From: Carl Hetherington <cth@carlh.net>
Date: Sun, 14 Jun 2020 20:12:51 +0000 (+0200)
Subject: Fix error when exporting stereo projects with "mixdown to stereo"
X-Git-Tag: v2.15.79
X-Git-Url: https://git.carlh.net/gitweb/?a=commitdiff_plain;ds=sidebyside;h=a863000bf1b7bdcd67286206916f5f9c4fdbd844;p=dcpomatic.git

Fix error when exporting stereo projects with "mixdown to stereo"
set.
---

diff --git a/src/lib/ffmpeg_encoder.cc b/src/lib/ffmpeg_encoder.cc
index 61e489f07..ee49a0646 100644
--- a/src/lib/ffmpeg_encoder.cc
+++ b/src/lib/ffmpeg_encoder.cc
@@ -104,12 +104,24 @@ FFmpegEncoder::FFmpegEncoder (
 		map = AudioMapping (ch, 2);
 		float const overall_gain = 2 / (4 + sqrt(2));
 		float const minus_3dB = 1 / sqrt(2);
-		map.set (dcp::LEFT,   0, overall_gain);
-		map.set (dcp::RIGHT,  1, overall_gain);
-		map.set (dcp::CENTRE, 0, overall_gain * minus_3dB);
-		map.set (dcp::CENTRE, 1, overall_gain * minus_3dB);
-		map.set (dcp::LS,     0, overall_gain);
-		map.set (dcp::RS,     1, overall_gain);
+		if (ch == 2) {
+			map.set (dcp::LEFT, 0, 1);
+			map.set (dcp::RIGHT, 1, 1);
+		} else if (ch == 4) {
+			map.set (dcp::LEFT,   0, overall_gain);
+			map.set (dcp::RIGHT,  1, overall_gain);
+			map.set (dcp::CENTRE, 0, overall_gain * minus_3dB);
+			map.set (dcp::CENTRE, 1, overall_gain * minus_3dB);
+			map.set (dcp::LS,     0, overall_gain);
+		} else if (ch >= 6) {
+			map.set (dcp::LEFT,   0, overall_gain);
+			map.set (dcp::RIGHT,  1, overall_gain);
+			map.set (dcp::CENTRE, 0, overall_gain * minus_3dB);
+			map.set (dcp::CENTRE, 1, overall_gain * minus_3dB);
+			map.set (dcp::LS,     0, overall_gain);
+			map.set (dcp::RS,     1, overall_gain);
+		}
+		/* XXX: maybe we should do something better for >6 channel DCPs */
 	} else {
 		_output_audio_channels = ch;
 		map = AudioMapping (ch, ch);
diff --git a/test/ffmpeg_encoder_test.cc b/test/ffmpeg_encoder_test.cc
index 10186abcc..d824ede30 100644
--- a/test/ffmpeg_encoder_test.cc
+++ b/test/ffmpeg_encoder_test.cc
@@ -376,3 +376,20 @@ BOOST_AUTO_TEST_CASE (ffmpeg_encoder_h264_test7)
 	encoder.go ();
 }
 
+
+/** Stereo project with mixdown-to-stereo set */
+BOOST_AUTO_TEST_CASE (ffmpeg_encoder_h264_test8)
+{
+	shared_ptr<Film> film = new_test_film2("ffmpeg_encoder_h264_test4");
+	film->examine_and_add_content(shared_ptr<DCPContent>(new DCPContent("test/data/scope_dcp")));
+	BOOST_REQUIRE(!wait_for_jobs());
+	film->set_audio_channels (2);
+
+	shared_ptr<Job> job(new TranscodeJob(film));
+	FFmpegEncoder encoder(film, job, "build/test/ffmpeg_encoder_h264_test8.mp4", EXPORT_FORMAT_H264_AAC, true, false, 23
+#ifdef DCPOMATIC_VARIANT_SWAROOP
+			       , optional<dcp::Key>(), optional<string>()
+#endif
+		);
+	encoder.go();
+}