AV1 Codec Explained: What It Means for Online Streaming (2021)
Here, we have explained the AV1 codec, what are its key features, whether AV1 can compete with HEVC, and more. You can expand the table below and move to the relevant section with just a click.
What is AV1 Codec?
In the world of online media delivery, codecs play a very important role. Currently, H.264 (MPEG-4) is the dominant codec followed by H.265 (popularly known as HEVC). Both of these codecs have been developed by a group primarily led by Samsung, General Electric, Dolby, Nippon Telegraph and Telephone, and more. Other than that, these codecs are royalty-bearing standards and require vendors to pay a negotiated licensing fee.
As we know, video consumption on the internet is increasing at a breakneck pace, so streaming companies needed a royalty-free codec to reduce the high cost of delivering online media. And that’s why notable Silicon Valley companies joined hands to bring an alternative to MPEG-4. Other than that, the best part about the AV1 codec is that it’s more efficient than HEVC or H.264 standards. I have discussed AV1’s performance and compared it with HEVC in the next section.
The Technology Behind AV1
The AV1 codec is based on Google’s VP9 codec. However, it adds more coding options for encoders which allows them to better adapt to different types of inputs.
To give you a really simple explanation of the process that encoders use while encoding videos with the AV1 codec, let me explain it to you in layman terms. For starters, the encoder partitions frames into same sized blocks of 128×128 or 64×64 pixels. These are called ‘Superblocks’ and are further partitioned into smaller blocks according to different patterns.
These patterns can be 4×4 (recursive), horizontal split (4:1), vertical split (1:4), or T-shaped patterns that were originally developed for the VP10 codec. These partitions are then quantized and coded into a bit stream.
Decoders pretty much take this encoded stream of information and run it back, with things like predictions, loop filtering, and film grain synthesis to form an output frame.
AOMedia Video 1 (AV1) Specifications
The AV1 codec can currently support up to 8K at 120FPS video. However, this might increase in the future as more levels are defined. Within itself, the AV1 codec has three profiles for decoders, as well as multiple decoder levels ranging from 2.0 to 6.3.
AV1 Profiles
As mentioned above, there are three profiles within the AV1 specification — Main, High, and Professional.
The Main profile supports 4:0:0 (greyscale) and 4:2:0 (quarter) chroma sampling in 8 bit or 10 bit depth. The High profile supports 4:0:0, 4:2:0, and 4:4:4 chroma sampling in 8 bit or 10 bit depth. Whereas, the Professional profile supports 8 bit, 10 bit, and 12 bit depth, and adds 4:2:2 (half), and 4:4:4 chroma subsampling.
AV1 Levels
There are a total of 14 levels defined so far within the AV1 spec (ranging between 2.0 and 6.3). These levels specify the MaxPicSize, MaxHSize, MaxVSize, Decode Rate, Header, bit-rate and more for the decoders — indirectly dictating the resolutions that can be decoded with the AOMedia Video 1 codec.
So, for example, level 2.0 supports resolutions such as 426×240 at 30FPS. Moving up, level 4.0 supports 1920×1080 (Full HD resolution) at 30FPS, level 5.1 supports 3840×2160 at 60FPS, while level 6.2 supports 7680×4320 (8K) at 120FPS.
Is AV1 Codec Better Than HEVC?
For video codecs, there are two metrics that let you gauge the performance — the quality and the bitrate. If you manage to lower the bitrate without affecting the video quality then you have got a very good data compression algorithm. In this sense, the AV1 codec is 30% better than HEVC at data compression. It means that for the same video quality, the AV1 codec reduces the bitrate by 30% which is a significant dip for online streaming companies.
A lower bitrate means lower bandwidth which brings down the server cost for companies like YouTube, Netflix, etc. Companies will have to store less data on their servers and consumers can save data even while watching high-definition content. Bear in mind, the HEVC codec is not the top player in online streaming, instead, its older version H.264 along with Google’s in-house VP9 codec is used almost everywhere. And if you compare H.264 with AV1 then the gap becomes even wider. AV1 is 50% and 25% better than H.264 and VP9 respectively.
Having said that, not everything is rosy about AV1 and there is one vital issue that is hampering its adoption across the web. While in terms of data compression, AV1 is much better, if we look at the time required to encode a video, it takes much more time than HEVC or H.264. Basically, to export a video in AV1 codec, it will take considerably more time — over double — than a HEVC/H.264 one.
This is mainly because the AV1 codec requires hardware encoding and currently, there are very few chips that support hardware-based AV1 encoding. On the other hand, HEVC or H.264 take advantage of hardware-based encoding which reduces the processing time significantly.
As of now, on smartphones, only a couple of SoCs support AV1 decoding. These include the Dimensity 1000, as well as the Exynos 2100. Therefore, there aren’t a lot of smartphones that can perform hardware-based AV1 decoding out there, although the number is growing slowly.
Meanwhile, Nvidia and Intel have announced some of their high-end chips with AV1 encoding support and AMD has also joined hands to bring mid-tier chips with accelerated AV1 support.
Where is AV1 Currently Used?
Even though AV1 has an issue with hardware decoding, a number of platforms, devices, and services have started supporting the AV1 coding. This is primarily due to the significantly lower bit rates that AV1 requires for high quality content as compared to HEVC, H.265 or H.264 encoded videos. Let’s take a look at which devices, services, and platforms support the AV1 codec as of now.
Devices that Support AV1
Samsung Galaxy S21 series (Exynos 2100)Dimensity 1000Roku UltraLG 8K TVsSamsung 8K TVsRTX 30 series graphics cards
What’s more, Google has mandated that any device that wants to use Android TV has to have an AV1 decoder built-in. The deadline for compliance was earlier this year in March. So, we should see a lot of smart TVs come out with hardware support for AV1 decoding.
Streaming Services that Support AV1
NetflixYouTubeVimeoTwitch (expected in 2022/23)IQIYI
Browsers that Support AV1
Chrome 70+Opera 57+BraveVivaldiFirefox 67+Microsoft Edge (requires the AV1 Video Extension add-on)
Platforms/Operating Systems with AV1 Support
Windows 10 (requires an add-on)LinuxAndroid 10 and aboveChrome OS
Note: Apple devices including iPhones, iPads, and Macs don’t support AV1 natively; the company is opting to support HEVC instead.
Apps and Video Players that Support AV1 Decode
VLCMPVPotPlayerGoogle Duo uses AV1 for video calls
Video Editing Software with AV1 Support
DaVinci Resolve
Conclusion: What is the Future of AV1?
As more chipsets come with hardware-based AV1 encoding/decoding support, things will look better for AV1 adoption. We should not forget that AV1 is quite a new standard. The development was started in 2015 so for mass adoption, we should wait for another 2-3 years. Android TVs including Google TV will also start supporting AV1 after ARM integrates the AV1 specs into its SoC design.
Even low-end and mid-tier chips will start having support for AV1 decoding in the next few years. It looks like the future of low-bitrate, high-quality streaming is not far. So, what do you think about the AV1 codec? Let us know in the comments.
