Resources Table of Contents:
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Frame-by-Frame Analysis:
Some labs will require the use of frame-by-frame (FBF) seeking. This is different to scrolling through videos as you may know it, like using the arrow keys on YouTube. Below are some recommended applications that can use FBF seeking for common device types and how to use them, and information on how to find out the framerate of your videos.
Applications for FBF seeking:
Media Player Classic (Default on Lab computers):
On the lab computers, the default applicaiton that opens videos should be Media Player Classic. To do frame by frame seeking, presss Ctrl + Right Arrow.
MacOS Devices:
MacOS devices like MacBook’s can use the default media player QuickTime Player. Using the arrow keys, you can move through videos frame by frame. If you would like to save images of each frame for analysis, you can copy the image using ⌘ + C. Then open Preview, File -> New from Clipboard.
Windows Devices:
Windows devices can make use of the default video player, Windows Media Player. The arrow keys will NOT scroll frame-by-frame. Instead, access the menu as such:
- Open the video with Windows Media Player.
- Right click anywhere on the video, and open the Enhancements menu.
- Open the Play Speed setting menu.
- At the bottom, there will be 2 buttons used for frame-by-frame seeking.
Using Third-party Apps:
There are a large number of third-party applications that can also use frame-by-frame seeking for Windows, MacOS, iOS, and Android. It is NOT recommended to use VLC, as there are bugs surrounding the use of FBF. Use of third party apps is discouraged because it will be your responsibility to learn and properly use their features.
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Finding Framerate:
Framerate is an important quality of videos when doing FBF analysis, as it tells you how many seconds pass between each frame, allowing you to track change in distance over time. Framerate is most commonly displayed in the properties of a video, and can be seen in the following ways:
- Some iPhone’s and Android devices allow you to select your framerate before recording, or change it in the camera settings of your devices
- In the gallery or photo’s app of your device, framerate is commonly displayed in the ‘properties’ or ‘details’ of the video.
- On a Mac, using the “inspector” from QuickTime player will show the framerate.
- On PC, right clicking and finding the video properties will display the framerate.
If for some reason these options are unavailable to you, you can manually find the framerate in the following way:
One can count the number of frames between two events in a video separated by a known time, for example, if there are 15 images in 0.5 s, then the frame rate is 30 fps (fps = frames per second), and the time between frames is then: τ = (1/30) seconds. This can be done by using the google stopwatch feature, and taking a video of your computer screen once the stopwatch is turned on. See how many frames are needed to advance one second and that is your frame rate (see the image below).
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Viewing Audio Track Waveforms
On an iMac, Quicktime lets you view the waveform of an audio or video track if you first click the Edit tab and select “Trim…”. You will then have the option to select “Show Audio Track” under the View menu bar.
Alternatively, many phone recording apps will allow you to view your audio waveforms directly. For example, on the iphone, you can use the “voice memos” app, record, and then click on the three dots to edit the recording. While in edit mode it is easy to zoom in and slide the track to find the times.
Another option is to use Audacity. Audacity is a free audio editing and viewing software which is available on most devices (MacOS, Windows, Linux).
Installation:
Follow this link. Naviagte to your device’s subpage and install the correct version following the installation instructions.
IMPORTANT NOTE: If you are trying to edit files ending in .M4A, which is the format iPhone and Android devices export voice memos as, you must install an additional package FFmpeg. Follow the link and instructions on the installation page to ensure you can work with this common file type if recording audio using a smartphone.
