High Efficiency Video Coding  a.k.a H.265 is the next generation standard Video Codec and is the successor to today’s H.264 a.k.a AVC (Advanced Video Coding) .

Amsterdam was the place that witnessed another landmark in the lineage of video compression standards, the HEVC (High Efficiency Video Coding ) at the International Broadcasting Convention 2012 earlier this month. High Efficiency Video Coding  a.k.a H.265 is the next generation standard Video Codec and is the successor to today’s H.264 a.k.a AVC (Advanced Video Coding) .

It has been almost a decade since the last standard (i.e AVC ) was released to the world. And now with HEVC entering the arena, the new codec is fully loaded to thrust in immense efficiency in decoding and encoding video streams .

Before getting into the nitty-gritty of what and how HEVC supersedes previous versions, let me fill you in with some of the basics of video compression.

DATA/VIDEO COMPRESSION :

Data compression, formally called ‘Source coding’, is the reduction of the data file size to minimize the usage of the system’s resources for efficient file transmission while enhancing the system’s performance.

The compression takes place in two different modes : Lossy and Lossless. Lossless compression restores the video to the exact state as it previously was, while the Lossy version takes the other way round , throwing away a handsome amount of redundant data when uncompressed . The Lossy reduces the video quality to just an acceptable level. However the compression ratio can be exponential with reference to the Lossless.

Video compression is one of the most significant practical implementation of ‘Source coding ’. Video compression today is so much in trend owing to the fact that unneeded data in the video signal can be discarded with very little loss of quality perceptible to the human eye.

With all these usefulness up the sleeves, it is only one side of the coin. The compressed data must undergo decompression before it can be put to use . This decompression costs in extra computational and processing demands from the processor. It may even require expensive hardware to decompress the video fast enough to be viewed as it had been decompressed. Now we see , Data Compression is no free lunch.

Zooming in on the video, the very existence of video compression lies in the fact that the video can be considered as a series of still images frames . Most of the video compression algorithms are lossy in nature . Typically, the operational area of the video compression is the square shaped group of pixels , termed as Macroblocks. It is only the difference between these macroblocks that the video codec operates upon.  Almost all the standard video compression techniques implement a Discrete Cosine Transform (DCT) algorithm to first convert each image into the frequency domain and then process the frequency coefficients to optimally reduce a video stream to the required bandwidth.

The DCT algorithm is well known and is widely used for data compression. The DCT converts data, such as the pixels in an image, into sets of frequencies. To compress data, the least meaningful frequencies are stripped away based on allowable resolution loss ,generally user-defined. This loss of resolution results in a lossy compressed image that is converted to frequencies.

VIDEO CODEC :

There is a complex dependency between the quality of the video and amount the of the data needed to represent it (termed as bit-rate). To handle this level of complexity , the encoding and decoding algorithms , error detection , robustness of the compression , is no child’s play . This is where Video Codec kicks in. A video codec is a software that enables video compression and decompression. There is a whole bulk of codecs available in the market today :

MPEG-4 Part 2 codecs – DivX Pro Codec , Xvid, FFmpeg

H.264/MPEG-4 AVC codecs – x264, Nero Digital, QuickTime H.264

Microsoft codecs – WMV(Windows Media Video), MS MPEG-4v3

On2 codecs – VP6, VP6-E, VP6-S, VP7, VP8, libtheora and the list goes on.

STANDARDIZATION OF THE CODECS :

The task for the standardization of the video codecs lies on the shoulders of the Moving Picture Experts Group (MPEG) and the International Telecommunication Union (ITU) together with the joining hands of the International Standards Organization(ISO)  .

There have been six significant standards developed so far : The MPEG-1 down to MPEG-2 , the H.2645(AVC) and our hottest new release the H.265(HEVC). The timeline of the international video standards can be put as follows:

Source : Wikipedia.

HEVC  as the next generation video compression standard:

High Efficiency Video Coding , popularly known as the HEVC is currently a drafted and the latest version of the video compression standard. The standard has been under the hood of the Joint Collaborative Team on Video Coding (JCT-VC). The project is a joint venture of the ISO/IEC Moving Picture Experts Group (MPEG) and ITU-T Video Coding Experts Group (VCEG). HEVC has proved to be a milestone in the evolution of the standards, producing enhanced video quality, almost doubles the compression ratio with respect to its predecessor H.264, and is capable of supporting resolutions as high as 7680 X 4320.

In addition to these, HEVC outdoes the other standards in a number of ways :

• HEVC breaks video frames into blocks of 64 x 64 in comparison to H.264’s 16 x 16.
• HEVC allows multi-threaded decoding , enabling multi-core processors to carry out the process  in the form of parallel subtasks.
• The bit-rate is as low as half as it was for the H.264.

                                      

With a bag-full of superlatives to its name, HEVC disappoints just in one aspect – the Patent. HEVC carries forward the patent issue regarding paying of the patent royalties by any user putting hands on it. All such royalties will be paid to a group called the MPEG-LA , an authority, licensing patents on behalf of a number of patent holders.

CONCLUSION:

HEVC was always built with an intention to take over the present standards flowing through the codec world. This standard was a need of today, and it has proved itself on every single test vested upon its development, that it is the “Next-Gen” . The digital TV experience is all set to take a leap , thanks to HEVC .  Ericsson and the Fraunhofer Institute have already put up their versions at the IBC, its only a matter of time for its implementations to come forth.

Sagar

Born and brought up in Gorakhpur, U.P , presently persuing my graduation at Assam University, silchar , Asam. My strength is turning technical mumbo-jumbo into easy to understand language. This is also my interest and passion and sums up what is at the heart of my ability to be the kind of technical writer you need.

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