For example, i started downloading Community on Netflix, most of the episodes are 21 minutes long, but they range in size from 76 to 116mb. They’ve got nearly identical run times, and therefore similar amounts of frames and audio, so what causes the noticeable discrepancy?
In: Technology
The videos are compressed. When you compress something, you look for redundant information and try to reduce it. Let’s say I made a 20 minute video of a white screen… I could record 1920×1080 pixels of white for 60 frames per second over 20 minutes… or I could just tell you that all the pixels are white for 20 minutes, and you’d get the same result. Or I could have a 20 minute video of a photo of a cat. I could send you the full data for it, or I could just send you the one image and then tell you that it’s just that image for 20 minutes.
Obviously most videos aren’t just a white screen or a cat… but think about any time you’re watching a video and the camera isn’t moving… 3/4 of the screen is completely stationary, so they just need to send the data representing what is changing.
Do this for every frame of video and you can have much less data.
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