     const double samplesPerTick = Opl2Emulator.sampleRate / 700.0;
 
-    // 1. Pre-calculate the total number of audio samples we need
     int totalTicks = 0;
     for (final inst in music.instructions) {
       totalTicks += inst.delay;
     }
-    int totalSamples = (totalTicks * samplesPerTick).round();
 
-    // 2. Pre-allocate a fixed-size buffer (blazing fast!)
-    final pcmBuffer = Int16List(totalSamples);
+    // Allocate buffer for Stereo (2 channels per sample)
+    int totalMonoSamples = (totalTicks * samplesPerTick).round();
+    final pcmBuffer = Int16List(totalMonoSamples * 2);
     int sampleIndex = 0;
 
-    for (final instruction in music.instructions) {
-      // Write the instruction to the chip
-      emulator.writeRegister(instruction.register, instruction.data);
+    // --- Stereo Widening (Haas Effect) ---
+    // 10ms at 44.1kHz = 441 samples.
+    // This is tight enough to sound like 'width' rather than 'echo'.
+    const int delaySamples = 441;
+    final delayLine = Float32List(delaySamples);
+    int delayPtr = 0;
 
-      // Generate the samples for the delay period
+    for (final instruction in music.instructions) {
+      emulator.writeRegister(instruction.register, instruction.data);
       int samplesToGenerate = (instruction.delay * samplesPerTick).round();
 
       for (int i = 0; i < samplesToGenerate; i++) {
-        if (sampleIndex >= pcmBuffer.length) break; // Safety bounds
+        if (sampleIndex + 1 >= pcmBuffer.length) break;
 
-        double sampleFloat = emulator.generateSample();
-        int sampleInt = (sampleFloat * 32767).toInt().clamp(-32768, 32767);
+        double monoSample = emulator.generateSample();
 
-        pcmBuffer[sampleIndex++] = sampleInt;
+        // Left channel: Immediate
+        double left = monoSample;
+        // Right channel: Delayed
+        double right = delayLine[delayPtr];
+
+        delayLine[delayPtr] = monoSample;
+        delayPtr = (delayPtr + 1) % delaySamples;
+
+        // Interleave L and R
+        pcmBuffer[sampleIndex++] = (left * 32767).toInt().clamp(-32768, 32767);
+        pcmBuffer[sampleIndex++] = (right * 32767).toInt().clamp(-32768, 32767);
       }
     }
-
     return pcmBuffer;
   }
 
-  /// Wraps raw 16-bit PCM data in a standard WAV file header
-  static Uint8List createWavFile(Int16List pcmData) {
-    int byteRate = Opl2Emulator.sampleRate * 2; // 1 channel * 16-bit (2 bytes)
-    int dataSize = pcmData.length * 2;
-    int fileSize = 36 + dataSize;
+  /// Wraps raw PCM data into a standard Stereo WAV file header.
+  static Uint8List createWavFile(
+    Int16List pcmData, {
+    int sampleRate = Opl2Emulator.sampleRate,
+  }) {
+    const int numChannels = 2;
+    const int bytesPerSample = 2;
+    const int blockAlign = numChannels * bytesPerSample;
+
+    final int dataSize = pcmData.length * bytesPerSample;
+    final int byteRate = sampleRate * blockAlign;
+    final int fileSize = 36 + dataSize;
 
     final bytes = BytesBuilder();
 
-    // "RIFF" chunk descriptor
+    // RIFF header
     bytes.add('RIFF'.codeUnits);
     bytes.add(_int32ToBytes(fileSize));
     bytes.add('WAVE'.codeUnits);
 
-    // "fmt " sub-chunk
+    // Format chunk
     bytes.add('fmt '.codeUnits);
-    bytes.add(_int32ToBytes(16)); // Subchunk1Size (16 for PCM)
-    bytes.add(_int16ToBytes(1)); // AudioFormat (1 = PCM)
-    bytes.add(_int16ToBytes(1)); // NumChannels (1 = Mono)
-    bytes.add(_int32ToBytes(Opl2Emulator.sampleRate)); // SampleRate
-    bytes.add(_int32ToBytes(byteRate)); // ByteRate
-    bytes.add(_int16ToBytes(2)); // BlockAlign
-    bytes.add(_int16ToBytes(16)); // BitsPerSample
+    bytes.add(_int32ToBytes(16));
+    bytes.add(_int16ToBytes(1));
+    bytes.add(_int16ToBytes(numChannels));
+    bytes.add(_int32ToBytes(sampleRate));
+    bytes.add(_int32ToBytes(byteRate));
+    bytes.add(_int16ToBytes(blockAlign));
+    bytes.add(_int16ToBytes(16));
 
-    // "data" sub-chunk
+    // Data chunk
     bytes.add('data'.codeUnits);
     bytes.add(_int32ToBytes(dataSize));
 
-    // Append the actual raw audio data (Blazing Fast version)
     final byteData = ByteData(dataSize);
     for (int i = 0; i < pcmData.length; i++) {
-      // Multiply by 2 because each Int16 takes up 2 bytes.
-      // Endian.little is strictly required for the standard WAV format.
       byteData.setInt16(i * 2, pcmData[i], Endian.little);
     }
     bytes.add(byteData.buffer.asUint8List());
@@ -85,7 +99,6 @@ class ImfRenderer {
     value & 0xff,
     (value >> 8) & 0xff,
   ];
-
   static List<int> _int32ToBytes(int value) => [
     value & 0xff,
     (value >> 8) & 0xff,

packages/wolf_3d_synth/lib/wolf_3d_synth.dart

@@ -3,4 +3,4 @@
 /// More dartdocs go here.
 library;
 
-export 'src/imf_renderer.dart' show ImfRenderer;
+export 'src/imf_renderer.dart' show ImfRenderer, NumChannels;