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Flash has always been developed and used for multimedia purposes, but until version 6, the possibilities for audio streaming were limited, and there was no video support. With versions 6 and 7, Macromedia introduced video support and a new file format to support various ways of streaming. This article covers only a streaming variant called "progressive download", which does not need server support. Copyright notice: All reader-contributed material on freshmeat.net is the property and responsibility of its author; for reprint rights, please contact the author directly. FLV StreamsStreaming is built upon a new file format called FLV, which separates the streamable content and the Flash movie. The results are a very compact Flash movie acting as a multimedia player and a container for streamable content, from which the Flash movie loads a stream on demand. A single FLV stream contains one audio stream and one video stream. Flash supports uncompressed sound and various compressed formats like MP3 and ADPCM, as well as the proprietary Nellymoser audio codec. With Flash version 6, Macromedia also introduced video support. In version 6, only the Sorenson H.263 video codec was supported. This is a slightly modified version of the open H.263 standard. The latest Flash version, 7, introduced a second video format called "Screen Video", which is a simple, lossless video format, especially developed for screen capturing. Converting and Creating ContentOne method for creating FLV streams is converting existing audio and video content with FFmpeg. FFmpeg is mature and excellent software for converting audio and video to and from various formats. Converting a video can be done simply with: $ ffmpeg -i infile.[avi|mpeg] stream.flv FFmpeg uses the Sorenson H.263 video format for encoding video data. There is no support for the Screen Video format at this time. While the Screen Video format is mainly useful for screen capturing applications, Sorenson's H.263 is a multipurpose video codec with good compression rates, suitable especially for encoding motion pictures. Another project dealing with FLV streams is called libflv. While FFmpeg is a general audio and video converting suite, libflv is focused on working with FLV streams. The project is still in a very early stage, but is able to encode videos in the Screen Video format and allows simple FLV stream manipulations like (de-)multiplexing of audio and video streams. A simple GTK-based screen capturing application can be found in the example directory. Building a Simple Multimedia PlayerAfter we've created some streamable content, a Flash multimedia player is needed. One huge advantage of a Flash-based player over other plugin-based multimedia players is that there are no constraints about its look and how it is integrated in your site's design. MING is an Open Source library which is able to create Flash files with almost all recent Flash features, including Action Script and sound and video support. It also has language bindings for a bunch of script and programming languages. The examples presented in this article are written in PHP4. Porting them to other supported languages like C/C++, Java, Python, or Perl should be trivial. To run the following example, a current CVS snapshot of MING is needed. It is available either via SourceForge's anonymous CVS service or pre-packaged at http://klaus.geekserver.net/ming/. First, we create a new movie instance and set the dimensions and background color: ming_useswfversion(7); $movie=new SWFMovie(7); $movie->setDimension($width, $height); $movie->Background($r,$g,$b);
The new Flash movie can now be filled with Flash objects called
characters. For the multimedia player example, we create a video canvas
object and add it to the movie. The
$stream = new SWFVideoStream();
$stream->setDimension($width, $height);
$item = $movie->add($stream);
$item->moveTo($x, $y);
$item->setname("video");
The
A multimedia player application should be able to load and play streams
dynamically. Therefore, the
connection = new NetConnection();
connection.connect(null);
stream = new NetStream(connection);
video.attachVideo(stream);
stream.setBufferTime(10);
stream.play('http://localhost/mystream.flv');
The ActionScript first creates a pseudo connection by passing
$action = new SWFAction($action_string); $movie->add($action);
Until now, the Flash movie just loads and plays a certain FLV stream. To
control its behavior, a simple user interface consisting of some buttons
and a seek-slider is needed. Flash has its own compressed lossless
bitmap format called DBL. MING provides a small utility called
$button = new SWFButton();
$flags = (SWFBUTTON_UP | SWFBUTTON_HIT | SWFBUTTON_OVER | SWFBUTTON_DOWN);
$button->addShape(ImageShape("images/pause.dbl"), $flags);
$action = new SWFAction("stream.pause();");
$button->addAction($action, SWFBUTTON_MOUSEDOWN);
$button_ref = $movie->add($button);
$button_ref->moveTo($x, $y);
The above example creates a pause button for the multimedia player. An interactive button is created in two steps. First, its look has to be defined by adding shapes for certain mouse events. In Flash, a shape is the basic representation for graphic objects. For each mouse event, a differently-shaped object can be assigned to the button. In the above example, the button always looks the same. In the second step, the button's action can be defined by assigning ActionScript to a special event. One drawback of using progressive download streaming without server support is that there is no possibility of getting the stream's total length. Therefore, the seek-slider's functionality is limited to seeking within the already-loaded parts of the stream. The dragable part of the seek-slider is realized as a movie-clip object. A movie-clip runs as an independent movie in the Flash movie. It has an independent timeline, can handle scripts, and handles external events itself.
