HEVC or H.265: main differences compared to H.264. In view of AV1


HEVC or H.265: main differences compared to H.264. In view of AV1 - Image 1

The importance of video codecs in terms of image quality and network bandwidth occupation.

HEVC ( High Efficiency Video Coding ), also known as H.265, is a standard for video compression that should be widely known by now. Launched in 2013, HEVC is now the reference point for the leading online streaming platforms such as Netflix, YouTube, Twitch, and similar: it guarantees higher video quality while consuming less space, a behavior that translates into less bandwidth required and less data consumption.

Compared to the predecessor H.264, HEVC allows you to compress twice the data with a birate halved: this implies that, for example, the quality of high definition is maintained while the “space” occupied is reduced by half.

In summary, HEVC offers the following advantages over the H.264 codec:

1) Allows 8K resolution up to 300 fps (H.264 is limited to 4K at 60 fps)

2) The video stream is distributed at half the bitrate while maintaining quality.

3) HEVC videos contain fewer errors and artifacts—the overall image quality benefits from this.

4) HEVC allows you to divide each frame’s pixels into groups of different sizes to optimize the video stream based on every single scene (the technique is called Coding Tree Unit ). The blocks of information are managed in groups of dimensions from 4×4 to 64×64, while H.264 only allows blocks up to 16×16.

5) HEVC improves segmentation algorithms: instead of using only one frame and the next to compare information, it uses others. Information that does not change from one frame to another is reused, obviously saving space and network bandwidth.

6) HEVC optimizes the motion tracking mechanism: even in this case, in images that are not completely static, the standard continues to exploit the information that is part of the previous frames.

Therefore, a video that has been compressed using the HEVC standard will guarantee the same or better quality than another compressed with H.264 while taking up much less space.

The use of the HEVC codec is also at the heart of the transition to DVB T2 – the new digital terrestrial – with the switch off scheduled for mid 2022: DVB T2, what it is and what changes with the new technology.

We briefly talked about the aspects related to the occupation of the client-side network band. Above all to contain costs, to optimize the respective infrastructures as the number of customers grows, the content providers are however trying to further reduce the bandwidth required to distribute high quality multimedia content, unaltered compared to current standards. or even improved.

AV1 was developed by the Alliance for Open Media, “consortium,” which sees Mozilla, Google, Apple, Microsoft, AMD, Cisco, Amazon, Netflix, Facebook, NVidia, and Adobe and Samsung.

Many of the novelties of AV1, released as a royalty-free and opensource codec, derive from VP9, ​​developed by Google (the specifications are illustrated at this address ).

At the beginning of February 2020, Netflix started using the AV1 codec on Android instead of VP9, ​​highlighting how the compression efficiency is improved by 20%, with a consequent reduction in the necessary bandwidth.

On desktop and notebook PCs, browsers such as Google Chrome, Firefox, Edge Chromium, and Opera (in the updated versions) support AV1 ( here a series of YouTube videos that it transcoded to AV1). From this page, it is possible to download the preview version of Windows 10, which introduces support for the AV1 codec at the operating system level.

The well-known media player VLC also supports AV1 by default.