Media player (software)

The media player (English for media player or media player ) is a generic term for a group of computer programs. With such programs, media content - such as video and audio data, or more rarely, single images or graphics - are reproduced with a computer.

These programs are often not clearly of similar applications - such as an audio player, video player, streaming client or an image viewer - limit.

Principle and functions

Media players are computer programs that read data from a variety of sources, decode and then forward as uncompressed digital data to an output unit. The control and surface or operation is often very different; in many products also various filters can be switched between that have access to the uncompressed signal and it can perform a variety of operations. Many players also offer the possibility of organizing multimedia content.

Examples are playing a DVD and play back MP3 or CD audio.

Apart from specialized or deliberately simple players they often make use of a modular plug-in architecture to be as flexible as possible. These plug- ins work in a chain that is assembled within the program because of the user settings. The user can always access the individual components and give them commands. Below is more detail about each of these functionalities.

Organization

• Loading of file names and URLs in a playlist: That is standard; the user can specify sources and register them. They are then played back as desired in order or at random. To start playback, you can simply click on an entry.
• Managing and storing various playlists: Mostly, Media Player remember the last present in the play list sources. These lists can be saved; when calling these lists in a file browser media player is started and added the entries contained in the playlist. Some players also offer the ability to manage multiple playlists separately.
• Management of the entire multimedia collection: Media Player, you want to support as many functions can also scan specified directories for multimedia data, read the meta data and paste it into your own multimedia collection. This collection can be searched by various criteria; you can also transfer to the playlist selected sources. Often also a number of additional data is stored, such as how often the source has already been played, as it was assessed, and the like. In the background, the player tries to keep this multimedia collection on stand, when new files are added or changed.

Read in

• From the File System: Here files from storage devices such as a hard disk, floppy disks of all kinds, USB mass storage devices and the like are read. In Unix -like operating systems may include files in the virtual file system on other computers; the data transport is here transparent.
• External or analog inputs: You can read data from line-in or AUX input of the local soundcard, eg from a connected microphone or MIDI -enabled instruments such as keyboards.
• From built-in appliances: Usual sources here would be the built- in computer CD or DVD drive that provides data on a disc. Other cases would be, for example, the reception of TV programs on a TV card or live transmission of data from a connected via FireWire digital video camera.
• About network of other computers: This is known as streaming and referred mostly the live broadcast of content via specialized network protocols such as Shoutcast, Icecast, RTP / RTCP / RTSP, VideoLAN or Real Media. However, it can also not specifically designed for files - just like a normal download from the Internet - loaded via the standard HTTP or FTP protocols, and then, as best it can be played live.

Decoding / decompressing

• Support various containers and audio / video formats: multimedia data are often packed in special containers that are chosen depending on the application and dissemination or target audience. It is similar with the audio and / or video data contained in the container. Containers usually contain metadata about the data contained, such as synchronization data ( timecode ) are included for the audio / video synchronization, which languages ​​to the video material and the usual data about artist, title, album, etc. Modern container can audio and contain video data in a variety of combination and number, as well as DVD-like menus, subtitles and chapter information; It is also possible and practical to pack all the container and its contents with one another. To mention here are the standard container formats: the outdated, but widespread AVI format, currently the most advanced Matroska format that good for streaming suitable Ogg format and the number of MPEG- containers (MPEG- 1, MPEG -2 and MP4). There are also numerous other container formats. The data are usually compressed and containing what is left encoded in a special format to save as much space and to optimize it for different purposes (eg for streaming capability, error correction, lower computation complexity when decoding ). To decode the data and then decompress it, usually is a program library - often called a codec - required. The version for viewing is always available for free and is easy to install. Some manufacturers, however, are very restrictive to spread also to the extensibility of their programs, for example to their own data formats. Important data formats for video are, eg DivX, Xvid, MPEG- 1, MPEG- 2, Windows Media, Real Media, QuickTime, FLV, X264 and Ogg Theora. In audio, are the main formats that should be supported, the following: MP3, Wave raw data, Ogg Vorbis, AAC, and possibly Windows Media Audio.
• Reading metadata (tags): Thank multimedia content will be information about the content, such as title, artist / artist / band, album, track number, language, or composer. This information is called metadata (Latin meta about something, something descriptive ) or abbreviation of the term tags (English for label or labeling ). These tags, if present, is usually displayed in place of the file name or the URL. Each format or each container format has its own tag format. The most famous is ID3 tag format that is used with MP3 files.
• Multi-channel support: Support for all major multi-channel formats, such as Dolby, AC3, but also simply more simultaneous audio channels within an audio container, such as Ogg Vorbis. Forwarding to filter and output plug-ins must be done correctly and may be converted, for example, if there is only one stereo output available or an external digital amplifier ( power amplifier) ​​is used, expects the data in an understandable multichannel format.
• Decoding in locally usable format: This includes the expansion of data that exists in a variable bit rate, in an uncompressed format with a constant bit rate ( RIFF WAVE). Other cases are the conversion into a different binary number representation (big endian, little endian), a different paragraph frequency or size of audio samples.

