X264 - Wikipedia

Encoder for the video coding format H.264 x264

Original author(s)	Laurent Aimar
Developer(s)	x264 team
Repository	code.videolan.org/videolan/x264
Written in	C, Assembly
Type	Video encoder
License	GPL-2.0-or-later[1] (a proprietary licensing scheme is also available)[2]
Website	www.videolan.org/developers/x264.html

x264 is a free and open-source software library and a command-line utility developed by VideoLAN for encoding video streams into the H.264/MPEG-4 AVC video coding format.[2] It is released under the terms of the GNU General Public License.[2]

History

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x264 was originally developed by Laurent Aimar, who stopped development in 2004 after being hired by ATEME.[3][circular reference] Loren Merritt then took over development. Later, in 2008, Fiona Glaser joined the project. They both stopped contributing in 2014. Today, x264 is primarily developed by Anton Mitrofanov and Henrik Gramner.

Capabilities

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x264 provides a command line interface as well as an API. The former is used by many graphical user interfaces, such as Staxrip[4] and MeGUI.[5] The latter is used by many other interfaces, such as HandBrake[6] and FFmpeg.[7]

x264 implements a large number of features compared to other H.264 encoders.

Further information: H.264/MPEG-4 AVC § Software encoders

x264 contains some psychovisual enhancements which aim to increase the subjective video quality of the encoded video.

• Adaptive quantisation in two modes using VAQ. The second mode, a later addition, adapts the strength per frame in an attempt to improve the quality.[8]
• Psychovisual rate–distortion optimization which attempts to maintain a similar complexity. The complexity is measured using a combination of sum-of-squares optimization (SSD) and sum of absolute transformed differences (SATD).[9]
• Macroblock-tree rate control, which controls the quality by tracking how often parts of the frame are used for predicting future frames.[10]

x264 has won awards in the following codec comparisons:

• Third Annual MSU MPEG-4 AVC/H.264 Video Codec Comparison, 2006[11]
• Fourth Annual MSU MPEG-4 AVC/H.264 Video Codec Comparison, 2007[12]
• Fifth Annual MSU MPEG-4 AVC/H.264 Video Codec Comparison, 2009[13]
• Sixth Annual MSU MPEG-4 AVC/H.264 Video Codec Comparison, 2010[14]
• Seventh Annual MSU MPEG-4 AVC/H.264 Video Codec Comparison, 2011[15]
• Eighth Annual MSU MPEG-4 AVC/H.264 Video Codec Comparison, 2012[16]

x264 has SIMD assembly code acceleration on x86, PowerPC (using AltiVec), and ARMv7 (using NEON) platforms.

x264 is able to use Periodic Intra Refresh instead of keyframes, which enables each frame to be capped to the same size enabling each slice to be immediately transmitted in a single UDP or TCP packet and on arrival immediately decoded.[3] Periodic Intra Refresh can replace keyframes by using a column of intra blocks that move across the video from one side to the other, thereby "refreshing" the image. In effect, instead of a big keyframe, the keyframe is "spread" over many frames. The video is still seekable: a special header, called the SEI Recovery Point, tells the decoder to "start here, decode X frames, and then start displaying the video." This hides the refresh effect from the user while the frame loads. Motion vectors are restricted so that blocks on one side of the refresh column don't reference blocks on the other side, effectively creating a demarcation line in each frame.

