X264
Encyclopedia
x264 is a free software
library for encoding video streams into the H.264/MPEG-4 AVC
format. It is released under the terms of the GNU General Public License
.
, Loren Merritt then took over development. Today, x264 is primarily developed by Loren Merritt, Jason Garrett-Glaser, Steven Walters, Anton Mitrofanov, Henrik Gramner and Daniel Kang.
. The former is used by many graphical user interface
s, such as Staxrip and MeGUI. The latter is used by many other interfaces, such as HandBrake
and FFmpeg
As of August 2008, x264 implements more features than any other H.264 encoder.
x264 has some notable psychovisual
enhancements which help to increase the visual quality
.
x264 has won awards in the following codec comparisons:
x264 has SIMD
assembly code acceleration on x86, PowerPC
(using AltiVec
), and ARMv7
(using NEON) platforms.
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. 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; however, 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
).
Warner Brothers has used x264 for commercial Blu-rays.
Telecom's (a Cisco Systems
subsidiary) patent application
s from December 2008 contains a step-by-step description of an algorithm he committed to the x264 codebase around two months earlier. 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, leading to Tandberg claiming that they discovered the algorithm independently.
Free software
Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
library for encoding video streams into the H.264/MPEG-4 AVC
H.264/MPEG-4 AVC
H.264/MPEG-4 Part 10 or AVC is a standard for video compression, and is currently one of the most commonly used formats for the recording, compression, and distribution of high definition video...
format. It is released under the terms of the GNU General Public License
GNU General Public License
The GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU Project....
.
History
x264 was originally developed by Laurent Aimar, who stopped development in 2004 after being hired by ATEMEAteme
ATEME is a French broadcast company specialising in video compression MPEG4 encoding/decoding solutions for contribution, video headend, and multi-screen transcoding as well as 3D technology...
, Loren Merritt then took over development. Today, x264 is primarily developed by Loren Merritt, Jason Garrett-Glaser, Steven Walters, Anton Mitrofanov, Henrik Gramner and Daniel Kang.
Capabilities
x264 provides a command line interface as well as an APIApplication programming interface
An application programming interface is a source code based specification intended to be used as an interface by software components to communicate with each other...
. The former is used by many graphical user interface
Graphical user interface
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...
s, such as Staxrip and MeGUI. The latter is used by many other interfaces, such as HandBrake
HandBrake
HandBrake is a general-purpose, open-source, cross-platform, multithreaded video transcoder software application. HandBrake was originally developed by titer in 2003 as a general-purpose video transcoder to make ripping a film from a DVD to a data storage device easier...
and FFmpeg
FFmpeg
FFmpeg is a free software project that produces libraries and programs for handling multimedia data. The most notable parts of FFmpeg are libavcodec, an audio/video codec library used by several other projects, libavformat, an audio/video container mux and demux library, and the ffmpeg command line...
As of August 2008, x264 implements more features than any other H.264 encoder.
x264 has some notable psychovisual
Psychophysics
Psychophysics quantitatively investigates the relationship between physical stimuli and the sensations and perceptions they effect. Psychophysics has been described as "the scientific study of the relation between stimulus and sensation" or, more completely, as "the analysis of perceptual...
enhancements which help to increase the visual quality
Subjective video quality
Subjective video quality is a subjective characteristic of video quality. It is concerned with how video is perceived by a viewer and designates his or her opinion on a particular video sequence...
.
- Adaptive quantisation in two modes using VAQVariance Adaptive QuantizationVariance Adaptive Quantization is a video encoding algorithm that was first introduced in the popular open source video encoder x264. It was later ported to programs which encode video content in other video standards, like MPEG-4 ASP or MPEG-2....
. The second mode, a later addition, adapts the strength per frame in an attempt to improve the quality. - Psychovisual Rate–distortion optimizationRate–distortion optimizationRate–distortion optimization is a method of improving video quality in video compression. The name refers to the optimization of the amount of distortion against the amount of data required to encode the video, the rate...
which attempts to maintain a similar complexity. The complexity is measured using a combination of SSDSum of squaresThe partition of sums of squares is a concept that permeates much of inferential statistics and descriptive statistics. More properly, it is the partitioning of sums of squared deviations or errors. Mathematically, the sum of squared deviations is an unscaled, or unadjusted measure of dispersion...
and SATDSum of absolute transformed differencesSum of absolute transformed differences is a widely used video quality metric used for block-matching in motion estimation for video compression. It works by taking a frequency transform, usually a Hadamard transform, of the differences between the pixels in the original block and the...
. - Macroblock-tree rate control which controls the quality by tracking how often parts of the frame are used for predicting future frames.
x264 has won awards in the following codec comparisons:
- Doom9'sDoom9Doom9 is a website featuring information on digital audio and video manipulation, mostly video, and digital copyrights. It is also the forum username of the author of the page, an Austrian then college student at the time of the creation of the site...
