06-04-2012, 12:16 PM
MPEG-4 VIDEO
MPEG-4 (Seminar Report) (1).pdf (Size: 792.35 KB / Downloads: 54)
Introduction
In the last years, enormous amounts of digital content have been developed based on modalities such as audio, video and text. In multimedia presentations, these modalities are combined. For storage and disclosure of digital content, a variety of formats, database structures, coding techniques, network protocols et cetera is available and used. Standards in this field can improve usability of digital content and make it available to all parties that comply with the standard. The MPEG forum establishes standards in the field of multimedia handling.
Video Standards Overview
Several formats have been developed for integrating independent multimedia objects into a single multimedia presentation, such as SMIL from the W3C consortium and VRML from the Web3D consortium. SMIL provides techniques for synchronization, layout, and association of hyperlinks. MPEG-4 was developed to offer more flexibility compared to these formats. E.g. the concept of scalable objects is not encapsulated in SMIL, and VRML does not support streaming over networks. It is this object scaling capability, which gives MPEG-4 so much more potential to be used for scalable applications over various types of networks.
Difference between MPEG-4 and MPEG 1 and 2
MPEG-1 and MPEG-2 are standards that focus on the compression and decompression of audio and video streams. Both standards address the needs of audio and video transport and synchronization. MPEG-1 was designed to provide a compression standard for media such as Video CD and CD-ROM, which have a typical playback rate of 1.2 Mbit/s. MPEG-2 was designed to provide higher quality for transmission applications, focusing mainly on Digital TV applications.
Relationship to H.263
H.263 was developed by the ITU standards organisation and shares many similarities with MPEG-4. In fact MPEG-4 was originally based around the baseline H.263 specification. Indeed in the MPEG-4 Simple Profile the tool known as MPEG-4 short header is equivalent to baseline H.263.
MPEG-4 Goals
MPEG-4 has been designed to address the following issues:
• Interoperability: The standard is not specific to any one platform but is designed for all platforms.
• Transport Independence: MPEG-4 leaves the choice of transport mechanism up to the service provider. This allows MPEG-4 to be used in a wide range of networking environments.
• Compression and Transmission of Rich Media: MPEG-4 has been designed for the low and mid bit-rate compression and transmission of rich media streams.
• Interactivity: MPEG-4 allows content authors and viewers to influence how they interact with a stream.
Describing and Decoding Objects in MPEG-4
MPEG-4's representation of multimedia content and its scheme for preparing that content for transportation, storage and decoding is versatile (see Figure 2). Objects are placed in so-called elementary streams (ESs). Some objects, such a sound track or a video, have a single elementary stream, while others objects may have two or more. In particular, scalable objects can have an ES for basic-quality information plus one or more so-called enhancement layers, each of which can have its own ES for improved quality, such as video with finer detail or faster motion. MPEG-4 has a versatile encoding and decoding process. A broad choice of transport protocols can be used with its interface, FlexMux [bottom].
Binary shape coder
Compared to other standards, the ability to represent arbitrary shapes is an important capability of the MPEG-4 video standard. In general, shape representation can be either implicit (based on chroma-key and texture coding) or explicit (boundary coding separate from texture coding). Implicit shape representation, although it offers less encoding flexibility, can result in quite usable shapes while being relatively simple and computationally inexpensive.
Sprite coding
In computer games, a sprite refers to an synthetic object that undergoes some form of transformation (including animation). Also, in the literature, and in connection with highly efficient representation of natural video, the term ‘mosaic’ or ‘world image’ is used to describe a large image built by integration of many frames of a sequence spatially and/or many frames of a sequence temporally; in MPEG-4 terminology, such an image is referred to as a static sprite.
CONCLUSION
Although quite massive in content, everything that has been discussed so far is but an inch in the perpetual functionalities of MPEG-4. The MPEG-4 also provides standards for audio, the most popular of which is the Advanced Audio Coding or the AAC. There are specifications for face and body animation based on the myriad expressions made by a human face, so that they may be more efficiently used for transferring interactive content worldwide.
