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key points and info on MPEG 4

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  1. 1. MPEG 4: The ultimate low bit rate format
  2. 2. Overview: ISO/IEC 14496 Coding of audio-visual objects <ul><li>Low bit rate multimedia system - typically less than MPEG 2 video </li></ul><ul><li>Object based - each element is coded separately </li></ul><ul><li>Open ended system that can continue to develop in the future </li></ul><ul><li>Scalable & Interactive </li></ul><ul><li>Version 1: October 1998 </li></ul>
  3. 3. Versions Version 1 Version 2
  4. 4. Profiles Quality Complexity DVD Video CD Mobiles HDTV Digital cinema MPEG-1 MPEG-2 Advanced Simple Profile Simple Profile MPEG 4
  5. 5. Current uses: <ul><li>3G mobile phones, </li></ul><ul><li>Portable devices, PDAs, video iPod </li></ul><ul><li>Interactive television / IPTV </li></ul><ul><li>New interactive multimedia formats </li></ul><ul><li>Web pages </li></ul><ul><li>Interactive music format </li></ul><ul><li>Security systems </li></ul>
  6. 6. Basics: <ul><li>Object based system: using Natural and/or Synthetic objects </li></ul><ul><li>Makes use of local processing power to recreate sounds and images </li></ul><ul><li>This makes it one of the most efficient compression systems </li></ul>
  7. 7. Basics: Object Types <ul><li>Photos - JPE, GIF, PNG, </li></ul><ul><li>Video - MPEG-2, Divx, AVI, H.264, QuickTime </li></ul><ul><li>Speech - CELP, HVXC, Text to Speech </li></ul><ul><li>Music - AAC, MP3, surround </li></ul><ul><li>Synthetic music </li></ul><ul><li>Graphics - Java code </li></ul><ul><li>Text </li></ul><ul><li>Animated objects, e.g., talking heads </li></ul>
  8. 8. Basics: <ul><li>The selected objects are put together into a 2D or 3D scene </li></ul><ul><li>In 3D the viewer can change the shape of the image and view it from other positions in the 3D space. Similar to VRML </li></ul><ul><li>Each object is compressed using the best and most optimum method for that type of data </li></ul>
  9. 9. Basics: Virtual Studio <ul><li>Virtual production techniques are increasingly used in TV production </li></ul><ul><li>Well known chroma-key method using a blue/green screen background </li></ul><ul><li>Actors are overlaid on to a ‘virtual studio’ background image </li></ul><ul><li>The composition of the screen image and the sound can now take place in the decoder at home </li></ul>
  10. 11. BIFS: <ul><li>Binary Format for Scene descriptor </li></ul><ul><li>New description language like HTML but written in binary not in English </li></ul><ul><li>Has scalable levels for audio and video which can be set by access rights or by interrogation of the receiver to set the best ‘Quality of Service’ (QoS) </li></ul>
  11. 12. Synchronised Streaming <ul><li>Each element can be time stamped to synchronise with other objects in the frame </li></ul><ul><li>Flexi Time: The viewer can vary the time for playback </li></ul><ul><li>There are 3 types, set by the producer, minimum, maximum and optimal </li></ul><ul><li>Audio can be set to change pitch or stay fixed </li></ul>
  12. 13. Compression : Speech <ul><li>HVXC - Harmonic Vector Excitation Coding </li></ul><ul><li>CELP - Code Excited Linear Prediction </li></ul><ul><li>2 - 24 K bit/sec </li></ul><ul><li>Synthesised speech: </li></ul><ul><li>Text to speech synthesis, 200-1200 bit/sec </li></ul><ul><li>Very low delay, 20 ms, for video phone use MP3 takes too long to encode/decode </li></ul>
  13. 14. Compression : Natural Audio <ul><li>MPEG - AAC (Advanced Audio Coding) </li></ul><ul><li>MP3, AAC, 5.1 surround </li></ul><ul><li>6 - 380 K bit/sec </li></ul>
  14. 15. Parametric audio coding <ul><li>Synthesised audio : </li></ul><ul><li>Spectral noise re-synthesised </li></ul><ul><li>This process separates unique audio sounds from predictable noise shapes which can then be re-synthesised locally </li></ul><ul><li>Signal is represented by three objects: </li></ul><ul><ul><li>Transients: localized in time, </li></ul></ul><ul><ul><li>Sinusoids: localized in frequency, </li></ul></ul><ul><ul><li>Noise: no strict localization… </li></ul></ul>
  15. 16. Parametric audio coding Transients: Castanets
  16. 17. Parametric audio coding Sinusoids: Harpsichord
  17. 18. Parametric audio coding Noise: Heavy metal
  18. 19. Compression : Structured Audio <ul><li>SAOL - Structured Audio Orchestra Language (pronounced sail) </li></ul><ul><li>Down loadable sound fonts </li></ul><ul><li>Wavetable synth + GM2 type spec. </li></ul><ul><li>Any kind of virtual instruments </li></ul><ul><li>Virtual effects algorithms and mixers </li></ul><ul><li>MIDI data rates e.g. 300 bit/sec </li></ul>
