The Adobe Flash Player is freeware software for viewing multimedia, executing rich Internet applications, and streaming video and audio, content created on the Adobe Flashplatform. Flash Player can run from a web browser (as a browser plug-in) or on supported mobile devices, but there also exist versions running directly on an operating systemintended both for regular users and content developers, denoted with the Projector (or Standalone) and Debugger name suffixes, respectively.[3] Flash Player runs SWF files that can be created by the Adobe Flash Professional authoring tool, by Adobe Flex or by a number of other Macromedia and third party tools. Flash Player was created byMacromedia and now developed and distributed by Adobe Systems after its acquisition.
Flash Player supports vector and raster graphics, 3D graphics, an embedded scripting language called ActionScript executed in ActionScript Virtual Machine, and streaming of video and audio. ActionScript is based on ECMAScript, and supports object-oriented code, and may be compared to JavaScript. Flash Player has a wide user base, with over 90% penetration on internet connected personal computers,[4][5][6] and is a common format for games, animations, and GUIs embedded into web pages. Adobe Systems, the developer of Adobe Flash Player, states that more than 400 million of total more than 1 billion connected desktops update to the new version of Flash Player within six weeks of release.[7]
Flash Player can be downloaded for free and its plug-in version is available for recent versions of web browsers (such as Internet Explorer, Mozilla Firefox, Google Chrome, Operaand Safari) on selected platforms. Google Chrome distribution comes bundled with the sandboxed Adobe Flash plug-in and will continue to support the plug-in in Windows 8Metro mode.[8][9][10] Each version of Adobe Flash Player is backwards-compatible.
Contents
[show]Architecture[edit]
Runtime[edit]
Adobe Flash Player is a runtime that executes and displays content from a provided SWF file, although it has no in-built features to modify the SWF file at runtime. It can execute software written in the ActionScript programming language which enables the runtime manipulation of text, data, vector graphics, raster graphics, sound and video. The player can also access certain connected hardware devices, including web cameras and microphones, after permission for the same has been granted by the user.
Flash Player is used internally by the Adobe Integrated Runtime (Adobe AIR), in order to provide a cross-platform runtime environment for desktop applications and mobile applications. Adobe AIR supports installable applications on Windows, Linux, OS X, and some mobile operating systems such as iOS and Android. Flash applications must specifically be built for the Adobe AIR runtime in order to utilize additional features provided, such as file system integration, native client extensions, native window/screen integration, taskbar/dock integration, and hardware integration with connected Accelerometer and GPS devices.[11]
Data formats[edit]
Flash Player includes native support for many different data formats, some of which can only be accessed through the ActionScript scripting interface.
- XML: Flash Player has included native support for XML parsing and generation since version 8. XML data is held in memory as an XML Document Object Model, and can be manipulated using ActionScript. ActionScript 3 also supports ECMAScript for XML (E4X), which allows XML data to be manipulated more easily.
- JSON: Flash Player 11 includes native support for importing and exporting data in the JavaScript Object Notation (JSON) format, which allows interoperability with web services and JavaScript programs.
- AMF: Flash Player allows cookies to be stored on users computers, in the form of Local Shared Objects, the Flash equivalent to browser cookies.[12] Flash Player can alsonatively read and write files in the Action Message Format, the default data format for Local Shared Objects. Since the AMF format specification is published, data can be transferred to and from Flash applications using AMF datasets instead of JSON or XML, reducing the need for parsing and validating such data.
- SWF: The specification for the SWF file format was published by Adobe, enabling the development of the SWX Format project, which utilized the SWF file format and AMF as a means for Flash applications to exchange data with server side applications.[13][14] The SWX system stores data as standard SWF bytecode which is automatically interpreted by Flash Player.[15] Another open-source project, SWXml allows Flash applications to load XML files as native ActionScript objects without any client-side XML parsing, by converting XML files to SWF/AMF on the server.[16][17]
Multimedia formats[edit]
Flash Player is primarily a graphics and multimedia platform, and has supported raster graphics and vector graphics since its earliest version. It supports the following different multimedia formats which it can natively decode and playback.
- MP3: Support for decoding and playback of streaming MPEG-2 Audio Layer III (MP3) audio was introduced in Flash Player 4. MP3 files can be accessed and played back from a server via HTTP, or embedded inside an SWF file, which is also a streaming format.
- FLV: Support for decoding and playing back video and audio inside Flash Video (FLV and F4V) files, a format developed by Adobe Systems and Macromedia. Flash Video is only a container format and supports multiple different video codecs, such as Sorenson Spark, VP6 and more recently H.264.[18] Flash Player uses hardware acceleration to display video where present, using technologies such as DirectX Video Acceleration and OpenGL to do so. Flash Video is used by YouTube,[19] Hulu,[20] Yahoo! Video, BBC Online[21] and other news providers. FLV files can be played back from a server using HTTP progressive download, and can also be embedded inside an SWF file. Flash Video can also be streamed via RTMP using the Adobe Flash Media Server or other such server-side software.
- PNG: Support for decoding and rendering Portable Network Graphics (PNG) images, in both its 24-bit (opaque) and 32-bit (semi-transparent) variants. Flash Player 11 can also encode a PNG bitmap via ActionScript.
- JPEG: Support for decoding and rendering compressed JPEG images. Flash Player 10 added support for the JPEG-XR advanced image compression standard developed by Microsoft Corporation, which results in better compression and quality than JPEG. JPEG-XR enables lossy and lossless compression with or without alpha channel transparency. Flash Player 11 can also encode a JPEG or JPEG-XR bitmap via ActionScript.
- GIF: Support for decoding and rendering compressed Graphics Interchange Format (GIF) images, in its single-frame variants only. Loading a multi-frame GIF will display only the first image frame.
Streaming protocols[edit]
- HTTP: Support for communicating with web servers using HTTP requests and POST data.[22] However, only websites that explicitly allow Flash to connect to them can be accessed via HTTP or Sockets, in order to prevent Flash being used as a tool for Cross-site request forgery,[23] Cross-site scripting, DNS rebinding[24] and Denial-of-service attacks. Websites must host a certain XML file known as a "cross domain policy",[24] allowing or denying Flash content from specific websites to connect to them. Certain websites, such as Digg, Flikr, Photobucket already host a cross domain policy that permits Flash content to access their website via HTTP.[25]
- RTMP: Support for live audio and video streaming using the Real Time Messaging Protocol (RTMP) developed by Macromedia. RTMP supports a non-encrypted version over the TCP or an encrypted version over a secure SSLconnection. RTMPT can also be encapsulated within HTTP requests to traverse firewalls that only allow HTTP traffics.
- TCP: Support for TCP socket communication to communicate with any type of server, using stream sockets. Sockets can only be utilized using ActionScript, and can transfer plain text, XML or binary data (ActionScript 3.0 and later).[26][27] In order to prevent security issues, web servers that permit Flash content to communicate with them using sockets must host an XML-based cross domain policy file, served on Port 843.[28] Sockets enable AS3 programs to interface with any kind of server software, such as MySQL.[29]
Performance[edit]
Hardware acceleration[edit]
Current versions of Flash Player are optimized to use hardware acceleration for video playback and 3D graphics rendering on many devices, including desktop computers. Performance is similar to HTML5 video playback.[30][31] Also, Flash Player has been used on multiple mobile devices as a primary user interface renderer.[32]
Compilation[edit]
Although code written in ActionScript 3 executes up to 10 times faster than the previous ActionScript 2,[33] the Adobe ActionScript 3 compiler is a non-optimizing compiler, and produces inefficient bytecode in the resulting SWF, when compared to toolkits such as CrossBridge.[34][35][36][37][38]
CrossBridge, a toolkit that targets C++ code to run within the Flash Player, uses the LLVM compiler to produce bytecode that runs up to 10 times faster than code the ActionScript 3 compiler produces, only because the LLVM compiler uses more aggressive optimization.[36][37][38]
Adobe has released ActionScript Compiler 2 (ASC2) in Flex 4.7 and onwards, which improves compilation times and optimizes the generated bytecode and supports method inlining, improving its performance at runtime.[39]
As of 2012, the Haxe multiplatform language can build programs for Flash Player that perform faster than the same application built with the Adobe Flex SDK compiler.[40]
Development toolset[edit]
Application development[edit]
Adobe has provided a free SDK in order to build Flash applications, now known as the Apache Flex SDK. The Flex SDK allows developers to use any text editor such as Notepad++ or FlashDevelop (an IDE) to edit ActionScript source code (.as files), and then build a corresponding Flash application application (.swf) or AIR application application and installer (.air file) from the same.
