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Wednesday, April 15, 2009

What is FLV

FLV is a "Flash Live Video" file. It is a format that is designed for web playback, offering high rates of compression. Several products output in FLV format, including Sorenson Squeeze (The term "movie" often refers to common Flash source files (.FLA) and deployed files (.SWF) and is not synonymous with "video").


The Flash Player browser plugin can play an FLV, but that FLV, must be either embedded in or linked to a SWF. That is, you can't just put the actual FLV on an HTML page. You can however reference the FLV file using action script and SWF

Flash Media server and RTMP Streaming -- Its been around for about 9 years now. In this system, a Flash application communicates through the RTMP Server. Usually these applications enable person-to-person communication (one-to-many, or many-to-many). Flash may also be used for machine-human communication, such as real-time data transmission and notification.
Even though the browser can play the file while connected to the server, there is no operating system player for the Flash FLV file format, so the file cannot be played locally. Given the connection to the MX server however, it allows the user to play the movie directly in their chosen browser. Flash MX Media server can also administer time spent and pending usage as previously purchased by the user.


Highlights of the Flash MX Server include the ability to provide your end users with the best possible experience via a seamlessly integrated client that lets you brand your broadcast the way you want to, with any devices containing the Flash Player being capable of delivering movies when connected to the MX Communications server or Media Server
Real Time Collaboration is a powerful programming model that will allow many multiple connected users to share data and user interfaces in real time, coupled with client and server data storage capabilities. Support for off-line usage in addition to on-line usage allows the creation of robust applications that can be used offline, and then synchronized automatically when the user goes back online.


The Flash Communication Server has functions for server-side scripts that may disconnect users, authenticate, and control. Applications can be developed for moderators or administrators to perform custom maintenance and monitoring.


The Macromedia Flash Communication Server works with multiple network adapters on the server machine. This allows the server to be built for maximum network throughput. In addition, "virtual hosts" may be configured on each adapter. Virtual hosts can be used to isolate different server users, allowing each server user to add applications freely while keeping their programs separate from others.


A Fantastic File Format
The file format used in this process is Flash FLV or Flash Live Video, and it plays in a Flash Player. While traditional methods of media delivery include some kind of download to the user's computer, either in a pre-loader or through temporary Internet files, Flash MX Communications server and a Flash FLV Player connect in a completely different manner. Simply put, it's a new connection to the file each time the user uses the controls in the player. This means that in the background it's a "start here" ? "stop here" ? "start again here" style of play, with no downloads or caching.



The Top Ten Reasons to Stream Video Using Flash
  1. FLV format file sizes after conversion are up to 60% smaller, saving server storage costs.
  2. FLV's start - stop connection style saves on bandwidth (which is as much as 60% less per month).
  3. FLV format has no local player in operating systems, so file sharing is virtually nullified.
  4. FLV format plays directly in more browsers than Windows Media, Real Player or QuickTime.
  5. FLV server can authenticate clients, and control users as you wish.
  6. FLV players can be completely customized for logos, branding and embedded links.
  7. FLV players can play files from a programmable database, and simple administration area.
  8. FLV players can be programmed to integrate with databases for free previews, time, users.
  9. FLV encoding can include user information for content tracking, misuse, or DRM.
  10. Flash Communications servers are easier to maintain than others, and less prone to security hacks.
Definitions
  • Bandwidth: The total amount of data a network connection is capable of sending through its system per second. This determines the length of time it will take to transmit data.
Example: a file that takes 10 minutes to transmit across a modem with a speed of 28,800 bits per second (bps) might take only one minute to transmit over a DSL line because the DSL line has a larger bandwidth capability, which can pass more bits through per second.

