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MPEG-2 Standard By Rigoberto Fernandez

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Title: MPEG-2 Standard By Rigoberto Fernandez


1
MPEG-2 StandardByRigoberto Fernandez
2
MPEG Standards
  • MPEG (Moving Pictures Experts Group) is a group
    of people that meet under ISO (International
    Standards Organization) to generate standards for
    digital video and audio compression. In
    particular, they define a compressed bit stream,
    which implicitly defines a decompressor.

3
The following MPEG standards exist
  • MPEG-1, a standard for storage and retrieval of
    moving pictures and audio on storage media.
  • MPEG-2, a standard for digital television.
  • MPEG-4, a standard for multimedia applications.
  • MPEG-7, a content representation standard for
    information searches.

4
MPEG-2 Video Compression
  • The MPEG-2 video compression
  • algorithm achieves very high rates of
  • compression by exploiting the redundancy
  • in video information. MPEG-2 removes
  • both the temporal redundancy and spatial
  • redundancy, which are present in motion
  • video.

5
  • Temporal redundancy arises when successive frames
    of video display images of the same scene. It is
    common for the content of the scene to remain
    fixed or to change only slightly between
    successive frames.
  • Spatial redundancy occurs because parts of the
    picture (called pels) are often replicated (with
    minor changes) within a single frame of video.

6
Video Stream Data Hierarchy
7
Video Sequence
8
Picture Types
  • The MPEG standard specifically defines three
    types of frames. The picture type defines which
    prediction modes may be used to code each block.
    These three type of pictures are defined as
    follows
  • Intra Pictures (I-Frames)
  • Predicted Pictures (P-Frames)
  • Bidirectional Predicted Pictures (B- Frames)

9
Frames
10
Profile and Levels
  • A profile is a subset of algorithmic tools and a
    level identifies a set of constraints on
    parameter values (such as picture size or bit
    rate).
  • The profiles and levels defined to date fit
    together such that a higher profile or level is
    superset of a lower one. A decoder, which
    supports a particular profile and level is only
    required to support the corresponding subset of
    algorithmic tools and set of parameter
    constraints.

11
Interlaced Video and Picture Structures
  • An interlaced video sequence uses one of two
    picture structures frame structure and field
    structure.The interlaced video sequence can
    switch between frame structures and field
    structures on picture-by-pictures basics. On the
    other hand, each picture in a progressive video
    sequence is a frame picture.

12
MPEG-2 Advance Audio Coding
  • It provides a low bitrate coding for multichannel
    audio.
  • In general there are five full bandwidth
    channels.
  • AAC basically makes use of the signal masking
    properties of the human ear in order to reduce
    the amount of data

13
Differences between MPEG-2 AAC and its
predecessor ISO/MPEG Audio Layer-3
  • Filter bank
  • Temporal Noise Shaping TNS
  • Bit-stream format
  • Prediction
  • Quantization

14
MPEG-2 standard features
  • Video compression which is backwards compatible
    with MPEG-1
  • Full-screen interlaced and/or progressive video
  • Enhanced audio coding
  • Transport multiplexing
  • Other services
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