THE THREE MAJOR VIDEO CODECS
H.264
THE MARKET LEADER
Before H.264 (also called AVC or Advanced Video Coding), there were other standards like MPEG2 and MPEG (Motion Picture Experts Group), with the former used for DVDs. But with the shift to high-definition content in the early 2000s, we needed something better. A consortium came up with new standards to enable higher resolution, higher quality content without bloating the bandwidth or bitrate requirements—H.264 was the result.
The initial release in 2003 consisted of three profiles: Baseline, Main, and Extended. In 2005, the High profile was added with several variations and, in 2007, a major update added Scalable Video Coding (SVC), which helped kickstart streaming video. With SVC, it was possible to scale down the bitrate of a video, while also reducing the quality, to stay within bandwidth requirements. If you watched a video stream that suddenly becomes blocky and pixelated, that was SVC at work. The only other major change was support for Multivideo Video Coding (MVC), which was necessary for content intended for stereoscopic displays.
A key factor in the popularity of H.264 was that the MPEG Licensing Association (MPEG LA) allowed the free use of H.264 technologies for video streaming to end users. It remains the standard, though the bitrates required for higher quality are starting to become rather bloated.
HEVC/H.265
A POORLY RECEIVED SEQUEL
H.264 was designed to work with relatively low-power hardware, especially for decoding purposes. What was once considered a demanding algorithm would become child’s play for modern hardware, and with excess computational power available, work was put into the next standard: H.265 or HEVC, High-Efficiency Video Coding.
First published in 2013, it built on the foundations of H.264, but with newer features designed to improve the achievable compression ratios.
The first consumer graphics cards to support HEVC encoding were Nvidia’s GTX 900-series back in 2014. Over the next several years, support for
HEVC continued to improve, but it never saw the widespread adoption of H.264. That’s largely thanks to more stringent enforcement of royalties for the standard, so while just about every modern laptop, PC, and smartphone supports HEVC, a lot of streaming internet content has opted to stick with H.264 or look for other options.
Ignoring uptake and popularity, HEVC delivers on the promise of higher video quality with lower bitrate requirements. It’s not a huge difference at 1080p, where a good quality HEVC video can do with 6Mbps what H.264 might need 8Mbps to manage. But move up to 4K video content and HEVC can potentially cut the bitrate in half relative to H.264.
AV1
THE ROYALTY FREE ALTERNATIVE
Because of the royalties associated with HEVC, some of the largest technology companies—Amazon, Apple, AMD, ARM, Google, Intel, Microsoft, Netflix, and Nvidia— formed the Alliance for Open
Media, which created an HEVC rival called AV1 in 2018. There was also VP9, a predecessor to
AV1, created by Google and used by YouTube, but while decoding support for VP9 has been around for some time, hardware-accelerated encoding support has been lacking. Ultimately, AV1 aims to do what neither HEVC nor VP9 could and offer a quality, royalty-free codec.
Despite being published as AV1 version 1.0.0 with Errata 1 in mid2019, with a reference softwarebased encoder and decoder, AV1 adoption didn’t immediately take off. In fact, it’s only in the past year or two that talk of AV1 decoding and encoding support started to become important. Existing graphics cards on the PC for example have used a hybrid software plus hardware decoding approach for AV1 video, which is fine for high-end hardware but can be a bit too demanding on low-power laptops. That all changed with Intel Arc, Nvidia Ada, and AMD RDNA 3, which provide full decoding and encoding support for AV1.