Recover analyzer DSP and realtime pipeline corrections

www/core/binary_protocol.js

@@ -0,0 +1,68 @@
+// Phoenix binary WebSocket packet decoders. Keep this module dependency-free so
+// protocol compatibility can be tested without a browser.
+
+export function decodePhoenixSpectroBuffer(buffer) {
+  if (!(buffer instanceof ArrayBuffer) || buffer.byteLength < 20) return null;
+  const view = new DataView(buffer);
+  if (view.getUint32(0, true) !== 0x50585350) return null;
+  const seq = view.getUint32(4, true);
+  const sampleRate = view.getUint32(8, true);
+  const fftSize = view.getUint32(12, true);
+  const count = view.getUint32(16, true);
+  if (count < 1 || buffer.byteLength !== 20 + count * 4) return null;
+  return {
+    seq,
+    sampleRate,
+    fftSize,
+    bins: new Float32Array(buffer, 20, count),
+  };
+}
+
+export function decodePhoenixVisualsBuffer(buffer) {
+  if (!(buffer instanceof ArrayBuffer) || buffer.byteLength < 32) return null;
+  const view = new DataView(buffer);
+  if (view.getUint32(0, true) !== 0x50585653 || view.getUint16(4, true) !== 1) return null;
+  const flags = view.getUint16(6, true);
+  const seq = view.getUint32(8, true);
+  const xyCount = view.getUint32(12, true);
+  const waveColumns = view.getUint32(16, true);
+  const waveChannels = view.getUint16(20, true);
+  const waveColumnSamples = view.getUint32(24, true);
+  const waveSampleRate = view.getUint32(28, true);
+  if (waveChannels > 2) return null;
+  const xyBytes = xyCount * 8;
+  const waveValues = waveColumns * waveChannels * 2;
+  const expectedBytes = 32 + xyBytes + waveValues * 4;
+  if (!Number.isSafeInteger(expectedBytes) || buffer.byteLength !== expectedBytes) return null;
+
+  let offset = 32;
+  let left = null;
+  let right = null;
+  if ((flags & 1) && xyCount > 0) {
+    left = new Float32Array(xyCount);
+    right = new Float32Array(xyCount);
+    for (let index = 0; index < xyCount; index++) {
+      left[index] = view.getFloat32(offset, true);
+      right[index] = view.getFloat32(offset + 4, true);
+      offset += 8;
+    }
+  } else {
+    offset += xyBytes;
+  }
+
+  let wave = null;
+  if ((flags & 2) && waveValues > 0 && (waveChannels === 1 || waveChannels === 2)) {
+    const data = new Float32Array(waveValues);
+    for (let index = 0; index < waveValues; index++) {
+      data[index] = view.getFloat32(offset + index * 4, true);
+    }
+    wave = {
+      data,
+      columns: waveColumns,
+      channels: waveChannels,
+      columnSamples: waveColumnSamples,
+      sampleRate: waveSampleRate,
+    };
+  }
+  return { seq, left, right, wave };
+}