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Information about X264

x264
Developer:x264 team
OS:Cross-platform
Genre:Multimedia framework
License:GPL
Website:[1]


x264 is a free software library for encoding H.264/MPEG-4 AVC video streams. Written from scratch by Loren Merritt, Laurent Aimar, Eric Petit, Min Chen, Justin Clay, Måns Rullgård, Radek Czyz, Alex Izvorski, Alex Wright, and Christian Heine, it is released under the terms of the GNU General Public License.

Several graphical user interfaces have been made for the command line version, including MeGUI, AutoAC and a .NET (1.1) based x264CLI GUI.

Capabilities

As of May 2007, x264 is one of the most advanced publicly available AVC encoders. Some of its features include:

Feature CLI option
Main Profile features
All P-frame inter-predicted macroblock types--partitions p8x8,p4x4
B-frame inter-predicted block types from 16x16 down to 8x8--partitions b8x8
B-frames as references (B-pyramid) and arbitrary frame order--b-pyramid
Context-adaptive variable-length coding (CAVLC)--no-cabac
Context-adaptive binary arithmetic coding (CABAC), an improved entropy encoding schemeenabled by default
Both Intra-predicted block types: 16x16 and 4x4--partitions i4x4
In-loop deblocking filter supportenabled by default
(to configure: --deblock <integer:integer>)
Interlaced video support--interlaced
Up to 16 consecutive B-frames--bframes <integer>
Up to 16 reference frames--ref <integer>
High Profile features
8x8 and 4x4 adaptive spatial transforms--8x8dct
8x8 intra-predicted blocks--partitions i8x8
Custom quantization matrices--cqm <string>
Lossless mode--qp 0
Features affecting the quality of decisions made by the encoder but not the profile of the output video stream or the features it uses
Adaptive B-frame placementenabled by default
Adaptive quantization, a newer feature which allows different quantizers to be used for different parts of a frame. This allows the allocation of extra bits to dark background areas to reduce blocking.--aq-strength <float>, --aq-sensitivity <float>
Adjustable scene cut detection--scenecut <integer>
Luma and chroma-based motion estimationenabled by default
Multiple motion estimation modes: diamond, hexagon, uneven multi-hexagon, and a highly optimized exhaustive motion search--me <string> (dia, hex, umh, or esa)
Multiple rate control modes: constant quantizer, constant quality (CRF), single or multi-pass average bitrate (ABR) with the option of VBV support--qp <integer>, --crf <float>, --bitrate <integer> and --pass <integer>, --vbv-maxrate <integer>, --vbv-bufsize <integer>
Rate-distortion optimization on all frame types--subme 6 or 7, --b-rdo
Trellis quantization--trellis <integer> (1 or 2)
Other features
Built-in PSNR and SSIM calculationenabled by default
Multithreaded encoding--threads <integer> or "auto"

Comparison with other codecs

x264 has won awards in the following codec comparisons: See also the Software encoder feature comparison in the H.264/MPEG-4 AVC article.

