What is the difference between 4K and H.265?

February 5, 2020.

4K, MPEG-4, H.265… are different concepts which may cause a confusion that often paves the way to abusive commercial practices. What are the differences?

4K is the definition. H.265 is the compression.

4K means the video picture displayed on screen has almost 4000 single vertical columns (4K = 4000). This is so much information that it must be compressed using mathematical algorithms such as the so called H.265, that reduce the amount of data needed to broadcast, store and depict the video.


4K and H.265 are not the same

What is the picture definition?

The definition or resolution is the amount of single points that form (“define”) the image displayed on screen. It is said the picture has greater definition as more single points it is composed of.

  • The standard definition (SD) in most countries is of 720x576 points.
  • The high definition (HD) is of 1920x1080 points (or 1280x720) and it is the most used in digital television transmission today.
  • The 4K or Ultra HD makes a qualitative leap forward offering a 3840x2160 pixels definition (four times the HD).

What is video compression?

Video compression (video codecs) are mathematical algorithms that reduce the amount of information needed to depict the image. If data is not compressed it would require a storage space and a transmission bandwidth of so high capacities that its economic cost (and technical viability) would be prohibitive..

Did you know? The standard definition (SD) with 720 x 576 points and 25 frames per second sums up more than 10 million single points per second… But 4k reaches near 200 million! They are so huge information amounts that, if not compressed, they cannot be stored nor broadcasted.

  • MPEG-2 is a video compression codec created in 1994 aimed to the SD. It is the chosen codec for the first digital broadcastings of satellite, terrestrial and cable television as well as the DVD video standard.
  • H.264 / AVC was developed in the beginning of the 2000s and it is aimed to the HD. Thus it is used in terrestrial, satellite and cable high definition broadcast as well as in Internet and Blu-Ray discs. It is also known as AVC (Advanced Video Codec).
  • H.265 / HEVC was approved in 2015 and it is the video codec used in the Ultra High Definition (Ultra HD) broadcast because it reduces by half the required bandwidth by the H.264. This way the providers can broadcast Ultra HD contents with no need to take a prohibitive amount of bandwidth.

It is worth to mention…

We often confuse MPEG-4 and H.264 codecs. They are not the same. MPEG-4 is a video codec featuring a number of variants, being one of them the H.264 which technically is MPEG-4 part 10.

H.264 and H.265 codecs are optimized but not limited to the High Definition and Ultra HD broadcasting respectively. This means it is possible to compress standard definition content in H.265. Therefore an H.265 broadcasting is not necessarily of Ultra HD.

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