  • Buffering: Media players assimilate the incoming data and present it to the viewer, as audio and/or video. During network congestion, this data is not sufficient for the media player to continue playback and therefore, the player must pause to receive more data before resuming playback. This process is called "rebuffering". To help avoid "rebuffering," the media players buffer a certain amount of data on reserve in the beginning before playing the clip. Flash Communication (Media 2) Server eliminates this "buffer" time.
  • Caching / Cache: Data that is frequently accessed is often stored in the computer's memory so that it may be re-accessed at a quicker rate than if this data was stored on the computer's hard disk drive. The process of storing this data is called caching. The type of memory that stores this data is called the cache.
  • Digital Rights Management: Refers to qualifying the end-user prior to allowing the end-user to view or listen to the media file. It is a term usually referring to the software that enables Internet 'Pay-Per-View'.
  • Digitizing and Encoding: Digitizing refers to the process of capturing original media (film, video, sound recordings, etc.) into a digital format onto your computer. Encoding refers to the process of converting this digitized file into a streaming format.
  • ISP: Internet Service Provider. Companies that offer access to the Internet to subscribers.
  • Latency: This is the delay of transmission of data. Refers to the time it takes for a router, upon receiving the data, to determine which router to forward the data to next.
  • Load-Balanced: A single computer is only able to transmit a fixed amount of data. If the server receives too many requests for data at the same time, a bottleneck forms causing a delay in transmission of data. Load balancing refers to the process of grouping multiple servers together to act as one single system This will minimize the risk of this type of delay.
  • MP3: Digital format specifically designed for music.
  • Network Congestion: Situation that occurs when the amount of data being transmitted exceeds the capacity of the network. This results in data transmission delays and possibly lost data. If a router becomes overloaded, it will discard data as a last resort to manage the volume of data transmission.
  • Peering: An agreement between Internet backbone carriers to exchange equal amounts of data at specified points along the Internet. Peering agreements enable competing companies to utilize cable laid by one another, thus reducing costs and duplication of cable routes. As the data is exchanged freely between the carriers, there is no economic incentive for one carrier to manage the incoming data of another carrier. Should one carrier submit data in excess of the "peering" agreement, the other carrier will usually discard the excess data. Peering connections on the Internet have often been associated with bottlenecks of Internet data transmission.
  • QuickTime: Digital media software created by Apple Computers.
  • RealPlayer: Streaming media software created by RealNetworks for the Internet.
  • Redundancy: Systematic approach to eliminating single points-of-failure in a network or data storage system.
  • Router: A Router is a hardware device used throughout a network that receives incoming data and determines the route for that data to travel in order to reach its intended destination. A router is a switch with built-in capabilities than enhance its functions and performance.
  • Scalability: The ability to expand capacity of an existing data storage system or network without requiring replacement.
  • Streaming Media: Like television and radio for the computer, streaming media technology converts other mediums (audio and video) to digital formats that can be played back instantly by computers. It is comparable to the process that enables one to turn on a TV set and instantly see a program, or turn on a radio and instantly receive sound. The general term Streaming Media incorporates all the formats created specifically for transmitting audio, video and multimedia over the Internet.
  • Webcast: media file distributed over the Internet using streaming media technology. A webcast may either be distributed live or on demand.
  • Windows Media: Streaming media software created by Microsoft. We do not offer Windows server space at the current time.
  • Macromedia Flash Websites: Video support in Macromedia Flash has continued to evolve since its introduction in Flash MX and Flash Player 6. Flash Player 7 greatly improves video quality, supports higher frame rates, and provides additional opportunities for loading dynamic media at runtime.

At the core of Flash video is the Flash for Video (FLV) file format. FLV files contain encoded audio and video data that is highly optimized (through the use of Sorenson's Spark codec) for delivery through the Flash Player. This keeps the Flash Player footprint as small as possible by using a single video rendering format.


Edited video content is encoded into the FLV format as it is imported into the Flash authoring environment (or encoded into FLV format from third party applications via the Flash Video Exporter plugin). Once imported into the Flash authoring environment, FLV files can be converted to movie clips and can benefit from all of the programmatic manipulations ActionScript has to offer, or exported back out as standalone FLV files that can be invoked and streamed by the Flash player.


On the delivery side, developers can choose from a variety of options for embedding video into Flash movies or options for streaming external video files at runtime, or options for exporting Flash video to other formats. Developers need to carefully consider the types of video content, bandwidth, length, and the level of user interaction needed before choosing a suitable delivery mechanism.


