From 824350b6e66ce7ef8a5449b60ce1abb2e4f462a5 Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Tue, 21 Apr 2026 22:26:25 +0200
Subject: Fix bug causing mangled audio analyses in some cases (#3155).

The duplicate ID detection was broken due to using the video stream
index rather than its ID for checks.
---
 run/tests                   |  2 +-
 src/lib/ffmpeg_examiner.cc  |  2 +-
 test/audio_analysis_test.cc | 36 ++++++++++++++++++++++++++++++++++++
 3 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/run/tests b/run/tests
index 40bbdcdf0..839dc8dd4 100755
--- a/run/tests
+++ b/run/tests
@@ -3,7 +3,7 @@
 # e.g. --run_tests=foo
 set -e
 
-PRIVATE_GIT="d64f166137a3f2ee5c950f112e48e52fd982f781"
+PRIVATE_GIT="7cbcb10afc73ab559ae9b907881881892aa6d57f"
 
 DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
 source $DIR/environment
diff --git a/src/lib/ffmpeg_examiner.cc b/src/lib/ffmpeg_examiner.cc
index 6b60f6de3..48b354394 100644
--- a/src/lib/ffmpeg_examiner.cc
+++ b/src/lib/ffmpeg_examiner.cc
@@ -221,7 +221,7 @@ FFmpegExaminer::check_for_duplicate_ids()
 	std::set<int> stream_ids;
 
 	if (_video_stream) {
-		stream_ids.insert(*_video_stream);
+		stream_ids.insert(_format_context->streams[*_video_stream]->id);
 	}
 
 	for (auto stream: _audio_streams) {
diff --git a/test/audio_analysis_test.cc b/test/audio_analysis_test.cc
index 8e04945ac..578250b2c 100644
--- a/test/audio_analysis_test.cc
+++ b/test/audio_analysis_test.cc
@@ -40,6 +40,7 @@
 #include "lib/playlist.h"
 #include "lib/ratio.h"
 #include "test.h"
+#include <dcp/scope_guard.h>
 #include <boost/test/unit_test.hpp>
 #include <numeric>
 
@@ -315,3 +316,38 @@ BOOST_AUTO_TEST_CASE(ebur128_test)
 }
 #endif
 
+
+static bool saw_ffmpeg_error = false;
+
+static
+void
+test_log_callback(void*, int level, const char*, va_list)
+{
+	if (level <= AV_LOG_WARNING) {
+		saw_ffmpeg_error = true;
+	}
+}
+
+
+/* The file in this test has the audio stream as index 0, video as 1,
+ * with both streams having the same ID.  This triggered a bug where
+ * on analysis (with video disabled) the video packets would be fed
+ * to the audio decoder, causing chaos manifesting as many audio decoder
+ * errors.
+ */
+BOOST_AUTO_TEST_CASE(analysis_stream_confusion_test)
+{
+	auto sound = content_factory(TestPaths::private_data() / "ge.mkv")[0];
+	auto film = new_test_film("analysis_stream_confusion_test", { sound });
+
+	av_log_set_callback(test_log_callback);
+	dcp::ScopeGuard sg = []() {
+		capture_ffmpeg_logs();
+	};
+
+	auto job = make_shared<AnalyseAudioJob>(film, film->playlist(), true);
+	JobManager::instance()->add(job);
+	BOOST_REQUIRE(!wait_for_jobs());
+
+	BOOST_CHECK(!saw_ffmpeg_error);
+}
-- 
cgit v1.2.3