Video Compression: Performance evaluation of available codec software Sridhar Godavarthy

Introduction

10/17/20153 What is Video?  Series of framed images, put together one after the other to simulate motion.  Takes advantage of the spatio-temporal properties of the human eye to simulate continuity in motion.  Several standards for television exist, which define the frame rate of the video being displayed. e.g.: NTSC, PAL  The frame rate varies from 25fps to 60fps depending on the standard.

10/17/20154 Compression - Why  Staggering amount of data.  Uncompressed data for 1.5hrs exceeds DVD.  Human eye does not recognize.  Waste of Bandwidth.

10/17/20155  Lossy  Lossless  General Run Length, Huffman  Psychovisual Lossy WMV, MPEG  Intraframe Subsampling, Quantization,Transforms  Interframe Difference Coding, Motion compensation Compression - How

10/17/20156 Video Encoding Formats 1)MPEG-1 2)MPEG-2 3)MPEG-4 4)H.263 5)ASF 6)WMV and lots more…

10/17/20157 What is a Codec?  Coder Decoder.  Capable of encoding and decoding.  H/W or S/W.  Several codecs for each format.  Separate for audio/video.

10/17/20158 Containers  Used to hold combination of video and audio ( also subtitles and other meta data).  Some formats are capable of holding different formats of audio and video but mostly fixed.  Decide the extensions. .avi,.mov,.mp4

10/17/20159 Evaluation Parameters Video Quality - MSE - PSNR - Absolute Colour Distance - Structural Similarity Codec Performance - File Size - Compression/Decompression time

Data Sets

10/17/ Resolution Evaluation

10/17/ Performance Evaluation

10/17/ Evaluation Parameters Contd… Mean Squared Error -Measure of amount by which result differs from original. -Second moment and indicates variance.

10/17/ Evaluation Parameters Contd… Peak Signal to Noise Ratio -Measure of peak signal to the noise introduced by compression. -High dynamic range. Expressed in db.

10/17/ Evaluation Parameters Contd… Mean Absolute Difference of colour components

10/17/ Evaluation Parameters Contd… Structural Similarity(SSIM) –Function of luminance, contrast and structural similarity.

10/17/ Evaluation Parameters Contd… Bitrates -600 kbps -1000kbps kbps

10/17/ Evaluation Parameters Contd… Size of compressed video Time for compression (encoding) Time for decompression (decoding)

10/17/ Mean Squared Error

10/17/ Peak Signal to Noise Ratio

10/17/ Absolute Color Distance

10/17/ Structural Similarity

10/17/ File Sizes

10/17/ Conclusion Selection of format depends on - Application Transmission Video Conferencing Archiving - Bandwidth Availability Internet Video Over IP Disc Viewing - Performance Requirements Real time video processing for UAVs etc. Video Viewing - Quality requirements Entertainment Conferencing Surgical procedures

10/17/ Things I wanted to do MSE PSNR Blocking Blurring Encoding Time Size Vary Bitrates SSIM Absolute Color Distance Decoding Time Vary FrameCount Vary FrameSize Operating Characteristics √ √ √ √ √ √

Merci Beaucoup

Time Line 10/17/201527