Video capabilities in Flash MX With the introduction of the Flash MX? platform, support for video has improved with the addition of many new capabilities to the authoring and runtime environment, giving developers more options for delivering embedded video and progressive and streaming files. In short, developers have many new choices to tailor the delivery method to best match the nature of differing video content and ultimately to deliver the best possible user experience.
  • Video Import Wizard
    The wizard adds many new choices for encoding imported audio and video as well as providing basic clip scaling, cropping functions and contrast and brightness controls.
  • Media Components
    a set of authoring components that enable connections to external video files and connections to Macromedia's Flash Communication Server (available separately), and a new set of Behavior actions that work with Slides to accelerate and simplify the creation of advanced interactive video presentations.
  • Flash Video Exporter
    a new plug-in for use with third party applications that enables users to export Flash encoded audio and video directly from a third party authoring environment.
Flash Websites There are several alternative approaches to using video with a Macromedia Flash-based website. The overriding factor in choosing the optimum method for delivery is performance, which developers can best address by matching the appropriate delivery mechanism with the actual content. For example, approaches that work for short video clips embedded into a Flash movie will not work with large video files that require external streaming. Likewise it is not efficient to architect, code, deploy, and maintain an elaborate client-server delivery mechanism when presenting short, highly-compressed and optimized clips.


Embedded SWF Embedded SWF video is a straightforward method of delivering short video clips and has been around since Flash Player 6. It is an easy to use, timeline based technique and gives quick results. Video clips can be imported and encoded into the Flash authoring environment. Playback is limited to simple play and stop commands, and the video framerate must match that of the host movie, an important consideration that will require authoring for the lowest-common-denominator download speed.


For web delivery, content must be completely downloaded and must fit into available memory on the user's machine before playback can begin. The biggest limitations to embedded video are movies having a maximum of 16,000 frames and audio sync cannot be maintained beyond about two minutes. The entire video clip must be published each time the movie is tested or previewed, which can lead to lengthy authoring sessions.


Progressive FLV Flash Player 7 introduced progressive download, a technique where external FLV files are cached on the user's local hard drive and played through the host SWF at runtime with no limitation to the file's size or duration. Audio and video stays in sync and the frame rate is completely independent from that of the movie host, enabling developers to create several versions of content optimized for different download speeds. Since an external FLV is published separately from the host FLA , authoring time is more efficient. For lengthy audio/video content that requires fairly straightforward delivery, external progressive FLVs can be a good choice.
The Flash MX Professional 2004 authoring environment contains Media Components that can be used to quickly add FLV or audio MP3 playback control to a Flash project. Media Components provide support for both progressive and streaming FLV files.


Streaming FLV Streaming FLV files have many of the same properties of Progressive FLV files but are remotely served from Macromedia's Flash Communication Server (available as a separate product). This approach provides the most efficient delivery of FLV and audio MP3 files by streaming data to the host SWF file and requires the least hard disk and memory resources on the client end. Since data is not cached locally on a user's hard disk, this technique also provides the most secure method of delivering media.


Macromedia's Flash Communication (Media 2) Server has the ability to deliver multiple simultaneous real-time communications, provides smarter delivery of content by adjusting to the client's connection speed, and has advanced monitoring of traffic and throughput. For media projects that require the greatest flexibility in efficiently handling the most complex data streams, this is the best choice for delivery.


Exported FLV & QuickTime Flash Tracks Flash can export movies to other formats such as Apple's QuickTime or Microsoft AVI. Flash can also export image sequences to a variety of formats, such as GIF, PNG, JPG, AI and EPS.


Note: AVI export is only available in Flash for Windows.


QuickTime video can be imported into Flash where Flash tracks can be added and exported back out as QuickTime and played with the QuickTime player or plugin. This provides much of the Flash feature set, especially navigational overlays and sprites, directly into a separate track within a QuickTime movie. Another use is to use Flash to ?translate? graphics formats not supported by QuickTime into QuickTime movies.


Note: QuickTime support for Flash is usually based on the next-to-latest version of Flash. The current version of the QuickTime Player? supports playback of Flash Player 5 SWF files. This is because Apple's development of QuickTime is not synchronous with Macromedia's latest Flash Player development. Also, it is up to the software developer to decide how much of the Flash player feature set to include in its own players, so it is likely that not all of the Flash player functionality will be present in all software titles. This can limit the scope of ActionScript that can be carried out on these titles. For details see Apple's Developer Center article on QuickTime 6 support for Flash.


The Flash Media Handler inside the QuickTime player supports an optimized case for the alpha channel graphics mode, allowing a Flash track to be cleanly composited over other tracks. QuickTime allows the SWF file format to execute any of the standard Flash movieclip actions.

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