How to Put Video Files in presentations

How to Put Video Files in Presentations

Introduction

You've probably heard the saying that "a picture is worth 1000 words". If this is true, a movie is probably worth even more. Putting a video file into a PowerPoint presentation can be a very effective way of showing a concept. However, you have to be careful to do it correctly, and also be aware of some of the pitfalls that can happen when using video files.

Including the video file

Microsoft Office PowerPoint 2003

This part of the task is easy. You can insert it as an object. Go to the menu at the top and select "Insert". On the pull down menu that appears, select "Movies and Sounds". On the next menu that appears, select "Movie from File". A dialog box will appear prompting you for the file to insert. First, navigate to the directory where your video is, then select it from the list of files, and click "Open" to put it into your presentation.

To confirm that you've selected the proper file, PowerPoint will show the first frame in the movie, its start.

You're done! It's that easy!

Microsoft Office PowerPoint 2007

This part of the task is easy. Click on the Insert tab on the ribbon. On the new ribbon, click on the Movie icon in the Media Clips group. A dialog box will appear prompting you for the file to insert. First, navigate to the directory where your video is, then select it from the list of files, and click "Open" to put it into your presentation.

To confirm that you've selected the proper file, PowerPoint will show the first frame in the movie.

You're done! It's that easy!

Things to consider

Before you actually include a video, there are a number of items you should consider.

File size

Videos are very large files. Adding a video to your presentation will probably significantly increase how long it takes to transmit and open the presentation. Also, if you're submitting the presentation to an online submission facility such as the MyPoly Digital Dropbox or the EG Website, your presentation may exceed the limit on file size the site will accept.

Links between the presentation and the video

PowerPoint handles videos differently than it does other objects that are included in the presentation. A complete description of how PowerPoint works is beyond the scope of this document. However, an easy way to avoid these issues is to have the video in the same directory as your presentation. This means you may have to move the video to the proper directory BEFORE including it in the presentation. Second, when submitting to an online submission facility, be sure to submit both the presentation and the video file. One way to do this would be to put both items in a ZIP or RAR file. You can learn how to do this by looking at the instructional Web page "How to Compress Your Files" in the "Instructional Web Pages" section of this manual. After you've created this file, you can submit it to the online submission facility, but check with your teacher first to make sure that this form will be acceptable.

If you don't do this, or the online submission fails, you'll only see the opening frame, not the entire video.

Chroma key

To understand the next issue, we'll have to digress and talk about how television and movies work. We've all seen special effects where an actor seems to be walking on thin air, jumping from a high place with no visible means of support, being thrown by an explosion, etc. Scenes like this are actually shot as two separate scenes (the actor and the background) and then combined. Similarly, the nightly weather report seems to be given by a person standing in front of a map or tabular data. Like the movie, this isn't really happening; their video picture is being combined with a second video that is typically computer generated.

In all these cases, the person is moving or standing in front of a wall consisting of a single color. Historically, this has been called a chroma key. For movies, this wall is typically an intense bright blue called Cadmium Blue, named after the spectral signature of the element Cadmium. For video work, the person is typically standing in front of a bright green wall. In both cases, the background is shot normally. Now the two pictures are combined. For the first picture (the person), all colors other than the chroma key are overlaid on the second picture, and the chroma key color is ignored. For movies, this has been done photographically, but these days it is more likely to be done using computers. For videos, it is almost always done by computers. This is why, in a movie, the person in the action doesn't wear anything that's bright blue – it would be too close to the chroma key and make the person transparent, like a ghost. (In fact, this is how movies make ghosts or body parts move around – the actor wears a chroma key bag on the parts that should be transparent.) Similarly, on television, the weather person is standing in front of a green wall (the chroma key) and is careful not to wear anything bright green (even on St. Patrick's Day). Occasionally you'll see people who forget this, and parts of them turn transparent.

Why were these colors chosen? In both cases they were chosen because human flesh doesn't contain these colors, insuring that they'll look good in when the shots are combined. Why did movies and video choose different chroma key colors? Movies came first, and it was relatively easy to make large areas of Cadmium Blue. Television signals use green to show shades of gray on black and white TV. In both cases the color is a very sharp point in the color spectrum. Any further discussion is beyond the scope of this page. However, it's easy to find additional information using any Internet search engine with the term "chroma key".

One note: during the making of the Star Trek television series and movies, it was very difficult to have space aliens in some scenes because their "flesh" contained significant components of the chroma key color, causing the scene to look wrong. Also, if you're wondering how the weather person is able to point to things on the maps, they're actually looking at a television monitor showing what's being transmitted, and moving their hand to the right place in the combined image.

Why is knowing about chroma key important? When PowerPoint includes your video, it makes a chroma key frame behind your video. In this case your computer is not shooting the video, but is showing it, so the chroma key color used is black (when you're displaying something adding black to it doesn't change it). If you're using a computer that's using multiple video ports (for example, a laptop that's showing the presentation on its LCD screen and also on a video projector), occasionally the video circuitry will not work properly, and all you'll see is a black frame on one or both screens. This is the chroma key without the video being overlaid on it properly.

Summary

Adding video to a presentation can make it much more interesting. If you are aware of the dangers involved in including it, you can include your video with confidence, and make a better presentation. However, ignoring these issues can lead to frustration.