Hint about problems with alpha channels (#3014).

2 files changed, 18 insertions, 1 deletions

diff --git a/src/lib/hints.cc b/src/lib/hints.cc
index 0979ce6a9..17aa16d47 100644
--- a/src/lib/hints.cc
+++ b/src/lib/hints.cc
@@ -487,6 +487,7 @@ try
 	check_subtitle_languages();
 	check_audio_language();
 	check_8_or_16_audio_channels();
+	check_video_alpha();
 
 	scan_content(film);
 
@@ -770,3 +771,19 @@ Hints::check_8_or_16_audio_channels()
 	}
 }
 
+
+void
+Hints::check_video_alpha()
+{
+	for (auto content: film()->content()) {
+		if (content->video && content->video->has_alpha()) {
+			hint(fmt::format(
+					_("Some of your video content contains an alpha channel, and {} cannot be "
+					  "certain how to process it.  Check that your video looks correct in the "
+					  "preview, and if not try enabling or disabling the 'premultiply' video filter "
+					  "in the content Advanced Settings dialogue box."),
+					variant::dcpomatic()));
+		}
+	}
+}
+
diff --git a/src/lib/hints.h b/src/lib/hints.h
index 0d6605e25..49fd32ea9 100644
--- a/src/lib/hints.h
+++ b/src/lib/hints.h
@@ -66,7 +66,6 @@ private:
 	void closed_caption(PlayerText text, dcpomatic::DCPTimePeriod period);
 	void open_subtitle(PlayerText text, dcpomatic::DCPTimePeriod period);
 
-
 	void check_certificates();
 	void check_interop();
 	void check_video_encoding();
@@ -87,6 +86,7 @@ private:
 	void check_subtitle_languages();
 	void check_audio_language();
 	void check_8_or_16_audio_channels();
+	void check_video_alpha();
 
 	boost::thread _thread;
 	/** This is used to make a partial DCP containing only the subtitles and closed captions that