Thursday, December 30, 2010

Geminid Meteor Shower 2010 Time-Lapse Movie

I’ve taken my 686 photos of the 2010 Geminid meteor shower on December 13/14 and transformed them into the following high-definition (1080p), time-lapse movie, which I hope you will enjoy. It spans 6¼ hours of time in two minutes, contains approximately 34 meteors, several airplanes, and a couple of satellites. Also, you get to watch the sky as it appears to rotate around the polestar, Polaris.

High-definition, time-lapse movie of the 2010 Geminid meteor shower.
87.1 MB, 1080p (1920 x 1080), MPEG-4 (H.264) video.
No sound.

Be aware that if you watch this video in your web browser, and your screen isn’t large enough to display the whole thing, Firefox and Chrome don’t seem to have any support for scaling down the video, but Safari does – just use the “Zoom Out” item in the “View” menu.

The original, 87.1 megabyte, 1080p movie linked-to above is hosted on the Internet Archive, where preservation of the original material matters. For user convenience and accessibility, the Internet Archive also makes it standard practice to offer scaled-down versions of movies, and versions transcoded into other common formats, but I recommend viewing only the original movie in this case – the scaled-down versions are much too small for most of the meteors to be seen.

(By the way, those 87.1 megabytes are real, original 220-byte megabytes, not NIST’s redefined, demented 106-byte megabytes. So, if you download the movie and are told by your web browser or operating system that the movie is 91.3 megabytes, you’ll know that you are being shown politically correct, little megabytes, rather than real ones. Pet peeve. Excuse the digression.)

Creating the Movie

Creating this movie, and getting it properly hosted somewhere, took quite some doing. The original photos were all 18 megapixel raw images in “portrait” (vertical) orientation. They had to be scaled down to 0.78 megapixel images to fit in a “high-definition” (don’t make me laugh) video, then I had to write software to letterbox each frame (if that’s the still the appropriate term when adding vertical bars to the sides, rather than horizontal bars to the top and bottom) while reading each frame’s metadata, so that a correct timestamp could be drawn into each frame. Then those frames had to be combined into a movie, which is easily done with QuickTime Player 7, but all of my efforts to convert that movie directly to an MP4 (H.264) movie seemed to produce quantization errors within the vertical gradation of brightness in the sky. In any case, I wanted to add some explanation, so the QuickTime movie composed of the separate PNG files produced by my letterboxer was imported into iMovie, then a few hours of futzing with iMovie (mostly trying to remember how to use it) were required. After that, there were four or five 30 minute rounds of exporting the movie, viewing it, deciding something wasn’t quite right, adjusting the errant element, re-exporting the movie, and repeating.

Oddly, iMovie 8.0.6 (from the iLife ’09 package) doesn't directly support exporting movies at 1080p, so I had to use its QuickTime export mode, and manually select the relevant parameters. Which is ironic, because, as mentioned, I couldn’t get QuickTime to encode the original movie in H.264 without it adding quantization artifacts to the sky. So, why wasn’t that a problem when using the same QuickTime codec from iMovie? I’m not sure. One possibility is that after all that time, I became oblivious to the quantization artifacts. Another is that iMovie made some adjustments to the movie to bring it within a gamut that QuickTime’s H.264 codec could handle gracefully. (FWIW, I’ve since acquired iMovie 9.0 from the iLife ’11 package, and it does support direct 1080p export – not that that's relevant to the encoding issues, since it'll be using the same QuickTime codecs as its predecessor.)

Publishing the Movie

Creating the movie was only half the problem. The other was finding a site to host the movie. After determining that YouTube will support 1080p high-definition video, my first thought was to publish it there, because (1) everyone is used to looking for video media there, and (2) many Internet-connected high-definition televisions, and related devices like the various high-def TiVos (1080i only, unfortunately), can download video directly from YouTube, which is convenient. Unfortunately, YouTube transcoded the video. Video transcoding is standard practice with YouTube, presumably to make everything compatible with their Flash video player, but also, I suspect, to reduce movie sizes. For some videos the loss of quality isn’t too obvious, but this is not one of those videos. Not only did the transcoding badly blur the fine details in the night sky, thereby eliminating various small stars, faint meteors, etc., but it also corrupted the start of the movie. I had worried about the blurring, but hoped they’d do less of that to high-def videos (wrong). The video corruption, however, really took me by surprise.

One of the early frames corrupted by YouTube.
Compare to the image up top, which is how the frame actually appeared.

My experience publishing on YouTube is minimal, but the possibility that they could still have bugs like that in their video processing system after processing untold millions of videos over the years, hadn’t occurred to me. I reported the bug, but there’s been no follow-up, perhaps, in part, because their bug reporting system, which includes the good idea of allowing you to capture screen shots in order to illustrate the bug, won’t capture any portion of the video on a page (at least not when I tried it in current versions of Safari, Chrome and Firefox on Mac OS X 10.6.5). Since the video was the subject of the bug report, their clever, but not clever enough, bug reporting system backfired quite effectively.

After acquiring iMovie 9.0, which has direct-to-YouTube 1080p video export built-in, I tried posting the movie again. This time it wasn’t corrupted, but the quality of the video is otherwise no better. If you want to compare-and-contrast with the Internet Archive video, you can see the YouTube video below. (Once it starts playing, be sure to go to the pop-up menu near the lower-right corner that’s labelled “240p” and pick the “1080p” option, instead, then expand the video to full-screen, by clicking the icon in the lower-right corner).

Unfortunately, the original, high-quality video available from the Internet Archive can’t be viewed on most (any?) high-definition televisions, not because of video format problems (the video is already in the MPEG-4 format used for high-definition television), but simply because the TVs don’t come with software for downloading video from the Internet Archive (or arbitrary URLs). However, if you care enough (and if your computer monitor is large enough, there’s no reason to care), you can view it indirectly by downloading the video to your computer, copying it to a USB flash drive, plugging that into most HDTVs (typically, there’s a USB port or two on the back), and watching it that way. Not exactly convenient, but it will work.


  1. Alison in Indiana8:38 PM CST

    I am glad you gave us the YouTube version, even if it is not so good - because I will never know if it is or not. The download symbol says "done" - but nothing is there.
    It probably would have maxed out my old computer anyway.
    Have the squirrels cleaned out the bee hive yet?

  2. played beautifully on safari. The windmill was a perfect reference point - also in movement, to its own tune. Good choice! thanks!