x265 and SVT-HEVC in the same house

With changeset a41325fc854f, the x265 library can invoke the SVT-HEVC library for encoding through the —svt option. We have mapped presets and command-line options supported by the x265 application into the equivalent options of SVT-HEVC, and have added a few specific options that are available only when the SVT-HEVC library is invoked. This page in our documentation describes the steps to build, and invoke the SVT-HEVC library in more detail.

Our reason for this integration was to enable our users to evaluate additional relative trade-offs between performance and compression efficiency while working behind the familiar API of the x265 library. In the long term, we plan to leverage this integration to further improve x265’s ability to handle real-time and low turn-around scenarios in pure software; this is the space that SVT-HEVC was focused on. In parallel, we will continue to innovate on our flagship presets that are used in offline encoding where x265 dominates.  You can expect to see these changes in the coming releases of x265, increasing the reach of open-source for video compression!

v3.0 is now out!

We are happy to announce now have version 3.0 of x265. The main focus of this version is to improve the quality, especially for the ‘veryslow’ and ‘slower’ presets. Moreover, Dolbyvision is included in this version. The detail description of all the new features and releases is available in our release notes.

Detailed white-paper on our results from AVX512 acceleration

By Pradeep Ramachandran

A month or so back, we published a white-paper that gave high-level results on the encoder gains that we saw from our recently implemented AVX512 kernels in x265. We have now published a more detailed paper that tears the results down into more detail, including per-kernel gains for AVX512 over AVX2. The paper can be accessed from here. We hope you find the detailed analysis more informative to understand the reasons behind the results that you see on your hardware.

Do share your findings with us. As you have probably already noticed, AVX512 is part of the recently-released v2.8 of x265!

x265 Version 2.8 Released

x265 version 2.8 with cool new features including AVX512 accelerating, dynamic refinement (that enables optimized encoding for ABR streaming), support for measuring VMAF has been released! More details in our release notes at http://x265.readthedocs.io/en/stable/releasenotes.html#version-2-8

x265 turns 5!

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.

Thanks for a great NAB 2018

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.

And finally, avx512 in x265!

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!

Excited about AV1 closing doors, but…

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!

NAB 2018, of course we will be there!

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!

x265 version 2.7 released!

By Ashok Kumar Mishra

x265 version 2.7 is now out! The key new improvements include support for RADL pictures, moving from YASM to NASM assembler and reduced x265 build time by more than 50%.

The tarball of this release can be downloaded from here. The latest release notes are available here.

Happy Compressing!