What is HEVC or H.265 ?

By January 19, 2017General

The newest Zgemma receivers are HEVC compliant. Namely the Zgemma H5, the H5.2S and the Zgemma H5.2TC

So what is it?
High Efficiency Video Coding (HEVC), also known as H.265, promises twice the compression possible with Blu-ray’s best video compression methods.
But how does it work, and is it enough to get us better-looking 4K content?
I’d like to call it H.265, because it sounds cool, but it’s full name is High Efficiency Video Coding (HEVC). It’s the new successor to Advanced Video Coding (AVC), also known as H.264, which is one of the compression schemes used by Blu-ray.

The idea of HEVC is to offer the same level of picture quality as AVC, but with better compression, so there’s less data to deal with. This is key if we want 4K/Ultra HD broadcasts (including satellite), 4K Blu-rays, and more.
But is it enough, and for that matter, how does it work?
There are many ways to do this, one of the easiest being reducing the quality. In some cases this is OK. Think of your average YouTube video. Not great, right? Often that’s because the video is highly compressed (either before or during the upload). Heavy compression might keep the resolution technically the same, but the image can appear softer, noisier, or have weird distracting artifacts (like those seen to the right).

But that’s not a great idea if the point is to preserve a director’s intent, or show off your new 77-inch OLED .

So the other option is to use better compression. In this case, you can basically think of “better” compression as “smarter” compression. So it’s taking the same original (the video), and finding out better ways to make the amount of data less, without sacrificing quality. Every few years the processing power of gear has improved enough to let more processor-intensive compression algorithms to be used, and further compress the data without making the image worse.

This distinction between “more” compression and “better” compression is important, as really, the terms aren’t interchangeable in this context. You can decrease the amount of data required for a signal either by cranking up the compression and making the image ugly (just “more” compression), or using a more efficient compression technique (“better” compression).

Let me put it this way. Say you have a bushel of apples. You need to fit 100 apples inside. You can do it with more compression (reducing the apples to sauce), or with better compression (finding a better way to make them all fit, but preserving their appleness).

More compression: applesauce
Better compression: more apples, same space

As you can see from this delicious example, “more” compression is easy (SMUSH) while “better” compression requires more thought and/or better technology.
Compression (the good, the bad, and the lossy)
The amount of raw data coming out the back of a professional HD camera is a massive. There’s no way to conveniently transport it to your home. Instead, the video is compressed to reduce the amount of data into a more manageable form.



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