+using boost::shared_ptr;
+using boost::weak_ptr;
+
+Decoder::Decoder (weak_ptr<const Film> film)
+ : _film (film)
+{
+
+}
+
+/** @return Earliest time of content that the next pass() will emit */
+ContentTime
+Decoder::position () const
+{
+ optional<ContentTime> pos;
+ shared_ptr<const Film> f = film();
+
+ if (video && !video->ignore() && (!pos || video->position(f) < *pos)) {
+ pos = video->position(f);
+ }
+
+ if (audio && !audio->ignore() && (!pos || audio->position(f) < *pos)) {
+ pos = audio->position(f);
+ }
+
+ BOOST_FOREACH (shared_ptr<TextDecoder> i, text) {
+ if (!i->ignore() && (!pos || i->position(f) < *pos)) {
+ pos = i->position(f);
+ }
+ }
+
+ return pos.get_value_or(ContentTime());
+}