Adobe AIR applications can be built either with the Apache Flex Framework, or without. The framework is an integrated collection of stylable Graphical User Interface, data manipulation and networking components, and applications built upon it are known as "Flex" applications. Applications built without the framework depend entirely on the developer's own skills and artistic abilities, and are commonly known as "pure ActionScript" projects.
In both methods, developers can access the full Flash Player set of functionalities, including text, vector graphics, bitmap graphics, video, audio, camera and microphone support, among others. Adobe AIR also includes additional features such as file system integration, native extensions, native desktop integration, and hardware integration with connected devices.
Adobe provides three ways of developing applications:
- Adobe Flash Builder (formerly Adobe Flex Builder)
- Adobe Flash Professional
- CrossBridge (compiles C++ code to run in Flash Player)
Third-party development environments are also available:
- FlashDevelop, an open-source Flash ActionScript IDE, which includes a debugger for AIR applications
- FDT by PowerFlasher Solutions, a commercial ActionScript IDE
- CodeDrive, an extension to Microsoft Visual Studio 2010 for ActionScript 3 development and debugging
Game development[edit]
Main article: CrossBridge
Adobe developed the CrossBridge toolkit which cross-compiles C/C++ code to run within the Flash Player, using LLVM and GCC as compiler backends, and high-performance memory-access opcodes in the Flash Player (known as "Domain Memory") to work with in-memory data quickly.[41] CrossBridge is targeted toward the game development industry, and includes tools for building, testing, and debugging C/C++ projects in Flash Player.
Open source[edit]
The documentation for the SWF file format is provided by Adobe free of cost on their website,.[42] after they relaxed the requirement of accepting a non-disclosure agreement to view the same in 2008.[43]
Adobe has not been willing to make complete source code of the Flash Player available for free software development. Free and open source alternatives to the Adobe Flash Player such as Gnash have been built, but are still incomplete and therefore not a viable alternative. The Lightspark Player is another such project, and has made more progress.[44]
The source code for ActionScript Virtual Machine 2 (AVM2) which implements ActionScript 3 was donated as open-source to Mozilla Foundation on November 7, 2006, to begin work on the Tamarin virtual machine that will finally implement the ECMAScript 4 language standard with the help of the Mozilla community.[45] It was released under the terms of a MPL/GPL/LGPL tri-license and includes the specification for the ActionScript bytecode format. Tamarin Project is jointly managed by Mozilla and Adobe Systems.[46]
The Adobe Flex SDK which compiles SWF files from source code was released as an open-source project and was donated to the Apache Software Foundation in 2011, and rebranded as Apache Flex.[47]
Adobe created the Open Screen Project which removes licensing fees and opens data protocols for Flash.
The Flash community has created many open-source projects that target Flash Player, such as FlashDevelop (an alternative IDE to Flash Builder), MTASC (compiler), and Haxe (multiplatform language).[48]
Some CPU emulators have been created for Flash Player, including Chip8,[49] Commodore 64,[50] ZX Spectrum[51] and the Nintendo Entertainment System.[52]
Availability[edit]
Desktop platforms[edit]
The latest version of Flash Player, is available for many major desktop platforms including Windows (XP and newer) and OS X (10.6 and later).[53][54] The latest version is also available on Linux but only on Google Chrome as Adobe no longer releases updates for the non-PPAPI plugin on Linux.[55]
Adobe released an alpha version of Flash Player 10 for x86-64 Linux on November 17, 2008. Adobe released a beta version of Flash Player 11 on July 13, 2011, which has 64-bit editions for all supported platforms.[56] Flash Player 11 was released to web on October 3, 2011.
