A   S t r e a m i n g   M e d i a   P r i m e r :    

W H A T   I S   S T R E A M I N G   M E D I A ?

Traditional download lets you save and redistribute media

I S   F L A S H   S T R E A M I N G ?

The downloadable approach is good for the end user who wants to keep the content and 

replay it whenever they like. In 1999, the phenomenal popularity of the 2 1/2 minute 

The Macromedia  Flash  (SWF) format 

movie trailer for  Star Wars: The Phantom Menace  a whopping big 25 MB fi le at 

was designed to deliver low bandwidth 

480x216 resolution (good quality) was proof that media hungry Internet audiences are 

motion graphics specifi cally for the Web. 

willing to be forgiving of long waits for large fi les. But if an artist or publisher does 

It's great strength lies in generating 

smooth vector animations.  

not want end users to be able to save and freely redistribute their media content, the 

downloadable approach is problematic that's the story of MP3s and Napster.

According to our defi nition of  true 

streaming,  Macromedia Flash anima 

Progressive download can get hung up

tions and other SWF format fi les are not 

Unlike traditional download, progressive download (also known as pseudo streaming 

streaming media. However, SWF fi les do 

and, in QuickTime, fast start streaming) allows playback to begin before the fi le is 

share some of the important character 

completely downloaded. Progressive download allows playback of content that has been 

istics of streaming media. 

received to continue, while the remainder is still being downloaded. Progressive down 

SWF fi les do:

load, therefore, allows the end user to view the beginning of the fi le, as the remainder is 

Deliver content with motion and 

being downloaded, and to quit the download if the content is not worth the wait. 

sound, as well as with interactivity 

Like streaming, progressive download does allow audiences to see and hear the content 

However, SWF fi les do not deliver full 

immediately as it is being downloaded but only if the download speed can be main 

motion video. AVI and MPEG fi les cannot 

tained at the rate needed to keep up with playback. If the Internet connection becomes 

be imported into Flash. QuickTime 

busy, causing the download to slow or stall, audio and video playback may not always 

(MOV) fi les can be imported, but do not 

become part of the Flash fi le and cannot 

stay synchronized, playback may become choppy or, as is often the case, may come to a 

be viewed with the Flash player. A utility 

halt, as the player waits for the download to catch up. 

can be used to reduce a video fi le to a 

Progressive download also leaves a copy of content behind

sequence of still bitmap images which 

can then be used in a series of key 

Unlike streaming, progressive download writes the media fi le to disk, leaving a copy of 

frames to simulate video, but the 

the content in the memory of the receiving device. Streaming media is processed, played, 

resulting movie does not deliver the 

and discarded, leaving no physical copy behind.

same quality as streaming video opti 

Despite the drawbacks of progressive download, it can be a good alternative if true 

mized in a native streaming fi le format 

streaming is not possible. Progressive download can be easier and less costly to imple 

and  played back on a video player.  

Furthermore, Flash fi les are limited in 

ment than true streaming. All the production techniques described in this Primer should 

size to 16,000 frames. At 15 frames per 

be applied to preparing media for progressive download, as well as for streaming. 

second, that's approximately 17 minutes 

True streaming is based on a different architecture

worth of material.  

Streaming media requires a different architecture from that used for downloadable 

Begin to play before the fi le is 

media an architecture that supports a higher level interactivity over the Web, and offers 

entirely downloaded

a wealth of additional advantages. Streaming allows you to browse through and jump 

However, SWF delivery is really pro 

back and forth in the content as opposed to progressive download, which requires 

gressive download. Served from a Web 

server and transmitted via HTTP, Flash 

viewing from beginning to end. Streaming supports both on demand and live content 

playback will stall if network congestion 

to be transmitted over the Web in real time, allowing audiences anywhere in the world 

is encountered, and transmission cannot 

to playback media whenever and however they need or want it, and to experience live 

be adjusted to accommodate real time 

events as they happen.

conditions as can true streaming.

True streaming requires a specialized media server

Can only play back using the media 

Downloadable media fi les including those prepared for progressive download are 

player that is part of the Flash 

architecture

typically served from a standard Web server that does not have any ability to adjust 

transmission to the uncontrollable fl uctuations in connection speed that are inherent in 

However, SWF fi les can be created using 

a variety of other software tools in 

the Internet environment. 

addition to Macromedia Flash, including 

Streaming exploits new Web transfer protocols, as well as communication techniques 

namic Media

but not limited to Adobe LiveMotion 

between clients and servers, to facilitate the continuous playback of synchronized audio 

y

and Adobe After Effects.

and video in real time. Streaming media fi les are usually encoded in several versions, 

According to the Macromedia Web site, 

optimized for different data rates. The streaming media server delivers the appropriate 

 Flash was created to make small, 

version, either as selected by the end user manually or as indicated by browser default 

streamable, vector based fi les for Web 

settings. In some cases, the server can automatically select the best version, based on 

obe D

delivery. This is  where Flash performs 

information brought back from the client regarding the platform and the connection 

d

best.  it's important for users to ask 

A

themselves, `Is this program designed to 

speed. Depending on the intelligence built into the media server and client player 

do what I am attempting''

software, the stream can be dynamically adjusted, at one or both ends, if the 

connection slows down. 

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