As it turns out, the x265 project turned 5 a couple of months back; our first commits from the HM encoder date back to March, 2013. And being the geeks that we are, we didn’t even realize it!

Many thanks to all those who have enabled x265 accomplish all that it has over 5 years! We continue to innovate inside x265 to improve both quailty, and performance and look forward to celebrating our 10th anniversary with you.

Cheers,

Team-x265.

By Pradeep Ramachandran

Now that the dust has settled, it is time to thank all the contributors for enabling a great showing by x265 at NAB 2018. We showed-off our new ML-accelerated content adaptive encoding for ABR, AVX-512 acceleration, and the recently added support for HDR10+/HLG at NAB. We received great feedback on what people would like to see in the coming releases, and will be working hard to continue to innovate in that space. We’ve also formed a committee to guide the future development of x265, and other open source media codecs that we will blog about more in the coming weeks; read this article for an initial idea of what this is about.

Until our next showing, don’t hesitate to reach out to us on the developer mailing list, doom9 (), or Facebook to talk.

By Pradeep Ramachandran

Finally, the acceleration that we’ve all been waiting for is here! We’ve been working extensively with Intel for the last few months to use Intel Advanced Vector Extensions 512 (AVX-512) to accelerate x265. After much effort, we’re delighted to share that we’ve been able to accelerate 4K HDR encoding in main10 profile by over 15% for high-quality offline encoding. Checkout this white-paper on the Intel site for more information.

The patches will be pushed to the default branch soon. Let us know the results of your tests – you know where to find us!

By Pradeep Ramachandran

After what seems to have been a long delay, AV1 finally froze its bitstream last week! Like many folks in the industry, we have been waiting for this moment for a long time to see what a truly ‘royalty-free’ codec can can bring in terms of tools to the encoding space.

A few months ago, we stopped looking further into how AV1’s tools compare to that of HEVC due to this peer-review paper  published in a leading journal from leading researchers in the field of video coding. That paper reported that the HM encoder provide average bitrate savings of 30% relative to AV1 with an encoding speed that was 25X that of the AV1 encoder; the informed would know that x265’s veryslow is very comparable in encoder efficiency to the HM encoder. While optimizations could bridge the gap in speed, bridging the gap in encoder efficiency would be hard unless some fundamental improvements (that are not covered by the HEVC-patents, mind you) are made. Now that the bitstream is frozen, we will be digging to see what new tools have been brought to the table that were not included in this comparison in the hope to answer the question “Is AV1 fundamentally better than HEVC as a standard?”. Stay tuned here to hear more, or share your thoughts on doom9/x265-devel mailing list.

And of course, there is the issue of patent royalties and licensing, but we will leave that up to the lawyers to deliberate and decide; lets talk more tech here!

By Pradeep Ramachandran

MulticoreWare, the developers of x265, will be available to discuss all things media at NAB 2018 in Las Vegas from April 9th – 12th in their booth at SU-14708. Swing by to talk about the soon-to-publish AVX512 acceleration, content adaptive optimizations for ABR encoding with x265, or if you just want a selfie with the creators of the world’s most popular HEVC encoder.

See you in Vegas!

PS: Make sure to mention this blog post if you stop by to stand a chance to win some open-source memorabilia!

By Pradeep Ramachandran

MSU recently released their 2017 codec comparison, where they compared x265 against other HEVC encoders, VP9 encoders, and the AV1 encoder. While the efforts that go into such large scale tests are appreciated, we as the x265 developers have to respectfully disagree with your conclusions drawn from this MSU report as we believe it is incomplete.

If you notice, these tests use v1.9 of x265 which is over 20months old! Since then, x265 has had 7 versions with an imminent 8th version. As anyone would expect, x265 has made considerable progress in speed and quality during this time. Specifically, we’ve made big changes to the lambda tables which considerably improved visual quality as reported by both consumers and customers.

That said, it is possible that maybe AV1 is a better codec than HEVC (at least in quality); maybe so is VP9. Maybe they have tools that are competent and can challenge HEVC. However, for the above said reasons, these results do not conclusively prove so, in our opinion!

Now as to why MSU used a 20month old encoder, there is some history there about the reservations of the x265 team to the validity of MSUs past tests as only objective scores were looked at. Quoting my dear friend, ‘we look at video and not at graphs!’. It is encouraging to see the MSU tests taking a turn towards doing subjective testing, which, in our opinion, is the right direction. Hopefully we will work with their newly mended ways in future for a more fair and realistic evaluation!

By Pradeep Ramachandran