Hyper-Hitchcock: Authoring Interactive Videos and Generating Interactive Summaries

1. Hyper-Hitchcock:Authoring Interactive Videos and Generating Interactive Summaries Frank Shipman Texas A&M University Andreas GirgensohnLynn Wilcox FX Palo Alto Laboratory, Inc.

2. Outline • Introduction • Detail-on-demand video • Hyper-Hitchcock hypervideo editor • Generating hypervideo summaries • Experience with Authoring • Conclusions

3. Computational Media • Computation-based mediums of communication are growing • E-mail, IM, Blogs, MMORPG, … • Text, images, animation, … • TV/DVD/PC merger (Sony PS3, Media Center PCs) • Interactive video • Vision: Seamlessly interact with charactersin the show • Reality: Difficult to author even simpleinteractive videos

4. Support for Hypervideo Authoring • Links in video can lead to other video segments • Short main video with branches providing additional detail • Hyperlinks to branches just like in Web pages • Making of a scene in a movie, biography of an actor, different camera angle • General hypervideo difficult to author • Simple hypervideo format with only a single active link • Novel approach: use automatic video analysis, create an easy-to-use interface, and support simple hypervideo format

5. Uses of Hypervideo • Hypervideo well-suited for training video • Overview of topic with links to more detail • Viewers can choose video content based on their prior knowledge and current task • Home video is more enjoyable if viewers can select content • Only a small portion of the video is really “usable” • Difficult to watch long home videos • Customize viewing experience for different viewers • More detail on sports events for some family members, more scenes with children for others

6. Detail-on-demand Hypervideo • General hypervideo • Links from objects in video to other video • Requires object tracking • Requires interface for indicating and selecting from multiple links • Detail-on-demand video • Single link from any video segment • No anchor regions to simplify viewing and authoring

7. Hierarchical Video with Links • Video sequences are represented as a containment hierarchy of video elements • Elements are video clips or composites grouping other video elements • Elements are played in sequence • Each element can be link anchor or link destination • Anchor for innermost element is available while element is playing • After link destinationvideo is played,play-back continuesat the link anchor

8. Detail-on-demand Links • Any video clip or composite can be link anchor or link destination • Optional link offsets into destination • Links have labels • Link return behaviors control the purpose of the link • Play from where the viewer left the video • Play from the end of the source anchor sequence • Play from beginning of thesource anchor sequence • Stop playback • Different behaviors fordestination completion oraborted playback

9. Hyper-Hitchcock Editor & Player Goals • Hyper-Hitchcock editor designed to • Reduce cost of producing interactive video • Make resulting video useful to wider audience • Simple video player to simulate DVD viewing experience

10. Hyper-Hitchcock Editor • Hyper-Hitchcock evolved from Hitchcock video editor • Video clips grouped in piles by similarity (e.g., recording time) • Workspace to arrange clips • Resize keyframes to trim clips • Clips ordered as horizontalor vertical lists • Place links between clips • Group clips into composites • Tree view to visualizecontainment hierarchy ofcomposites

11. Determining Suitable Video Clips • Unsuitability score • Single score for video features such as camera motion and brightness • Estimate camera pan by shifting frames against each other • Require minimum brightness • Determine clip boundaries • Select clips that fall in “valleys” between unsuitability peaks • Look for areas completely above unsuitability threshold • Peak is clip boundary candidate • Enforce the minimum length requirement • Trimming clips • Select portion of clip with minimal area under the curve • Expand the area for longer requested portions

12. Selected Clip Portions

13. Trimming Clips in the Workspace • Best five seconds of clip selected by default • Resizing keyframe changes length of clip • Picks the best portion around initial five-second portion • Start and end can jump to sentence boundary silence • Clip start and/or end can be locked in timeline • Locked ends can be dragged • Audio energyvisualized in timelineto spot words andsentences

14. cross(area error minimized) sliding dividers(area proportional to clip length) Visualizing Video Composites Video clips to be grouped into a composite (keyframe area proportional to clip length) Composite visualizations

15. Attaching Links to Clips and Composites • Link anchors and destinations can be clips, composites, or elements inside composites • Color-coding and position indicates link attachment in workspace • Links in and out of composite • Blue: attached to compositeRed: attached to elementDashed: between composite and element

16. Hypervideo Player • Video player with controls for following and returning from links • Several improvements based on user feedback • First version indicated linksin timeline and showed thelabel for the active link • Next version showedlabels in timeline • Current version includeskeyframes for active linkand for link history • User study suggestsfurther improvements

17. Navigation Aids in Hypervideo Player • Keyframe list for navigation history • Shows followed links with more remote navigation indicated by size of keyframe • Label of followed link as video caption • Link indicator in timeline (in blue) • Link labels and keyframes in timeline • Keyframe grows, label completes, and link recolored when active

18. Impressions from Users • Pilot editing study with two participants • Subjects own video • report on a trip to Japan • family outing to mountain bike race • Few problems but link return behaviorwas confusing for one participant • Study of hypervideo player (6 subjects) • Plumbing training video re-authored as hypervideo • All participants were able to find answersquickly in the hypervideo (9 - 20 minutes in 60-minute video) • Navigation through video can be confusing. As player was altered to better support navigation, playback becomes less like video.

