- virtual float video_frame_rate () const = 0;
- virtual libdcp::Size video_size () const = 0;
- virtual VideoFrame video_length () const = 0;
+ virtual boost::optional<float> video_frame_rate () const = 0;
+ virtual dcp::Size video_size () const = 0;
+ virtual ContentTime video_length () const = 0;
+ virtual boost::optional<float> sample_aspect_ratio () const {
+ return boost::optional<float> ();
+ }