In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is 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. Typically, a device that performs data compression is referred to as an encoder, and one that performs the reversal of the process (decompression) as a decoder.
Lossless compression is a class of data compression that allows the original data to be perfectly reconstructed from the compressed data with no loss of information. Lossless compression is possible because most real-world data exhibits statistical redundancy. By contrast, lossy compression permits reconstruction only of an approximation of the original data, though usually with greatly improved compression rates.
Theora is a free lossy video compression format. It was developed by the Xiph.Org Foundation and distributed without licensing fees alongside their other free and open media projects, including the Vorbis audio format and the Ogg container.
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 Advanced Audio Coding, MP3, Vorbis, and Opus. Therefore, it may be decompressed to a file that is identical to the source material.
A compression artifact is a noticeable distortion of media caused by the application of lossy compression. Lossy data compression involves discarding some of the media's data so that it becomes small enough to be stored within the desired disk space or transmitted (streamed) within the available bandwidth. If the compressor cannot store enough data in the compressed version, the result is a loss of quality, or introduction of artifacts. The compression algorithm may not be intelligent enough to discriminate between distortions of little subjective importance and those objectionable to the user.
FFmpeg is a free and open-source software project consisting of a suite of libraries and programs for handling video, audio, and other multimedia files and streams. At its core is the command-line ffmpeg tool itself, designed for processing video and audio files. It is widely used for format transcoding, basic editing, video scaling, video post-production effects, and standards compliance.
GStreamer is a pipeline-based multimedia framework that links together a wide variety of media processing systems to complete complex workflows. For instance, GStreamer can be used to build a system that reads files in one format, processes them, and exports them in another. The formats and processes can be changed in a plug and play fashion.
DirectShow, codename Quartz, is a multimedia framework and API produced by Microsoft for software developers to perform various operations with media files or streams. It is the replacement for Microsoft's earlier Video for Windows technology. Based on the Microsoft Windows Component Object Model (COM) framework, DirectShow provides a common interface for media across various programming languages, and is an extensible, filter-based framework that can render or record media files on demand at the request of the user or developer. The DirectShow development tools and documentation were originally distributed as part of the DirectX SDK. Currently, they are distributed as part of the Windows SDK.
Transcoding is the direct digital-to-digital conversion of one encoding to another, such as for video data files, audio files, or character encoding. This is usually done in cases where a target device does not support the format or has limited storage capacity that mandates a reduced file size, or to convert incompatible or obsolete data to a better-supported or modern format.
In Unix-like computer operating systems, a pipeline is a mechanism for inter-process communication using message passing. A pipeline is a set of processes chained together by their standard streams, so that the output text of each process (stdout) is passed directly as input (stdin) to the next one. The second process is started as the first process is still executing, and they are executed concurrently.
In software engineering, a pipeline consists of a chain of processing elements, arranged so that the output of each element is the input of the next. The concept is analogous to a physical pipeline. Usually some amount of buffering is provided between consecutive elements. The information that flows in these pipelines is often a stream of records, bytes, or bits, and the elements of a pipeline may be called filters. This is also called the pipe(s) and filters design pattern which is monolithic. Its advantages are simplicity and low cost while its disadvantages are lack of elasticity, fault tolerance and scalability. Connecting elements into a pipeline is analogous to function composition.
A multimedia framework is a software framework that handles media on a computer and through a network. A good multimedia framework offers an intuitive API and a modular architecture to easily add support for new audio, video and container formats and transmission protocols. It is meant to be used by applications such as media players and audio or video editors, but can also be used to build videoconferencing applications, media converters and other multimedia tools. Data is processed among modules automatically, it is unnecessary for app to pass buffers between connected modules one by one.
AviSynth is a frameserver program for Microsoft Windows, Linux and macOS initially developed by Ben Rudiak-Gould, Edwin van Eggelen, Klaus Post, Richard Berg and Ian Brabham in May 2000 and later picked up and maintained by the open source community which is still active nowadays. It is free software licensed under the GNU General Public License.
Quartz Composer is a node graph system provided as part of the Xcode development environment in macOS for processing and rendering graphical data. It is capable of making sophisticated animations for keynote or presentations and creating animated screensavers.
GraphEdit is a utility which is part of the Microsoft DirectShow SDK. It is a visual tool for building and testing filter graphs for DirectShow. Filters are displayed as boxes, with a text caption showing the name of the filter. Pins appear as small squares along the edge of the filter. Input pins are shown on the left side of the filter, and output pins are on the right side of the filter. A pin connection appears as an arrow connecting the output pin to the input pin. Connection mediatypes can be viewed as "properties" on pins and connections. GraphEdit can automatically build a filter graph that plays a file.
In computing, a sink, or data sink generally refers to the destination of data flow.
This article describes audio APIs and components in Microsoft Windows which are now obsolete or deprecated.
Media Foundation (MF) is a COM-based multimedia framework pipeline and infrastructure platform for digital media in Windows Vista, Windows 7, Windows 8, Windows 8.1, Windows 10, and Windows 11. It is the intended replacement for Microsoft DirectShow, Windows Media SDK, DirectX Media Objects (DMOs) and all other so-called "legacy" multimedia APIs such as Audio Compression Manager (ACM) and Video for Windows (VfW). The existing DirectShow technology is intended to be replaced by Media Foundation step-by-step, starting with a few features. For some time there will be a co-existence of Media Foundation and DirectShow. Media Foundation will not be available for previous Windows versions, including Windows XP.
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 the carriage of uncompressed video over computer networks.
Shotcut is a free and open-source, cross-platform video, audio, and image editing program for FreeBSD, Linux, macOS and Windows. Started in 2011 by Dan Dennedy, Shotcut is developed on the MLT Multimedia Framework, in development since 2004 by the same author.
