Advertisements and other media content may be placed with or in content items according to contextual information relating to particular portions of the content. For example, advertisements may be matched to products shown in a movie, lyrics used in a song or places named in a work of literature. The contextual information may be defined in a contextual data track of the content item similar to video tracks for video and audio tracks for audio. Accordingly, a content provider or a viewing device may, prior to or during play of a content item, automatically request advertisements or other media content based at least in part on the contextual information stored in the contextual data track of the content item. In one or more arrangements, contextual data may be automatically generated using various image, audio and text processing techniques.