Fill in the blanksQuestion 1 · Recall
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By the end you can explain why files are compressed and give real examples of where compression is used.
A two-hour 4K film stored as raw pixels (24-bit colour, 24 frames a second) is about 4.3 TB. That's more than thirty 128 GB phones' worth of storage. For one film.
Yet you stream films like that without a second thought. The trick that makes it possible is compression.
Compression
Encoding data using fewer bits, so that the file size is reduced. A compressed file must be decompressed before it can be used (played, displayed or edited).
A smaller file means:
Those three lead to the everyday wins: files fit within email attachment limits, web pages load faster, and music and video can be streamed in real time with less buffering.
Worked example: One minute of music
One minute of CD-quality stereo sound has 44 100 samples per second, 16 bits per sample and 2 channels. How long does it take to download over an 8 Mbit/s connection, uncompressed and as a 128 kbit/s MP3? (Network speeds use decimal prefixes: 1 Mbit/s = 1 000 000 bits per second.)