Tuesday, June 30, 2015

fulldome short - 2015 - Year of Light

2015 YEAR OF LIGHT - the International Year of Light is a global initiative adopted by the United Nations to raise awareness of how optical technologies promote sustainable development and provide solutions to worldwide challenges in energy, education, agriculture, communications and health. In this short immersive film by Carl Zeiss, seven minutes of memorable visualisations highlight various significant aspects of light. Visible or invisible, light is everywhere. We are reminded of its omnipresence and how - amongst other things - light creates moods and emotions, is turned into electricity, is a manufacturing tool and is used for communications.
FILM TYPE - Science
Key Stages 2-5, General audiences
Length: 7 min

Available from British Fulldome Institute,


fulldome clip - GALACTIC JOURNEY

GALACTIC JOURNEY - fly your audience across immense regions of deep space with this accurate visualisation of 120,000 galaxies viewed from the southern hemisphere. Courtesy of the Anglo-Australian Observatory, Paul Bourke, Peter Morse & Glenn Rogers
Key Stages 3-5, General audiences
Length: 2.5 min

Available from BFI,


Monday, June 29, 2015

extracting audio from mov file

A quicktime video file (.mov) from eplanetarium displayed unknown input format in KMplayer, which did play it, but was not being recognized by directshow. Avidemux was able to extract the audio - chose audio output PCM and saved it as .pcm - then Cool Edit Pro could read it. 

Thursday, June 25, 2015

problems with Unicode fonts on QuickTime7 for Windows

Working with the eplanetarium team for Indian language subtitles, we ran into a road-block - the workaround seems to be only burnt-in subtitles.

The issue seems to be that QT7 on Windows - and MediaShow, which runs on QT - does not support Unicode for subtitles. Excerpts from my emails below:

... I tried this technique given here,

Unfortunately, the Hindi option does not even appear ... The reason seems to be that only ISCII Hindi (Devanagari script) is supported and not Unicode Devanagari, as seen in the code conversion tables. So, it may not be possible to display the Unicode Hindi characters using the current subtitling tool and playback tool combination on Windows. Unicode capable playback tools seem to be able to display, like KMPlayer ... One caveat for Indian languages is that many operating systems have limited support for complex scripts. We may have to check if your subtitle creation software as well as the subtitle display software have proper Indic support. If not, the script would be jumbled. ....

Tuesday, June 16, 2015

Assignments in Matlab

One of the students requested pointers for some assignments or mini projects he could do in Matlab. Here was my reply:

Since I'm not familiar with abstract math problems with Matlab, I'll have to suggest what I know about, and also what is got by googling. So, please take these only as vague pointers, discuss with your concerned teacher before proceeding further.
1. Visualizations. Matlab has got very nice built in plotting tools. Visualizations of fractals, chaotic system equations, other differential equations etc could be done. The Mandelbrot function is already implemented, you could play around with it to learn more, and implement other fractals.
If you make high-resolution circularly symmetric movies, you could also help the planetarium,
All sorts of value-added stuff can be done with visualizations - making guis for varying parameters, interactive graphs, etc etc.
2. Matlab has got a Symbolic Math toolkit. All sorts of higher level math can be modelled using this, like
3. Linear Algebra problems, Manifolds and such are very much solvable with Matlab, so taking up some problems with these might be useful, eg.
http://www.manopt.org/and many more,
4. Scilab and Octave are open source Matlab clones. If you are looking at the programming side, there are many small functions which can be written for Scilab and Octave for better Matlab compatibility. 

Thursday, June 11, 2015

dropped samples - clicks on Audition recordings

Found this issue of dropped samples - leading to clicks - on Audition recordings at Studio with the Audiogram interface. And maybe even with the Presonus too. The workaround was to record using Nuendo. S emailed with the solution as implemented by PB - 

The clicks problem recurred and PB has once again reset the Preferences/Audition folder.
Now it is fine. 

Finder/Go/Option key/Library/Pref/Audition -->Trash

Wednesday, June 10, 2015

full playback of downloaded youtube 1080p videos

In my earlier post, I had noted that the files repaired with mp4box -isma still would not play with DirectShow etc. Finally did a better analysis of the issue and found a solution.

As the mp4box documentation says, mp4box -info file.mp4 gives information about the file. Found that the downloaded youtube mp4 file, after the -isma fix, had three streams, like
Track # 1 Info - TrackID 201 - TimeScale 90000 - Duration 00:30:14.033
Track # 2 Info - TrackID 2 - TimeScale 90000 - Duration 00:00:01.000
Track # 3 Info - TrackID 1 - TimeScale 90000 - Duration 00:00:01.000

So, taking out only the genuine video track, in this case TrackID 201, made the file playable. In my case, I added the audio from the 360p file also, as below.

mp4box -add E1080p.mp4#201 -add E360p.mp4#audio E.mp4

So the output file E.mp4 contains the video track with TrackID 201 and the audio track from the second file - this file plays fine with DirectShow. 

Friday, June 05, 2015

recording tests with Zoom H1

The Zoom H1 I had sent for RK's Hindi voice-over has arrived here now. It can also work as a USB mic. Simplest way to record seems to be with Cool Edit Pro.

With Reaper, have to make sure that the sampling rate is set to the same sampling rate as on the H1, otherwise the recording comes out with breaks. File -> Project Settings -> Project Sample Rate, then Options -> Preferences -> Audio -> Device -> Audio System has to be set to ASIO and again the sample rate has to be set.

Noise floor is impressively low. A sample I recorded at the Studio on the Presonus digital mixer there, using a dynamic mic and with air-conditioning on had a noise floor of -50 dB. Compared to that, from my office room, with the computer, AC, fan etc turned off, the Zoom H1 with input level set to 40% had a noise floor of -63 dB! That was recording to the micro-SD card. With computer on and recording via USB - using the H1 as a USB mic - the noise floor was around -54 dB - mostly the computer fan noise. Bird sounds and outside traffic sounds were below -50 dB when the mic was next to my mouth,  input level set to 40%, covered with a foam windscreen (pop filter). With AC on, a floor of around -45 dB.