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key points and info on MPEG 4

key points and info on MPEG 4



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    MPEG 4 MPEG 4 Presentation Transcript

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