How to Collect and Analyze Multiple Simultaneous Media Files – and why it’s worth the trouble.
When we know there will be more going on than we can observe and preserve at once, one solution is to create a plan to collect video as a representation of the reality we will observe. While video certainly has limitations, (for example, where you point the camera matters a lot,) it also has the advantages of permanence, allowing, for example, repeated viewing and easy sharing with colleagues for consultation. There are times when recording data with more than one camera at a time can provide exponentially more information that we can explore and interpret afterwards.
As video recording gets easier, more affordable, and more ubiquitous, researchers can more easily capture multiple perspectives by recording multiple, simultaneous video or audio data. One of the analytic challenges researchers face is that of managing those multiple simultaneous media streams so that they can be meaningfully analyzed. Fortunately, Transana offers a solution to this problem, allowing up to 4 simultaneous media files to be analyzed as a synchronized media stream.
We won’t talk about the mechanics of working with multiple simultaneous media files here, as that is covered well in Transana’s ScreenCasts. Adding Multiple Media Files to Transana shows how to add multiple simultaneous media files to Transana and how to synchronize the files. Creating Clips with Multiple Simultaneous Media File Data shows how to select which video or videos are included in the meaningful analytic segments you create from this coordinated data stream to allow you to make exactly the analytic point you want to make with your data. The Media Conversion ScreenCast can be helpful in showing you how to prepare your data so that your computer will be able to display multiple media streams at once.
Here are a few guidelines for preparation that can make the process of capturing and analyzing multiple simultaneous media files much easier:
- Start all cameras and recorders at about the same time. It’s easy to synchronize when there is common data at the start of all of the recordings, but if there are several minutes of difference in when recordings start, it can make identifying an overlap much more difficult.
- Have all cameras record a common sound at the beginning of the recording period, if possible. This can provide a useful anchor point for synchronization.
- If one or more of your streams involves video capture from a computer, while another involves using a camera, point the camera at the computer screen, tightly zoomed in, then make something visual happen on the computer screen to provide a visual anchor for synchronizing the streams.
- Make sure your camera operators know their roles and can coordinate who is responsible for capturing what.
- Once you start recording, do not pause or stop the recording until data collection is done. Pauses will make the streams lose synchronization. (This can be resolved through video editing, but that can be difficult and unnecessarily time consuming!)
- If possible, use the same make and model for all cameras. Sadly, different cameras occasionally have different concepts of the length of an hour, making ongoing synchronization difficult.
- Use Transana’s Media Conversion tool to reduce the resolution and density of your media files. Generally, video widths of 800 pixels or less (with the proportional height) and video bitrates of 2,500 kbps or less work well.
- If you use a Windows computer, install the QuickTime Media Player, convert your media files to a QuickTime-friendly format (such as MP4 or MOV), and configure Transana to use the QuickTime Player for MP4 files if appropriate. The QuickTime player can display multiple media files simultaneously, while Windows Media Player struggles and often fails with this task. (While there is a known security issue with the QuickTime Player for Windows, you should be fine as long as you only use it to play media files you have created yourself.)
With a little bit of forethought and planning, capturing really useful information with multiple cameras is within reach of most researchers. Working with such overlapping video can be tremendously rewarding, as it can provide a significantly greater level of detail for the events and interactions you observe during data collection. This allows a greater level of subtlety in your analytic observations and allows you to demonstrate what you have seen in ways that can be very credible and trustworthy.