Comments on: Captivate File Size Tips

By: Russ Hall

Russ Hall — Fri, 03 Oct 2008 20:26:38 +0000

I found that using .jpg files as the background image dramatically increases the file size of the .swf output. The above comment about a bmp algorithm explains what I found. I also found that resizing the C3 project dramatically increases the .swf output – my guess is that it also affects a compression algorithm. I downsized from 1014X713 to about 10% smaller (don’t recall exact dimensions) and the .swf output doubled in some cases (ex: 1.5 MB to 3.02; 1.42 to 2.46 MB; 1.89 to 3.25 MB). Thankfully I made copies of most of the .cp files before I resized so I was able to revert to the original size.

By: Rod Ward

Rod Ward — Wed, 04 Jun 2008 07:37:53 +0000

As to the reason why BMPs are preferable to JPGs I would offer the following information from my experience using other capture tools such as SnagIt. My suspicion is that when you paste a screenshot into Captivate as a BMP (and you can see it as a BMP listed under Images or Backgrounds in the library), when Captivate publishes out using Standard quality it turns it into a GIF file. I have noticed that with Standard quality settings you get only 256 colours…same as GIF. If your screenshot is of a software interface, and it doesn’t happen to have lots of fancy gradients, then 256 colours is likely to be plenty to render it perfectly. A BMP image of the same screen will usually be about ten times the filesize of a 256 colour GIF, and may look identical. The reason is the algorithm that GIF uses to compress the data. GIF compression works in lines of pixels and basically says: “Repeat this colour for the next n pixels until it changes.” GIF is especially efficient in compressing images that have large areas of flat colour (e.g. software screens), whereas JPG compression is designed to be more efficient where you have lots of gradients (e.g. photos). The overall effect is that if you use GIF for a screenshot the edges of the onscreen text will be nice and crisp and sharp. But if you use JPG the edges will appear “fuzzy” because JPG is trying to average out the differences between pixels.

By: Liz

Liz — Mon, 28 Apr 2008 22:20:51 +0000

If you record at 1024 x 768, what are your final dimensions?

By: Mark

Mark — Thu, 17 Jan 2008 04:46:29 +0000

Oh – in case you were wondering…the same exact jpg file was used as the source for both the importing and the pasting. Likewise for the bitmap.

By: Mark

Mark — Thu, 17 Jan 2008 04:44:17 +0000

I just did a test (it’s been a couple of versions since I last tested and revised my entry on this in accordance with the test – basically, when copying and pasting into Captivate, BMP files result in a smaller filesize over jpg’s. But importing works as one would expect. See the screenshot.

By: wfz

wfz — Thu, 17 Jan 2008 01:13:58 +0000

can you elaborate on why bmp is the way to go? What are the benefit of using BMP than other formats? size? quality?

Why would import a huge BMP instead of JPG if it’s a photo?

Thanks,

By: Mark

Mark — Fri, 26 Oct 2007 19:38:13 +0000

By “importing into Flash” I assume you either mean:

a. Importing the Captivate source file (.cp) into Flash.

b: Wrapping the Captivate-generated swf with a Flash IDE generated swf via loadMovie(), MovieClipLoader, etc.

I always opt for option b unless I want to just use the built-in Captivate navigation.

I *never* import a .cp into Flash because I don’t see the point. I’ve never seen a convincing argument/reason for doing so. I’m sure there is, but I haven’t seen one yet!

Now, if all you want to do is stream the Captivate-generated swf directly on a page then just embed it using swfobject or something like that.

By: Kim Cole

Kim Cole — Fri, 26 Oct 2007 17:58:13 +0000

Do you know of a way to force the Captivate SWF file to stream (without importing into Flash)?