25-06-2012, 01:30 PM
MPEG-4 VIDEO COMPRESSION
[attachment=25417]
INTRODUCTION:
MPEG-4 is an ISO/IEC standard being developed by MPEG (Moving Picture Experts Group), the committee which also developed the Emmy Award winning standards known as MPEG-1 and MPEG-2. These standards made interactive video on CD-ROM and Digital Television possible. MPEG-4 will be the result of another international effort involving hundreds of researchers and engineers from all over the world. MPEG-4, whose formal ISO/IEC designation will be ISO/IEC 14496, is to be released in November 1998 and will be an International Standard in January 1999.MPEG-4 is building on the proven success of three fields: digital television, interactive graphics applications (synthetic content) and the World Wide Web (distribution of and access to content) and will provide the standardized technological elements enabling the integration of the production, distribution and content access paradigms of the three fields.
SCOPE AND FEATURES OF THE MPEG-4 STANDARD:
The MPEG-4 standard under development will provide a set of technologies to satisfy the needs of authors, service providers and end users alike.
• For authors, MPEG-4 will enable the production of content that has far greater reusability, has greater flexibility than is possible today with individual technologies such as digital television, animated graphics, World Wide Web (WWW) pages and their extensions. Also, it will be possible to better manage and protect content owner rights.
• For network service providers MPEG-4 will offer transparent information which will be interpreted and translated into the appropriate native signaling messages of each network with the help of relevant standards bodies having the appropriate jurisdiction. However the foregoing excludes Quality of Service considerations, for which MPEG-4 will provide a generic QoS parameter set for different MPEG-4 media. The exact mappings for these translations are beyond the scope of MPEG-4 and are left to be defined by network providers. Signaling of the QoS information end-to-end,will enable transport optimization in heterogeneous networks.
• For end users, MPEG-4 will enable much functionality which could potentially be accessed on a single compact terminal and higher levels of interaction with content, within the limits set by the author. An MPEG-4 applications document exists which describes many end user applications including, among others, real time communications, surveillance and mobile multimedia.
For all parties involved, MPEG wants to avoid the emergence of a multitude
of proprietary, non-interworking formats and players.
gives an example that highlights the way in which an audiovisual scene in MPEG-4 is composed of individual objects. The figure contains compound AVOs that group elementary AVOs together. As an example: the visual object corresponding to the talking person and the corresponding voice are tied together to form a new compound AVO, containing both the aural and visual components of a talking person. Such grouping allows authors to construct complex scenes, and
Enables consumers to manipulate meaningful (sets of) objects. The MPEG-4 systems layer facilitates the use of different tools and signaling this, and thus codecs according to existing standards can be accommodated. Therefore MPEG-4 allows the use of several highly optimized coders, such as those
Standardized by the ITU-T, which were designed to meet a specific set of requirements. Each of the coders is designed to operate in a stand-alone mode with its own bit stream syntax. Additional functionalities are realized both within individual coders, and by means of additional tools around the coders. An example of functionality within an individual coder is pitch change within the parametric coder.
SYNTHESIZED SOUND:
Decoders are also available for generating sound based on structured inputs. Text input is converted to speech in the Text-To-Speech (TTS) decoder, while more general sounds including music may be normatively synthesized. Synthetic music may be delivered at extremely low bitrates while still describing an exact sound signal.
Text To Speech TTS allows a text or a text with prosodic parameters (pitch contour, phoneme duration, and so on) as its inputs to generate intelligible synthetic speech. It includes the following functionalities.
Speech synthesis using the prosody of the original speech
Facial animation control with phoneme information.
Trick mode functionality: pause, resume, jump forward/backward.
International language support for text.
International symbol support for phonemes.
Support for specifying age, gender, language and dialect of the speaker
SYNTHETIC OBJECTS:
Synthetic objects form a subset of the larger class of computer graphics, as an initial focus the following visual synthetic objects will be described:
• Parametric descriptions of
a) A synthetic description of human face and body
b) Animation streams of the face and body
• Static and Dynamic Mesh Coding with texture mapping
• Texture Coding for View Dependent applications
FACIAL ANIMATION:
The face is an object capable of facial geometry ready for rendering and animation. The shape, texture and expressions of the face are generally controlled by the bit stream containing instances of Facial Definition Parameter (FDP) sets and/or Facial Animation Parameter (FAP) sets. Upon construction, the Face object contains a generic face with a neutral expression. This face can already be rendered. It is also immediately capable of receiving the FAPs from the bit stream, which will produce animation of the face: expressions, speech etc. If FDPs are received, they are used to transform the generic face into a particular face determined by its shape and (optionally) texture. Optionally, a complete face model can be downloaded via the FDP set as a scene graph for insertion in the face node.