$mc = new SWFSprite();
$shape = new SWFShape();
$shape->setLine(4,25,0,0,128);
$shape->movePenTo(0, 5);
$shape->drawLineTo(0, 10);
$mc->add($shape);
$mc->nextFrame();
$slider = $movie->add($mc);
$slider->moveTo($xMin, $y);
A movie clip (SWFSprite) has methods similar to those of a movie object.
The
$a = new SWFAction("startDrag(this, $xMin, $y, $xMax, $y, 1); drag = true;");
$slider->addAction($a, SWFACTION_MOUSEDOWN);
$a = new SWFAction("stopDrag(); drag=flase;");
$slider->addAction($a, SWFACTION_MOUSEUP);
The third, lengthier script sets the stream position, depending on the slider's x-position if the slider is actually moved by the user, or sets the slider's x-position, depending on the stream's current time:
// width in px
width = xMax - xMin;
paused = false;
if(drag) {
// pause stream while seeking
_global.stream.pause(true);
paused = true;
x = _root._xmouse - xMin;
seekTo = (_global.streamLen / width) * x;
_global.stream.seek(seekTo);
}
else {
pos = (_global.stream.time * (width / _global.streamLen)) + xMin;
this._x = pos;
this._y = y;
}
// restart paused stream
if(paused)
{
_global.stream.pause(false);
}
This script is assigned to the
After we've added all the elements to the Flash movie, the first frame
has to be closed with the
$movie->nextFrame();
$movie->save("FLVPlayer.swf");
ConclusionWith Flash, it is easy to create a lightweight, fully customized, embedded video and audio player. There are powerful Open Source tools available for creating content and creating Flash movies. This article introduced the basic concepts of Flash streaming and working with MING. The mediaplayer presented here provides only the most basic features and was only intended as a simple example. It can be extended in many ways, which is left to the reader. Author's bio: Klaus Rechert is involved in the MING and in libflv development, and is developing e-learning applications at the University of Freiburg. The source code of the example player can be found at libflv project pages. T-Shirts and Fame! We're eager to find people interested in writing articles on software-related topics. We're flexible on length, style, and topic, so long as you know what you're talking about and back up your opinions with facts. Anyone who writes an article gets a t-shirt from ThinkGeek in addition to 15 minutes of fame. If you think you'd like to try your hand at it, let jeff.covey@freshmeat.net know what you'd like to write about. [Comments are disabled]
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Great tip! I had no idea it was so easy to make something like this in Flash! This could come in very handy on some of my websites. This is the coolest tip I've seen in a while. Thanks! :) --
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opensource list any one is having the list of tools for converting rm to mp3 tools
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Re: opensource list
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flash is not free You may obtain a copy of a flash player only for yourself, you cannot
redistribute it (for example into a liveCD) which ends up in a bad
situation: Macromedia holds all the control in what is being
reproduced. --
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Re: flash is not free
Would you be referring to GPLFlash, or a completely new alternative?
[»]
Re: flash is not free
completely new, still developed since long time and with a very active community behind: Blender and something interesting you will find in Freej as well, scriptable with Javascript syntax, still under active development FreeJ from the point of view of a programmer ;) there are even more possible alternatives, while i phear that Macromedia corp. is going to hold on Flash the same way Sun corp. is doing with Java... see this article for more details. ciao--
[»]
Re: flash is not free
[»]
Re: flash is not free
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[»]
Re: flash is not free
[»]
Re: flash is not free
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