Saturday, December 24, 2011

Documenting Computer Work Onscreen - Second Try

I had previously used my Shotshooter.bat batch file to capture screenshots once or more per second, and had combined them into an IrfanView slideshow .exe to display a timelapse account of what I had been doing on the computer during a certain period of time.  I preferred to create a regular video file rather than an executable, and I also wanted to be able to add music, narration, or other audio.  So I tried again.

The problem wasn't video capture per se.  I had purchased a copy of Debut for that, after mixed results with freeware alternatives.  The problem was getting from the raw Debut output to the final video.  When I would import the Debut .avi into a video editor like Adobe Premiere Elements or CyberLink PowerDirector, the video quality would be seriously degraded.  It was possibly a problem with a simple setting in the editing program, but I hadn't yet figured out the solution.  At this point, for whatever reason, the resulting video of events on my computer's monitor was so poor as to be unreadable.

But let me back up.  Here's how I started.  I decided to try capturing my work in writing an essay.  It would wind up being a one-page document, so the whole thing was visible onscreen in Microsoft Word.  I had Word set to remember changes, so after hours of editing, I held down the Ctrl-Z key combination to keep undoing changes until I was back at the beginning.  (Before doing that, I saved a copy of the text.  One false keystroke would have destroyed the trail, and my essay would have been lost.)  When I was back at the beginning, I started the screen capture, using Debut.  Then, in Word, I held down the Ctrl-Y key combination to redo everything I had done, at a very rapid pace, while Debut was capturing.  I think I had set Debut to capture at seven frames per second (fps), so as to keep the .avi file somewhat smaller than it would have been at 30 fps.  When it was done, I stopped Debut and saved the .avi.

Now came the hard part.  Adobe and CyberLink weren't the only ones having problems with the Debut .avi output.  Media Player Classic (MPC) would likewise display that .avi in a severely distorted form.  In other trials, MPC played the audio but gave me only a black screen for the video.  QuickTime did just the opposite, playing the video but crapping out on the audio after a few seconds.  But for some reason, VLC and Microsoft's Windows Media Player (WMP) had no problem with it.  It was not clear why.  I would have guessed that my codecs needed updating, but I had just installed the latest K-Lite Mega Pack.

After much playing around, I found that VirtualDub was able to add an audio track, adjust the length of the video to the length of that audio track, and produce a relatively small .avi (but, regrettably, not an .mpg or some other compressed format) that WMP would play.  This video was about four minutes long and, at a 250 kbps setting (Microsoft Video 1, quality 100), it was about 70MB.  That was still huge in comparison to the IrfanView output, but it was nice to have the audio option.  At that bitrate, the video contained fade-like artifacts.  That is, when I deleted or changed some text in the original video, it faded out rather than just instantly disappearing.  It actually wasn't a bad effect, and I didn't want to upload a 700MB video, so I left it at that for now.

There seemed to be some artistic possibilities for this technique.  At some points, the beat of the music would coincide with the disappearance of lines of text, as if there were a rhythm to the editing.  Maybe there was, in some cosmic sense.

The remaining question was whether anyone else would be able to view this video.  I wasn't sure how it would turn out on YouTube.  So I uploaded and tried it.  It looked OK in full-screen mode on YouTube, viewed in Firefox and also in Chrome.  I downloaded it from YouTube, using NetVideoHunter.  The download was in .mp4 format.  It still didn't play right in WMP, but it played better in QuickTime, and it was less than half the size of the .avi I had uploaded.  So I thought perhaps I could have uploaded the 700MB version and used YouTube to compress it for me.

I still didn't have a straightforward process for putting high-quality screen capture video into a format that I could edit in a normal video editing program like Adobe Premiere Elements.  It seemed that, next time, I might try recording my original video in something other than Debut, to explore the possibility that that particular program had saved my video in an odd format that Premiere Elements and other programs couldn't handle.  I could also explore rapid Shotshooter screenshots, at least to the extent that my computer would be able to save multiple screenshots per second.  Then maybe I could also try using Premiere Elements, instead of IrfanView, to stitch those screenshots together into a time-compressed but visually high-quality production to which I could also add audio.

1 comments:

raywood

I just found (but haven't yet tried) the suggestion to use this command to take instant screenshots with a file timestamp, using IrfanView: "i_view32.exe /capture=0 /convert=c:\temp\capture_$U(%d%m%Y_%H%M%S).jpg"