+ /** @return video length in frames; must not be called if has_video() == false */
+ virtual Frame video_length () const = 0;
+ /** @return video sample aspect ratio (if known); must not be called if has_video() == false */
+ virtual boost::optional<double> sample_aspect_ratio () const {
+ return boost::optional<double> ();
+ }
+ /** @return true if this video is in YUV; must not be called if has_video() == false */
+ virtual bool yuv () const = 0;
+ virtual VideoRange range () const = 0;
+ virtual PixelQuanta pixel_quanta () const = 0;