# Video recording

If you want to work with video for analysis there are several things to think about:

• Permission: Remember to get a permission to record the performance
• Lighting: The better light, the better image result and the better analysis result. This is not so easy to control in the concert situation, unless you are able to talk to the light technician beforehand (if there is one).

## Recording tips

Before starting the discussion of various types of visualisation techniques, it might be useful to quickly review some things that may be worth thinking about when preparing video material for this type of analysis. Recording and editing video for analytical purposes is often quite different than when the video material is mainly going to be used for visual inspection. Here are some hints that may help improve the recordings:

Background: Try to place the camera so that there are as few distractions as possible in the background. This makes it easier to separate the foreground (e.g. a musician) from the background, something which is of vital importance for quantitative analysis but also very useful for qualitative analysis. In a laboratory setting this can be achieved easily by using a simple single-coloured backdrop. Outside the lab it might not be possible to change the background, but often it is possible to improve the result by looking for camera angles that give a better visual result.

Lighting: Having good and even lighting will always result in better video recordings, which again will lead to better analysis results. In a concert situation where the lighting is changing (colours and/or luminosity) it may be worth thinking about recording with night mode on the camera, or use a filter on the camera that will only let infrared light through.

Motion: Since most of the visualisation techniques that will be presented here are based on creating a \emph{motion image} (see Section~\ref{sect:motion-image}), it is important that there are no external moving elements in the image (people, curtains, etc.) in the background. The computer won't be able to differentiate meaningful from non-meaningful movements, so any external movements will also be reflected in the visualisation.

Stand: Camera motion will also influence the analysis, so it is best to use a camera stand and leave the camera untouched while recording. This includes any type of panning and zooming, since this will also show up in the final analysis. To get both detail and an overview (e.g. a single musician vs. a group of musicians), it is often better to use multiple cameras than trying to get both with one camera.

Microphones: It is often easier to place the camera(s) at a distance (e.g. in concert halls), and use the zoom to frame the image correctly. This is seldom the best placement in terms of getting a good sound quality, so it might be worth trying to record sound through external microphones placed closer to the sound source.

Thinking about some of these points will result in recordings that are better suited for visualisation and analysis.

## Recording with multiple cameras

Often it is best to record with two cameras. Place one camera in the back that will record everything, and use one camera to record closeups. In the editing software you can add both video streams to the timeline, and then use the best shot for the final video.

Synchronization of the two (or more) recordings is always a challenge. The classic method of doing this is by clapping in front of the camera, or taking a photo with a camera firing a flash. These markers can then be used to synchronize the video afterward. An alternative method, if the cameras allow for it, is to use something like SMPTE time code to handle the syncing.

## Selecting camera

There are lots of cameras out there. Which one to choose? A few things that are important from a musical point of view:

• Microphone input: many cameras do not have the ability to connect an external microphone, and should be avoided. Most cameras that do have a connector only offers a minijack, while some of the larger professional cameras also include an expander with XLR and phantom power.
• 3 CCD: lighting conditions often differ greatly during concerts, so having 3 CCD is important for getting the best light conditions
• Lens: in a typical concert situation you will either have to place the camera at the back or at the front of the room. Somewhere in between will most likely lead to problems with people getting the camera in the sightline, people bumping into the camera etc. If you are at the back you probably need a zoom lens, if you are in the front you need a wide angle lens or converter.
• HD: this is the future of digital video, and it does not make sense to buy a SD camera nowadays.

Some possible cameras:

Reviews:

## Editing

There is a multitude of video editing programs available. OSX ships with iMovie, Windows ships with Windows MovieMaker.

Many people don't know that QuickTime Pro is also a really quick and easy to use video editor.

## Converting

Converting files is often a challenge.

OSX:

• MPEG Streamclip
• HandBrake
• WonderShare Video Converter (shareware)

Windows: