Who has not watched a video on the Internet?  YouTube anyone? Sometimes I get asked what is the difference between progressive video and streaming video?

The answer is very simple.   Progressive video is actually downloaded to your computer as you watch it.  When you press play on the video player (regardless if it’s QuickTime, Windows Media or Flash), the video will start playing, usually after it buffers around 5 to 10 seconds.  As the video plays, it is also downloading the actual file to your computer and stores it in a temporary hard drive directory chosen by the video player you are playing in (QuickTime, Windows Media or your browser’s temp location for Flash).

If you wish to “fast forward” or skip to another section of the video, you can not do this, unless that section you are skipping to has been downloaded.  So if you are watching a 10 minute video, and only 3 minutes have downloaded as you are watching it, you can only move freely between the 0 and the 3 minute mark.  You can’t get past the 3 minute mark until more video downloads.

The other drawback to progressive video is that you can only skip forward or backwards to the point of where the publisher placed “key frames”.  That is, if the publisher create a video with keyframes every 5 seconds, you can only move forward or backwards every 5 seconds, nothing in between.

With streaming media,  video is delivered to you via a streaming server (whether it be a QuickTime streaming server, Windows Media Streaming server or the Flash Media Server).  As soon as you press play, the video will start to play.  if you decided to skip to the last portion of the video, you can do it immediately and it will start to play from that point.  Also, you can move around any portion of the video because keyframes (as described above) are created dynamically on the fly as it plays, so you can move forward 1 second, 3 seconds or 1/2 a second.

One of the big positives of streaming media is that you only use the bandwidth that you’ve watched.   That is, nothing is downloaded.  You only get the portion of video as you watch it and then throw it away.  Nothing is kept on the client side.  Everything is on the server side.

So, you ask, why use progressive video versus streaming video?   Simple.  Cost.   Implementing progressive video is as easy as dropping the file on your web server and pointing to it.  Implementing streaming video is more complicated and definitely much more costly and requires more coding.

So there you have it.  Now on your next cocktail party, you can share this information and impress whomever you are talking to…or not.

Cheers!

- Marcelo Lewin

The Digital Media Dude

http://www.thedigitalmediadude.com/

http://www.marcelolewinphotography.com/