Wednesday, August 20, 2014

Screencasting on Linux Mint 17

Sometimes I post philosophical essays, and sometimes I describe important teaching experiences, and sometimes I reflect on my miniature painting hobby. Today, however, I go to that much more pragmatic use of the blog: writing down how I actually got screencasting to work on my work machine.

I have a Dell Precision T3600 running Linux Mint 17. I switched from KUbuntu to Mint on my work machines last year, when I had some trouble with hardware recognition. Since I've been using KDE for over a decade (from Mandrake to Mandriva to KUbuntu), I use the KDE distribution of Mint as well. It seems this puts me in the minority, as most of the Q&A I see online assumes one is running something newfangled.

I have USB Logitech headphones that used for the screencast. After a bit of fighting with my mixer, I was able to get the microphone to work: the system wants to default to the hardware ports, even when there's nothing connected there. Audacity makes it very easy to test the sound configuration, and so I was sure that the microphone was working.

However, getting that microphone to work through screencast software was another problem entirely. I had no luck with the old standard recordmydesktop at all: video capture was fine, but the audio came up with nothing. A bit of searching revealed some newer applications I had never heard of. Vokoscreen had a reasonable user-interface with several configuration options, and I was confident enough to record an 11-minute take. Unfortunately, upon playing back, the audio was terribly choppy. I spent quite a bit of time fiddling with the framerate and pulseaudio settings trying to fix this, since otherwise Vokoscreen was convenient to use, but a tutorial with no audio is hardly a tutorial at all. Since the mic was working fine in Audacity, I inferred that it was a software problem, not a hardware problem.

I switched over to Kazam, and this ended up doing the trick. It allowed me to select an area of the screen where I could hop between Eclipse, Chromium, and the console, and the audio was captured with no trouble. The default file format uploaded flawlessly to YouTube, and I was able to share the video with my students. I had actually tried Kazam before Vokoscreen, but it wasn't working—turns out it was because I had the mixer settings for my mic much too low, and they needed to be at almost 100%. (Recordmydesktop still did not work with this fix, incidentally.)

The screencast itself is just an explanation of how to set up a PlayN project and hook it up to a Mercurial repository using the Computer Science Department's Redmine server. Hopefully next time I want to do an 11-minute screencast, it will take less than two hours of tinkering.

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