In September I became a planetarium director. It made sense, I'm a professional astronomer and have run shows using a couple of different Spitz projectors and even an old Zeiss. This was my first fisheye fulldome experience. Should be straightforward, right? The fulldome projector is offset from the dome center, however, because the Spitz is still in residence in its doghouse in the geometric center of the 44' dome.

The projector is a JVC SX21 D-ILA (native 1400x1050) so the "1K" circular image is 1024 across, but the controlling software is Konica-Minolta's MediaGlobe2. This is not a new system. It was about to be discontinued when the planetarium purchased it in 2009, in fact, so the MG2 software demands demuxed video-plus-audio of the pretty much antique m2v-plus-ogg format.

Our planetarium has almost no budget for content right now, since the board have had to repair the projector and take care of other deferred maintenance. In order to get "new-to-us" content I've been signing up for whatever free fulldome shows NSF or NASA or ESA funding has permitted to be offered to planetaria for educational showing. There is no separate fee for the planetarium shows, and the planetarium fills an informal educational role, hosting school field trips and the like.

OK, I've been able to locate some free shows that don't demand hundreds of dollars for "a hard drive to hold it, plus shipping and handling charges" (which is one way of charging something for a government grant-supported production despite the requirement that the grant-supported production be made freely available). [Seriously? These shows in 1K format are a couple of gig, you could stick 'em on a thumb drive or put them into dropbox...]  What is even more challenging from my POV is that the free shows are almost all distributed in more recent video formats. Usually as mp4 files. Hey, even that is OK, there are programs that will take an mp4 and demux it into an m2v-plus-ogg pair of files, BUT... the free one that does this well is a Linux program called ffmpeg.

So, copy files over to Linux machine, break mp4 into m2v-plus-ogg, note that the two files have the same run time when played separately, load into the Mediaglobe system using their very picky procedure, and boom, the files run but they start out ever-so-slightly out of sync and then as the ogg file plays at a perfectly steady and sedate rate, the video is farther and farther ahead of it! It's not a constant offset, it expands as time goes on, which suggests the sampling rate is off or the playback rate is off. The audio is not out of tune or compressed or otherwise weird-sounding, so this has got to be a problem with the m2v replay rate.

More later...