19. Generating Hypervideo Summaries • Locating content in video is time consuming. • Much effort into generating “good” video summaries. • But what is good for one task is not good for another. • Generate hypervideo summaries that allow users to determine the level of detail viewed.

20. Process for Generating Summaries • Determine number of summary levels • Based on length of source video • Select clips to include in each summary level • Clips found by subdividing takes by camera motion • Select clips via clip distribution, take distribution, or best-first algorithms • Add links between summary levels • Group clips by takes • Links between clips from the same take using simple take-to-take or take-to-take with offsets algorithms

21. Clip Distribution Selection • Selecting n clips out of m candidate clips • Evenly distribute in among candidate clips • Selects more clips from takes with many recognized clips. • Good when take includes more than one topic/activity. • Bad when lots of clips are for a single topic/activity.

22. Take Distribution for Clip Selection • Evenly distribute in time and takes • Divide video duration into n time segments • Select clip nearest center of segment in take not already represented. • Bad when take includes more than one topic/activity. • Good when lots of clips are for a single topic/activity.

23. Best-first Clip Selection • Assumes human or automated ordering of value of clips • Simply selects n best clips • Good in cases of edited video – not currently applicable for unedited video. • Best can be introductory material • Best can be highlights of material

24. Links in Video Summary • All clips from a take are grouped into composite • Single clip from take or take composite is used as link anchor and destination • Simple take-to-take algorithm • Links take composite to take composite • Best when single activity divided into multiple clips. • Take-to-take with offsets algorithm • Each clip from take links to take composite in next level with offset to temporally closest clip. • Best when clips portray multiple activities in take. • Complete takes for entire video

25. Automatically Generated Summary Time 0:33 3:35 14:44 60:42 A four-level hypervideo summary of a one-hour source video. Lower levels provide more detail.

26. Future Systems Research • MPEG-4 players support hypervideo • No good authoring tools • Demand for easy-to-use tools for quickly editing hypervideo • Research problems for hypervideo player • Navigation: easy to get lost; how to visualize place • Viewing: user interface for TV remote control; other input devices such as data gloves • Keyframes for links represent a first step towards solutions • Research problems for hypervideo summaries • Different summaries for different genres (e.g., home video, produced training video) • Clip selection and link placement dependent on the genre

27. Hypervideo in Practice

28. Experience with Use • Nine hypervideos each authored by 1-2 students in a Computers and New Media class • Recorded up to 1 hour using a DV camera then authored hypervideo in HH • Students had about 1 week for authoring activity.

29. Riding Down University DriveMost directly maps geographic structureLinks are choices to stop in at sites along road.

30. Perspectives on BridgesShows bridges between College Station and Austin.Presents different perspectives (roadway, construction, wildlife) in order.Links are to seeing different perspective.

31. “In Danger” BuildingsVisits to buildings identified for demolition on TAMU campus.Links are to seeing interior and details.

32. International Dance FestivalShows bits of performances.Brief “how-to use hypervideo player” at start.Links are to seeing more and to next performance.

33. Game WalkthroughShows what happens while playing game.Links represent choice points in game.

34. Preparing for the In-LawsHow-to for cleaning and cooking, includes constant audio commentary.Links are to greater detail.

35. How To Make a SandwichPresents choices in sandwich creation.Includes video of options.Links are to select another option.

36. Music Hypervideopublic-domain video, remixed audio

37. Home Hypervideoidiosyncratic structure

38. Feedback on Hyper-Hitchcock

39. Evaluation of Hyper-Hitchcock • Easy to use hypervideo player, to work with video clips, to create composites. • Not as easy to manipulate composites and create links. • Spatial parser correctly interpreted composites. • Link labels were valued by many. • Audio energy graph was only valued by a few. • Automatic segmentation of source video into clips and automatic selection of in/out points did not help.

40. Structuring Problems • Authoring the two separate structures confused some students • Composition of video clips into linear videos • Links between linear videos • Need for greater explanation of how the two structures interact

41. Suggested Features • Ability to have more than one link active at a time. • Ability to specify for video to stop playing at decision point. • Separate audio editor • Text overlays and video effects

42. Roles of Links • Detail Links • Prerequisite Links • Related Information Links • Alternate View Links • Action Choice Links

43. Hypervideos Mimicking Hypertext • Detail links resulted in sieves. • Some sieves included links from one detailed section to the next (shortcuts). • Related information links also created tangles. • Alternate view links likely to generate mirrorworld or counterpoint structures.

44. Hypervideo Differences • Split/joins and mirrorworlds used to merge alternate courses of actions or perspectives. • Return behaviors used to cause merging paths, thus the structure looks like a sieve.

45. Summary • Hyper-Hitchcock used to author documentary, how-to, music, and home hypervideos. • Links in hypervideos used for: details, prerequisites, alternate views, action choices, and related information. • Structures in hypervideo were impacted by the inclusion of return behaviors.

46. Conclusions • Detail-on-demand video well-suited for training and home video • Simple interaction style appropriate for DVD-player interfaces • Enables wide range of authors due to emphasis on ease of learning and use over richness of interaction • Early user study results of both authors and viewers very encouraging • Hypervideo summaries • Remove need for single context-free video summary • Multiple clip selection and link generation algorithms • Act as starting point for human-authored summary