White Paper: Test & Measurement
Video Metadata for Science and Engineering
What happened? Why did it happen? How did it happen? What is going on? These are questions we ask when studying behaviors, events, and exploring the unknown.
While a picture is worth a thousand words, to find the answers to why, how, and what often requires measurements of influences on the behavior. So, capturing data that is aligned to the pictures in a movie is important.
Collecting data with movies has been an ongoing development. In the film era, a stripe alongside of the pictures was added to provide sound and synchronize it to the pictures. When the Society of Motion Picture and Television Engineers designed the digital video frames, it kept whole scan lines and reserved pixel space on all lines for data storage. In HD/UHD video, metadata is any information included in these pixel spaces. Metadata may or may not (coded as black pixels) be present in a frame.
One structure is Key Length Value (KLV), which is a general-purpose packet. An important KLV packet is the Microsecond Timestamp, which is used to indicate when the image was captured by the camera. You will learn how to use this packet to accurately measure camera to display latency in real time. Adding more KLV packets embeds relevant measurements with images. There is no postproduction to achieve alignment.
Recording correlated images and data requires equipment that embeds and preserves the KLV packets and their correlation to the video frames. Using devices capable of capturing and playing back whole digital frames (the HANC and VANC spaces too) can deliver this capability and will reduce the tedious labor intensive effort to correlate images with relevant data.
This paper explains KLV metadata, how it works, how it is structured, and provides example applications.
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