From 61e895a75a1436a8b8985b4a975238b5b2ce519e Mon Sep 17 00:00:00 2001
From: Enriquefft <enriquefft2001@gmail.com>
Date: Thu, 16 Apr 2026 14:18:40 -0500
Subject: [PATCH] fix: sanitize packet-scan range against NaN/Infinity duration
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mediaInfo.duration from web-demuxer can be NaN or Infinity on Chromium
Linux (same MediaRecorder bug this PR otherwise addresses). That value
flowed straight into Math.max + demuxer.read() as scanEndSec, producing
an invalid range argument and breaking the ground-truth packet scan.

Guard both mediaInfo.duration and videoStream.duration with
Number.isFinite before Math.max; validateDuration() already handled the
downstream use.

Drop redundant WebDemuxer.read() / getDecoderConfig() type casts while
here — the generics infer the chunk/config type from the media string
literal, so the `as ReadableStream<EncodedVideoChunk>` and
`as AudioDecoderConfig` are no-ops.
---
 src/lib/exporter/audioEncoder.ts     | 11 +++++------
 src/lib/exporter/streamingDecoder.ts | 13 +++++++++----
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/src/lib/exporter/audioEncoder.ts b/src/lib/exporter/audioEncoder.ts
index e373702..611ef5b 100644
--- a/src/lib/exporter/audioEncoder.ts
+++ b/src/lib/exporter/audioEncoder.ts
@@ -62,7 +62,7 @@ export class AudioProcessor {
 	): Promise<void> {
 		let audioConfig: AudioDecoderConfig;
 		try {
-			audioConfig = (await demuxer.getDecoderConfig("audio")) as AudioDecoderConfig;
+			audioConfig = await demuxer.getDecoderConfig("audio");
 		} catch {
 			console.warn("[AudioProcessor] No audio track found, skipping");
 			return;
@@ -87,11 +87,10 @@ export class AudioProcessor {
 			typeof readEndSec === "number" && Number.isFinite(readEndSec)
 				? Math.max(0, readEndSec)
 				: undefined;
-		const audioStream = (
+		const audioStream =
 			safeReadEndSec !== undefined
 				? demuxer.read("audio", 0, safeReadEndSec)
-				: demuxer.read("audio")
-		) as ReadableStream<EncodedAudioChunk>;
+				: demuxer.read("audio");
 		const reader = audioStream.getReader();
 
 		try {
@@ -396,8 +395,8 @@ export class AudioProcessor {
 
 		try {
 			await demuxer.load(file);
-			const audioConfig = (await demuxer.getDecoderConfig("audio")) as AudioDecoderConfig;
-			const reader = (demuxer.read("audio") as ReadableStream<EncodedAudioChunk>).getReader();
+			const audioConfig = await demuxer.getDecoderConfig("audio");
+			const reader = demuxer.read("audio").getReader();
 			let isFirstChunk = true;
 
 			try {
diff --git a/src/lib/exporter/streamingDecoder.ts b/src/lib/exporter/streamingDecoder.ts
index b0866f5..fca92e2 100644
--- a/src/lib/exporter/streamingDecoder.ts
+++ b/src/lib/exporter/streamingDecoder.ts
@@ -231,11 +231,16 @@ export class StreamingVideoDecoder {
 		// MediaRecorder (especially on Linux) writes unreliable container durations.
 		// Packet timestamps are ground truth — no decode needed, just timestamp reads.
 		// Pass explicit range because some containers are truncated without one.
-		const scanEndSec = Math.max(mediaInfo.duration, videoStream?.duration ?? 0, 0) + 0.5;
+		// Sanitize because mediaInfo.duration can be NaN/Infinity (Chromium Linux bug),
+		// which would propagate into demuxer.read() as an invalid endpoint.
+		const containerDurationSec = Number.isFinite(mediaInfo.duration) ? mediaInfo.duration : 0;
+		const streamDurationSec =
+			typeof videoStream?.duration === "number" && Number.isFinite(videoStream.duration)
+				? videoStream.duration
+				: 0;
+		const scanEndSec = Math.max(containerDurationSec, streamDurationSec, 0) + 0.5;
 		let maxPacketEndUs = 0;
-		const scanReader = (
-			this.demuxer.read("video", 0, scanEndSec) as ReadableStream<EncodedVideoChunk>
-		).getReader();
+		const scanReader = this.demuxer.read("video", 0, scanEndSec).getReader();
 		try {
 			while (true) {
 				const { done, value } = await scanReader.read();