Filter

• Visualizations: These are graphical entities that move in rhythm to the music and are constantly changing. Often the color and visualization switch between them.
• Normalization: This is an adaptation of the volume so that all the songs are played equally loud. Normalization can be done in a certain set level or contained metadata (eg ReplayGain ).
• Digital signal processing ( DSP): For this, the admixing eg moderator prompts, inserting transitions between audio files and applying heard various effects, such as votes Remove ( Karaoke Mode ), low pass, high pass, distortions, or dynamic deep bass.
• Preamplification and audio profiles: Also known as an equalizer, you can here preamplifying digital or attenuate audio signals depending on the frequency range; often you can here also select different audio profiles, such as rock, classical, pop or techno.

Output

• On local output devices: The normal case is sure the local output to the screen and a built-in sound card via appropriate libraries and drivers, depending on the operating system. Important here are the correct use of the capabilities of the devices and device drivers (including hardware acceleration ) and a good synchronization between audio and video - finally go audio and video in various ways, but to be output so that the user feels the play as the same time.
• Broadcast to streaming server: sometimes implemented as a filter plug-ins, it is possible to convert the output in a compressed format ( encode ) and this audio and / or video data to be sent to a central streaming server, where from potentially numerous listeners (or viewers ) to pick up this data in real time and listen / can view.
• In the file system: This standard feature allows you to save the uncompressed audio and possibly video data in the file system ( eg hard disk). This is called dumping (English unload ) these files dumps. They often serve to further processing or compression.
• Recompression: In some cases, directly a recompression be made in a different format (English transcoding ). In this case, the computer must be fast enough to compress at least in real time. This function is often implemented as a plug-in filter.

Control

• Various user interfaces: Depending on the purpose, target audience and operating various finishes are available. These range from text based on widget -based to full-graphic or even three-dimensional surfaces. Often a suppression of various elements can be, for example, the playlist of the visualization, or even a possibility of change in size, in which case different amounts of information to be displayed, such as a full mode and a reduced compact mode.
• Customizable look (skins ): With a fully graphical media players a popular feature is the support of skins. Here the appearance ( fonts, colors, buttons ), and possibly behavior of the entire surface is changed. Today there are for almost every taste skins.
• Alternative control methods: In addition to using keyboard and / or mouse support some players also alternative control methods such as infrared remote controls or configurable keyboard shortcuts. The use of multimedia buttons on Internet and multimedia keyboards is now widely used. Often the control over an icon in the task bar is offered.
• Navigation between and within tracks: Important course is jumping between different multimedia sources (eg between files), but also between chapters and between the individual tracks contained (eg between German and English).

Software

Both of proprietary as well as in free software, there is a great selection.