In April 2010, the x264 project announced full Blu-ray compliant video encoding capability making x264 the first free Blu-ray compliant software H.264 encoder.[17] x264 has always had the ability to create video streams that are playable on most Blu-ray devices. However, it was up to the user to choose appropriate conversion settings. The default x264 preset chooses adequate compatibility for Blu-ray players but it is now possible to choose more complex conversion settings while simply maintaining compatibility by explicitly enabling Blu-ray compatibility mode. Blu-ray compatibility can be useful when striving for cross device compatibility, especially in the realm of high definition hardware media players.

x264 has been used to author commercial Blu-ray Disc titles released by Warner Bros.[18]

Tandberg controversy

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In November 2010, Fiona Glaser, an x264 developer, published information in which she claims that one of Tandberg Telecom's (a Cisco Systems subsidiary) patent applications from December 2008 contains a step-by-step description of an algorithm she committed to the x264 codebase around two months earlier.[19][20] This was relayed by media, which remarked that the company who filed the patent was following the x264 project IRC development channel and was known to the project developers,[21][22] leading to Tandberg claiming that they discovered the algorithm independently.[23]

x264 frontends

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• Avidemux
• FFmpeg[7]
• HandBrake[6]
• OpenShot
• Gstreamer
• MediaCoder
• MeGUI[5]
• MEncoder[24]
• RipBot264[25]
• SUPER
• StaxRip[4]
• Telestream Episode
• TMPGEnc Video Mastering Works 5[26]
• Harmonic Rhozet Workflow System[27]

See also

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• MPEG-4 — A standard of various MPEG formats including video, audio, subtitle, and interaction.
• Doom9 — A forum for video creation help and technical discussions.
• x265 — Open source HEVC/H.265 encoder that has licensed the rights to use the x264 source code.

References

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1. ^ "x264.c · master · VideoLAN / x264 · GitLab". VideoLAN. Retrieved 2021-07-05. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
2. ^ a b c "x264, the best H.264/AVC encoder - VideoLAN". VideoLAN. Retrieved 2021-07-01. In addition to being free to use under the GNU GPL, x264 is also available under a commercial license. Contact x264licensing@videolan.org for more details.
3. ^ a b "x264". Archived from the original on 2018-07-31. Retrieved 2012-07-14.
4. ^ a b "staxrip/staxrip: 🎞 Video encoding GUI for Windows". GitHub. Retrieved 2021-07-01.
5. ^ a b "MeGUI - x264/XviD/lavc/Snow encoder with MP4/MKV/AVI output & audio". 2005-06-18. Retrieved 2010-12-28.