MPEG-4 (Seminar Report) (1).pdf (Size: 792.35 KB / Downloads: 54)
Introduction
In the last years, enormous amounts of digital content have been developed based on modalities such as audio, video and text. In multimedia presentations, these modalities are combined. For storage and disclosure of digital content, a variety of formats, database structures, coding techniques, network protocols et cetera is available and used. Standards in this field can improve usability of digital content and make it available to all parties that comply with the standard. The MPEG forum establishes standards in the field of multimedia handling.
Video Standards Overview
Several formats have been developed for integrating independent multimedia objects into a single multimedia presentation, such as SMIL from the W3C consortium and VRML from the Web3D consortium. SMIL provides techniques for synchronization, layout, and association of hyperlinks. MPEG-4 was developed to offer more flexibility compared to these formats. E.g. the concept of scalable objects is not encapsulated in SMIL, and VRML does not support streaming over networks. It is this object scaling capability, which gives MPEG-4 so much more potential to be used for scalable applications over various types of networks.
Difference between MPEG-4 and MPEG 1 and 2
MPEG-1 and MPEG-2 are standards that focus on the compression and decompression of audio and video streams. Both standards address the needs of audio and video transport and synchronization. MPEG-1 was designed to provide a compression standard for media such as Video CD and CD-ROM, which have a typical playback rate of 1.2 Mbit/s. MPEG-2 was designed to provide higher quality for transmission applications, focusing mainly on Digital TV applications.
Relationship to H.263
H.263 was developed by the ITU standards organisation and shares many similarities with MPEG-4. In fact MPEG-4 was originally based around the baseline H.263 specification. Indeed in the MPEG-4 Simple Profile the tool known as MPEG-4 short header is equivalent to baseline H.263.
MPEG-4 Goals
MPEG-4 has been designed to address the following issues:
• Interoperability: The standard is not specific to any one platform but is designed for all platforms.
• Transport Independence: MPEG-4 leaves the choice of transport mechanism up to the service provider. This allows MPEG-4 to be used in a wide range of networking environments.
• Compression and Transmission of Rich Media: MPEG-4 has been designed for the low and mid bit-rate compression and transmission of rich media streams.
• Interactivity: MPEG-4 allows content authors and viewers to influence how they interact with a stream.
Describing and Decoding Objects in MPEG-4
MPEG-4's representation of multimedia content and its scheme for preparing that content for transportation, storage and decoding is versatile (see Figure 2). Objects are placed in so-called elementary streams (ESs). Some objects, such a sound track or a video, have a single elementary stream, while others objects may have two or more. In particular, scalable objects can have an ES for basic-quality information plus one or more so-called enhancement layers, each of which can have its own ES for improved quality, such as video with finer detail or faster motion. MPEG-4 has a versatile encoding and decoding process. A broad choice of transport protocols can be used with its interface, FlexMux [bottom].
Binary shape coder
Compared to other standards, the ability to represent arbitrary shapes is an important capability of the MPEG-4 video standard. In general, shape representation can be either implicit (based on chroma-key and texture coding) or explicit (boundary coding separate from texture coding). Implicit shape representation, although it offers less encoding flexibility, can result in quite usable shapes while being relatively simple and computationally inexpensive.
Sprite coding
In computer games, a sprite refers to an synthetic object that undergoes some form of transformation (including animation). Also, in the literature, and in connection with highly efficient representation of natural video, the term ‘mosaic’ or ‘world image’ is used to describe a large image built by integration of many frames of a sequence spatially and/or many frames of a sequence temporally; in MPEG-4 terminology, such an image is referred to as a static sprite.
CONCLUSION
Although quite massive in content, everything that has been discussed so far is but an inch in the perpetual functionalities of MPEG-4. The MPEG-4 also provides standards for audio, the most popular of which is the Advanced Audio Coding or the AAC. There are specifications for face and body animation based on the myriad expressions made by a human face, so that they may be more efficiently used for transferring interactive content worldwide.