Saturday, September 5, 2015

What is the difference between H.264/AVC and H.265/HEVC?

Both of them are Video Compression Standards while H.265 is more recent.

Videos are essential for  enjoying Web, YouTube, or streaming movies. The amount of data produced by any video is very large and to send it over to you over the Internet fast enough for you to enjoy is not easy. It can be sent fast  by reducing its size. However size reduction by itself is not enough since size reduction is accompanied by a reduction in video quality. A lot of processing has to be done to get efficient compression without greatly reducing the quality.

H.264/AVC known variously as MPEG-4 Part 10 or H.264/MPEG-4 AVC, or MPEG-4/H.264 AVC is a video coding format that uses the block-oriented motion-compensation-based video compression standard. This standard was developed jointly by ITU-T Video Coding Experts Group (VCEG) and the ISO/IEC JTC1 Moving Picture Experts Group(MPEG).

H.264 is the standard for Blu-ray Discs and all Blu-ray disc players must be able to decode H.264. Most of the following support H.264:
  • Vimeo
  • YouTube
  • iTunes store
  • Adobe Flah Player,
  • Microsoft Silverlight
  • and also HDTV terrestrial broadcasts.
Read more about it here.
Read about this licensing battle between Microsoft and Motorola related to H.264 here.

H.265\HEVC (High Efficiency Video Coding) is an improvment over the previous H.264 coding technology and probably in some form will be the successor for compressed video. H.265 will give the same picture quality as H.264 but with better compression (giving you smaller file size to deal with).

Video coding exploits the redundancy that exists in Videos both spatial and temporal and removes or takes this into consideration to efficiently reduced the size. This may just be using pixels, blocks of pixels, pixles that do no change at all or changes very little; predicting the motion of pixles in a rapid scene change etc.
I recommend you read this excellent paper by Elemental to understand the H.265 basics(http://go.elementaltechnologies.com/rs/elementaltechnologies/images/HEVC_Demystified.pdf).
 

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