subs->write (path / "subs.mxf");
shared_ptr<dcp::ReelSubtitleAsset> reel_subs(new dcp::ReelSubtitleAsset(subs, dcp::Fraction(24, 1), 240, 0));
subs->write (path / "subs.mxf");
shared_ptr<dcp::ReelSubtitleAsset> reel_subs(new dcp::ReelSubtitleAsset(subs, dcp::Fraction(24, 1), 240, 0));