“A nearly impenetrable thicket of geekitude…”

"Trust" Bonus Track

Posted on August 21, 2007 at 14:15

I’ve previously mentioned my Networkshop 35 presentation in Exeter, and the fact that some of the material I prepared went unused because of lack of time.

As an experiment, I’ve narrated the unused slides and they are now available for download in one of the following formats:

The presentation is a little under 20 minutes long. Please let me have feedback if you find this kind of thing useful, or for that matter if you find my voice too soporific or annoying. I’m considering doing more along these lines, and it would help to know in advance whether I’d be wasting my time.

Gearheads can read on for technical details…

I’ve been meaning to get round to this project for some time; what finally prompted me to complete it was the release of Apple’s Keynote ‘08 presentation software, which finally allows recording an audio track synchronised with slide timings. I’m sure the PowerPoint users in the audience are snickering at this point; they’ve had this ability for ages.

Of course, I ran into a couple of bugs along the way, the most annoying one being that you can’t export a movie from a presentation that you’ve backed up at any point, for example to re-do a slide you fluffed delivery of.

In any case, it turns out that I make enough mistakes in narration to need a lot of post-production work to avoid sounding like an idiot with a terminal respiratory disease. So my current workflow for each major section goes a little like this:

  • Do a first run-through narrating the slides in Keynote. Don’t worry at this stage about getting a clean take, just keep at it until I have everything I need in sequence.
  • Ignore Keynote’s (broken) ability to export the slide timings. Instead, “Show Package Contents” on the Keynote document and pull out the QuickTime file inside that contains the narration audio.
  • Convert that audio to AIFF using QuickTime Pro (well worth the price as a general-purpose audio and video tool, by the way).
  • Drag the exported audio to the Gigavox Levelator. This is a wonderful time-saving tool that pretty much sorts out varying audio levels in a file at zero effort. It’s free for non-commercial use.
  • Fire up Audacity audio editor and edit out the mistakes, pregnant pauses and weird mouth noises. Add a 30-second silence to the start to allow some wiggle room when re-running Keynote (see later).
  • Pipe the output from Audacity back into Keynote via the Soundflower audio routing utility. Audacity has its own output device selector; you can get Keynote to record from Soundflower by changing the input device in the system Sound input preference tab.
  • Do a second run-through in Keynote “recording” the edited narration coming in from Audacity while stepping through the slides again.
  • Export this clean recording from Keynote as a QuickTime movie. To make sure I don’t lose any detail at this stage, I select custom settings and the Apple Intermediate Codec. The resulting file can be quite large, but I find that you don’t want to compress using a final output codec like H.264 until you really are done.
  • Final joining of sections of a larger presentation, and trimming of the content, can be done in QuickTime Pro. After that, you have a file you can convert to any delivery format you like.

On the hardware side, I’m using a Sennheiser e815S microphone and an M-Audio Fast Track USB interface. Which is to say, I’m using the cheapest non-junk bundle I could find a year or so back. While this is far from professional studio audio standard in any sense, it is a huge step above either a built-in microphone or one of those desktop microphones that used to come with PC sound cards.

The biggest problems I’ve had with sound quality from this setup have all been rookie mistakes; for example, the golden ears among my readership will easily discern a quality jump in the recording at the start of the “Trust” section. Before that point, I had the microphone on a metal desk stand which meant that it was picking up keyboard and other noise through the stand. From “Trust” onwards, the microphone was mounted on a photographic tripod pretending to be a microphone boom by having its legs splayed out in interesting ways and weighted with lumps of metal. Far from ideal, but it makes a surprisingly large difference to the sound. If I do any more of this kind of thing, top of my list is a proper boom-style microphone stand.

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