+ void video (boost::weak_ptr<Piece>, ContentVideo);
+ void audio (boost::weak_ptr<Piece>, AudioStreamPtr, ContentAudio);
+ void image_subtitle (boost::weak_ptr<Piece>, ContentImageSubtitle);
+ void text_subtitle (boost::weak_ptr<Piece>, ContentTextSubtitle);
+ boost::shared_ptr<Resampler> resampler (boost::shared_ptr<const AudioContent> content, AudioStreamPtr stream, bool create);