x265

x265 builds on source code from x264, an open-source video encoder for the previous MPEG video coding standard, H.264/MPEG-4 AVC. The project has licensed the rights to use the x264 source code. Development on x265 began in March 2013. MulticoreWare made the source code for x265 publicly available on July 23, 2013.

The x265 project was initially funded by a small group of charter licensee companies that direct the development requirements and receive commercial licenses to use x265 in their products without having to release their products under the GPL 2 license. In February 2014, x265 was integrated into the popular multimedia transcoding tool FFmpeg and its fork Libav.Volker Zota (heise online), 14. 2. 2014: [https://heise.de/-2113223 Videokodierung: HEVC/H.265-Encoder hält Einzug bei FFmpeg und LibAV]

Version 1.0 was completed in May 2014.{{cite web|url=https://bitbucket.org/multicoreware/x265/commits/tag/1.0|title=multicoreware / x265 / Commits — Bitbucket|website=bitbucket.org}} The stable version (2.0) was released on July 14, 2016.{{cite web|url=https://mailman.videolan.org/pipermail/x265-devel/2016-July/010528.html|title=[x265] [ANN] x265 2.0 released|date=13 July 2016 }}

x265 source code is written in C++ and x86 assembly.

x265 supports the Main, Main 10, Main 12 and Main Still Picture profiles{{cite web|url=https://x265.readthedocs.io/en/master/cli.html#cmdoption-profile|title=Command Line Options — x265 documentation|access-date=2024-03-12}} of HEVC (including intra-only profiles), utilizing a bit depth of either 8 bits or 10 bits per sample YCbCr with 4:2:0, 4:2:2 or 4:4:4 chroma subsampling.{{cite web|url=https://x265.readthedocs.io/en/master/cli.html#cmdoption-input-csp|title=Command Line Options — x265 documentation|access-date=2024-03-12}} x265 supports most of the features of x264 including all rate control modes: Constant QP (CQP), Constant Rate Factor (CRF), Average Bit Rate (ABR), 2-pass or multi-pass and video buffering verifier rate control.{{cite web|url=https://x265.readthedocs.io/en/master/index.html|title=x265 Documentation — x265 documentation|access-date=2024-03-12}} Visual quality algorithms include CU-Tree (the successor to x264's macroblock-tree), adaptive quantization, b-pyramid, weighted prediction and psycho-visual optimizations (psy-rd and psy-rdoq). A fully lossless mode is also supported. Temporal scalability is supported, allowing for a video to be encoded into a base layer HEVC bitstream that is half the frame rate of the input video frame rate, and an enhancement layer that can be decoded along with the base layer to enable playback at the full frame rate.

In April 2015, at the NAB Show in Las Vegas, MulticoreWare demonstrated high quality real-time 4K 10-bit HEVC encoding{{cite web|url=http://www.design-reuse.com/news/37109/multicoreware-4k-10-bit-real-time-hevc-video-encoding-with-x265.html|title=MulticoreWare demonstrates high quality 4K 10-bit real-time HEVC video encoding with x265|work=Design And Reuse}} at frame rates in excess of 60 FPS on a dual Intel Xeon E5 v3 server, occupying only one standard rack unit.

Judged by the objective quality metric VQM in 2015, x265 delivered video quality on par with the reference encoder of the royalty-free VP9 format that competes with HEVC.Jan Ozer, April 2015: [http://www.streamingmedia.com/Articles/Editorial/-103577.aspx The Great UHD Codec Debate: Google's VP9 Vs. HEVC/H.265]

