Log in

View Full Version : AV2 Codec Under Active Development - Impressive Quality Improvements Revealed


CodecWar
3rd August 2023, 22:26
Today, I bring some exciting news about the AV2 codec developed by the AVM team. As many of you might be aware, AV2 is the successor to AV1 and aims to provide even better video compression and quality. In this post, I'll be discussing the recent advancements in AV2 and how it compares to its predecessor, AV1.

Active Development of AV2 Codec:
The AVM team has been hard at work, continuously refining the AV2 codec to enhance its performance. Over the last couple of years, they have released several research tags to showcase their progress. In August 2021, the research2 tag was unveiled, followed by research3 in May 2022, and research4 in April 2023.

Comparative Analysis on AOM AV2 CTC Streaming Classes:
Recently, a comprehensive report was published that compared the performance of these three AV2 implementations on AOM AV2 CTC Streaming classes, namely A5, A4, A3, and A2, focusing on resolutions up to FullHD. The objective was to evaluate the quality metrics of PSNR (Peak Signal-to-Noise Ratio), VMAF (Video Multi-Method Assessment Fusion), and SSIM (Structural Similarity Index) for the different research releases.

Steady Quality Improvements:
The results of the study were nothing short of impressive. Across all quality metrics, there was a consistent improvement as the research progressed from version 2 to version 4. For example, the PSNR: Y (luma) with BD-Rate data aggregation showed a remarkable 8.76% improvement between research3 and research4. This demonstrates the commitment of the AVM team to refining their codec and pushing the boundaries of video compression technology.

Spread and Variance:
It's important to note that while the best and worst results also improved with each iteration, the spread and variance between different video streams increased. This suggests that the AV2 codec is becoming more specialized in handling certain types of video content optimally.

Conclusions from the Study:
Based on the findings of this study, some significant conclusions were drawn:

On average, the AOM_post-AV1 codec showed an 8.76% improvement over the AOM_post-AV1 reference codec across all video streams.
Comparing the average performance on all video streams, the AOM_post-AV1 codec outperformed the AOM_post-AV1 reference codec by an impressive 15.15%.
In summary, the AV2 codec is showing immense promise and dedication from the AVM team. As the development progresses, it is evident that AV2 is significantly surpassing its predecessor, AV1, in terms of video quality and compression efficiency. However, with the increasing specialization, the codec might perform differently depending on the content being encoded.

It's an exciting time for video compression enthusiasts, and we can't wait to see how AV2 evolves further. Feel free to share your thoughts and insights in the comments below! Let's discuss the future of video codecs together.

Source: https://codecwar.com/compare/av2-research-evolution

benwaggoner
4th August 2023, 22:24
15.15% over AV1 is pretty weak tea, and less than I've heard from other people working on AV2. Certainly a 15% compression efficiency improvement has never been enough for industries to adopt a new codec technology, which is very expensive process for premium content and broadcast markets. And 15% would still put it well below VVC, which has a finished standard and silicon and will be shipping in devices this year. And MPEG's post-VVC research is hitting about a 30% improvement last I heard.

Historically, a new codec has to either offer a compelling new feature (MPEG-2 had interlaced, HEVC had HDR) or a path to doubling compression efficiency to see broad commercial adoption.

The biggest wildcard for AV2 is the machine learning stuff, which is hard to predict the real-world benefit of. And AOM's secret weapon is Film Grain Synthesis. No one is really using it for AV1 as too many early HW decoders shipped with broken FGS support, but presumably all AV2 decoders will be able to use it reliably due to bugs having been ironed out and conformance tests being available. Of course, as an out-of-loop metadata-driven filter, VVC and other codecs could also take advantage of AOM FGS. But a good, reliably, always-available FGS implementation in itself could drop the ABR of grainy content by half on top of other encoder/decoder improvements.

I doubt we'll have a good sense of AV2's potential until ML implementations have had some time to refine based on a final draft spec.