Give subtract() lists for both parameters.

3 files changed, 5 insertions, 6 deletions

diff --git a/src/lib/audio_merger.cc b/src/lib/audio_merger.cc
index 0bc1ad008..836da7da3 100644
--- a/src/lib/audio_merger.cc
+++ b/src/lib/audio_merger.cc
@@ -132,7 +132,7 @@ AudioMerger::push (std::shared_ptr<const AudioBuffers> audio, DCPTime time)
 	}
 
 	/* Add the non-overlapping parts */
-	for (auto i: subtract(period, periods)) {
+	for (auto i: subtract({period}, periods)) {
 		auto before = _buffers.end();
 		auto after = _buffers.end();
 		for (auto j = _buffers.begin(); j != _buffers.end(); ++j) {
diff --git a/src/lib/dcpomatic_time.h b/src/lib/dcpomatic_time.h
index 9e7191b1e..57ffb1faf 100644
--- a/src/lib/dcpomatic_time.h
+++ b/src/lib/dcpomatic_time.h
@@ -342,14 +342,13 @@ public:
 };
 
 
-/** @param A Period which is subtracted from.
+/** @param A Periods which are subtracted from, must be in ascending order of start time and must not overlap.
  *  @param B Periods to subtract from `A', must be in ascending order of start time and must not overlap.
  */
 template <class T>
-std::list<TimePeriod<T>> subtract (TimePeriod<T> A, std::list<TimePeriod<T>> const & B)
+std::list<TimePeriod<T>> subtract (std::list<TimePeriod<T>> const & A, std::list<TimePeriod<T>> const & B)
 {
-	std::list<TimePeriod<T>> result;
-	result.push_back (A);
+	std::list<TimePeriod<T>> result = A;
 
 	for (auto i: B) {
 		std::list<TimePeriod<T>> new_result;
diff --git a/src/lib/empty_audio.cc b/src/lib/empty_audio.cc
index a2d914bf9..8f905abd9 100644
--- a/src/lib/empty_audio.cc
+++ b/src/lib/empty_audio.cc
@@ -47,7 +47,7 @@ EmptyAudio::EmptyAudio (shared_ptr<const Film> film, shared_ptr<const Playlist>
 		}
 	}
 
-	_periods = subtract (DCPTimePeriod(DCPTime(), length), coalesce(full));
+	_periods = subtract ({DCPTimePeriod(DCPTime(), length)}, coalesce(full));
 
 	if (!_periods.empty()) {
 		_position = _periods.front().from;