Try to put mono sound tracks on the centre speaker.

4 files changed, 33 insertions, 4 deletions

diff --git a/src/lib/encoder.cc b/src/lib/encoder.cc
index 07ce8f3bc..4a829bafd 100644
--- a/src/lib/encoder.cc
+++ b/src/lib/encoder.cc
@@ -65,7 +65,7 @@ Encoder::Encoder (shared_ptr<const Film> f, shared_ptr<const EncodeOptions> o)
 		/* Create sound output files with .tmp suffixes; we will rename
 		   them if and when we complete.
 		*/
-		for (int i = 0; i < _film->audio_channels(); ++i) {
+		for (int i = 0; i < dcp_audio_channels (_film->audio_channels()); ++i) {
 			SF_INFO sf_info;
 			sf_info.samplerate = dcp_audio_sample_rate (_film->audio_stream()->sample_rate());
 			/* We write mono files */
@@ -163,7 +163,7 @@ Encoder::process_end ()
 		close_sound_files ();
 		
 		/* Rename .wav.tmp files to .wav */
-		for (int i = 0; i < _film->audio_channels(); ++i) {
+		for (int i = 0; i < dcp_audio_channels (_film->audio_channels()); ++i) {
 			if (boost::filesystem::exists (_opt->multichannel_audio_out_path (i, false))) {
 				boost::filesystem::remove (_opt->multichannel_audio_out_path (i, false));
 			}
@@ -380,6 +380,20 @@ Encoder::process_audio (shared_ptr<AudioBuffers> data)
 	}
 #endif
 
+	if (_film->audio_channels() == 1) {
+		/* We need to switch things around so that the mono channel is on
+		   the centre channel of a 5.1 set (with other channels silent).
+		*/
+
+		shared_ptr<AudioBuffers> b (new AudioBuffers (6, data->frames ()));
+		b->make_silent (libdcp::LEFT);
+		b->make_silent (libdcp::RIGHT);
+		memcpy (b->data()[libdcp::CENTRE], data->data()[0], data->frames() * sizeof(float));
+		b->make_silent (libdcp::LFE);
+		b->make_silent (libdcp::LS);
+		b->make_silent (libdcp::RS);
+	}
+
 	write_audio (data);
 	
 	_audio_frame += data->frames ();
@@ -388,7 +402,7 @@ Encoder::process_audio (shared_ptr<AudioBuffers> data)
 void
 Encoder::write_audio (shared_ptr<const AudioBuffers> audio)
 {
-	for (int i = 0; i < _film->audio_channels(); ++i) {
+	for (int i = 0; i < audio->channels(); ++i) {
 		sf_write_float (_sound_files[i], audio->data(i), audio->frames());
 	}
 
diff --git a/src/lib/make_dcp_job.cc b/src/lib/make_dcp_job.cc
index 4605d1724..5272d6bad 100644
--- a/src/lib/make_dcp_job.cc
+++ b/src/lib/make_dcp_job.cc
@@ -131,7 +131,7 @@ MakeDCPJob::run ()
 				&dcp.Progress,
 				dfr.frames_per_second,
 				frames,
-				_film->audio_channels()
+				dcp_audio_channels (_film->audio_channels())
 				)
 			);
 		ascend ();
diff --git a/src/lib/util.cc b/src/lib/util.cc
index 45965385c..395c53e31 100644
--- a/src/lib/util.cc
+++ b/src/lib/util.cc
@@ -364,6 +364,20 @@ dcp_audio_sample_rate (int fs)
 	return 96000;
 }
 
+int
+dcp_audio_channels (int f)
+{
+	if (f) {
+		/* The source is mono, so to put the mono channel into
+		   the centre we need to generate a 5.1 soundtrack.
+		*/
+		return 6;
+	}
+
+	return f;
+}
+
+
 bool operator== (Size const & a, Size const & b)
 {
 	return (a.width == b.width && a.height == b.height);
diff --git a/src/lib/util.h b/src/lib/util.h
index 3832cc579..0744d9c09 100644
--- a/src/lib/util.h
+++ b/src/lib/util.h
@@ -184,6 +184,7 @@ struct Rect
 extern std::string crop_string (Position, Size);
 extern int dcp_audio_sample_rate (int);
 extern DCPFrameRate dcp_frame_rate (float);
+extern int dcp_audio_channels (int);
 extern std::string colour_lut_index_to_name (int index);
 extern int stride_round_up (int, int const *, int);
 extern int stride_lookup (int c, int const * stride);