How to create a podcast using Keynote
I searched around the Net for this information and didn't find any discussion, so here goes with the solution I found. Suppose you want to make a video podcast out of a [amazon:B0007LW23A|Keynote] presentation? The obvious step, to use the Export feature in Keynote, just results in overly large files. I want to take this step by step and explain what I did to get a reasonably sized file.
First, in Keynote I created my presentation. It's a normal presentation so don't sweat over this part.
Next you want to create the audio portion. Keynote does not have audio recording abilities built in. However a non-intuitive feature of Keynote is if you drag an audio file onto a slide, then that audio will be played when you view the slide.
Using Audacity I recorded a segment of audio for each slide. Since Audacity doesn't support MP3 export out of the box I saved the audio in WAV format (File / Export as WAV). Once the audio is edited down (to remove "Um"'s and the like) and exported to WAV, simply drag the file from Finder to the Keynote slide. A little speaker icon will show up and if you double click it you'll be greeted by whatever you recorded.
You can click the Play button in Keynote to make sure it plays well. If, like me, you have a dual head setup, Keynote will show a time track on the second screen. You can use this to verify the length of time and that the presentation plays well.
Now it's time to create the video. It's a two step process to get the video out of Keynote into a reasonably sized file. Further, for it to be a podcast that is playable in an iPod the video must be 320x240 in size and in Quicktime format. The obvious thing to try is the "Export" choice in Keynote, but I tried all options and the files always ended up overly large.
What I did was to export it in high resolution video, and that does result in a large file. But I next brought that file into [amazon:B0007LW22G|iMovie]. I didn't do any editing, but instead I immediately used iMovie to export the movie. In iMovie one of the choices is "Web" which is in the 320x240 format required to play in an iPod. Maybe this could have been done in Quicktime Pro, but I don't have Quicktime Pro. Maybe this could have been done with ffmpeg, but I don't have that either.
iMovie, however, turned the 160 megabyte file exported from Keynote into a relatively diminutive 9 megabyte file. For distributing as a podcast this is a very reasonable size.