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RealMedia HD
RealMedia is a proprietary multimedia container format created by RealNetworks with the filename extension . RealMedia is generally used in conjunction with RealVideo and RealAudio, while also being used for streaming content over the Internet. Typically these streams are in CBR ( constant bitrate), but a container for VBR (variable bitrate) streams named RMVB (RealMedia variable bitrate) has been developed. Overview A RealMedia file consists of a series of chunks that can be of several different types: * ''.RMF'': RealMedia file header * ''PROP'': File properties header * ''MDPR'': Media properties header * ''CONT'': Content description header * ''DATA'': Data header * ''INDX'': Index header Supported audio formats * RealAudio 1.0 (VSELP), * RealAudio 2.0 (LD-CELP), 28_8 * AC3, * * Cook, cook * ATRAC3, * RealAudio Lossless Format, * LC-AAC, * HE-AAC, Supported video formats * ClearVideo (from helix spec) * H.263, RV10 * H.263, RV13 * H.263+, RV20 * H.264 precu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RealNetworks
RealNetworks, Inc. is a provider of artificial intelligence and computer vision based products. RealNetworks was a pioneer in Internet streaming software and services. They are based in Seattle, Washington, United States. The company also provides subscription-based online entertainment services and mobile entertainment and messaging services. History RealNetworks (then known as Progressive Networks) was founded in 1994 by Rob Glaser, an ex-Microsoft executive, and a management team including Phil Barrett, Andy Sharpless, and Stephen Buerkle. The original goal of the company was to provide a distribution channel for politically progressive content. It evolved into a technology venture to leverage the Internet as an alternative distribution medium for audio broadcasts. Progressive Networks became RealNetworks in September 1997, in advance of the company's initial public offering (IPO) in October 1997 when shares of the company started trading on Nasdaq as "RNWK". RealNetwo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable Bitrate
Variable bitrate (VBR) is a term used in telecommunications and computing that relates to the bitrate used in sound or video encoding. As opposed to constant bitrate (CBR), VBR files vary the amount of output data per time segment. VBR allows a higher bitrate (and therefore more storage space) to be allocated to the more complex segments of media files while less space is allocated to less complex segments. The average of these rates can be calculated to produce an average bitrate for the file. MP3, WMA and AAC audio files can optionally be encoded in VBR, while Opus and Vorbis are encoded in VBR by default. Variable bit rate encoding is also commonly used on MPEG-2 video, MPEG-4 Part 2 video (Xvid, DivX, etc.), MPEG-4 Part 10/H.264 video, Theora, Dirac and other video compression formats. Additionally, variable rate encoding is inherent in lossless compression schemes such as FLAC and Apple Lossless. Advantages and disadvantages of VBR The advantages of VBR are tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helix (project)
Helix DNA is a project to produce computer software that can play audio and video media in various formats and aid in producing such media. It is intended as a largely free and open-source digital media framework that runs on numerous operating systems and processors (including mobile phones) and was started by RealNetworks which contributed much of the code. The Helix Community is an open collaborative effort to develop and extend the Helix DNA platform. Helix DNA Client is a software package for multi-platform multi-format media playback. Helix Player is a media player that runs on Linux, Solaris, Symbian and FreeBSD and uses the Helix DNA Client. The Helix DNA Producer application aids in the production of media files, and Helix DNA Server can stream media files over a network. Licenses The code is released in binary and source code form under various licenses, notably the proprietary RealNetworks Community Source License and the free and open source software RealNet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comparison Of Video Player Software
The following comparison of video players compares general and technical information for notable software media player programs. For the purpose of this comparison, ''video players'' are defined as any media player which can play video, even if it can also play audio files. General Active players Inactive players Operating system compatibility This section lists the operating systems on which the player works. There may be multiple versions of a player, each one for a given operating system. Features Extended features Consumer video format ability Information about what video formats the players understand. Footnotes lead to information about abilities of future versions of the players or plugins/filters that provide such abilities. Production video format ability Audio format ability Information about what audio formats the players understand. Footnotes lead to information about abilities of future versions of the players or plugins/filters that prov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comparison Of Video Container Formats
These tables compare features of multimedia container formats, most often used for storing or streaming digital video or digital audio content. To see which multimedia players support which container format, look at comparison of media players. General information In many ways, derived containers are similar to those on which they are based, sometimes extending them, sometimes limiting their capabilities. * QTFF ** ISO BMFF *** MP4 *** 3GPP, 3GPP2 *** F4V * MPEG-PS ** MPEG-TS *** M2TS ** VOB *** EVOB * MCF ** Matroska *** WebM * RIFF ** AVI *** DMF * RM ** RMVB Attachments (additional files, such as fonts for subtitles) are only supported in Matroska, MP4 and QTFF. M2TS supports attachments as multiple files in a specific file structure: fonts for subtitles are in .otf files in the /BDMV/AUXDATA/ directory. Some common multimedia file formats are not completely distinct container formats. Some are containers for specific audio and video ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Container Format