x264 frontends

See also

External links

 •  • [ e]
Data compression software implementations
Video codecs
(Comparison)
MPEG-4 ASP
3ivx DivX Nero Digital FFmpeg MPEG-4 HDX4 Xvid 		H.264/MPEG-4 AVC
CoreAVC Nero Digital AVC QuickTime H.264 x264 		Lossless
CorePNG FFV1 Huffyuv Lagarith MSU Lossless 		Others
Cinepak Sorenson Dirac Indeo VP3 VP7 Pixlet Snow Tarkin Theora WMV SIF1
Audio codecs
(Comparison)
General
ADPCM ATRAC Dolby Digital Musepack TwinVQ Vorbis WMA 		Speech/Voice
iLBC IMBE iSAC QCELP Speex Truespeech 		Lossless
Apple Lossless Dolby TrueHD FLAC Monkey's Audio OptimFROG TTA WavPack WMA Lossless
Archivers
(Comparison)
Open Source
7-Zip Ark File Roller KGB Archiver PeaZip The Unarchiver 		Freeware
DGCA Filzip GCA IZArc StuffIt Expander TUGZip Zipeg ZipGenius WinUHA 		Proprietary
ALZip BOMArchiveHelper MacBinary PowerArchiver Squeez StuffIt WinAce WinRAR WinRK WinZip 		Command line
ARC ARJ JAR bzip2 compress gzip Info-ZIP LHA lzop NABOB PAQ PKZIP RAR SBC UPX
See for methods and for formats
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GNU General Public License
Author: Free Software Foundation
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Copyright on the license: Free Software Foundation, Inc.
Publication date: 29 June 2007
OSI approved: Yes
Debian approved: Yes
Free Software:
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H.264 is a standard for video compression. It is also known as MPEG-4 Part 10, or AVC (for Advanced Video Coding). It was written by the ITU-T Video Coding Experts Group (VCEG) together with the ISO/IEC Moving Picture Experts Group (MPEG) as
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GNU General Public License
Author: Free Software Foundation
Version: 3
Copyright on the license: Free Software Foundation, Inc.
Publication date: 29 June 2007
OSI approved: Yes
Debian approved: Yes
Free Software:
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graphical user interface (GUI) is a type of user interface which allows people to interact with a computer and computer-controlled devices which employ graphical icons, visual indicators or special graphical elements called "widgets", along with text, labels or text
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meGUI is an Open Source GUI to encode primary ISO MPEG-4 material. It's GPL-licensed and written in .NET 2.0/C#. It can also be used to create AviSynth scripts (AVS), multiplex (mux) multimedia streams, and encode audio.
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command line interface or CLI is a method of interacting with an operating system or software using a command line interpreter. This command line interpreter may be a text terminal, terminal emulator, or remote shell client such as PuTTY.
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Macroblock is a term used in video compression, which represents a block of 16 by 16 pixels. Each macroblock contains 4 Y block, 1 Cb block, 1 Cr block (4:2:0). (It also could be represented by 4:2:2 or 4:4:4 YCbCr format).
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Macroblock is a term used in video compression, which represents a block of 16 by 16 pixels. Each macroblock contains 4 Y block, 1 Cb block, 1 Cr block (4:2:0). (It also could be represented by 4:2:2 or 4:4:4 YCbCr format).
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Context-adaptive variable-length coding (CAVLC) is a form of entropy coding used in H.264/MPEG-4 AVC video encoding. It is used to encode residual, zig-zag order 4x4 (and 2x2) blocks of transform coefficients.
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Context-adaptive binary arithmetic coding (CABAC) is a form of entropy coding used in H.264/MPEG-4 AVC video encoding. As such it is an inherently lossless compression technique.
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In information theory an entropy encoding is a lossless data compression scheme that is independent of the media’s specific characteristics.

One of the main types of entropy coding assigns codes to symbols so as to match code lengths with the probabilities of the
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A deblocking filter is applied to blocks in decoded video to improve visual quality and prediction performance by smoothing the sharp edges which can form between blocks when block coding techniques are used. The filter aims to improve the appearance of decoded pictures.

H.


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Interlace is a technique of improving the picture quality of a video signal without consuming any extra bandwidth. It was invented by RCA engineer Randall C. Ballard in the 1930s.
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For the physics topic, see .
Reference frames are frames of a compressed video that are used to define future frames. As such they are only used in inter-frame compression techniques.
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Macroblock is a term used in video compression, which represents a block of 16 by 16 pixels. Each macroblock contains 4 Y block, 1 Cb block, 1 Cr block (4:2:0). (It also could be represented by 4:2:2 or 4:4:4 YCbCr format).
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Lossless data compression is a class of data compression algorithms that allows the exact original data to be reconstructed from the compressed data. This can be contrasted to lossy data compression, which does not allow the exact original data to be reconstructed from the
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As applied to video signals, luma represents the brightness in an image (the "black and white" or achromatic portion of the image). Luma is typically paired with chroma. Luma represents the achromatic image without any color, while the chroma components represent the color
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Chrominance (chroma for short), is the signal used in many video systems to carry the color information of the picture separately from the accompanying luma signal.
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Quantization, involved in image processing, is a lossy compression technique achieved by compressing a range of values to a single quantum value. By reducing the number of discrete symbols in a given stream, the stream becomes more compressible.
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The video buffering verifier (VBV) is a theoretical MPEG video buffer used to assess whether a video stream complies with the MPEG standard buffering requirements. By definition, the VBV buffer shall not overflow nor underflow when its input is a compliant stream except the case of
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