1 / 17

MPEG/JPEG

MPEG/JPEG. MPEG JPEG MPEG/Audio compression -SIVARAMAN SAMPATH. MPEG (A video compression standard for multimedia applications). MPEG stands for Moving P ictures Experts Group and is currently a part of ISO-IEC/JTC1/SC2/WG11.

danica
Télécharger la présentation

MPEG/JPEG

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MPEG/JPEG • MPEG • JPEG • MPEG/Audio compression -SIVARAMAN SAMPATH

  2. MPEG(A video compression standard for multimedia applications) MPEG stands for Moving Pictures Experts Group and is currently a part of ISO-IEC/JTC1/SC2/WG11. The MPEG activities cover more than video compression. MPEG Video is addressing the issue of synchronization and multiplexing of multiple compressed audio and video bit streams. MPEG video is addressing the compression of video signals at about 1.5 Mbits, MPEG audio is addressing the compression of digital audio signals at the rates of 64,128,192 Kbits per channel.

  3. Background:- The activities of JPEG played a considerable role in the beginning of MPEG, since both the groups were in the same working group of ISO and there has been a considerable overlap in membership.

  4. Why MPEG? The sequence of still images approach has the disadvantage that it fails to take into the consideration the extensive frame to frame redundancy present in all video sequences.

  5. MPEG Standardization Effort • Methodology:- The MPEG methodology was divided into three phases:- • Requirements • Competition • Convergence • Schedule:- The schedule of MPEG was derived with the goal of obtaining a draft of the standard by 1990.

  6. Storage Media and Channels where MPEG could have Applications CD ROM DAT Winchester Disk Writable Optical Disks ISDN LAN Other Communication Channels

  7. MPEG Compression Algorithm The difficult challenge in the decision of the MPEG algorithm is the following: on one hand the quality requirements demand a very high compression not achievable with intraframing coding alone; on the other hand, the random access requirement is best achieved with pure intraframe coding. The MPEG video compression algorithm relies on two basic techniques: block based motion

  8. Contd. Compensation for the reduction of the temporal redundancy and transform domain(DCT)based compression for the reduction for the spatial redundancy.

  9. JPEG(Joint Photographic Experts Group) It has been working toward establishing the first international digital image compression standard for continuous tone still images for both grayscale and color. The “joint” in JPEG refers to the collaboration between CCITT and ISO. JPEG has undertaken the ambitious task of developing a general purpose compression standard to meet the needs of almost all continuous tone still image applications.

  10. Background: Requirements and selection process JPEG’s goal has been to develop a method for continuous-tone image compression which meets the following requirements: Be at or near the state of the art with regard to compression rate and accompanying image fidelity. Be applicable to practically any kind of continuous tone digital source image. Have tractable computational complexity.

  11. Contd. • Have the following modes of operations:- • Sequential encoding. • Progressive encoding. • Lossless encoding. • Hierarchical encoding. The four modes of operations and their various codecs have resulted from JPEG’s goal of being generic and from the diversity of image formats across applications.

  12. Compression and Picture Quality For color images with moderately complex scenes, all DCT based modes of operation typically produce the following levels of picture quality for the indicated ranges of compression. • 0.25-0.5 bits/pixel:- moderate to good quality sufficient for some applications. • 0.5-0.75 bits/pixel:- good to very good quality, sufficient for many applications. • O.75-1 .5 bits/pixel:-excellent quality, sufficient for most applications. • 1.5-2.0 bits/pixel:-usually indistinguishable from the original, sufficient for most demanding applications.

  13. MPEG/Audio Compression The MPEG audio compression algorithm is the first international standard for the digital compression of the high-fidelity audio. Other audio compression algorithms address speech-only applications or provide only medium-fidelity audio compression performance. The MPEG/Audio standard is the result of over 3 years of collaborative work by an international committee of high-fidelity audio experts known as MPEG/Audio.

  14. MPEG/Audio features and applications MPEG/Audio is a generic audio compression standard. MPEG/Audio offers a diverse form assortment of compression nodes: • The audio sampling rate can be 32,44.1 0r 48 KHz. • The compression bit can take one or two audio channels in one of four possible modes: • Monophonic mode. • A dual –monophonic mode. • A stereo mode. • A Joint-stereo mode.

  15. Contd. • MPEG/Audio offers a three different layers of compression: • LAYER I: above 128 kbits/s per channel. Eg:- philip’s digital compact cassette • LAYER II: at around 128 kbits/s per channel.Eg:- audio for digital audio broadcasting. • LAYER III: at around 64 kbits/s per channel. Eg:- It is best suited for audio compression over ISDN. All three layers are simple enough to allow single-chip, real time decoder implementations.

  16. Contd. The coded bit stream supports an Optical Cyclic Redundancy check(CRC) error detection code. MEG/Audio provides a mean of including ancillary data within the bitstream. In addition, the MPEG/Audio bit stream makes use of features such as random access, audio fast forwarding, and audio reverse.

  17. REFERENCES “MPEG: A Video Compression Standard for Multimedia Applications”; Le Gall, D “The JPEG Still Picture Compression Standard”, Wallace, G. K. “A Tutorial on MPEG/Audio Compression”; Pan, D.

More Related