M P E G A Presentation by Sebastian Graf and Thomas Winterscheid.

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?

    leonardo.chiariglione@tilab.com

Thanks for your attention...