  19. 20. Interactive Audio <ul><li>Download and remix tracks </li></ul><ul><li>Flash interface and compressed audio loops </li></ul>www. yourspins .com
  20. 21. Compression : Video <ul><li>Overall MPEG-4 supports a wide range of standards from very small, poor quality, pictures up to HDTV </li></ul><ul><li>MPEG 1 & 2 </li></ul><ul><li>MPEG 4 - part 2 </li></ul><ul><li>MPEG 4 - part 10, 'Advanced Video Coding’ AVC H.264 - high quality video codec </li></ul><ul><li>Developed jointly by MPEG and the ITU </li></ul>
  21. 22. Compression : Video - H.264 <ul><li>Half to one quarter of the normal bit rate of MPEG-2 </li></ul><ul><li>Scalable from 3G to HD </li></ul><ul><li>More advanced B frame operation where the frame can link to any frame in the video sequence </li></ul><ul><li>Smaller 4X4 grids of pixels </li></ul><ul><li>4 Profiles and 16 Levels </li></ul><ul><li>Bit rates from 64 Kbps - 240 Mbps </li></ul>
  22. 23. Compression : Video <ul><li>Mixture of pixel based and vector graphics </li></ul><ul><li>Video is no longer a rectangular shape, it can be any shape </li></ul><ul><li>Synthetic images with bit rates from 5 kbit/sec - 10 Mbit/sec </li></ul><ul><li>Supports the mapping of video textures onto moving objects and meshes </li></ul>
  23. 24. 2D mesh model of a fish By deforming the mesh the fish can be animated
  24. 25. Animated Objects: <ul><li>The Animation Framework eXtension, AFX </li></ul><ul><li>Face animation: The face models are not part of MPEG-4 only the movement codes for the expressions, eye movement, etc. </li></ul><ul><li>Body animation works in the same way and can be used in games </li></ul>
  25. 26. Future Options: <ul><li>MPEG-4 is still being developed and all new parts will work with the old formats </li></ul><ul><li>Studio quality versions for HDTV </li></ul><ul><li>Digital cinema 45 - 240 Mbit/sec H.264 </li></ul><ul><li>Home video cameras with MPEG-4 output straight to the web from the hard drive </li></ul>
  26. 27. Future Options: <ul><li>Integrated Service Digital Broadcast (ISDB) </li></ul><ul><li>Newspaper + TV + data </li></ul><ul><li>Integration with MPEG 7 databases </li></ul><ul><li>Games with 3D texture mapping </li></ul>
  27. 28. Future Options: <ul><li>TeleVision Modelling Language (TVML) </li></ul><ul><li>Computer generated TV programs + presenters - Max Headroom?? </li></ul>
  28. 29. Future Options: <ul><li>Information booths </li></ul><ul><li>Talking objects - fridge, cars, toaster? </li></ul><ul><li>Security cameras over the web </li></ul><ul><li>Interactive manuals and training materials </li></ul><ul><li>New downloadable interactive music format, SAOL </li></ul>
  29. 30. MPEG 7
  30. 31. MPEG 7 <ul><li>Multimedia Content Descriptor Standard </li></ul><ul><li>Database system to automatically define, organise and search for text, pictures, sound FX, graphics, video clips, songs, music, etc. </li></ul><ul><li>On-line Music library </li></ul><ul><li>Automatic identification of music </li></ul><ul><li>Uses XML to store metadata </li></ul>
  31. 32. MPEG 7 <ul><li>Proposed uses: </li></ul><ul><li>Live broadcast monitoring, radio output </li></ul><ul><li>Digital libraries e.g., image catalogue, musical dictionary, bio-medical imaging, sound FX, film, video and radio archives </li></ul><ul><li>Cultural services history museums, art galleries, etc. </li></ul>
  32. 33. MPEG 7 <ul><li>Home entertainment e.g., systems for the management of personal multimedia collections, e.g. music, home video, searching a game, karaoke </li></ul><ul><li>E-Commerce e.g., personalised advertising, on-line catalogues, directories of e-shops </li></ul><ul><li>Education e.g., repositories of multimedia courses, multimedia search for support material </li></ul>
  33. 34. MPEG 7 <ul><li>Investigation services e.g., human characteristics recognition, forensics </li></ul><ul><li>Journalism e.g. searching speeches of a certain politician using their name, voice or face </li></ul><ul><li>Multimedia directory services e.g. Yellow Pages, tourist information, geographical information systems </li></ul>
  34. 35. MPEG 7 <ul><li>Multimedia editing e.g., personalised electronic news service, media authoring </li></ul><ul><li>Social e.g. on-line dating services </li></ul><ul><li>Surveillance e.g., traffic control </li></ul>
  35. 36. MPEG 21
  36. 37. MPEG 21 <ul><li>An infrastructure for the delivery and consumption of multimedia content </li></ul><ul><li>Users are seen as either creators, consumers, rights holders, content providers, or distributors </li></ul>
  37. 38. MPEG 21 <ul><li>Every media element is defined as a ‘Digital Item’ </li></ul><ul><li>Metadata defines what media we can use, what we can do with it and who owns it </li></ul><ul><li>Designed to work with MPEG 4 files and MPEG 7 database </li></ul>