2005 codec shoot-out - Third Annual MSU MPEG-4 AVC/H.264 Video Codec Comparison, 2006
- Fourth Annual MSU MPEG-4 AVC/H.264 Video Codec Comparison, 2007
- Fifth Annual MSU MPEG-4 AVC/H.264 Video Codec Comparison, 2009
- Sixth Annual MSU MPEG-4 AVC/H.264 Video Codec Comparison, 2010
- Seventh Annual MSU MPEG-4 AVC/H.264 Video Codec Comparison, 2011
x264 has SIMD
SIMD
Single instruction, multiple data , is a class of parallel computers in Flynn's taxonomy. It describes computers with multiple processing elements that perform the same operation on multiple data simultaneously...
assembly code acceleration on x86, PowerPC
PowerPC
PowerPC is a RISC architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM...
(using AltiVec
AltiVec
AltiVec is a floating point and integer SIMD instruction set designed and owned by Apple, IBM and Freescale Semiconductor, formerly the Semiconductor Products Sector of Motorola, , and implemented on versions of the PowerPC including Motorola's G4, IBM's G5 and POWER6 processors, and P.A. Semi's...
), and ARMv7
ARM architecture
ARM is a 32-bit reduced instruction set computer instruction set architecture developed by ARM Holdings. It was named the Advanced RISC Machine, and before that, the Acorn RISC Machine. The ARM architecture is the most widely used 32-bit ISA in numbers produced...
(using NEON) platforms.
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. 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; however, 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
HD media player
HD media player or HDD media player is a generic term used for a category of consumer product that combines a hard drive enclosure with hardware and software for playing audio, video and photos through a home entertainment system...
).
Warner Brothers has used x264 for commercial Blu-rays.
Tandberg controversy
In November 2010, Jason Garret-Glaser, an x264 developer, published information in which he claims that one of TandbergTandberg
This article is about the video-conferencing vendor, a Cisco company. Other companies with the same name such as Tandberg Television or Tandberg Data for data storage: see here and here...
Telecom's (a Cisco Systems
Cisco Systems
Cisco Systems, Inc. is an American multinational corporation headquartered in San Jose, California, United States, that designs and sells consumer electronics, networking, voice, and communications technology and services. Cisco has more than 70,000 employees and annual revenue of US$...
subsidiary) patent application
Patent application
A patent application is a request pending at a patent office for the grant of a patent for the invention described and claimed by that application. An application consists of a description of the invention , together with official forms and correspondence relating to the application...
s from December 2008 contains a step-by-step description of an algorithm he committed to the x264 codebase around two months earlier. 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, leading to Tandberg claiming that they discovered the algorithm independently.
x264 frontends
- AvidemuxAvidemuxAvidemux is a free and open-source video editing program designed for video editing and video processing. It is written in C++, and uses either the GTK+ or Qt.- Features :...
- Blaze
- FFmpegFFmpegFFmpeg is a free software project that produces libraries and programs for handling multimedia data. The most notable parts of FFmpeg are libavcodec, an audio/video codec library used by several other projects, libavformat, an audio/video container mux and demux library, and the ffmpeg command line...
- HandBrakeHandBrakeHandBrake is a general-purpose, open-source, cross-platform, multithreaded video transcoder software application. HandBrake was originally developed by titer in 2003 as a general-purpose video transcoder to make ripping a film from a DVD to a data storage device easier...
- MediaCoderMediaCoderMediaCoder is a transcoding program for Microsoft Windows. It has been developed by Stanley Huang since 2005.MediaCoder uses various open source audio and video codecs, among several proprietary codecs and tools to transcode different audio/video formats and has many extra features...
- MeGUI
- MEncoderMEncoderMEncoder is a free command line video decoding, encoding and filtering tool released under the GNU General Public License. It is a close sibling to MPlayer and can convert all the formats that MPlayer understands into a variety of compressed and uncompressed formats using different codecs.MEncoder...
- MiniCoder
- RipBot264
- SUPERSUPER (software)SUPER is a closed-source freeware front-end for open-source software video players and encoders provided by the FFmpeg, MEncoder, MPlayer, x264, ffmpeg2theora, musepack, Monkey's Audio, True Audio, WavPack, libavcodec, and the Theora/Vorbis RealProducer plugIn projects...
- Staxrip
- XMedia RecodeXMedia RecodeXMedia Recode is a donationware video and audio transcoding program for Microsoft Windows developed by Sebastian Dörfler. It can import and export many types of files such as WMV, MP4, MP3, 3GP, Matroska and more. XMedia Recode can convert unprotected DVDs or DVD files to any supported output file...
See also
- H.264H.264/MPEG-4 AVCH.264/MPEG-4 Part 10 or AVC is a standard for video compression, and is currently one of the most commonly used formats for the recording, compression, and distribution of high definition video...
- The video compression standard (format) implemented by x264. - MPEG-4MPEG-4MPEG-4 is a method of defining compression of audio and visual digital data. It was introduced in late 1998 and designated a standard for a group of audio and video coding formats and related technology agreed upon by the ISO/IEC Moving Picture Experts Group under the formal standard ISO/IEC...
- A standard of various MPEG formats including video, audio, subtitle, and interaction. - Doom9Doom9Doom9 is a website featuring information on digital audio and video manipulation, mostly video, and digital copyrights. It is also the forum username of the author of the page, an Austrian then college student at the time of the creation of the site...
- A forum for video creation help and technical discussions.