From 2463ccd08fabdd3a5c8b628d9afe5f539f9168b2 Mon Sep 17 00:00:00 2001
From: Pierre Ossman <ossman@cendio.se>
Date: Thu, 21 Nov 2024 13:16:56 +0100
Subject: [PATCH] Detect broken Firefox H.264 decoder

The Firefox H.264 decoder on Windows might simply just refuse to deliver
any finished frames. It also doesn't deliver any errors.

Detect this early by expecting a frame after flush() has completed.
---
 core/util/browser.js | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/core/util/browser.js b/core/util/browser.js
index b55264fe..407cad9c 100644
--- a/core/util/browser.js
+++ b/core/util/browser.js
@@ -113,10 +113,11 @@ async function _checkWebCodecsH264DecodeSupport() {
         'NjAgcXBtaW49MCBxcG1heD02OSBxcHN0ZXA9NCBpcF9yYXRpbz0xLjQwIGFx' +
         'PTE6MS4wMACAAAABZYiEBrxmKAAPVccAAS044AA5DRJMnkycJk4TPw=='));
 
+    let gotframe = false;
     let error = null;
 
     let decoder = new VideoDecoder({
-        output: (frame) => {},
+        output: (frame) => { gotframe = true; },
         error: (e) => { error = e; },
     });
     let chunk = new EncodedVideoChunk({
@@ -135,6 +136,13 @@ async function _checkWebCodecsH264DecodeSupport() {
         error = e;
     }
 
+    // Firefox fails to deliver the error on Windows, so we need to
+    // check if we got a frame instead
+    // https://bugzilla.mozilla.org/show_bug.cgi?id=1932579
+    if (!gotframe) {
+        return false;
+    }
+
     if (error !== null) {
         return false;
     }