As we saw it in the previous section, several factors influence the size of your video files and the amount of space available on your storage device. Here’s a breakdown:
Video bitrate
This is the most important factor. It refers to how many bits of data are processed per second in your video file. Generally, a higher bitrate means better quality but also a larger file size, measured in Mbps.
In practical terms, it’s possible for a 4K video to have a lower bitrate than a 720p video. In such cases, although the 4K video occupies less disk space, its quality would be inferior to the 720p video. If your video includes an audio track, remember that this audio component also has its own separate bitrate.
For HD to 4K videos, bitrates can range from 8 to 70 Mbps, varying with the frame rate. Higher frame rates require higher bitrates. GoPro, for instance, uses a variable bitrate, and activating Protune mode increases the bitrate and, consequently, the file size.
FPS (Frame rates per second)
FPS, or frames per second, indicates how many frames appear on the screen each second. A standard video might display anywhere from 15 to 120 frames per second. Movies often use 24 FPS, while 30 FPS is typical for television.
It’s important not to confuse frame rate with shutter speed. Shutter speed is a setting within the camera that controls the level of motion blur in video production.
Higher FPS results in smoother playback but also leads to larger file sizes.
Video duration
The longer the video, the more storage space it requires. A 4-minute video will occupy twice as much space as a 2-minute video with identical settings.
Container/File format
The file format your camera uses to save videos also affects file size. Common formats include AVI, MOV, and MP4. GoPro cameras typically use the MP4 format with h.264 and h.265 codecs.
Photo files and other data
It’s rare to use a storage card exclusively for videos. Remember, photo files will also consume space, particularly if you’re capturing extensive time-lapse sequences. Some devices generate extra files besides video and photo files. For example, GoPro cameras create LRV and THM files, which also use up storage space.