6. ^ a b "Handbrake Details". Handbrake Project. Archived from the original on 2011-07-27. Retrieved 2011-03-11.
7. ^ a b "FFmpeg General Documentation". FFmpeg Team. Retrieved 2021-07-01.
8. ^ "Variance AQ Megathread (AQ v0.48 update--defaults changed)". 2007-02-15. Archived from the original on 2021-06-14. Retrieved 2021-07-01.
9. ^ "Psy RDO: Official testing thread (version 0.6 out!)". 2008-05-31. Archived from the original on 2021-05-06. Retrieved 2021-07-01.
10. ^ "x264 "Macroblock Tree Ratecontrol" testing (committed)". 2009-08-03. Archived from the original on 2018-05-29. Retrieved 2021-07-01.
11. ^ "Third Annual MSU MPEG-4 AVC/H.264 Video Codec Comparison". Retrieved 2010-12-28.
12. ^ "Fourth Annual MSU MPEG-4 AVC/H.264 Video Codec Comparison". Retrieved 2010-12-28.
13. ^ "Fifth MSU MPEG-4 AVC/H.264 Video Codec Comparison". Retrieved 2010-12-28.
14. ^ "MSU Sixth MPEG-4 AVC/H.264 Video Codecs Comparison". Retrieved 2010-12-28.
15. ^ "MSU Seventh MPEG-4 AVC/H.264 Video Codecs Comparison". Retrieved 2011-05-26.
16. ^ "MSU Eighth MPEG-4 AVC/H.264 Video Codecs Comparison". Retrieved 2012-06-22.
17. ^ "Announcing the first free software Blu-ray encoder". 2010-04-25. Archived from the original on 2014-02-21. Retrieved 2010-12-28.
18. ^ "x264 encoded discs — Authoring a professional Blu-ray Disc with x264". Archived from the original on 2020-10-23.
19. ^ Fiona Glaser (2010-11-25). "Original Tandberg blog post". x264.nl. Archived from the original on 2010-11-29. Retrieved 2010-11-28. So why the deja vu? Because this patent application was an exact, step-by-step description of the algorithm I came up with for decimate_score (and later coeff_level_run) in x264 in 2008!
20. ^ Fiona Glaser (2010-11-25). "Patent skullduggery: Tandberg rips off x264 algorithm". Archived from the original on 2010-11-28. Retrieved 2010-11-28.
21. ^ "Tandberg coder accused of open source theft". usave.co.uk. 2010-11-26. Archived from the original on 2021-07-11. Retrieved 2010-11-28.
22. ^ "Tandberg rips off an open source project". The Inquirer. 2010-11-26. Archived from the original on 2010-11-28. Retrieved 2010-11-28. Tandberg hardly employed any subtlety. The company has one of its employers following the x264 project's IRC development channel and the guy who registered the patent is known to the X264 project.{{cite web}}: CS1 maint: unfit URL (link)
23. ^ "Tandberg illustrates stupidity of software patent policy". ZDNet. 2010-11-27. Retrieved 2021-07-01.
24. ^ "Selecting Codecs and Container Formats". MPlayer. Retrieved 2011-03-11.
25. ^ "RipBot264 1.16.3 - VideoHelp.com Downloads". Retrieved 2010-12-28.
26. ^ "TMPGEnc Video Mastering Works 5: New Features". Retrieved 28 September 2012.
27. ^ "Compiling x264 for ProMedia Xpress" (PDF). Harmonic Inc. 2014. Retrieved 2014-09-22.[permanent dead link‍]

