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Bitrate Peeling
Bitrate peeling is a technique used in Ogg Vorbis audio encoded streams, wherein a stream can be encoded at one bitrate but can be served at that or any lower bitrate. The purpose is to provide access to the clip for people with slower Internet connections, and yet still allow people with faster connections to enjoy the higher quality content. The server automatically chooses which stream to deliver to the user, depending on user's connection speed. , Ogg Vorbis bitrate peeling existed only as a concept as there was not yet an encoder capable of producing peelable datastreamBounties - XiphWiki Difference from other technologies The difference between SureStream and bitrate peeling is that SureStream is limited to only a handful of pre-defined bitrates, with significant difference between them, and SureStream encoded files are big because they contain all of the bitrates used, while bitrate peeling uses much smaller steps to change the available bitrate and quality, and only ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vorbis
Vorbis is a free and open-source software project headed by the Xiph.Org Foundation. The project produces an audio coding format and software reference encoder/decoder ( codec) for lossy audio compression, libvorbis. Vorbis is most commonly used in conjunction with the Ogg container format and it is therefore often referred to as Ogg Vorbis. Version 1.0 of Vorbis was released in May 2000. Since 2013, the Xiph.Org Foundation has stated that the use of Vorbis should be deprecated in favor of the Opus codec, an improved and more efficient format that has also been developed by Xiph.Org. Name Vorbis is named after the character Exquisitor Vorbis in the '' Discworld'' novel '' Small Gods'' by Terry Pratchett. The Ogg format is named after ''ogging'', jargon from the computer game '' Netrek''. Development Vorbis is a continuation of audio compression development started in 1993 by Chris Montgomery. Intensive development began following a September 1998 letter from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Subscriber Line
Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric digital subscriber line (ADSL), the most commonly installed DSL technology, for Internet access. In ADSL, the data throughput in the upstream (networking), upstream direction (the direction to the service provider) is lower, hence the designation of ''asymmetric'' service. In symmetric digital subscriber line (SDSL) services, the downstream and upstream data rates are equal. DSL service can be delivered simultaneously with plain old telephone service, wired telephone service on the same telephone line since DSL uses higher frequency bands for data transmission. On the customer premises, a DSL filter is installed on each telephone to prevent undesirable interaction between DSL and telephone service. The bit rate of consumer ADSL services typ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio Storage
Sound recording and reproduction is the electrical, Mechanical system, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording. Acoustic analog recording is achieved by a microphone diaphragm that senses changes in atmospheric pressure caused by acoustics, acoustic sound waves and records them as a mechanical representation of the sound waves on a medium such as a phonograph record (in which a stylus cuts grooves on a record). In magnetic tape recording, the sound waves vibrate the microphone diaphragm and are converted into a varying electric current, which is then converted to a varying magnetic field by an electromagnet, which makes a representation of the sound as magnetized areas on a plastic tape with a magnetic coating on it. Analog sound reproduction is the reverse process, with a large ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio Signal Processing
Audio signal processing is a subfield of signal processing that is concerned with the electronic manipulation of audio signals. Audio signals are electronic representations of sound waves—longitudinal waves which travel through air, consisting of compressions and rarefactions. The energy contained in audio signals or sound power level is typically measured in decibels. As audio signals may be represented in either Digital signal (signal processing), digital or analog signal, analog format, processing may occur in either domain. Analog processors operate directly on the electrical signal, while digital processors operate mathematically on its digital representation. History The motivation for audio signal processing began at the beginning of the 20th century with inventions like the telephone, phonograph, and radio that allowed for the transmission and storage of audio signals. Audio processing was necessary for early radio broadcasting, as there were many problems with stud ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio File Format
An audio file format is a file format for storing digital audio data on a computer system. The bit layout of the audio data (excluding metadata) is called the audio coding format and can be uncompressed, or audio compression (data), compressed to reduce the file size, often using lossy compression. The data can be a raw bitstream in an audio coding format, but it is usually embedded in a container format or an audio data format with defined storage layer. Format types It is important to distinguish between the audio coding format, the Container format (digital), container containing the Raw audio format, raw audio data, and an audio codec. A codec performs the encoding and decoding of the raw audio data while this encoded data is (usually) stored in a container file. Although most audio file formats support only one type of audio coding data (created with an audio codec, audio coder), a multimedia container format (as Matroska or Audio Video Interleave, AVI) may support multiple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Streaming Media
Streaming media refers to multimedia delivered through a Computer network, network for playback using a Media player (other), media player. Media is transferred in a ''stream'' of Network packet, packets from a Server (computing), server to a client-server model, client and is rendered in real-time; this contrasts with file downloading, a process in which the end-user obtains an entire media file before consuming the content. Streaming is more commonly used for video on demand, streaming television, and music streaming services over the Internet. While streaming is most commonly associated with multimedia from a remote server over the Internet, it also includes offline multimedia between devices on a local area network. For example, using DLNA and a home server, or in a personal area network between two devices using Bluetooth (which uses radio waves rather than Internet Protocol, IP). Online streaming was initially popularized by RealNetworks and Microsoft in the 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Codec
