From b74c13621d17c4536ce49ecf366f8ae8789483ed Mon Sep 17 00:00:00 2001
From: Victor Giers <mail@victorgiers.com>
Date: Tue, 14 Jul 2026 11:48:26 +0200
Subject: [PATCH] Update pad parser to handle fractional pitch and trim length
 correctly

---
 src/lib/parsers.ts       | 13 ++++++++----
 tests/pad-parser.test.ts | 44 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 4 deletions(-)
 create mode 100644 tests/pad-parser.test.ts

diff --git a/src/lib/parsers.ts b/src/lib/parsers.ts
index 0dff24c..7502c10 100644
--- a/src/lib/parsers.ts
+++ b/src/lib/parsers.ts
@@ -167,10 +167,15 @@ export function collectPads(files: TarFile[], sounds: Sound[]) {
         const soundId = (file.data[2] << 8) + file.data[1];
         const sound = sounds.find((s) => s.id === soundId);
         const pitch = file.data[17] <= 12 ? file.data[17] : -(256 - file.data[17]); // pitch from -12 to +12
-        const pitchDecimal = file.data[26];
+        const pitchFraction = (file.data[26] ?? 0) / 100;
         const pan = (file.data[18] >= 240 ? -(256 - file.data[18]) : file.data[18]) / 16; // normalized pan
         const trimLeft = (file.data[6] << 16) + (file.data[5] << 8) + file.data[4];
-        const trimRight = trimLeft + (file.data[10] << 16) + (file.data[9] << 8) + file.data[8];
+        const trimLength = new DataView(
+          file.data.buffer,
+          file.data.byteOffset,
+          file.data.byteLength,
+        ).getUint32(8, true);
+        const trimRight = trimLeft + trimLength;
 
         result[group.id].push({
           pad: i,
@@ -187,12 +192,12 @@ export function collectPads(files: TarFile[], sounds: Sound[]) {
           trimRight,
           playMode: file.data[23] === 0 ? 'oneshot' : file.data[23] === 1 ? 'key' : 'legato',
           soundLength: sound ? calculateSoundLength(sound) : 0,
-          pitch: Math.max(-12, Math.min(12, parseFloat(`${pitch}.${pitchDecimal}`))),
+          pitch: Math.max(-12, Math.min(12, pitch + pitchFraction)),
           rootNote: file.data[24],
           timeStretch: timeStretch(file.data[21]),
           timeStretchBpm: Number(bytesToFloat32(file.data.slice(12, 16)).toFixed(2)),
           timeStretchBars: timeStretchBars(file.data[25]),
-          inChokeGroup: file.data[22] === 1,
+          inChokeGroup: file.data[22] !== 0,
           midiChannel: file.data[3],
         });
       }
diff --git a/tests/pad-parser.test.ts b/tests/pad-parser.test.ts
new file mode 100644
index 0000000..034c9ff
--- /dev/null
+++ b/tests/pad-parser.test.ts
@@ -0,0 +1,44 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { collectPads } from '../src/lib/parsers';
+import { TarFile } from '../src/lib/untar';
+
+function padFile(name: string, length: 26 | 27) {
+  const data = new Uint8Array(length);
+  return { data, file: new TarFile(name, data.length, data) };
+}
+
+test('decodes optional fractional pitch arithmetically for 26- and 27-byte pad records', () => {
+  const native = padFile('pads/a/p01', 26);
+  native.data[17] = 0xff;
+  const extended = padFile('pads/a/p02', 27);
+  extended.data[17] = 0xff;
+  extended.data[26] = 91;
+
+  const pads = collectPads([native.file, extended.file], []);
+
+  assert.equal(pads.a[0].pitch, -1);
+  assert.ok(Math.abs(pads.a[1].pitch - -0.09) < 1e-12);
+});
+
+test('reads trim length as unsigned 32-bit little-endian data', () => {
+  const pad = padFile('pads/a/p01', 26);
+  pad.data.set([0x03, 0x02, 0x01], 4);
+  pad.data.set([0x04, 0x03, 0x02, 0x01], 8);
+
+  const parsed = collectPads([pad.file], []).a[0];
+
+  assert.equal(parsed.trimLeft, 0x010203);
+  assert.equal(parsed.trimRight, 0x010203 + 0x01020304);
+});
+
+test('treats every nonzero mute byte as shared mute-group membership', () => {
+  const member = padFile('pads/a/p01', 26);
+  const nonmember = padFile('pads/a/p02', 26);
+  member.data[22] = 200;
+
+  const pads = collectPads([member.file, nonmember.file], []).a;
+
+  assert.equal(pads[0].inChokeGroup, true);
+  assert.equal(pads[1].inChokeGroup, false);
+});