From 52b3eee4e7285e26469b2a5f4d9d9eac20aba387 Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Fri, 12 Dec 2025 11:43:45 +0100
Subject: Fix error when seeking a file with no video and >1 audio stream
 (#3128).

---
 src/lib/ffmpeg_decoder.cc        |  9 ++++-----
 test/data                        |  2 +-
 test/ffmpeg_decoder_seek_test.cc | 22 ++++++++++++++++++++++
 3 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/src/lib/ffmpeg_decoder.cc b/src/lib/ffmpeg_decoder.cc
index c70733c4c..ec85bb56c 100644
--- a/src/lib/ffmpeg_decoder.cc
+++ b/src/lib/ffmpeg_decoder.cc
@@ -418,11 +418,10 @@ FFmpegDecoder::seek (ContentTime time, bool accurate)
 	if (_video_stream) {
 		stream = _video_stream;
 	} else {
-		DCPOMATIC_ASSERT (_ffmpeg_content->audio);
-		auto s = dynamic_pointer_cast<FFmpegAudioStream>(_ffmpeg_content->audio->stream());
-		if (s) {
-			stream = s->index (_format_context);
-		}
+		DCPOMATIC_ASSERT(_ffmpeg_content->audio);
+		auto streams = _ffmpeg_content->ffmpeg_audio_streams();
+		DCPOMATIC_ASSERT(!streams.empty());
+		stream = streams[0]->index(_format_context);
 	}
 
 	DCPOMATIC_ASSERT (stream);
diff --git a/test/data b/test/data
index 7bc927ee1..090abdff0 160000
--- a/test/data
+++ b/test/data
@@ -1 +1 @@
-Subproject commit 7bc927ee1c828ce5f6f8e376176c8a44f193ed1e
+Subproject commit 090abdff0d1f62f363792a13982d836f891b3908
diff --git a/test/ffmpeg_decoder_seek_test.cc b/test/ffmpeg_decoder_seek_test.cc
index ee0da99da..a3212318c 100644
--- a/test/ffmpeg_decoder_seek_test.cc
+++ b/test/ffmpeg_decoder_seek_test.cc
@@ -28,6 +28,8 @@
  */
 
 
+#include "lib/audio_decoder.h"
+#include "lib/content_audio.h"
 #include "lib/content_video.h"
 #include "lib/ffmpeg_content.h"
 #include "lib/ffmpeg_decoder.h"
@@ -152,3 +154,23 @@ BOOST_AUTO_TEST_CASE(seek_when_backward_fails)
 	}
 }
 
+
+BOOST_AUTO_TEST_CASE(seek_with_no_video_two_audio)
+{
+	auto content = make_shared<FFmpegContent>("test/data/no_video_two_audio.mov");
+	auto film = new_test_film("seek_with_no_video_two_audio", { content });
+	auto decoder = make_shared<FFmpegDecoder>(film, content, false);
+
+	optional<Frame> frame;
+	auto audio = [&](AudioStreamPtr, ContentAudio audio) {
+		frame = audio.frame;
+	};
+
+	decoder->audio->Data.connect(boost::bind<void>(audio, _1, _2));
+	decoder->seek(dcpomatic::ContentTime::from_seconds(1), false);
+	while (!decoder->pass() && frame == boost::none) {}
+
+	BOOST_REQUIRE(frame != boost::none);
+	BOOST_CHECK(*frame > 0);
+}
+
-- 
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