View Full Version : Optimal file size for the web


Marcia Janine Galles
November 27th, 2004, 10:50 AM
Someone told me that I should keep the file size for my trailer to under 20 mb, but isn't that still pretty large even for DSL/cable? I had been planning on putting my site up (hopefully today) with two trailer options. One was a 18.2 mb file (that looks great) and the other one at 7.22 mb. My thinking was that since it's to promote my doc, that the execs that I've sent it to would have DSL/cable and I'd like them to see it in the best possible light (though it's certainly a far cry from how great the DVD looks). OTOH, since it's about kids with Type 1 diabetes, parents who want to watch the trailer might well have dial-up, and for them, seeing it matters more than color saturation, etc.

Thoughts? Suggestions?

I'm concerned that even w/ a DSL/cable line, suit types may be waiting so long to download that they will just download the other version, which to me, looks so much worse. Maybe in the end it really doesn't matter all that much and I'm worry for nothing...
Marcia

(It's TRT is 3:11. I compressed it w/ Windows Media 9, and since it was shot 24p, I left it at a frame rate of 23.976.)

Mark Sloan
November 27th, 2004, 11:59 AM
Drop the frames to save on size for everything under your 20MB file. You can go with 12fps and it will be pretty good. If you are worried about 56k modem users you really need something a bit smaller than 7.2 MB, but I guess it depends on how long you think it is okay for users to wait for the video.

A couple of things to consider, 1) You can reduce the size of the video in terms of dimensions 240x180 instead of 320x240 for instance, and lower the bit rate to reduce the file size tremendously 2) You can compress the audio a bit more 3) People can start watching the video before it is completely downloaded, so really you just need to worry about how long it takes for the video to have enough buffer to start playing.

I always try to keep download time for 56k users to below 3x the time of the video. So try to keep 56k users from having to wait over 10 minutes to see your video... but that is just a rule of thumb I use.

Stephen Jackson
November 27th, 2004, 05:15 PM
Are you using progressive downloading or are you streaming the content through a CDN?

I ask because if you're streaming the content to the viewers then the file size is not that much of an issue.

I have 8 and 9 minute webisodes that are approx 30megs in size that are 320X240 with a variable bit rate and CD stereo audio that streams just fine. On average a user would approx. less than a minute to begin viewing the videos.

For the dial-up users I shrunk the screen size to 160X120 with a constant bitrate.

Marcia Janine Galles
November 27th, 2004, 09:33 PM
Thanks for the feedback, guys. Couple of questions...

Mark, how do you determine the download time for 56K users exactly? In Go Live I can judge the page download time, but not the associated files that pop into their browser when they click.

Stephen, what do you mean by "streaming the content through a CDN?" Sorry to be so clueless about this stuff.

Marcia

Stephen Jackson
November 27th, 2004, 10:24 PM
The two most popular ways to present windows media files are to either make the video a progressive download which means that the video sits on your web server and is downloaded as a web page to be viewed when the entire file is downloaded or to make the video stream from a server on a Content Delivery Network CDN.

I use a CDN because with streaming video the video plays while the rest of the file is downloading to the viewer's media player. That means that people can see the video before the entire is downloaded usually within a miniute of calling for the file.

There are companies like Playstream, AudioVideoWeb and some ISPs that provide Window streaming servers for clients.

For me it's as easy as encoding my files, FTPing them to the server and creating the links to view the files.

Hope this helps

Mark Sloan
November 27th, 2004, 11:23 PM
I have seen about 1MB take anywhere from 2 to 3 minutes on an average 56K modem. The thing is, 56K can mean any number of things... but I'd say that is a safe estimate.

Streaming is nice if you have access to it. I personally use Quicktime Streaming when I need it because it is free with my web host.

Good luck!

Stephen Jackson
November 28th, 2004, 08:57 AM
I forgot that Adobe's website has several primers. One is on Streaming Media and another is on DV compresion.

The primers are in PDF form so make sure you have Acrobat Reader.

Here is the link: http://www.adobe.com/motion/primers.html