Media Fragments WG Pointers

Duration: September 2008 - January 2010

This slide: http://www.w3.org/2008/WebVideo/Fragments/talks/2009-02-06/

Home: http://www.w3.org/2008/WebVideo/Fragments/

Wiki: http://www.w3.org/2008/WebVideo/Fragments/wiki/

Archive: http://lists.w3.org/Archives/Public/public-media-fragment/

Part of: Video in the Web Activity / Hypertext Coordination Group / Interaction Domain

Media Fragment History

W3C Video on the Web Workshop

12-13 December 2007, San Jose, California and Brussels, Belgium

Hosted by Cisco Systems

Motto: Make video a first-class object on the Web

W3C Workshop Participants

Accenture, Adobe Systems, Annodex Association, Apple, CBS Interactive, CableLabs, Canon, Capgemini, CWI, Cisco Systems, Dailymotion, Hitachi, Hot Potato, IBBT, IJS, MTV Networks, Meraka Institute, Motorola, Move Networks, Mozilla Foundation, Nemours Foundation, Nokia Corporation, RealNetworks, Samsung Electronics, Sony, Sun Microsystems, Thomson, Turner Broadcasting System, University Of California at Santa Cruz, University of Wollongong, VRT medialab, Via Licensing, Walt Disney Internet Group, Web3D Consortium, Wright State University, YouTube, thePlatform

Workshop Laundry list

• <video> HTML 5.0
• Codecs and formats
• Metadata ⇒ Media Annotations WG
• Content protection
• Fragment ⇒ Media Fragments WG
• Accessibility (still an issue)
• Tagging
• Searchability
• Synchronization, Temporal properties for styling
• Distribution: cost, QoS, tracking, mobile, etc.
• Playlist files
• …

Media Fragments WG Goal

Provide URI-based mechanisms for uniquely identifying fragments for media objects on the Web, such as video, audio, and images.

Media Fragments WG Activities

• Chairs: Erik Mannens (IBBT), Raphaël Troncy (CWI)
• Team contact: Yves Lafon, (alternate Thierry Michel)
• 13 Participants:
  • from 8 organizations: Apple Inc., DERI Galway, CWI, IBBT, Meraka Institute, Samsung, K-Space, W3C/ERCIM
  • +1 Invited Expert: Silvia Pfeiffer
• 14 teleconferences so far (weekly frequency)
• 3 Face to Face meetings:
  • 20-21/10/2008 (@TPAC, Cannes, FR): agenda, minutes Monday, Tuesday and slides & resources
  • 09-10/12/2008 (IBBT, Ghent, BE), agenda, minutes Tuesday, Wednesday and slides & resources
  • 16-17/04/2009 (@WWW, Barcelona, ES)

Use Cases & Requirements

• Document: http://www.w3.org/2008/WebVideo/Fragments/wiki/Use_Cases_&_Requirements_Draft
  • Link to, Display, Bookmark, Annotate, Search, etc. media fragments
• Type of fragments: four dimensions considered
  • time ([point?] interval), space ([point?] rectangle), track and id (named fragment)
  • Restrict to what the container format (encapsulating the compressed media content) can express (and expose), thus no transcoding
• Protocols covered: HTTP(S), RTSP
  • ... what about mms, rtmp, p2p protocols, etc. ? They are often proprietary (see also usage statistics)

Technological Survey

• Media Fragments URI already present on the web ... but with very different syntax and behavior
  • Google Video: (#50m16s)
    http://video.google.com/videoplay?docid=3047771997186190855&ei=MCH-SNfJD5HS2gKirMD2Dg&q=%22that%27s+a+tremendous+gift%22#50m16s
  • YouTube: (#t=1m45s)
    http://www.youtube.com/watch?v=1bibCui3lFM#t=1m45s
  • Archive.org powered by TemporalURI: (?t=74.5 )
    http://www.archive.org/download/to-SF/toSF_512kb.mp4?t=74.5
  • Videosurf: (?t=140&e=184)
    http://www.videosurf.com/video/michael-jordan-1989-playoffs-gm-5-vs-cavs-the-shot-904591?t=140&e=184
  • Microsoft IIS 7.0:
    http://SmoothHD.com/Media.ism/QualityLevels(1024000)/Fragments(video=20000000)
  • Metacafe, Dailymotion, etc. ?
• Other time-clipping and spatial clipping methods:
  • MPEG-21: time, space, track, id (http://www.example.com/myVideo.mp4#mp(/CD/track/~time(%27npt%27,%270%27,%2760%27)))
  • SVG: space (http://www.example.com/myImage.svg#svgView(14.64,15.73,146.98,147.48))
  • SMIL: time (clipBegin, clipEnd), space (panZoom, area), media markers
  • MPEG-7: time, space, modality

Media Fragments 1.0

• Syntax:

  http://www.example.com/movie.mov#t=12.33,21.16
  http://www.example.com/movie.mov#t=smpte-25:00:12:33:06,00:21:16:00
  http://www.example.com/movie.mov#xywh=20,20,40,40
  http://www.example.com/movie.mov#xywh=pixel:20,20,40,40
  http://www.example.com/movie.mov#track='audio1'
  http://www.example.com/movie.mov#id='the%20kiss%20scene'
  http://www.example.com/movie.mov#track='audio2'&t=12.33,21.16
    

• Communication between the User Agent and the Server:
  General principle is that smart UA will strip out the fragment definition and encode it into custom http headers ...
  • 2 way-handshakes: use custom HTTP range units, defined along the different axis suitable to describe media fragments
  • 4 way-handshakes: custom resources that will direct the client on how and where to get all the data needed to construct a fragment
• (Media) Servers will handle the request, slice the media content and serve just the fragment
  ... while old ones will serve the whole resource
• Server, caches and proxies: use byte/time ranges to cache (merge) fragments

Issues (non exhaustive list)

1. Addressing vs Retrieving a media fragment?
   • FRBR (manifestation vs item): the fragment could be specified on an abstraction of a particular encoding format
   • Content Negotiation could be used to serve an RDF description of a media fragment, the media fragment encoded in mp3, in wav, etc.

   @prefix event: .
   @prefix ps: .
   @prefix rdfs: .
   :chorus1 a ps:Chorus;
       rdfs:label "First chorus";
       event:time [
          url "http://www.example.com/beatles-let_it_be.mp3#t=0,20";
       ].
   

2. Media Fragments semantics?
   • RFC3986: semantics of URI fragment depends on the media type
     ... by default, the semantics is considered unknown
   • TBL suggests to register video/*, audio/*, image/*
     ... but some of them have already been registered (e.g. MPEG-21 Part 17

Thank you

Video on the Web is not just what you see

— it's what you can search, discover, create, distribute and manage.