When to Zip Downloadable Files

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When to Zip Downloadable Files

Tenaya

12:26 am on May 28, 2010 (gmt 0)

Hi folks,

It’s been a long time since I last posted here, and I’m still very new to web design/development as a hobby. However, I am now at least feeling a little less like a deer caught in headlights now that I’ve aced my first XHTML class, and hope to continue my education here in the future.

To begin, I was wondering if anyone could give me advice on when files that you want to be downloadable from your website should be compressed as zip files. I’ve read that compression works best for very large text files and .bmp’s. But is there a way to reduce the file size and time that it takes to download .jpg’s or music files that get as big as several MB?

Thank you very much in advance to anyone willing and able to help.

phranque

12:49 am on May 28, 2010 (gmt 0)

with text files it is best to use gzip compression and most servers and browsers will support that.
the trick with media files is to used a compressed format to start with.
bmp is a bit mapped image whereas jpg, png and others are compressed image formats.
mp3 is an example of a compressed audio format, there are a variety of compressed video formats, etc.
you may get some additional media file compression using zip but in many cases it is not significant.

Samizdata

1:41 am on May 28, 2010 (gmt 0)

advice on when files that you want to be downloadable from your website should be compressed as zip files

While putting a file in a zip archive may not always reduce the size, it will ensure that the file is downloaded to the desktop (or other default location) rather than displayed in the browser.

...

phranque

1:48 am on May 28, 2010 (gmt 0)

in my browser a zip file typically opens the dialog to select the save or open in winzip options.

another advantage of the zip archive is that it retains path/location information.

tangor

2:35 am on May 28, 2010 (gmt 0)

Some file types (as noted above) benefit with zip, PDF for example, but that also presupposes that the end user expects a zip they have to manipulate after downloading. With today's faster connections the need for zip is not a great as it was back in the BBS days. Zip, however, does offer something additional such as applying an encrypted password on the zip wrapper. On some sites I use that to ensure folks want it, and pay for the content, too (sending via email the password to open the zip after payment has been sent).

In GENERAL, however, zip is not as important as once before, unless one needs to send path/directories along at the same time.

Tenaya

3:10 am on May 28, 2010 (gmt 0)

Thanks, all, and good points.

Is there a general rule as to whether it’s best to combine audio files into a single very large zip file, or make them downloadable separately as individual files? Obviously, I can see that making large files available separately would allow users to decide exactly which ones they do or don’t want to download, and would decrease the risk of a download being interrupted, while zipping large files into an even larger zip file would have the benefit of requiring less supervision on the site visitor’s part. Is there a convention for how to handle this that I’m unaware of, or is it just a matter of personal preference?

tangor

3:43 am on May 28, 2010 (gmt 0)

Audio files such as mp3 are already compressed. No benefit to zip. Can't think of any "rules" as to when one uses zip. I offer (for example) only a handful of datafiles (really big ones!) as zips. These days I assume users arrive other than dialup...

phranque

6:35 am on May 28, 2010 (gmt 0)

since i missed my chance the first tinme around, welcome to WebmasterWorld [webmasterworld.com], Tenaya!

Tenaya

6:44 am on May 28, 2010 (gmt 0)

Thank you! :)

webguru2020

8:46 am on May 30, 2010 (gmt 0)

Nice info and useful to me. Thz anyway