Performance, programming and user interfaces: The Fifth eDance Intensive

11 08 2008

Last week, I attended the fifth eDance intensive in Bedford.  Upon arriving, we discovered that we were to put on a public performance on Friday (unfortunatly after I had to leave).  This increased the pressure somewhat, although our confidence in the recording software had recently improved after it had been successfully used to record the Research Methods Festival “What Is” sessions in Oxford over 4 days without incident.  To add further to this task, we were also to set up two separate spaces for this performance, with three cameras in each and audio conferencing between the spaces, and we hadn’t brought any echo-cancelling microphones and only powerful laptop!  We immediatly got on with the task of setting up the two spaces. 

One of the aspects of eDance that is different from Access Grid is the requirement of high-quality video at high frame-rates.  Access Grid has historically used H.261 video, which is transmitted at a resolution of 352 x 288, and tends to reach about 20 frames per second.  For eDance (and the related CREW project), we decided to use miniDV camcorders for the cameras using the firewire interface.  This allows 25 fps video at 720 x 576, 4 times the quality of regular Access Grid video.  Thankfully, AG is easily extensible, which allow us to make this change without much effort.  The main issue is however with the laptop processing load.  We initially thought that our tool was not very good in terms of CPU loading, and assumed that this was because we are using Java.  However, we tried to use Vic, the video tool that AG uses, and found that with the same resolution and frame-rate, this also tends to result in high CPU usage.  The main advantage that vic has over our tool is that it allows you to control the bandwidth and frame-rate of the transmitted video.  Fortunatly, the piece that Helen was composing did not require us to use all of our video streams simultanously, so we managed to get away without too much overloading (although the fans on the laptops were running full steam ahead)!

The first of the successful uses of the videos between the two spaces was a piece where the video from the top half of one person was displayed over the video of the bottom half of another.  The two dancers then had to coordinate their movements so that they appeared to be one person.  This produced some wonderful images, as well as some good comedy moments!

Our next issue came with a misunderstanding about what our software could do.  We had bragged about how we could now have transparent windows.  We also tested to see if the video underneath would also show through the one on top (rather than drawing a pink area as had happened before).  This lead Helen to start planning a piece that could use this functionality (it looked like it could be really cool – overlaying people onto a model of a village)!  Unfortunalty, the way the technology was working was to capture the scene behind the transparent video, and then statically mix this in.  This meant that the image behind the transparent window could not move.  I set to fixing this problem straight away (I had already thought about how this might work previously), but by the time I had made it work, Helen had moved away to something else.

 During the course of the week, there was a small saga related to the ordering of some drawing pads to arrive by next-day delivery on the Monday.  When these did arrive on the Thursday, Helen immediatly devised a new idea involving overlaying the drawings done on the devices over the video.  As I now had the transparent video working, we immediatly got this working by having the transparent video window on top of the drawings.  Michelle also worked out how to give this a nice black background with a light grey pen colour, so this looked good behind the video windows.

The second successful use of the software was then the drawing on the overlayed transparent video windows.  The dancers moved around the space, and then when the drawing pad operator said “Stop”, they froze while the operator drew around their shapes (and also sometimes the shape of their shadow).  This resulted some quite complex images!

 We also realised on the Thursday that we had still not got the audio working between the spaces.  As we did not have echo-cancelling equipment, our efforts using the audio in the software tended to result in loud noises being played into the spaces!  We decided that we should therefore use some software that had echo-cancelling built in, such as Skype or MSN Messenger.  Skype turned out not to work too well as it had not been tested on the Bedford campus.  Although this was resolved before the end of the week, we decided to stick with MSN Messenger as it seemed to work fine.  This meant that the audio was not recorded, but did mean that it didn’t echo!

Another limitation of the software was revealed when we were asked to play back some recorded media.  During the course of the week, we were joined by a video specialist who had recorded the performers using Google Maps (which looked very impressive) and also whilst out walking in a forest (which gave us some much-needed time to get the transparencies working, and to look at other software – see later).  We then had to ask her to write this back to DV tape to be imported into our software, as we couldn’t yet import avi or mpeg files.  We also realised that we would have to launch a separate instance of the software to play back each of the clips quickly, otherwise the audience would have to wait while we loaded each clip up.  With the CPU load high from receiving video, we had to add an option for these extra instances not to receive the transmitted videos, otherwise the computer would quickly become overloaded.  Anja did this and this worked well.

Finally, one important outcome from the intensive was us all finally working out how the interface might look from the video perspective.  We worked out that we had over-complicated the interface in terms of representing video timelines, and that it might be best if the interface looked a little bit like Microsoft PowerPoint (or other presentation editing software).  This would obviously have major differences, such as being able to edit what was seen on the live screen without exiting what would be Presentation Mode in PowerPoint.  We were also shown the user interfaces to other tools used during and before performances, such as Arkaos for “VJing” (like DJing but with video).  I have since developed a mockup (in PowerPoint funnily enough), for this interface, which takes some features from each of these tools, and adds some of our own.



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