Adobe Flash Player 11 is available in three flavors: "ActiveX", "Plug-in" and "Projector". The "ActiveX" version is an ActiveX control for use in Internet Explorer and any other Windows applications that supports ActiveX technology. The "plug-in" version is available for Netscape-compatible browsers on Microsoft Windows, Macintosh and Linux. The "projector" version is a standalone player that can open SWF files directly.[57]
In February 2012, Adobe announced it would discontinue development of Flash Player on Linux for all browsers except Google Chrome.[58][59] As of 9 July 2013 version 11.7 is the extended support release.[60] As of March 2014 version 13 is the Adobe Labs preview release.[1]
Mobile platforms[edit]
Main article: Adobe Integrated Runtime
In 2011, Flash Player had emerged as the de facto standard for online video publishing on the desktop, with adaptive bitrate video streaming, DRM, and fullscreen support.[19][20] On mobile devices however, after Apple refused to allow the Flash Player within the inbuilt iOS web browser, Adobe changed strategy enabling Flash content to be delivered as native mobile applications using the Adobe Integrated Runtime.
Up until 2012, Flash Player 11 was available for the Android (ARM Cortex-A8 and above),[53][61] although in June 2012, Google announced that Android 4.1 (codenamed Jelly Bean) will not support Flash by default. Starting in August 2012, Adobe no longer updates flash for Android.[62] In spite of this, Adobe Flash is still available to install on Android devices via Adobe's update archives.
Flash Player is certified to be supported on a select range of mobile and tablet devices, from Acer, BlackBerry 10, Dell, HTC, Lenovo, Logitech, LG, Motorola, Samsung, Sharp, SoftBank, Sony (and Sony Ericsson), andToshiba.[63][64][65] As of 2012, Adobe has stopped browser-based Flash Player development for mobile browsers in favor of HTML5,[66][67] however Adobe continues to support Flash content on mobile devices with the Adobe Integrated Runtime, which allows developers to publish content that runs as native applications on certain supported mobile phone platforms.
Version 9 is the most recent version currently available for the Linux/ARM-based Nokia 770/N800/N810 Internet Tablets running Maemo OS2008, classic Mac OS and Windows 95/NT.[68][69] Version 10 can be run under Windows 98/Me using KernelEx. HP offers Version 6 of the player for HP-UX.[70] Other versions of the player have been available at some point for OS/2, Symbian OS, Palm OS, BeOS and IRIX.[71] The Kodak Easyshare One includes Flash Player.[72]
Adobe said it will optimize Flash for use on ARM architecture (ARMv6 and ARMv7 architectures used in the ARM11 family and the Cortex-A series of processors) and release it in the second half of 2009. The company also stated it wants to enable Flash on NVIDIA Tegra, Texas Instruments OMAP 3 and Samsung ARMs.[73][74] Beginning 2009, it was announced that Adobe would be bringing Flash to TV sets via Intel Media Processor CE 3100 before mid-2009.[75]Later on, ARM Holdings said it welcomes the move of Flash, because "it will transform mobile applications and it removes the claim that the desktop controls the Internet."[76] However, as of May 2009, the expected ARM/Linux netbookdevices had poor support for Web video and fragmented software base.[77]
Among other devices, LeapFrog Enterprises provides Flash Player with their Leapster Multimedia Learning System and extended the Flash Player with touch-screen support.[78] Sony has integrated Flash Player 6 into the PlayStation Portable's web browser via firmware version 2.70 and Flash Player 9 into the PlayStation 3's web browser in firmware version 2.50.[79] Nintendo has integrated Flash Lite 3.1, equivalent to Flash 8, in the Internet Channel on the Wii.
