Tutorial:Screencasts
From EdMUG
Contents |
[edit] Making a Screencast with iShowU and iMovie
[edit] Introduction
iShowU is very good at basic screencast recording, but if you want to edit or spice up your screencast with titles, transitions and effects then the obvious answer is to turn to iMovie (if like me you cannot afford Final Cut Pro). However, the overiding problem is that when iMovie imports video files, it processes them into the project resolution, so if your start a DV-NTSC project, it will re-code the imported video file into a 720 by 480 resolution, causing the imported screencast to heavily distort.
This tutorial will guide you through some basic steps in making a decent screencast with particular emphasis on how to avoid the video pre-processing that plagues importing iShowU export files into iMovie.
[edit] Software Requirements
iMovie is of course part of the free iLife suite. This demonstration uses the iMovie HD 06 so you may have to purchase an iLife upgrade to fully achieve the desired output, but the principles should apply to older versions.
iShowU is an extremely good app for screencasts and is relatively inexpensive: ~£10 at current exchange rates. Visit the shinywhitebox.com homepage for a fully working trial (contains copyright overlay on export movie) or to purchase the software.
[edit] Getting Started
The best place to start is to think about what you are trying to screencast and what is the desired output size, and to match them up. For the purposes of this tutorial, we are going to create a software demonstration screencast of the Flock blog editor and an extension written for it. We want the final movie to be suitably low in file size but clear enough resolution for viewing over the internet.
The available resolutions for iMovie projects are:
| Type | Resolution |
| DV PAL | 720 x 576 |
| DV NTSC | 720 x 480 |
| DV-PAL Widescreen | 853 x 576 |
| DV-NTSC Widescreen | 853 x 480 |
| HDV 1080i | 1920 x 1080 |
| HDV 720p | 1280 x 720 |
| MPEG-4 | 640 x 480 |
Now we need to turn our attention to iShowU and recording the software demo. We need to match up the iShowU exported movie to the exact same resolution so no iMovie pre-processing is carried out. As might be quite apparent, the software is going to look a little strange if we set it's window size, for example, to 640 * 480; in the next section we will look at ways to get around this.
[edit] iShowU Capture Size
The easest option is to record the iShowU movie at the HDV 720p setting of 1280 x 720, and this should cater for most screencasts. However, what if you are after a 4:3 ratio movie? The 640 x 480 option will be very difficult to capture all of the software you are demonstrating. For this we turn to iShowU's scaling option. This allows you to capture at a higher resolution, and it is scaled by either 75% or 50%. So we could capture 1280 x 960 with a scaling of 50% to get our desired 640 x 480. The table below illustrates the available resolutions:
| Type | iMovie Resolution | iShowU 100% | iShowU 75% | iShowU 50% |
| DV PAL | 720 x 576 | 720 x 576 | 960 x 768 | 1440 x 1152 |
| DV NTSC | 720 x 480 | 720 x 480 | 960 x 640 | 1440 x 960 |
| DV-PAL Widescreen | 853 x 576 | 853 x 576 | 1138 x 768 | 1706 x 1152 |
| DV-NTSC Widescreen | 853 x 480 | 853 x 480 | 1138 x 640 | 1706 x 960 |
| HDV 1080i | 1920 x 1080 | 1920 x 1080 | too large | too large |
| HDV 720p | 1280 x 720 | 1280 x 720 | 1654 x 960 | too large |
| MPEG-4 | 640 x 480 | 640 x 480 | 854 x 640 | 1280 x 960 |
See the advanced tip section at the bottom of this page for a 100% scaling, 4:3 ratio 960 x 720 capture.
Adjust the window of the software app to fit the size of the capture window (or roughly if you do not mind a small amount of the desktop to show around the edges).
If any of the above resolutions are still not quite right, you could record at the closest setting and set the iShowU capture window to follow the mouse. That way you can capture everything you are trying to show.
I have choosen to record at 854 x 640 at 75% scaling to give me a 640 x 480 screencast.
[edit] iShowU Settings
There is a huge amount of settings, codecs, framerates etc that are available within iShowU for the exported movie, and it would take many an hour to explore and explain all of them. However, if you want to import into iMovie the best bet is to try and get as lossless export file as possible without going overboard.
In experiments I have found the h264 codec at 15 fps to perform well for a final movie, but for an intermediatry between iShowU and iMovie I quite like Apple Animation (reasonable file size, good quality and excellent colours); I would not put the mouse on a seperate sprite track unless you are recording at a much lower framerate and do not want a jerky cursor in your movie.
[image]
Although I have not done so for the demo screencast, you can record audio in iShowU as you demo. Alternatively use garageband or audacity to create an audio file to drop into iMovie, or as I have done which is to record the audio within iMovie itself.
[edit] Capture Screencast
Now you have everything in place, start your capture (command+shift+a). When finished, stop the capture (command+shift+t) and you have your quicktime movie file ready for iMovie import.
[edit] Screencast Tips
- Try using the Universal Access zoom in and zoom out to add a little extra diversity/clarity to your screencast when capturing.
- The free mouselocator pref pane can be a useful tool to highlight your mouse, rather than the annoying (imho) 'cursor wiggle'.
- Capture/show keyboard input with keycastr
[edit] iMovie Import
Open up a new iMovie project in the correct format (I choose mpeg-4 to match the screencast output size). Go to file > Import and navigate to the iShowU export video. Please Note that the imported movie will still look a little pixelated in the iMovie preview, but once shared as a quicktime movie will look fine.
There it is, do your iMovie magic and share. I personally prefer quicktime movies so choose share > expert settings > h264 compression at best quality and a size to match. Voila, we are done for today :-)
[edit] Final Screencast Movie
Here is the final movie. Not the best of quality, but given it has been resized and compressed for delivery over the internet, could be worse!
[edit] Advanced Tips
There may be times where you want a larger resolution file, but none of the iMovie project settings are suitable. In this case, I would start an iMovie HDV 720p project and record at 1280 x 720. This might well be too wide for your purposes, and you want a 4:3 scale screencast. What you need to do is set up the software windows to be 960 x 720 in the middle of the larger capture area, record at 1280 x 720 thus including bands of desktop either side.
[image of capture area and strips]
When sharing from iMovie, create a custom output of 960 x 720 with cropping. This takes away the strips of desktop either side and gives you a higher resolution 4:3 screencast.
[image - imovie share dialog]
This movie could be shared as the more standard 4:3 resolution of 800 x 600 with minimal distortion, remembering to crop also.
