Fix regression #44

Author: dy

packages/decode-aac/decode-aac.js

@@ -360,11 +360,18 @@ function parseBoxes(buf, start, end, cb) {
 		} else if (size < 8) {
 			break
 		}
-		if (off + size > end) size = end - off
 
 		let bodyOff = off + 8
+		let truncated = off + size > end
 
-		if (type === 'stsd') parseSampleDesc(buf, bodyOff, size - 8, cb)
+		// mdat carries raw frames — partial is fine; callers honour availability
+		if (type === 'mdat') {
+			cb(type, buf.subarray(bodyOff, truncated ? end : off + size), bodyOff)
+			if (truncated) break
+		}
+		// any other box must be fully present before parsing — partial tables yield garbage
+		else if (truncated) break
+		else if (type === 'stsd') parseSampleDesc(buf, bodyOff, size - 8, cb)
 		else if (CONTAINERS.has(type)) parseBoxes(buf, bodyOff + (type === 'meta' ? 4 : 0), off + size, cb)
 		else cb(type, buf.subarray(bodyOff, off + size), bodyOff)
 
@@ -432,8 +439,10 @@ function extractFrames(buf, stsz, stco, stsc) {
 		}
 		let off = stco[ci]
 		for (let s = 0; s < spc && si < stsz.length; s++) {
-			let sz = stsz[si++]
-			if (off + sz <= buf.length) frames.push(buf.subarray(off, off + sz))
+			let sz = stsz[si]
+			if (off + sz > buf.length) return frames  // sequential: first missing → rest missing
+			frames.push(buf.subarray(off, off + sz))
+			si++
 			off += sz
 		}
 	}

packages/decode-aac/test.js

@@ -95,6 +95,34 @@ console.log('lifecycle')
 	d.free()
 }
 
+// ---- M4A streaming (moov split across chunks, non-faststart layout) ----
+// Regression: github #44 — init fired on partial moov → garbage stsz/stco → 0 frames.
+console.log('M4A streaming')
+{
+	let ref = await decode(m4a)
+
+	for (let chunkSize of [16384, 4096, 1024, 256]) {
+		let dec = await decoder()
+		let chunks = []
+		for (let off = 0; off < m4a.length; off += chunkSize) {
+			let r = dec.decode(m4a.subarray(off, Math.min(off + chunkSize, m4a.length)))
+			if (r.channelData.length) chunks.push(r.channelData[0])
+		}
+		let f = dec.flush()
+		if (f.channelData.length) chunks.push(f.channelData[0])
+		dec.free()
+
+		let total = chunks.reduce((s, c) => s + c.length, 0)
+		ok(total === ref.channelData[0].length, 'chunk=' + chunkSize + ' count matches (' + total + ')')
+
+		let stream = new Float32Array(total), pos = 0
+		for (let c of chunks) { stream.set(c, pos); pos += c.length }
+		let maxDiff = 0
+		for (let i = 0; i < total; i++) maxDiff = Math.max(maxDiff, Math.abs(stream[i] - ref.channelData[0][i]))
+		ok(maxDiff === 0, 'chunk=' + chunkSize + ' content identical')
+	}
+}
+
 // ---- ADTS streaming (partial frame buffering) ----
 console.log('ADTS streaming')
 {