video compression and the internet. need for compression important to advancement of internet video...
Post on 21-Dec-2015
216 views
TRANSCRIPT
Need for Compression
• Important to advancement of internet• Video prevalent all over the net• Compression has improved greatly over the
past 10 years• Helped revolutionize the way internet delivers
content
How it works
• Exploits flaw in human perception• Algorithms written to do this• Areas of similar color averaged out• Image is the same over period of time• All works to make files smaller, with better
quality• Allowing faster transmission online• Able to fit onto ipods, phones, etc
What is a codec?
• Allows for the compression (co), and decompression (dec) of a video file
• Represents analog information in a digital way• Bitrate – amount of data per second required– Lower is better
List of codecs through the years• MPEG1• MPEG2• Sorenson• Realplayer• Quicktime• DivX• XviD• H.264/x264• VC-1
Importance of flash
• Allowed sites like Youtube to flourish• Unified the standard of how to deliver video• Prior to flash video, different standards,
confusing• Including Windows Media player, Quicktime,
Realplayer and more• Everybody already has flash, so no ambiguity
The flash video format
• Flv files embedded in websites– Contain video files
• H.264, VP6, Sorenson H.263• Previous flash versions starting at 6 supported
different formats
Why encode video• Too large to upload to YouTube– 1gb file limit
• Most digital cameras use poor codecs with little to no compression, wasting hard drive space, also making sending over internet unfeasible
• Rip your dvds to your computer• Digitalize old home movies on analog sources for
preservation and sharing online• To put on your portable media player (ipod)• Use of filters to improve video quality from bad
sources
What does it take to encode video?
• Choose a codec– h.264/x264 and xvid are common
• A video file• An encoder– FFMpeg, MeGUI, Handbrake
What’s next
• GPU based encoding• Badaboom– Uses Nvidia graphics cards
• Faster than CPU• Quality an issue currently
Further Information
• www.doom9.org
• www.videohelp.com
Sources• http://www.doom9.org/index.html?/gknot-main6.htm• http://www.animemusicvideos.org/guides/avtech/
video4_2.htm#Interesting• http://www.adobe.com/devnet/flv/pdf/
video_file_format_spec_v10.pdf• http://www.kaourantin.net/2007/08/what-just-
happened-to-video-on-web_20.html• http://www.maximumpc.com/article/features/
is_era_gpubased_computing_really_upon_us• http://www.anandtech.com/video/showdoc.aspx?
i=3339&p=2