1 == Exploring Julia in 4 dimensions ==
3 The discovery of the [[http://www.skytopia.com/project/fractal/mandelbulb.html | Mandelbulb]] awekened my old
6 So I took the time to re-encode my old rendering of the [[http://en.wikipedia.org/wiki/Quaternion | Quaternion]]
7 [[http://en.wikipedia.org/wiki/Julia_set | Julia set]] done with POV-Ray. Behold:
9 {{pictures/julia4D/julia4D-640x360.ogv | Quaternion Julia 4D fractal (640x360 @ 1200Kbit/s, Ogg Theora encoded)}}
11 The sound track is [[http://lite.modarchive.org/index.php?request=view_by_moduleid&query=59288 | UranChrome]],
12 an old-skool Amiga SoundTracker module composed by TorbJ0rn in 1989.
16 If your browser sucks at HTML5, you can directly download the video files, available in several formats:
18 || **Filename** || **Resolution**|| **Birate** ||**Video**||**Audio**||**Size**||
19 || [[pictures/julia4D/julia4D.ogv | julia4D.ogv (Ogg)]] || 1280x720 || 6000Kbit/s || Theora || Vorbis || 60MB ||
20 || [[pictures/julia4D/julia4D-640x360.ogv | julia4D-640x360.ogv (Ogg)]] || 640x320 || 1200Kbit/s || Theora || Vorbis || 13MB ||
21 || [[pictures/julia4D/julia4D.avi | julia4D .avi]] || 1280x720 || 6000Kbit/s || H.264 || - || 60MB ||
22 || [[pictures/julia4D/julia4D-640x360.avi | julia4D-640x360.avi]] || 640x360 || 1200kbit/s || H.264 || - || 12MB ||
24 === Rendering notes ===
26 It took about 2 weeks of computation on a dual-core machine to render the 2048 high resolution frames contained in 82 seconds of video.
27 My previous renderings at lower resolution and lower iteration count were much faster.
29 A The high iteration count actually makes the fractal surface a little too polverized to appreciate. Adding transparency
30 and gradients is another bad idea as it complicates things even more. If I find the time and motivation to re-render the
31 animation, I'll look for better balance.
33 In case someone wants to experiment, these are the [[pictures/julia4D/julia4D.pov | scene source]]
34 and [[pictures/julia4D/julia4D.ini | ini file]] I used.
36 === Video encoding notes ===
38 The files were encoded from a sequence of PNG frames generated by POV-Ray,
39 using **ffmpeg** and **mencoder**:
43 please mencoder 'mf://julia4D????.png' -mf fps=25 \
44 -ovc x264 -x264encopts bitrate=6000:pass=1:threads=2 -o julia4D.avi
47 please mencoder 'mf://julia4D????.png' -mf fps=25 -vf scale=640:360 \
48 -ovc x264 -x264encopts bitrate=1200:pass=1:threads=2 -o julia4D-640x360.avi
51 please ffmpeg -f image2 -i julia4D%04d.png \
52 -threads 2 -vb 6000k -vcodec libtheora -acodec libvorbis -f ogg julia4D.ogv \
53 -i UranChrome-fx-short.wav -acodec libvorbis -ab 96k -newaudio
56 please ffmpeg -f image2 -i julia4D%04d.png \
57 -threads 2 -s 640x360 -vb 1200k -vcodec libtheora -f ogg julia4D-640x360.ogv \
58 -i UranChrome-fx-short.wav -acodec libvorbis -ab 96k -newaudio
61 This is the software I have used:
64 MEncoder SVN-r29800-4.4.2 (C) 2000-2009 MPlayer Team
65 FFmpeg version SVN-r20372, Copyright (c) 2000-2009 Fabrice Bellard, et al.
68 x264-libs-0.26.20091026
71 The quality of the low-res Theora stream is noticeably lower than the corresponding low-res H.264. I don't know why.