A container format (informally, sometimes called a wrapper) or metafile is a file format that allows multiple data streams to be embedded into a single file, usually along with metadata for identifying and further detailing those streams. Notable examples of container formats include archive files (such as the ZIP format) and formats used for multimedia playback (such as Matroska, MP4, and AVI). Among the earliest cross-platform container formats were Distinguished Encoding Rules and the 1985 Interchange File Format. Design Although containers may identify how data or metadata is encoded, they do not actually provide instructions about how to decode that data. A program that can open a container must also use an appropriate codec to decode its contents. If the program doesn't have the required algorithm, it can't use the contained data. In these cases, programs usually emit an error message that complains of a missing codec, which users may be able to acquire. Contai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RealPlayer
RealPlayer, formerly RealAudio Player, RealOne Player and RealPlayer G2, is a cross-platform media player app, developed by RealNetworks. The media player is compatible with numerous container file formats of the multimedia realm, including MP3, MP4, QuickTime File Format, Windows Media format, and the proprietary RealAudio and RealVideo formats. RealPlayer is also available for other operating systems; Linux, Unix, Palm OS, Windows Mobile, and Symbian versions have been released. The program is powered by an underlying open-source media engine called Helix. History The first version of RealPlayer was introduced on April 3, 1995 as "RealAudio Player" and was one of the first media players capable of streaming media over the Internet. Then, version 4.01 of RealPlayer was included as a selectable Internet tool in Windows 98's installation package. Subsequent versions of the software were titled "RealPlayer G2" (version 6) and "RealOne Player" (version 9), while free "Basic" ver ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RMVB
RealMedia Variable Bitrate (RMVB) is a variable bitrate extension of the RealMedia multimedia digital container format developed by RealNetworks. As opposed to the more common RealMedia container, which holds streaming media encoded at a constant bitrate (CBR), RMVB is typically used for multimedia content stored locally. Files using this format have the file extension ".rmvb". Details RealMedia uses compression similar to MPEG-4 Part 10 encoders such as x264. RMVB files are popular for distributing Asian content, especially Chinese television episodes and movies. For this reason, they have become noticeably present (though not entirely popular, partly due to their incompatibility with other media players) on file sharing platforms such as BitTorrent, eDonkey and Gnutella. On the Windows platform, the proprietary RealPlayer SP and the open-sourced Media Player Classic support RMVB, using an appropriate DirectShow filter or Real Alternative. On Linux and other Unix-like platf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constant Bitrate
Constant bitrate (CBR) is a term used in telecommunications, relating to the quality of service. Compare with variable bitrate. When referring to codecs, constant bit rate encoding means that the rate at which a codec's output data should be consumed is constant. CBR is useful for streaming multimedia content on limited capacity channels since it is the maximum bit rate that matters, not the average, so CBR would be used to take advantage of all of the capacity. CBR is not optimal for storing data as it may not allocate enough data for complex sections (resulting in degraded quality); and if it maximizes quality for complex sections, it will waste data on simple sections. The problem of not allocating enough data for complex sections could be solved by choosing a high bitrate to ensure that there will be enough bits for the entire encoding process, though the size of the file at the end would be proportionally larger. Most coding schemes such as Huffman coding or run-lengt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Container Format (digital)
A container format (informally, sometimes called a wrapper) or metafile is a file format that allows multiple data streams to be embedded into a single file, usually along with metadata for identifying and further detailing those streams. Notable examples of container formats include archive files (such as the ZIP format) and formats used for multimedia playback (such as Matroska, MP4, and AVI). Among the earliest cross-platform container formats were Distinguished Encoding Rules and the 1985 Interchange File Format. Design Although containers may identify how data or metadata is encoded, they do not actually provide instructions about how to decode that data. A program that can open a container must also use an appropriate codec to decode its contents. If the program doesn't have the required algorithm, it can't use the contained data. In these cases, programs usually emit an error message that complains of a missing codec, which users may be able to acquire. Containe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Streaming Media
Streaming media is multimedia that is delivered and consumed in a continuous manner from a source, with little or no intermediate storage in network elements. ''Streaming'' refers to the delivery method of content, rather than the content itself. Distinguishing delivery method from the media applies specifically to telecommunications networks, as most of the traditional media delivery systems are either inherently ''streaming'' (e.g. radio, television) or inherently ''non-streaming'' (e.g. books, videotape, audio CDs). There are challenges with streaming content on the Internet. For example, users whose Internet connection lacks sufficient bandwidth may experience stops, lags, or poor buffering of the content, and users lacking compatible hardware or software systems may be unable to stream certain content. With the use of buffering of the content for just a few seconds in advance of playback, the quality can be much improved. Livestreaming is the real-time delivery ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RealAudio
RealAudio, or also spelled as Real Audio is a proprietary audio format developed by RealNetworks and first released in April 1995. It uses a variety of audio codecs, ranging from low-bitrate formats that can be used over dialup modems, to high-fidelity formats for music. It can also be used as a streaming audio format, that is played at the same time as it is downloaded. In the past, many internet radio stations used RealAudio to stream their programming over the internet in real time. In recent years, however, the format has become less common and has given way to more popular audio formats. RealAudio was heavily used by the BBC websites until 2009, though it was discontinued due to its declining use. BBC World Service, the last of the BBC websites to use RealAudio, discontinued its use in March 2011. File extensions RealAudio files were originally identified by a filename extension of .ra (for Real Audio). In 1997, RealNetworks also began offering a video format called RealVide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
