In signal processing, data compression, source coding, or bit-rate reduction involves encoding information using fewer bits than the original representation. Compression can be either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy. No information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information.
gzip is a file format and a software application used for file compression and decompression. The program was created by Jean-loup Gailly and Mark Adler as a free software replacement for the compress program used in early Unix systems, and intended for use by GNU. Version 0.1 was first publicly released on 31 October 1992, and version 1.0 followed in February 1993.
Lossless compression is a class of data compression algorithms that allows the original data to be perfectly reconstructed from the compressed data. By contrast, lossy compression permits reconstruction only of an approximation of the original data, though usually with improved compression rates.
zlib is a software library used for data compression. zlib was written by Jean-loup Gailly and Mark Adler and is an abstraction of the DEFLATE compression algorithm used in their gzip file compression program. zlib is also a crucial component of many software platforms including Linux, Mac OS X, and iOS. It has also been used in gaming consoles such as the PlayStation 4, PlayStation 3, Wii U, Wii, Xbox One and Xbox 360.
Compression may refer to:
FLAC is an audio coding format for lossless compression of digital audio, and is also the name of the free software project producing the FLAC tools, the reference software package that includes a codec implementation. Digital audio compressed by FLAC's algorithm can typically be reduced to between 50 and 70 percent of its original size and decompress to an identical copy of the original audio data.
Monkey's Audio is an algorithm and file format for lossless audio data compression. Lossless data compression does not discard data during the process of encoding, unlike lossy compression methods such as AAC, MP3, Vorbis and Musepack.
The rzip program is huge-scale data compression software designed around initial LZ77-style string matching on a 900 MB dictionary window, followed by bzip2-based Burrows–Wheeler transform and entropy coding (Huffman) on 900 kB output chunks.
Lempel–Ziv–Oberhumer (LZO) is a lossless data compression algorithm that is focused on decompression speed.
SheerVideo was a family of proprietary lossless video codecs developed by BitJazz Inc. to enable capture, editing, playback, and archival of professional-quality lossless video formats in real time on low-power inexpensive hardware such as laptop computers and video cameras. As tested on a standard set of Kodak images used in image compression research, SheerVideo's average compression ratio is over 2:1 for real-world footage. Because SheerVideo generally runs faster than a computer system's data throughput speed, this compression power means that SheerVideo runs more than twice as fast as uncompressed data while taking less than half the storage space. It no longer appears to be under development, and the last available version does not appear to be compatible with the current Mac OS.
Executable compression is any means of compressing an executable file and combining the compressed data with decompression code into a single executable. When this compressed executable is executed, the decompression code recreates the original code from the compressed code before executing it. In most cases this happens transparently so the compressed executable can be used in exactly the same way as the original. Executable compressors are often referred to as "runtime packers", "software packers", "software protectors".
Core Video is the video processing model employed by macOS. It links the process of decompressing frames from a video source to the rest of the Quartz technologies for image rendering and composition. Both QuickTime X and QuickTime 7 depend on Core Video.
Snappy is a fast data compression and decompression library written in C++ by Google based on ideas from LZ77 and open-sourced in 2011. It does not aim for maximum compression, or compatibility with any other compression library; instead, it aims for very high speeds and reasonable compression. Compression speed is 250 MB/s and decompression speed is 500 MB/s using a single core of a circa 2011 "Westmere" 2.26 GHz Core i7 processor running in 64-bit mode. The compression ratio is 20–100% lower than gzip.
Voice compression may mean different things:
Uncompressed video is digital video that either has never been compressed or was generated by decompressing previously compressed digital video. It is commonly used by video cameras, video monitors, video recording devices, and in video processors that perform functions such as image resizing, image rotation, deinterlacing, and text and graphics overlay. It is conveyed over various types of baseband digital video interfaces, such as HDMI, DVI, DisplayPort and SDI. Standards also exist for carriage of uncompressed video over computer networks.
LZ4 is a lossless data compression algorithm that is focused on compression and decompression speed. It belongs to the LZ77 family of byte-oriented compression schemes.
Compression arthralgia is pain in the joints caused by exposure to high ambient pressure at a relatively high rate of compression, experienced by underwater divers.
Also referred to in the US Navy diving Manual as compression pains.
SPIRIT DSP is a Russian company that develops embedded software solutions for real-time voice and video communication over IP networks – voice and video engines. Its voice and video software platform is used by carriers, mobile messaging apps, and social networks, serving more than 1 billion users in 100 countries.
LZFSE is an open source lossless data compression algorithm created by Apple Inc.
Zstandard is a lossless data compression algorithm developed by Yann Collet at Facebook. The name also refers to the reference implementation in C.
Version 1 of the implementation was released as free software on 31 August 2016.
