PREPARING MEDIA FOR ANALYSIS
Preparing Media Files for Analysis
This page is primarily designed to help people who are having trouble importing their media files into Transana. Try importing your media file before you read further. Chances are good your media files will work with Transana. If you run into difficulties, such as video not playing smoothly or Transana crashing repeatedly when you are analyzing video, then revisit this page.
It is not necessary to fully understand all the subtleties of video encoding to prepare your media and import it into Transana for analysis. Some people find the terminology intimidating. However, the process describe here is usually not too difficult, and this page strives to explain only as much as you need to get your video data working with Transana.
Getting Your Media Ready To Bring Into Transana
Because media files can come in so many different forms and formats, you may need to prepare your media data for import into Transana. Unfortunately, it’s not as simple as listing the formats that Transana supports, as many of these formats can be rendered in many, many different ways using a variety of underlying settings that complicate the process.
Media Support and Conversion
Transana strives to support a wide variety of media formats, but it is impossible to support all video file types and settings that exist. We suggest the following approach to media files in Transana:
First, try to upload and play one of your files. It might just work.
If your media file doesn’t work, or if your video does not play smoothly in Transana, or if Transana crashes repeatedly when you are transcribing or analyzing your video, try converting your media file to a more “Transana-friendly” format using Transana’s internal Media Conversion tool.
We recommend a resolution of 1920 x 1080 or less. We suggest a video bitrate of between 3,500 kbps and 5,000 kpbs. The media conversion tool always uses 30 FPS. Finally, we suggest MP4 format, which is the most common format in use today.
Resolution, Bit Rate, FPS, and Format
There are 4 basic aspects of video files that it helps to understand.
Resolution is the number of colored dots, or pixels, that make up each frame of your video file. As video technology advances, resolution keeps increasing, with 4K and 8K resolutions becoming more and more common.
Transana works really well with video that has 1920 x 1080 pixels per frame or less. I have not yet encountered a situation where higher resolution made a difference in my qualitative analysis.
Bit Rate refers to how much data goes into each frame of video, so how “dense” the video data is. The more data that goes into each frame, the better the video quality, at least up to a point. Video bitrates of 30 megabits per second or higher are becoming more common. Most research video does not need to be this high a quality.
FPS (Frames per second)
Historically, video has been stored at 30 frames per second. As video technology advances, it is becoming more common to see video stored at 60 frames per second. In my experience, 30 FPS is adequate for research.
Format refers to the standard used to store video data. There are hundreds or even thousands of different formats available, with more being created all the time. Transana supports many common video formats. Transana relies on the operating system’s built-in video player (Windows Media Player on Windows and the QuickTime Player on macOS) to display video.
This video demonstrates the use of Transana’s Media Conversion tool.
Please note that this video is now several years old and suggests lower setting values than are necessary on newer hardware. However, the underlying process for media conversion has not changed.
Format options for output files include MPEG-4 for video, WAVE for audio, and JPEG for still image. The correct value for this setting will likely be selected automatically.
Destination Media File
The Destination Media File is the file that will be output. You may change this if you wish, but you should be careful to avoid over-writing your source media file. Do not change the file extension provided, which must match the Format you have selected. If you are saving to JPEG format, the Destination Media File name must include a “%06d” specification or the conversion will not function properly.
Video Size is the frame resolution of the video in video output. For analysis in Transana, you will probably want to reduce the video size significantly if your original video is 4K or 8K quality to make video files significantly smaller and more manageable for the computer. We recommend that the video width (the first value in this field) be between 1920 and 1024. Transana will automatically select a value for the height that maintains the original aspect ratio for the media file. Transana’s media conversion tool can reduce video size but cannot increase video size from that of the original file.
Video Bit Rate
Video Bit Rate is the amount of data that goes into each second’s video frames. This value can often be set in the 2,500 kb/s to 5,000 kb/s range without noticeably affecting the quality of the media file for most users with video widths of 1920 or less. If you see poor quality in your video files, increase this value. If your video does not play smoothly, reducing this value (and the video size) often helps considerably.
usually make much less difference than video parameters do. We recommend an Audio Bit Rate of 192 or 128 kb/s, and a Sample Rate of 44,100 Hz.
Transana’s Media Conversion tool does a pretty good job in many cases, but it doesn’t work with everything. If your media file is not compatible with Transana’s Media Conversion tool, you will have to find an alternative conversion program or video editing program that supports your source media files. Often, a web search of “XXX to MPEG-4 video conversion”, where XXX is the file extension of your media file, will provide a wealth of options for tools.
Converting the first file, if the recommendations provided here don’t prove satisfactory, can take a bit of trial and error. However, once you find a good recipe or formula for converting your files, the process quickly becomes manageable.
Convert Multiple Videos at Once
If your computer has multiple CPU cores, Transana can convert multiple media files simultaneously with only limited impact on the conversion time involved for a given file. If you have multiple files to convert, this can save a significant amount of time in the process.