[attachment=25417]
INTRODUCTION:
MPEG-4 is an ISO/IEC standard being developed by MPEG (Moving Picture Experts Group), the committee which also developed the Emmy Award winning standards known as MPEG-1 and MPEG-2. These standards made interactive video on CD-ROM and Digital Television possible. MPEG-4 will be the result of another international effort involving hundreds of researchers and engineers from all over the world. MPEG-4, whose formal ISO/IEC designation will be ISO/IEC 14496, is to be released in November 1998 and will be an International Standard in January 1999.MPEG-4 is building on the proven success of three fields: digital television, interactive graphics applications (synthetic content) and the World Wide Web (distribution of and access to content) and will provide the standardized technological elements enabling the integration of the production, distribution and content access paradigms of the three fields.
SCOPE AND FEATURES OF THE MPEG-4 STANDARD:
The MPEG-4 standard under development will provide a set of technologies to satisfy the needs of authors, service providers and end users alike.
• For authors, MPEG-4 will enable the production of content that has far greater reusability, has greater flexibility than is possible today with individual technologies such as digital television, animated graphics, World Wide Web (WWW) pages and their extensions. Also, it will be possible to better manage and protect content owner rights.
• For network service providers MPEG-4 will offer transparent information which will be interpreted and translated into the appropriate native signaling messages of each network with the help of relevant standards bodies having the appropriate jurisdiction. However the foregoing excludes Quality of Service considerations, for which MPEG-4 will provide a generic QoS parameter set for different MPEG-4 media. The exact mappings for these translations are beyond the scope of MPEG-4 and are left to be defined by network providers. Signaling of the QoS information end-to-end,will enable transport optimization in heterogeneous networks.
• For end users, MPEG-4 will enable much functionality which could potentially be accessed on a single compact terminal and higher levels of interaction with content, within the limits set by the author. An MPEG-4 applications document exists which describes many end user applications including, among others, real time communications, surveillance and mobile multimedia.
For all parties involved, MPEG wants to avoid the emergence of a multitude
of proprietary, non-interworking formats and players.
gives an example that highlights the way in which an audiovisual scene in MPEG-4 is composed of individual objects. The figure contains compound AVOs that group elementary AVOs together. As an example: the visual object corresponding to the talking person and the corresponding voice are tied together to form a new compound AVO, containing both the aural and visual components of a talking person. Such grouping allows authors to construct complex scenes, and
Enables consumers to manipulate meaningful (sets of) objects. The MPEG-4 systems layer facilitates the use of different tools and signaling this, and thus codecs according to existing standards can be accommodated. Therefore MPEG-4 allows the use of several highly optimized coders, such as those
Standardized by the ITU-T, which were designed to meet a specific set of requirements. Each of the coders is designed to operate in a stand-alone mode with its own bit stream syntax. Additional functionalities are realized both within individual coders, and by means of additional tools around the coders. An example of functionality within an individual coder is pitch change within the parametric coder.
SYNTHESIZED SOUND:
Decoders are also available for generating sound based on structured inputs. Text input is converted to speech in the Text-To-Speech (TTS) decoder, while more general sounds including music may be normatively synthesized. Synthetic music may be delivered at extremely low bitrates while still describing an exact sound signal.
Text To Speech TTS allows a text or a text with prosodic parameters (pitch contour, phoneme duration, and so on) as its inputs to generate intelligible synthetic speech. It includes the following functionalities.
Speech synthesis using the prosody of the original speech
Facial animation control with phoneme information.
Trick mode functionality: pause, resume, jump forward/backward.
International language support for text.
International symbol support for phonemes.
Support for specifying age, gender, language and dialect of the speaker
SYNTHETIC OBJECTS:
Synthetic objects form a subset of the larger class of computer graphics, as an initial focus the following visual synthetic objects will be described:
• Parametric descriptions of
a) A synthetic description of human face and body
b) Animation streams of the face and body
• Static and Dynamic Mesh Coding with texture mapping
• Texture Coding for View Dependent applications
FACIAL ANIMATION:
The face is an object capable of facial geometry ready for rendering and animation. The shape, texture and expressions of the face are generally controlled by the bit stream containing instances of Facial Definition Parameter (FDP) sets and/or Facial Animation Parameter (FAP) sets. Upon construction, the Face object contains a generic face with a neutral expression. This face can already be rendered. It is also immediately capable of receiving the FAPs from the bit stream, which will produce animation of the face: expressions, speech etc. If FDPs are received, they are used to transform the generic face into a particular face determined by its shape and (optionally) texture. Optionally, a complete face model can be downloaded via the FDP set as a scene graph for insertion in the face node.