ARJ » Video http://www.arj.no Alexander Refsum Jensenius Thu, 09 Sep 2010 15:10:57 +0000 en hourly 1 http://wordpress.org/?v=3.0.1 Screen recording in QuickTime X http://www.arj.no/2010/08/27/screen-recording-in-quicktime-x/ http://www.arj.no/2010/08/27/screen-recording-in-quicktime-x/#comments Fri, 27 Aug 2010 12:25:15 +0000 alexarje http://www.arj.no/?p=1194 I just discovered that QuickTime X has built in support for screen recording. I have been using iShowU for screen recordings for a while, and while it has the advantage of recording only a portion of the screen, the QT approach seems to be easier and quicker to work with. Short tutorial below:

]]> http://www.arj.no/2010/08/27/screen-recording-in-quicktime-x/feed/ 0 New motiongram features http://www.arj.no/2010/07/02/motiongram/ http://www.arj.no/2010/07/02/motiongram/#comments Fri, 02 Jul 2010 15:12:39 +0000 alexarje http://www.arj.no/2010/07/02/motiongram/ Inspired by the work Static no. 12 by Daniel Crooks that I watched at the Sydney Biennale a couple of weeks ago, I have added the option of scanning a single column in the jmod.motiongram% module in Jamoma. Here is a video that shows how this works in practice:

About motiongrams A motiongram is a way of displaying motion (e.g. human motion) in the time-domain, somehow similar to how we are used to working with time-representations of audio (e.g. waveform displays and sono/spectrograms). The method is based on creating a motion image, doing a matrix reduction on it and plotting the resultant 1xn or nx1 matrices over time either horizontally or vertically.

Comparison of motiongrams Below is an image showing three different types of motiongrams:

  1. Single line scan based on regular image
  2. Average scan based on regular image
  3. Average scan based on motion image

I think all of them are interesting, so the use of them will have to be adjusted according to what type of material you are working with.

 

]]> http://www.arj.no/2010/07/02/motiongram/feed/ 0 Black box in the lab http://www.arj.no/2008/07/17/black-box-in-the-lab/ http://www.arj.no/2008/07/17/black-box-in-the-lab/#comments Thu, 17 Jul 2008 07:27:05 +0000 alexarje http://www.arj.no/?p=623 Last week we started setting up a “black box” in the new lab space. It is great to finally have a more permanent motion lab set up that we can use for various types of observation studies and recording sessions.

Motion lab

]]> http://www.arj.no/2008/07/17/black-box-in-the-lab/feed/ 2 AudioVideoAnalysis http://www.arj.no/2008/06/17/audiovideoanalysis/ http://www.arj.no/2008/06/17/audiovideoanalysis/#comments Tue, 17 Jun 2008 09:36:17 +0000 alexarje http://www.arj.no/?p=619 To allow everyone to watch their own synchronised spectrograms and motiongrams, I have made a small application called AudioVideoAnalysis.

It currently has the following features:

  • Draws a spectrogram from any connected microphone
  • Draws a motiongram/videogram from any connected camera
  • Press the escape button to toggle fullscreen mode

Built with Max/MSP by Cycling ’74 on OS X.5. I will probably make a Windows version at some point, but haven’t gotten that far yet.

A snapshot of the main interface:

The main window of the AudioVideoAnalysis application

The fullscreen can be toggled with the escape button:

Fullscreen mode in the AudioVideoAnalysis application

The are, obviously, lots of things that can and will be improved in future versions. Please let me know of any problems you experience with the application, and if there is anything in particular you think should be included.

]]> http://www.arj.no/2008/06/17/audiovideoanalysis/feed/ 4 Sonification of Traveling Landscapes http://www.arj.no/2008/05/15/sonification-of-traveling-landscapes/ http://www.arj.no/2008/05/15/sonification-of-traveling-landscapes/#comments Thu, 15 May 2008 08:22:04 +0000 alexarje http://www.arj.no/2008/05/15/sonification-of-traveling-landscapes/ I just heard a talk called “Real-Time Synaesthetic Sonification of Traveling Landscapes” (PDF) by Tim Pohle and Peter Knees from the Department of Computational Perception (great name!) in Linz. They have made an application creating music from a moving video camera. The implementation is based on grabbing a one pixel wide column from the video, plotting these columns and sonifying the image. Interestingly enough, the images they get out (see below) of this are very close to the motiongrams and videograms I have been working on.