A codec comparison from 2015 found x265 to be a leading HEVC implementation measured by SSIM metric.Jan Ozer, November 9, 2015: [http://www.streamingmedia.com/Articles/Editorial/-107455.aspx Moscow State Releases First HEVC Comparison] In August 2016, Netflix published a comparison of x264, VP9, and x265 using video clips from 500 movies and TV shows using 6 different quality metrics and found that both VP9 and x265 have 40%–50% better quality at 1080p than x264. Netflix stated that with the VMAF metric (which closely mirrors human visual experience according to the author) x265 performed substantially (19% to 22%) better than VP9.{{Cite news|url=http://www.streamingmedia.com/Articles/Editorial/Featured-Articles/Netflix-Finds-x265-20-More-Efficient-than-VP9-113346.aspx|title=Netflix Finds x265 20% More Efficient than VP9 - Streaming Media Magazine|last=Ozer|first=Jan|newspaper=Streaming Media Magazine|access-date=2016-11-09}}

x265 can be invoked as a command-line app or integrated into another application through the application programming interface.{{cite web|title=Command Line Options — x265 documentation|url=https://x265.readthedocs.io/en/master/cli.html|access-date=2024-03-12}}{{cite web|title=Application Programming Interface — x265 documentation|url=https://x265.readthedocs.io/en/master/api.html|access-date=2024-03-12}}

Open source software projects which utilize x265 for HEVC encoding:

• Avidemux{{cite web|url=http://fixounet.free.fr/avidemux/news.html|title=Avidemux – News}}
• FFmpeg{{cite web|url=http://ffmpeg.org/general.html|title=General Documentation}}
• HandBrake{{cite web|url=https://handbrake.fr/features.php|title=HandBrake: Features}}
• Internet Friendly Media Encoder{{cite web|url=https://x265.github.io|title=x265 GUI Encoder with Internet Friendly Media Encoder!}}
• MeGUI{{cite web|url=http://sourceforge.net/projects/megui|title=MeGUI|author=berrinam|work=SourceForge|date=7 May 2023 }}
• OpenShot{{cite web|url=http://www.openshot.org/features/|title=OpenShot}}
• ShareX{{Cite web|url=https://getsharex.com/changelog/#sharex-1310---2020-03-01|title=ShareX 13.1.0 - changelog|date=2020-03-01}}
• Shotcut{{cite web|url=https://www.shotcut.org/features/|title=Shotcut}}
• Staxrip{{cite web|url=https://staxrip.readthedocs.io/|title=StaxRip}}
• x265vfw{{cite web|url=http://mpxplay.sourceforge.net/|title=x265vfw}}

Commercial products that utilize x265 for HEVC encoding:

• BBright SLED-4K and SLED-HD Encoder{{cite web|url=http://www.bbright.com/#!prx265/c1xqn|title=BBright – Ultra HD / 4K Video Products and Laser Light Sources|work=BBright}}
• Blackmagic DaVinci Resolve Studio{{Cite web|title=DaVinci Resolve 16 {{!}} Blackmagic Design|url=https://www.blackmagicdesign.com/products/davinciresolve/|access-date=2020-07-17|website=www.blackmagicdesign.com}}{{Failed verification|date=July 2020}}
• CloudApp
• Sorenson Squeeze Desktop Pro and Squeeze Server{{cite web|url=http://www.sorensonmedia.com/squeeze/squeeze-desktop/squeeze-pro/|title=Squeeze Desktop Pro – Sorenson Media|work=Sorenson Media|access-date=2015-07-22|archive-date=2015-09-17|archive-url=https://web.archive.org/web/20150917075958/http://www.sorensonmedia.com/squeeze/squeeze-desktop/squeeze-pro/|url-status=dead}}
• Telestream Vantage Media Processing Platform{{cite web|url=http://www.telestream.net/vantage/overview.htm#VantageFormat|title=Video Workflow Automation Software – Vantage Workflow Features & Benefits – Telestream|date=29 May 2024 }}
• TMPGEnc Video Mastering Works{{cite web|url=http://tmpgenc.pegasys-inc.com/en/product/tvmw6.html|title=TMPGEnc Video Mastering Works 6}}

• x265 HEVC Upgrade{{cite web|url=http://x265.com|title=x265 HEVC Upgrade|work=x265}}

{{Reflist|30em}}

• [http://x265.org/ Official website] for the Open Source Project

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Category:C++ libraries

Category:Computer file formats

Category:Free software programmed in C++

Category:Free video codecs

Category:Free video software

Category:Lossy compression algorithms

Category:Open standards covered by patents

Category:Video compression