Video Compression Based on DCT-DWT Technique Miss. S. S. Wadd Dr. JJ.Magdum College of Engineering,Jaysingpur,India Dr. Mrs. S. B. Patil Dr. JJ.Magdum College of Engineering,Jaysingpur,India Abstract - The increasing demand to incorporate video data into telecommunications services, the corporate environment, the entertainment industry, and even at home has made digital video technology a necessity. To reduce bandwidth requirement in transferring files is a major challenge today. This review paper introduces advancement in video compression technology with perceiving quality and content of video. Block matching algorithms used for motion estimation in video compression Index terms: Block matching, motion estimation, video compression 1. INTRODUCTION With the advent of multimedia age and spread of internet video storage on CD/DVD and streaming video has been gaining a lot of popularity. The ISO Moving Picture Experts Group (MPEG) video coding standards pertain towards compressed video storage on physical media like CD/DVD, where as the International telecommunications Union (ITU) addresses real-time point-to-point or multi-point communications over a network.[6] Video compression algorithms manipulate video signals to dramatically reduce the storage and bandwidth required while maximizing perceived video quality. The video compression algorithms are "lossy." That is, the original uncompressed image can’t be perfectly reconstructed from the compressed data, so some information from the original image is lost. Lossy compression algorithms attempt to ensure that the differences between the original uncompressed image and the reconstructed image are not perceptible to the human eye. 2. Basic Video Compression System The basic video compression system comprises of the video encoder at the transmitter side, which encodes the video to be transmitted in terms of bits and the video decoder at the receiver side, which reconstructs the video in its original form from the bit sequence received. The sub systems of encoder and decoder are discussed below with the detailed technology aspects from theory point of view.[8] Basic Block diagram of video encoder shown in Figure 1. Figure 1. Block diagram of Video Encoder 2.1 Video encoder is designed as follows: Video data may be represented as a series of still image frames. Group of frames are selected and store the image inYCbCr color space. There are three kinds of frames in group of picture (GOP).GOP: I frame, P frame and B-frame. 2.1.1 Intra Coded (I frame): I frames are independent frames. The encoding of I frame is similar to still image sequence. I frames are coded as Intra coded frames. [6] 2.1.2 Intra Frame Coding Techniques: Process the data in blocks of 8x8 samples. The first step in the compression process involves switching from the RGB color space to the YCrCb color space. YCrCb describes a color space where the three components of color are luminance, red chrominance, and blue chrominance. This switch is made because the human eye is less sensitive to chrominance than it is to luminance.[3] Chrominance data can then be sampled at a quarter the rate of luminance data insignificant. The next step in compression involves reducing spatial redundancy. This is done using essentially the same methods as JPEG. The image is divided into 16 x 16 pixel macroblocks. Each macroblock contains 16 x 16 luminance pixels, and 8 x 8 red/blue chrominance pixels. The luminance block is then split into 4 8 x 8 blocks. Now we have 6 8 x 8 blocks on which a DCT is performed. Energy tends to be concentrated into a few significant DCT 847 International Journal of Engineering Research & Technology (IJERT) Vol. 3 Issue 2, February - 2014 ISSN: 2278-0181 www.ijert.org IJERTV3IS20205