From 82690ef32781e2890fa71acd88da5cc4b7589527 Mon Sep 17 00:00:00 2001
From: Vanilagy <1696106+Vanilagy@users.noreply.github.com>
Date: Tue, 2 Jun 2026 13:06:41 +0200
Subject: [PATCH] Clean up AVC packet NALUs with AUD in them for Chromium key
 frame detection (fixes #396)

---
 src/media-sink.ts | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/media-sink.ts b/src/media-sink.ts
index fda943f..c245b16 100644
--- a/src/media-sink.ts
+++ b/src/media-sink.ts
@@ -8,6 +8,7 @@
 
 import { parsePcmCodec, PCM_AUDIO_CODECS, PcmAudioCodec, VideoCodec, AudioCodec } from './codec';
 import {
+	AvcNalUnitType,
 	concatAvcNalUnits,
 	deserializeAvcDecoderConfigurationRecord,
 	determineVideoPacketType,
@@ -997,6 +998,14 @@ class VideoDecoderWrapper extends DecoderWrapper<VideoSample> {
 
 					for (const loc of iterateAvcNalUnits(packet.data, this.decoderConfig)) {
 						const type = extractNalUnitTypeForAvc(packet.data[loc.offset]!);
+
+						if (type === AvcNalUnitType.AUD) {
+							// If packets contain an AUD and have NALUs before it, this trips up Chromium's key frame
+							// detector. Clear the NALUs if an AUD is encountered.
+							// https://github.com/Vanilagy/mediabunny/issues/396
+							filteredNalUnits.length = 0;
+						}
+
 						// These trip up Chromium's key frame detection, so let's strip them
 						if (!(type >= 20 && type <= 31)) {
 							filteredNalUnits.push(packet.data.subarray(loc.offset, loc.offset + loc.length));