External links

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• Official website

v t e Multimedia compression and container formats
Videocompression	ISO, IEC, MPEG DV MJPEG Motion JPEG 2000 MPEG-1 MPEG-2 Part 2 MPEG-4 Part 2 / ASP Part 10 / AVC Part 33 / IVC MPEG-H Part 2 / HEVC MPEG-I Part 3 / VVC MPEG-5 Part 1 / EVC Part 2 / LCEVC ITU-T, VCEG H.120 H.261 H.262 H.263 H.264 / AVC H.265 / HEVC H.266 / VVC SMPTE VC-1 VC-2 VC-3 VC-5 VC-6 TrueMotion and AOMedia TrueMotion S VP3 VP6 VP7 VP8 VP9 AV1 Chinese Standard AVS1 P2/AVS+(GB/T 20090.2/16) AVS2 P2(GB/T 33475.2,GY/T 299.1) HDR Vivid(GY/T 358) AVS3 P2(GY/T 368) Others Apple Video AVS Bink Cinepak Daala DVI FFV1 Huffyuv Indeo Lagarith Microsoft Video 1 MSU Lossless OMS Video Pixlet ProRes 422 4444 QuickTime Animation Graphics RealVideo RTVideo SheerVideo Smacker Sorenson Video/Spark Theora Thor Ut WMV XEB YULS
Audiocompression	ISO, IEC, MPEG MPEG-1 Layer II Multichannel MPEG-1 Layer I MPEG-1 Layer III (MP3) AAC HE-AAC AAC-LD MPEG Surround MPEG-4 ALS MPEG-4 SLS MPEG-4 DST MPEG-4 HVXC MPEG-4 CELP MPEG-D USAC MPEG-H 3D Audio ITU-T G.711 A-law µ-law G.718 G.719 G.722 G.722.1 G.722.2 G.723 G.723.1 G.726 G.728 G.729 G.729.1 IETF Opus iLBC Speex Vorbis FLAC 3GPP AMR AMR-WB AMR-WB+ EVRC EVRC-B EVS GSM-HR GSM-FR GSM-EFR ETSI AC-3 AC-4 DTS Bluetooth SIG SBC LC3 Chinese Standard AVS1 P10(GB/T 20090.10) AVS2 P3(GB/T 33475.3) Audio Vivid(GY/T 363) DRA(GB/T 22726) ExAC(SJ/T 11299.4) Others ACELP ALAC Asao ATRAC CELT Codec 2 iSAC Lyra MELP Monkey's Audio MT9 Musepack OptimFROG OSQ QCELP RCELP RealAudio RTAudio SD2 SHN SILK Siren SMV SVOPC TTA True Audio TwinVQ VMR-WB VSELP WavPack WMA MQA aptX aptX HD aptX Low Latency aptX Adaptive LDAC LHDC LLAC
Imagecompression	IEC, ISO, IETF, W3C, ITU-T, JPEG CCITT Group 4 GIF HEIC / HEIF HEVC JBIG JBIG2 JPEG JPEG 2000 JPEG-LS JPEG XL JPEG XR JPEG XS JPEG XT PNG TIFF TIFF/EP TIFF/IT Others APNG AV1 AVIF BPG DjVu EXR FLIF ICER MNG PGF QOI QTVR WBMP WebP
Containers	ISO, IEC MPEG-ES MPEG-PES MPEG-PS MPEG-TS ISO/IEC base media file format MPEG-4 Part 14 (MP4) Motion JPEG 2000 MPEG-21 Part 9 MPEG media transport ITU-T H.222.0 T.802 IETF RTP Ogg Matroska SMPTE GXF MXF Others 3GP and 3G2 AMV ASF AIFF AVI AU BPG Bink Smacker BMP DivX Media Format EVO Flash Video HEIF IFF M2TS Matroska WebM QuickTime File Format RatDVD RealMedia RIFF WAV MOD and TOD VOB, IFO and BUP
Collaborations	NETVC MPEG LA Alliance for Open Media
Methods	Entropy Arithmetic Huffman Modified LPC ACELP CELP LSP WLPC Lossless Lossy LZ DEFLATE LZW PCM A-law µ-law ADPCM DPCM Transforms DCT FFT MDCT Wavelet Daubechies DWT
Lists	Comparison of audio coding formats Comparison of video codecs List of codecs
See Compression methods for techniques and Compression software for codecs

v t e Data compression software
Archivers with compression (comparison)	Free software 7-Zip Ark Expander FreeArc GNOME Archive Manager Info-ZIP KGB Archiver PAQ pax PeaZip XAD (decompression only) Xarchiver Zipeg ZPAQ Freeware Filzip LHA Lhasa (decompression only) StuffIt Expander (decompression only) The Unarchiver (decompression only) TUGZip ZipGenius Commercial ARC ALZip Archive Utility ARJ BetterZip MacBinary PKZIP/SecureZIP PowerArchiver StuffIt WinAce WinRAR WinZip
Non-archivingcompressors	Generic bzip2 compress gzip lzip lzop pack rzip Snappy XZ Utils zstd For code UPX
Audio compression (comparison)	Lossy AAC Fraunhofer FDK AAC Nero AAC Codec FAAC Helix DNA Producer MP3 l3enc LAME TooLAME libavcodec libcelt libopus libspeex Musepack libvorbis Windows Media Encoder Lossless ALAC FLAC libavcodec Monkey's Audio mp4als OptimFROG Shorten WavPack
Video compression (comparison)	Lossy MPEG-4 ASP 3ivx DivX Nero Digital FFmpeg HDX4 Xvid H.264 CoreAVC Blu-code DivX FFmpeg Nero Digital OpenH264 QuickTime x264 HEVC DivX x265 Others CineForm Cinepak Daala DNxHD Helix DNA Producer Indeo libavcodec Schrödinger (Dirac) SBC Sorenson VP7 libtheora libvpx Windows Media Encoder Lossless FFV1 Huffyuv Lagarith MSU Lossless YULS
See also: compression methods and compression formats