Understanding Video Formats: SWF & MPEG-4
This tutorial describes the differences between the SWF (Jing) and MPEG-4 (Snagit) video file formats. In this example, three sets videos were recorded with the same dimensions and video duration to demonstrate the strengths and weaknesses of each file format.
- Recorded scrolling through a web page.
- Recorded a simple Microsoft PowerPoint presentation.
- Recorded iTunes Visualizer.
You can look at the samples and compare the results for yourself. We're interested in two main categories--file size and video quality/clarity.
Note that your results may not be exactly like mine depending on the power of your computer, other programs that may be running, whether you're on Windows or Macintosh, etc. However the principles remain the same.
What does it look like and how big is the file?
Example 1: Scrolling Webpage
I held down the down arrow on my keyboard to ensure a similar scrolling pace down the Jing blog.
Video 1a: Scrolling webpage SWF (5.3 MB)
Video 1b: Scrolling webpage MPEG-4 (4.3 MB)
What do you think? They look pretty similar? The MPEG-4 is a little smaller. The video is certainly smoother, but maybe not quite as clear? The SWF has clear frames but some frames are dropped resulting in a more choppy or jerky viewing experience.
Example 2: Simple Power Point Presentation
What do I mean by simple? Not a lot of motion--no embedded video or transitions. Not a lot of gradients.
Video 2a: Power Point SWF (1.7 MB)
Video 2b: Power Point MPEG-4 (3.2 MB)
Did you notice a difference? They both look really clear. The SWF might look a little better. And the SWF is smaller! What gives?
Here's the take-away lesson: SWF is really good at capturing video that doesn't change a lot. SWF doesn't do well with motion. It's also what they call "lossless" which means that it doesn't lose any quality. It's pixel perfect. You could almost think of SWF as a camera that snaps a screenshot of your screen (or part(s) of your screen that change) some number of times per second. SWF might be best if you are recording static charts with a lot of detail, or if you are recording a very simple app where not much is changing on the screen except your mouse cursor and a few menus or actions.
Example 3: iTunes Visualizer
Here's a screenshot of a moment in the SWF video in case you weren't sure what a visualizer was or the files below are too big for you to open. http://www.screencast.com/t/NnJmDy1jsb The colors and patterns won't be the same in both videos because they are randomly generated.
Video 3a: Visualizer SWF (70.2 MB)
Video 3b: Visualizer MPEG-4 (52.6 MB)
Here's the take-away lesson: If you were able to download and compare the videos, you probably noticed at least 3 things:
- The SWF is bigger. The MPEG-4 in this case is still a big file...but it was recording a lot of action. The SWF would have been way bigger, but it had to start dropping frames.
- The MPEG-4 manages to keep up with the action, but you might notice that it's not as crystal clear as if you watched the visualizer live.
- The SWF one looks great...on the frames that weren't dropped. Watching that video looks like time-lapse photography around the 17-second mark. When I made that recording the SWF went into what I think of as a panic state. It's snapping images of my screen when it can...but it can't very often. It's getting better than one frame per second, but not much more in places.
MPEG-4 vs. SWF File Formats
- The SWF file format is available for video captures in Jing.
- The MPEG-4 file format is available for video captures in Snagit.
The SWF file format:
- Captures with pixel-perfect precision
- Ideal for viewing on the Web
- Is royalty-free
MPEG-4 has some advantages over SWF:
- It’s better at capturing high-motion content.
- It is supported in most video editing software such as Camtasia Studio, Camtasia for Mac, and other third-party applications.
- It’s usually a smaller file size since it is encoded using H.264 compression technology.
- It’s a standard video format that works on most sites that support video.
- Ideal for viewing on the Web, but playback is also supported in other players and outside of a web browser.