X-Git-Url: https://git.carlh.net/gitweb/?a=blobdiff_plain;f=src%2Flib%2Fmid_side_decoder.cc;h=4f619ad572f347309e21e5354c8dba1b57e70ad8;hb=b9842263a402b5ce1d2f85a1346ca11a419f816e;hp=842d5c8ee56d066b49a2e631cfa73cabd7eb5d88;hpb=9a2dca23967ff404dab1a36ec3fb9075d5e8e66e;p=dcpomatic.git

diff --git a/src/lib/mid_side_decoder.cc b/src/lib/mid_side_decoder.cc
index 842d5c8ee..4f619ad57 100644
--- a/src/lib/mid_side_decoder.cc
+++ b/src/lib/mid_side_decoder.cc
@@ -59,16 +59,27 @@ MidSideDecoder::clone (int) const
 }
 
 shared_ptr<AudioBuffers>
-MidSideDecoder::run (shared_ptr<const AudioBuffers> in)
+MidSideDecoder::run (shared_ptr<const AudioBuffers> in, int channels)
 {
-	shared_ptr<AudioBuffers> out (new AudioBuffers (3, in->frames ()));
+	int const N = min (channels, 3);
+	shared_ptr<AudioBuffers> out (new AudioBuffers (channels, in->frames ()));
 	for (int i = 0; i < in->frames(); ++i) {
 		float const left = in->data()[0][i];
 		float const right = in->data()[1][i];
 		float const mid = (left + right) / 2;
-		out->data()[0][i] = left - mid;
-		out->data()[1][i] = right - mid;
-		out->data()[2][i] = mid;
+		if (N > 0) {
+			out->data()[0][i] = left - mid;
+		}
+		if (N > 1) {
+			out->data()[1][i] = right - mid;
+		}
+		if (N > 2) {
+			out->data()[2][i] = mid;
+		}
+	}
+
+	for (int i = N; i < channels; ++i) {
+		out->make_silent (i);
 	}
 
 	return out;