Restore short-cutting of analysis gain updates.

If we have an analysis of one piece of content and
the gain changes we don't re-run the analysis, instead
applying a suitable `correction' in the UI.

4 files changed, 37 insertions, 1 deletions

diff --git a/src/lib/analyse_audio_job.cc b/src/lib/analyse_audio_job.cc
index 1cec15c2a..2f48d12a9 100644
--- a/src/lib/analyse_audio_job.cc
+++ b/src/lib/analyse_audio_job.cc
@@ -89,6 +89,16 @@ AnalyseAudioJob::run ()
 	}
 
 	_analysis->set_peak (_overall_peak, DCPTime::from_frames (_overall_peak_frame, _film->audio_frame_rate ()));
+
+	if (_playlist->content().size() == 1) {
+		/* If there was only one piece of content in this analysis we may later need to know what its
+		   gain was when we analysed it.
+		*/
+		shared_ptr<const AudioContent> ac = dynamic_pointer_cast<const AudioContent> (_playlist->content().front ());
+		DCPOMATIC_ASSERT (ac);
+		_analysis->set_analysis_gain (ac->audio_gain ());
+	}
+
 	_analysis->write (_film->audio_analysis_path (_playlist));
 
 	set_progress (1);
diff --git a/src/lib/audio_analysis.cc b/src/lib/audio_analysis.cc
index 7e1dc6e78..127def807 100644
--- a/src/lib/audio_analysis.cc
+++ b/src/lib/audio_analysis.cc
@@ -102,6 +102,7 @@ AudioAnalysis::AudioAnalysis (boost::filesystem::path filename)
 
 	_peak = f.number_child<float> ("Peak");
 	_peak_time = DCPTime (f.number_child<DCPTime::Type> ("PeakTime"));
+	_analysis_gain = f.optional_number_child<double> ("AnalysisGain");
 }
 
 void
@@ -149,5 +150,9 @@ AudioAnalysis::write (boost::filesystem::path filename)
 		root->add_child("PeakTime")->add_child_text (raw_convert<string> (_peak_time.get().get ()));
 	}
 
+	if (_analysis_gain) {
+		root->add_child("AnalysisGain")->add_child_text (raw_convert<string> (_analysis_gain.get ()));
+	}
+
 	doc->write_to_file_formatted (filename.string ());
 }
diff --git a/src/lib/audio_analysis.h b/src/lib/audio_analysis.h
index 2411b4316..478b0e532 100644
--- a/src/lib/audio_analysis.h
+++ b/src/lib/audio_analysis.h
@@ -75,12 +75,25 @@ public:
 		return _peak_time;
 	}
 
+	boost::optional<double> analysis_gain () const {
+		return _analysis_gain;
+	}
+
+	void set_analysis_gain (double gain) {
+		_analysis_gain = gain;
+	}
+
 	void write (boost::filesystem::path);
 
 private:
 	std::vector<std::vector<AudioPoint> > _data;
 	boost::optional<float> _peak;
 	boost::optional<DCPTime> _peak_time;
+	/** If this analysis was run on a single piece of
+	 *  content we store its gain in dB when the analysis
+	 *  happened.
+	 */
+	boost::optional<double> _analysis_gain;
 };
 
 #endif
diff --git a/src/lib/film.cc b/src/lib/film.cc
index 5310ef71f..e19b309f7 100644
--- a/src/lib/film.cc
+++ b/src/lib/film.cc
@@ -241,7 +241,15 @@ Film::audio_analysis_path (shared_ptr<const Playlist> playlist) const
 
 		digester.add (ac->digest ());
 		digester.add (ac->audio_mapping().digest ());
-		digester.add (ac->audio_gain ());
+		if (playlist->content().size() != 1) {
+			/* Analyses should be considered equal regardless of gain
+			   if they were made from just one piece of content.  This
+			   is because we can fake any gain change in a single-content
+			   analysis at the plotting stage rather than having to
+			   recompute it.
+			*/
+			digester.add (ac->audio_gain ());
+		}
 	}
 
 	if (audio_processor ()) {