M P E GM P E G
A Presentation
by
Sebastian Graf and
Thomas Winterscheid
Topics
• What is MPEG?
• Different MPEG Standards
• What is a movie?
• The MPEG video compression
• Conclusion
What is MPEG?
What is MPEG exactly?
• „Moving Picture Experts Group“• Established in 1988• The convener of the MPEG group is
Dr. Leonardo Chiariglione• Vice president of Multimedia Telecom Italia Lab
http://leonardo.telecomitalialab.com/
What is MPEG exactly?
• Comission directed by ISO an IEC
• Develops standards for video and audio coding
• Nickname given to a family of international standards
Approved MPEG Standards
• MPEG-1 Nov. `92
• MPEG-2 Nov. `94
• MPEG-4 • Version 1 Oct. `98
• Version 2 Dec `99
Planned for the future...
• MPEG-4• Version 3,4 and 5
• MPEG-7
• MPEG-21
MPEG-1
• Quality ~ VHS – video
• Originally for 1x CD-ROM drives (1,4 MBit/s)
• Constant datarate
• Standard for Video CDs
MPEG-2
• HDTV (High Definition TeleVision)
• Premiere World (lower rates for more chan.)
• Still important for new digital TV norms
• DVD
• Variable datarates
MPEG-3 ?
• MPEG-3 standard was under construction, but never finished
• Was planned for newer HDTV
• Parts of technology and techniques are implemented in MPEG-2
Overview
1,4 Mbit/325x288
High Compression
Audiocodec
Assymetric compression
Only in SIF Format
Codec for Multimedia
files on your PC
4 Mbit/325x288
15 Mbit/720x576
60 Mbit/1440x1152
80 Mbit/1920x1152
Different Formats
Supports Dolby
Surround
Much more complicated as MPEG-1
Multimedia PC
Digital TV
Satellite TV
MPEG-1
MPEG-2
Datarate/Resolution Advantages Disadvantages Scope
The Future: MPEG-7
• Planned to be released in fall 2001
• Is formally called „Multimedia Content Description Interface“
• Includes a new standard of handling DDL
• More easier to implement into multimedia
• Intends to be an allrounder for all multimedia formats
The Future: MPEG-7
• MPEG 1-2-4 won`t be replaced by MPEG-7
• Works indepentend of it`s predecessors
• Because of file description data query in special multimedia databank is possible
• Several search options will be included
• But this isn`t enough................
More Future: MPEG-21
• Development is running, planned to be finished in 2003
• Includes a new description language (DIDL)
• Universal player for all standards
• Multimedia files are more communicative
• And also there is to say...............
More Future: MPEG-21
The general goal of MPEG-21 activities is to describe an open framework which allows the integration of all components of a delivery chain necessary to generate, use, manipulate, manage, and deliver multimedia content across a wide range of networks and devices.http://ipsi.fhg.de/delite/Projects/MPEG7/Mpeg21.htmlhttp://ipsi.fhg.de/delite/Projects/MPEG7/Mpeg21.html
Topics
• What is MPEG?
• Different MPEG Standards
• What is a movie?
• The MPEG video compression
• Conclusion
What is a movie?
video track
audio track
timecode
What is a movie?
timecode
encode or decode?
• encoder • decoder
100111010011
100111010011
MPEG video compression
movie picture 1 movie picture 2
MPEG video compression
• High similarity of 2 successive pictures
• => correlation
• Same pixel´s movement in Camera turns
• =>motion compensation • DCT & quantization
MPEG video compression
The block layer
• Picture is divided in 8x8 blocks (JPEG)
• The blocks are processed independent from each other
• DCT
• Quantization
DCT & Quantization
• Very similar to the fourier transformation
• Information are transformed to a frequenz-exhibition (nearly no data loss)
• Matrix of DCT-coefficients
• Coefficients are divided by quantization values (given by the JPEG group) and then rounded to the next integer value
Discrete Cosinus Transformation
5050
100100
150150
200200
00
00 5050 100100 150150 200200 250250 00 5050 100100 150150 200200 250250
-503-503
-314-314
-125-125
6565
The macro layer
• I – Frame, P – Frame or B – Frame?
The macro layer
• I – Frames:• „intra coded image“
• highest amount of data
• coding is very similar to a JPEG picture
• can be processed independent from other frames
• have a specified distance to the next I-Frame
The macro layer
• B – Frames:• „bi-directionally interpolated image“
• lowest amount of data
• most frequent type of frame
• depending on the previous or following P / I-Frame
• can also depend on the previous and following frame
The macro layer
• P – Frames:• „predicted image“
• medium amount of data
• difference to the previous I – Frame is stored
• have motion compensation ability
The macro layer
• Motion Compensation in P – Frames :
I - Frame P - Frame
The slice layer
• Slices are a group of succesive macro-blocks
• There is no dependence of slices on each other
The picture layer
I B B P B B P
I P B B P B B
Display
Datastream
The „group of picture“ layer
• Unrestricted number of pictures in their natural sequence
• At least one I-Frame per GOP
• Quantization values can be different for each GOP
The sequence layer
• Union of GOPs
• Movie width
• Movie height
• Movie format (e.g. 4:3 / 16:9)
• Framerate (fps)
• Bit-rate
Conclusion
• MPEG is a very common standard• Look forward to the new codec
technologies• Contains numerous new features • New standards will be much more
user friendly• Many options to adjust the compression• Even better techniques for even better
quality
Any questions?
Thanks for your attention...