COMPRESSION

ANCY MARIAM BABU, VIT UNIVERSITY

Compression

Compression is used to reduce the volume of data to be transmitted (text , images ,fax)

To reduce the bandwidth required for transmission and to reduce storage requirements (video, audio , speech) Compression

Define compression Compression can be simple and kind of compression

reduce a text file to 50% of original file. How compression is possible…?? - redundancy in video,audio,image file -human preception properties

Compression

Classification

Lossless compression - for legal and medical documents,computer programs -exploit only data redundency lossy compression - digital video,images,audio where some eroors can be correlated. - both data redundancy and human preception properties.

Video compression

Video as a sequence of pictures or frames

Exploits only spatial redundancy High correlation between successive

frames.only small portion of each frames is involved with any motion that is taking place

The combination of actual frame content and predicted frame content are used.

Video compression techniques

The examples are: Avi : audio video interleave -used to store audio and video data in file

- formatted as .avi JPEG2000: COMPRESSION STANDARD FOR STILL IMAGE -LOWER LATENCY - TYPE OF LOSSLESS COMPRESSION MPEG2 &MPEG4: VIDEO COMPRESSION STANDARD - WIDELY USED TO DVD DISCS AND DIGITAL

TELEVISON BROAD CASTING - USED IN As ENCODER BEFORE TRANSMISSION