In case you were wondering: This is the Difference between VP9 and HEVC for 4K resolution
Stephan Jukic – June 12, 2015
In the world of 4K video in all its varied formats that get distributed to the public –such as streaming, VOD, Blu-ray, etc—compression codecs are an integral part of making that ultra HD video we want to much more easily fit whatever medium it’s stored in or moving through to reach your TV.
This is where the names HEVC and VP9 come into the picture. These are the two most widely used codecs right now and almost everyone who’s taken a serious interest in buying a 4K TV has heard of both.
HEVC, also known as H.265, and VP9 are the competing next generation video compression formats that have been deemed efficient enough to replace the former universal standard known as H.264, which is frequently used for HD and Full HD content. They are in fact almost twice as efficient as H.264 and this is why both are being used for the compression of 4K UHD movies and content for delivery to our UHD TVs, PCs, tablets and other devices.
Furthermore H.265 and VP9 also compress 720p and HD content to half its normal size and thus they’re also often used in streaming movies in these lower resolution formats over slow internet connections.
Furthermore, both of these new compression formats are designed to support even the extreme UHD format known as 8K, which we can expect to become more widespread within as little as 2 to 3 years.
Given that physical video delivery mediums are mostly dying off to be replaced by streaming as the main way in which we get movies and shows to our machines, The HEVC and VP9 codecs are a crucial part of the digital entertainment future (at least until even more efficient streaming comes along).
So, with this introduction in mind, you’re probably wondering what the difference between the two is and whether you need both codecs in your 4K home media technology.
Quite simply, yes you do need your 4K TV to be compatible with both codecs for maximum 4K content compatibility and ideally, your PC will also come with mutual compatibility sooner or later. Each of them has their benefit for certain types of content, though HEVC is by far the most popular and important of the two codecs so far.
As for the differences:
H.265, as it’s also called, was originally designed and refined by two organizations called the Video Coding Experts Group and the Moving Picture Experts Group (VCEG and MPEG, yes, the same MPEG that created the MPEG video format). The HEVC stands for High Efficiency Video Coding and the codec itself was designed to be the successor to H.264, a job for which it was approved as of April of 2013. Just like its predecessor, HEVC is usable in third party hardware and transmission systems under license, for a fee.
HEVC’s 2.65 version is now found in all name brand 4K TVs, all VOD media players designed for 4K content and is also used by all the major providers of streaming pay content for compressing their ultra HD videos before they send them out to audiences. We’re talking here about content sources like Netflix and Amazon Prime Instant Video.
In contrast to HEVC, VP9 is open source and can be used without paying royalties to anyone. However, it was developed by Google mainly for the sake of compressing their own collection of ultra HD content on YouTube for easy transmission to users PC screens, assuming they happen to have a 4k monitor with which they can actually enjoy the content. Google has integrated VP9 to Chrome as well to create a 4K-ready browsing experience.
So How Do they Both Work?
In simplest terms, both VP9 and HEVC (H.265) work by doing the exact opposite of what 4K resolution itself does. Ultra HD means a gigantic amount of pixels, roughly 8.2 million to a single frame of imagery and both of these codecs need to make shrink this quantity for transmission at a correspondingly smaller bitrate without ruining the actual quality of the original resolution and thus negating its point.
Thus, what VP9 and HEVC do is expand the size of the smaller than normal pixels which go into 4K resolution and then after transmission, perform a vast and complex series of computational processing and guessing tricks to reassemble them in a way that doesn’t lead to lost details.
For example, with H.265, macroblocks of pixels, of sizes such as 16×16, 64×64 or even as little as 4×4 are compressed as single units and then after transmission, a computation series of what are called “intra-prediction directions” are performed to rebuild these macroblocks into the same original image, only with slightly less detail in areas that aren’t crucial. This means that the codec grabs smaller macroblocks of just 4×4 or 8×8 for detailed areas of a 4K image and much larger blocks of 64×64 for large areas of featureless video segment, like skies and ocean water. Slight loss of detail in these isn’t as important as it is in important, complex sections.
Furthermore, HEVC, much like VP9, can also grab and compress oddly shaped blocks of pixels from larger single square macroblocks either via Asymmetric positioning (AMP) or via symmetric positioning (SMP). Thus, for example, during asymmetric division, HEVC would take a square 16 x 16 chunk of pixels and break it down into two differently sized pieces, one of 16 x 12 and the other of 16 x 4 dimensions. And during symmetric division, a single 16 x 16 block could be broken down into two non-square blocks of 16 x 8 pixels.
As far as computational power goes, both codecs require lots of it! So much, in fact, that they’re far more powerful than H.264 or VP8 and wouldn’t have even been commercially possible back in 2003 when H.264 was launched.
What you need to understand is that both codecs perform extremely complex internal calculations to reconstitute 4K video after transmission and the above description keeps things very, very simple. Furthermore, both are excellent at their job.
It’s hard to say just which is slightly better but HEVC is at least definitely the more popular of the two.
While VP9 is used by Google in its 4K video streaming apps on YouTube, it’s also supported by a wide range of major TV makers like LG, Sony, Samsung, Panasonic, Toshiba, Philips and even GPU/processor makers like Intel and Nvidia.
However, H.265 gets support from all the same players as well as others, and more importantly, it’s the compression codec that’s actually being used to compress some of the best and most popular studio-grade 4K streaming media. This means that 4K episodes of shows like Breaking Bad, Marco Polo, House of Cards and Amazon’s newest 4K series are compressed via HEVC, not VP9.
On the other hand, as 4K video in smaller, Android-based devices takes off and as Android TV starts appearing in new 4K TVs (Like Sony’s 2015 line of Bravia UHD models) we’ll also see VP9 gain more traction, particularly because it also happens to be non-proprietary.
Whichever becomes the more popular, you’ve got little to worry about for the foreseeable future. Both are pretty much equally excellent at their jobs and currently at least, both are supported in virtually all major media devices. Google even supports HEVC in Chrome, if not in YouTube quite yet.
Story by 4k.com