A codec is a computer hardware or software component that encodes or decodes a data stream or signal. ''Codec'' is a portmanteau of coder/decoder. In electronic communications, an endec is a device that acts as both an encoder and a decoder on a signal or data stream, and hence is a type of codec. ''Endec'' is a portmanteau of encoder/decoder. A coder or encoder encodes a data stream or a signal for transmission or storage, possibly in encrypted form, and the decoder function reverses the encoding for playback or editing. Codecs are used in videoconferencing, streaming media, and video editing applications. History Originally, in the mid-20th century, a codec was a hardware device that coded analog signals into digital form using pulse-code modulation (PCM). Later, the term was also applied to software for converting between digital signal formats, including companding functions. Examples An audio codec converts analog audio signals into digital signals for transmissi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portable Network Graphics
Portable Network Graphics (PNG, officially pronounced , colloquially pronounced ) is a raster graphics, raster-graphics file graphics file format, format that supports lossless data compression. PNG was developed as an improved, non-patented replacement for Graphics Interchange Format (GIF). PNG supports palette-based images (with palettes of 24-bit RGB color model, RGB or 32-bit RGBA color space, RGBA colors), grayscale images (with or without an Alpha compositing, alpha channel for transparency), and full-color non-palette-based RGB or RGBA images. The PNG working group designed the format for transferring images on the Internet, not for professional-quality print graphics; therefore, non-RGB color spaces such as CMYK color model, CMYK are not supported. A PNG file contains a single image in an extensible structure of ''chunks'', encoding the basic pixels and other information such as textual comments and Integrity checker, integrity checks documented in Request for Comments ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adam7 Algorithm
Adam7 is an interlacing algorithm for raster images, best known as the interlacing scheme optionally used in PNG images. An Adam7 interlaced image is broken into seven subimages, which are defined by replicating this 8×8 pattern across the full image. The subimages are then stored in the image file in numerical order. Adam7 uses seven passes and operates in both dimensions, compared to only four passes in the vertical dimension used by GIF. This means that an approximation of the entire image can be perceived much more quickly in the early passes, particularly if interpolation algorithms such as bicubic interpolation are used. History Adam7 is named after Adam M. Costello, who suggested the method on February 2, 1995, and after the seven steps involved. It is a rearrangement of this five-pass scheme that had earlier been proposed by Lee Daniel Crocker: Alternative speculative proposals at the time included square spiral interlacing and using Peano curves, but these w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scalable Video Coding
Scalable Video Coding (SVC) is a video compression standard developed jointly by the ITU-T and the ISO/IEC. The two organizations formed the ''Joint Video Team'' (JVT) to create the H.264/ MPEG-4 AVC standard (ITU-T Rec. H.264 , ISO/IEC 14496-10 AVC). SVC aims to provide adaptable or ''scalable'' content, allowing a single encoded video stream to be decoded at various bitrates, resolutions, and quality levels, thus catering to diverse devices and network conditions. History In October 2003, the '' Moving Picture Experts Group'' (MPEG) issued a ''Call for Proposals on SVC Technology''. Fourteen proposals were submitted, twelve of which utilized wavelet compression, while the remaining two were extensions of H.264/MPEG-4 AVC. The proposal from the Heinrich-Hertz-Institut (HHI) was selected by MPEG as the foundation for the SVC standardization project. In January 2005, MPEG and the Video Coding Experts Group (VCEG) agreed to finalize SVC as an amendment to the H.264/MPEG-4 A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JPEG
JPEG ( , short for Joint Photographic Experts Group and sometimes retroactively referred to as JPEG 1) is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable trade off between storage size and image quality. JPEG typically achieves 10:1 compression with noticeable, but widely agreed to be acceptable perceptible loss in image quality. Since its introduction in 1992, JPEG has been the most widely used image compression standard in the world, and the most widely used digital image format, with several billion JPEG images produced every day as of 2015. The Joint Photographic Experts Group created the standard in 1992, based on the discrete cosine transform (DCT) algorithm. JPEG was largely responsible for the proliferation of digital images and digital photos across the Internet and later social media. JPEG compression is used in a number of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JPEG 2000
JPEG 2000 (JP2) is an image compression standard and coding system. It was developed from 1997 to 2000 by a Joint Photographic Experts Group committee chaired by Touradj Ebrahimi (later the JPEG president), with the intention of superseding their original JPEG standard (created in 1992), which is based on a discrete cosine transform (DCT), with a newly designed, wavelet-based method. The standardized filename extension is .jp2 for International Organization for Standardization, ISO/International Electrotechnical Commission, IEC 15444-1 conforming files and .jpx for the extended part-2 specifications, published as ISO/IEC 15444-2. The Internet media type, MIME types for JPEG 2000 are defined in RFC 3745. The MIME type for JPEG 2000 (ISO/IEC 15444-1) is image/jp2. The JPEG 2000 project was motivated by Ricoh, Ricoh's submission in 1995 of the CREW (Compression with Reversible Embedded Wavelets) algorithm to the standardization effort of JPEG LS. Ultimately the Lossless JPEG#LOCO-I_a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