The following table documents Flash Player and Adobe AIR support on mobile operating systems:
| Operating System | Prerequisites | Usage | Latest Adobe Flash Player |
|---|---|---|---|
| Android | Android 2.2+, ARM Cortex-A8+ | Standalone Applications & Internet Browser[80] | Flash Player 11.1, AIR 3.1[61][81][82] |
| Android | Android 2.1, available on some rare Android Devices like the Motorola Flipout | Internet Browser | Flash Lite 3.0 |
| Apple iOS | None | Standalone Applications | Flash Player 11.1, AIR 3.1[53][81] |
| BlackBerry 10 | Any version of BlackBerry 10 | Internet Browser & Standalone Applications | Flash Player 11.1, AIR 3.1 |
| BlackBerry Tablet OS | None | Standalone Applications & Internet Browser | Flash Player 11.1, AIR 3.1[81][83] |
| Maemo | Internet Browser | Flash Player 9.4[84] | |
| PS3 | Firmware 2.50, NetFront 2.81 | Internet Browser | Flash Player 9.1 (update 3) |
| PSP | Firmware 2.70 | Internet Browser | Flash Player 6)[85] |
| Symbian OS | Internet Browser | Flash Lite 4.0[86] | |
| Wii | Opera | Internet Channel | Flash Lite 3.1[87] |
| Pocket PC | Pocket PC 2003[88] | Internet Browser | Flash Player 7 (stand-alone apps v6)[89][90] |
| Windows Mobile | Windows Mobile 5[88] | Internet Browser | Flash Player 7[89] |
Criticism[edit]
Usability[edit]
In some browsers, previous Flash versions have had to be uninstalled before an updated version could be installed.[91][92] However, as of version 11.2 for Windows, there are now automatic updater options.[93] Linux is partially supported, as Adobe is cooperating with Google to implement it via Chrome web browser on all Linux platforms.[94]
Mixing flash applications with HTML leads to inconsistent behavior with respect to input handling (keyboard and mouse not working as they would in an HTML-only document). This is often done in web sites [95] and can lead to poor user experience with the site.
The 2014-02-20 update to 12.0.0.70 introduced a reported bug, producing green video with sound only. This defect is related to hardware acceleration and may be overcome by disabling hardware acceleration via the Adobe settings in Firefox (accessed by right clicking within the video) or in Internet Explorer (within the Tools settings).[96] This defect may be related to widely-used graphics hardware, AMD Radeon HD video cards, and similar visual defects have occurred in earlier Flash updates, with the same workaround.
Privacy[edit]
Flash Player supports persistent local storage of data (also referred to as Local Shared Objects), which can be used similarly to HTTP cookies or Web Storage in web applications. Local storage in Flash Player allows websites to store non-executable data on a user's computer, such as authentication information, game high scores or saved games, server-based session identifiers, site preferences, saved work, or temporary files. Flash Player will only allow content originating from exactly the same website domain to access data saved in local storage.[97]
Because local storage can be used to save information on a computer that is later retrieved by the same site, a site can use it to gather user statistics, similar to how HTTP cookies and Web Storage can be used. With such technologies, the possibility of building a profile based on user statistics is considered by some a potential privacy concern. Users can disable or restrict use of local storage in Flash Player through a "Settings Manager" page.[98][99]These settings can be accessed from the Adobe website or by right-clicking on Flash-based content and selecting "Global Settings".
Local storage can be disabled entirely or on a site-by-site basis. Disabling local storage will block any content from saving local user information using Flash Player, but this may disable or reduce the functionality of some websites, such as saved preferences or high scores and saved progress in games.
Flash Player 10.1 and upward honor the privacy mode settings in the latest versions of the Chrome, Firefox, Internet Explorer, and Safari web browsers, such that no local storage data is saved when the browser's privacy mode is in use.[100]
Security[edit]
See also: Flash client security
Flash Player 10.3 introduced a Local Settings Manager that can be accessed from the Microsoft Windows Control Panel or the OS X System Preferences panel. This panel superseded the previous Global Online Settings Manager.[98]The Privacy Settings panel allows users to specify whether websites must ask their permission before using the web camera or microphone.[101] This was apparently part of a fix for vulnerabilities that enabled the use of Flash for spying via web camera.[102][103]
Steve Jobs criticized the security of Flash Player, noting that "Symantec recently highlighted Flash for having one of the worst security records in 2009".[104] Adobe responded by pointing out that "the Symantec Global Internet Threat Report for 2009 found that Flash Player had the second lowest number of vulnerabilities of all Internet technologies listed (which included both web plug-ins and browsers)."[105][106]
Adobe security bulletins and advisories announce security updates, but Adobe Flash Player release notes do not disclose the security issues addressed when a release closes security holes, making it difficult to evaluate the urgency of a particular update. A version test page allows the user to check if the latest version is installed, and uninstallers may be used to ensure that old-version plugins have been uninstalled from all installed browsers.a
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