Picture 1.png

]]> http://www.arj.no/2008/05/15/sonification-of-traveling-landscapes/feed/ 0 GeoVision MPEG4 Codec http://www.arj.no/2007/11/14/geovision-mpeg4-codec/ http://www.arj.no/2007/11/14/geovision-mpeg4-codec/#comments Wed, 14 Nov 2007 17:48:20 +0000 alexarje http://www.arj.no/2007/11/14/geovision-mpeg4-codec/ I recently received a video file with some material I am supposed to analyse. The problem was that I couldn’t figure out what type of codec was used. VLC told me that it uses a codec called GMP4. After some research I have found that this means an MPEG-4 codec developed by GeoVision. I have found a windows version of this codec, but nothing for OS X. If anyone has any ideas, please shout out.

]]> http://www.arj.no/2007/11/14/geovision-mpeg4-codec/feed/ 1 Flash Movie Conversion on OS X http://www.arj.no/2007/10/15/flash-movie-conversion-on-os-x/ http://www.arj.no/2007/10/15/flash-movie-conversion-on-os-x/#comments Mon, 15 Oct 2007 15:12:38 +0000 alexarje http://www.arj.no/2007/10/15/flash-movie-conversion-on-os-x/ Looking for a solution to make flash movies on OS X, I came across this nice tutorial based on FFMPEGX. In terms of video quality I prefer to create videos with H.264 compression using MPEG Streamclip, but since flash seems to be the de facto standard on the web these days I will try to use this for an upcoming project.

ffmpegx_flv1.png

]]> http://www.arj.no/2007/10/15/flash-movie-conversion-on-os-x/feed/ 0 Video broadcasting http://www.arj.no/2007/09/14/icast-you-iconcert-to-your-ifans-at-musikkteknologen/ http://www.arj.no/2007/09/14/icast-you-iconcert-to-your-ifans-at-musikkteknologen/#comments Fri, 14 Sep 2007 12:45:57 +0000 alexarje http://www.arj.no/2007/09/14/icast-you-iconcert-to-your-ifans-at-musikkteknologen/ Vegard mentioned QuickTime Broadcaster in a blog entry yesterday. While QT broadcaster is certainly easy to set up and use, I have found it even easier to use some of the video broadcasting solutions in Max/MSP/Jitter. The jit.qt.broadcast object allows for QT streaming, but I have found the jit.broadcast object using RTSP to be somewhat more stable. Using Jitter also opens for all sorts of image manipulation, text overlays etc. as we are used to in the Max/MSP world.

Below is a snapshot from the help file of jit.broadcast. Getting started broadcasting video is as easy as clicking on a couple of buttons.

Help file of jit.broadcast

]]> http://www.arj.no/2007/09/14/icast-you-iconcert-to-your-ifans-at-musikkteknologen/feed/ 2 Choosing the Right Video Format http://www.arj.no/2007/04/05/choosing-the-right-video-format/ http://www.arj.no/2007/04/05/choosing-the-right-video-format/#comments Thu, 05 Apr 2007 10:36:04 +0000 alexarje http://www.arj.no/2007/04/05/choosing-the-right-video-format/ The discussion about video standards for live processing has been summarised as:

  1. Codec: Motion JPEG (for interlaced footage) or Photo JPEG.

  2. Compression ratio/quality: Quality 80 is a decent baseline for JPEG, though you can crank as high as 97 to improve quality.

  3. Keyframes: Encode a keyframe on every frame so it’s ‘scratch-ready’.

  4. Alpha channels: For video containing alpha channels, PNG is the format of choice.

Sounds like more or less the same conclusion that has been reached in the Jitter forum, when this question comes up there once in a while.

]]> http://www.arj.no/2007/04/05/choosing-the-right-video-format/feed/ 0 Optical Illusions and Visual Phenomena http://www.arj.no/2007/01/29/optical-illusions-and-visual-phenomena/ http://www.arj.no/2007/01/29/optical-illusions-and-visual-phenomena/#comments Mon, 29 Jan 2007 18:17:53 +0000 alexarje http://www.arj.no/2007/01/29/optical-illusions-and-visual-phenomena/ illusionTalking about optical illusions, here’s a bunch of them. Great that many of them are made as javascripts so that the effects can be changed.

[ youtube=http://youtube.com/w/?v=_dIya1aJJKA]

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