Adobe Flash (previously called Macromedia Flash) is a multimedia platform originally acquired by Macromedia and currently developed and distributed by Adobe Systems. Since its introduction in 1996, Flash has become a popular method for adding animation and interactivity to web pages. Flash is commonly used to create animation, advertisements, and various web page components, to integrate video into web pages, and more recently, to develop rich Internet applications.
Flash can manipulate vector and raster graphics, and supports bidirectional streaming of audio and video. It contains a scripting language called ActionScript. Several software products, systems, and devices are able to create or display Flash content, including Adobe Flash Player, which is available free for most common web browsers, some mobile phones and for other electronic devices (using Flash Lite). The Adobe Flash Professional multimedia authoring program is used to create content for the Adobe Engagement Platform, such as web applications, games and movies, and content for mobile phones and other embedded devices.
Files in the SWF format, traditionally called "ShockWave Flash" movies, "Flash movies" or "Flash games", usually have a .swf file extension and may be an object of a web page, strictly "played" in a standalone Flash Player, or incorporated into a Projector, a self-executing Flash movie (with the .exe extension in Microsoft Windows or .hqx for Macintosh). Flash Video files[spec 1] have a .flv file extension and are either used from within .swf files or played through a flv-aware player, such as (VLC), or QuickTime and Windows Media Player with external codecs added.
On May 1, 2008 Adobe announced Open Screen Project, which hopes to provide a consistent application interface across devices such as personal computers, mobile devices and consumer electronics.[7] When the project was announced, several goals were outlined: the abolition of licensing fees for Adobe Flash Player and Adobe Integrated Runtime, the removal of restrictions on the use of the Shockwave Flash (SWF) and Flash Video (FLV) file format, the publishing of application programming interfaces for porting Flash to new devices and the publishing of The Flash Cast protocol and Action Message Format (AMF), which let Flash applications receive information from remote databases.
As of February 2009, the specifications removing the restrictions on the use of SWF and FLV/F4V specs have been published.[8] The Flash Cast protocol - now known as the Mobile Content Delivery Protocol - and AMF protocols have also been made available,[8] with AMF available as an open source implementation, BlazeDS. Work on the device porting layers is in the early stages. Adobe intends to remove the licensing fees for Flash Player and Adobe AIR for devices at their release for the Open Screen Project.
Flash can be used to embed video in web pages, a feature available since Flash Player version 6. The technique is to create a flash file (.swf) that acts as a player for the video file. This is the basis for many popular video sites, including YouTube and Google Video. The actual video file is either an FLV or H.264 file; both can easily be played by generic video player software. However, getting browsers to display video is still a platform specific issue due to lack of a common video format, and the subject of a web standard for video is a heated debate (see HTML 5). Using Flash has the advantage of Flash Player's wide distribution, but as this is proprietary technology for which there is no real alternative, it also makes multimedia embedded in this way notoriously difficult to access for non-users of the Flash Player, particularly if the location of the multimedia file is moved out of the HTML.
Flash movies can run in browsers with the proper Flash player installed, although it is important to note that Flash movies cannot run within an e-mail client. Outlook, Gmail, Hotmail, etc., cannot run flash movies within an e-mail.* Movies must be linked from the message so that a new browser window opens up. Flash has the ability from here to determine if the browser has the correct player installed and whether or not to display the movie, or an alternate message if the user does not have Flash.
Flash Video (.flv files) is a container format, meaning that it is not a video format in itself, but can contain other formats. The video in Flash is encoded in H.263, and starting with Flash player 8, it may alternatively be encoded in VP6. The audio is in MP3. The use of VP6 is common in many companies, because of the large adoption rates of Flash Player 8 and Flash Player 9.
On August 20, 2007, Adobe announced on its blog that with Update 3 of Flash Player 9, Flash Video will also support the MPEG-4 international standard.[31] Specifically, Flash Player will have support for video compressed in H.264 (MPEG-4 Part 10), audio compressed using AAC (MPEG-4 Part 3), the MP4, M4V, M4A, 3GP and MOV multimedia container formats (MPEG-4 Part 14), 3GPP Timed Text specification (MPEG-4 Part 17) which is a standardized subtitle format and partial parsing support for the 'ilst' atom which is the ID3 equivalent iTunes uses to store metadata. Adobe also announced that they will be gradually moving away from the proprietary FLV format to the standard MP4 format owing to functional limits with the FLV structure when streaming H.264. The final release of the Flash Player supporting MPEG-4 had become available in Fall 2007.
The proprietary nature of Flash is a major concern to advocates of open standards and free software. Its widespread use has, according to some such observers, harmed the otherwise open nature of the World Wide Web.[36] A response may be seen in Adobe's Open Screen Project.
Representing open standards, inventor of CSS and co-author of HTML 5, Håkon Wium Lie explained in a Google tech talk the proposal of Theora as the video codec for HTML 5[37] (see also the Ogg controversy):
I believe very strongly, that we need to agree on some kind of baseline video format if [the video element] is going to succeed. Flash is today the baseline format on the web. The problem with Flash is that it's not an open standard.
Presenting the free software movement, Richard Stallman stated in a speech in October 2004 that:[38]
The use of Flash in websites is a major problem for our community.
Stallman's argument then was that no free players were comparatively good enough. As of February 2009, Gnash and Swfdec have seen very limited success in competing with Adobe's player. The fact that many important and popular websites expect users to have Adobe's player, combined with the lack of good free alternatives have led to frustration among users,[39] suggesting that this is the most common obstacle to enjoying the web in freedom, which presumably relates to the continual high ranking of Gnash on the Free Software Foundation's list of high priority projects.
Referring to the web's openness, an essential feature is that web pages as well as the files they consist of are coupled together by human readable text. Similarly, the openness of the internet lies in its protocols. Thus, the common practice by video centric websites of hiding the URL of web embedded multimedia using Flash or Silverlight, obfuscating the URL with javascript, or using custom protocols like RTMP (Flash) or MMS (Windows Media streams), may seem threatening to the openness of the web. It also limits interoperability and imposes an illusion that it is technically impossible for users to do whatever they want with such content. Reflecting the latter, the terms "streaming" and "download" are often used in this context as if they were mutually exclusive events, although the distinction is purely on the client side.
