A216
Basics Facts and Equations.

Last Updated: February 27, 2012

Below are facts and equations we will expect you to know and learn for A216. We will add to this list as we progress in the course. On occasion, a fact or equation may appear here before we discuss it in class or lab.

We will expect you to know these facts and equations for a quiz or assignment only after we have discussed or mentioned them in lecture or lab.

While some of this may seem simple to some of you, we want to make sure every one has equal access to these basic resources.

Also note that some of these facts you should not have to memorize. For example: If you know what a kilobyte (kB) is, how many kB in a GB (Gigabyte) and how many bits in a byte, then you can calculate how may bits in a GB. I have given you this fact below just to be complete.

Basic Facts for A216.

1 bit can have either value 1 or value 0

1 byte = 8 bits

1 kilobit (kb) = 1000 bits

1 kilobyte (kB) = 1024 bytes = 8192 bits

1 Megabit (Mb) = 1000 kb = 1,000,000 bits

1 Megabyte (MB) = 1024 kB = 1,048,576 bytes = 8,388,608 bits

1 Gigabit (Gb) = 1000 Mb = 1,000,000,000 bits

1 Gigabyte (GB) = 1024 MB = 1,073,741,824 bytes = 8,589,934,592 bits

In other contexts "kilo" (k) usually means 1,000

In other contexts "mega" (M) usually means 1,000,000

In other contexts, "giga" (G) usually means 1,000,000,000

A "Hertz" (Hz) is a "cycle per second." So a kiloHertz (kHz) is 1000 cycles/sec.

Example: "22kHz" [22 kiloHertz] means 22,000 cycles/second

Example: "3MHz" [3 MegaHertz] means 3,000,000 cycles/second

Example: "4GHz" [4 GigaHertz] means 4,000,000,000 cycles/second

Time.

1 minute = 60 seconds

1 hour = 60 minutes = 3600 seconds

Powers of 2.

8 bits means 2⁸ possible combinations = 256

16 bits means 2¹⁶ possible combinations = 65,536

24 bits means 2²⁴ possible combinations = ~ 16.7 million [16,777,216]

32 bits means 2³² possible combinations = ~ 4.29 billion [4,294,967,296]

Audio Memory, Bitrates, Sampling rates, and Storage.

3 relevant factors: Sampling rate, bits/sample, Mono/Stereo/Multichannel.

Sampling rate is usually in kHz (1000s of cycles/second).

Bits/sample is usually either: 8-bits/sample, 16-bits/sample, 24-bits/sample. [Note that this is identical to 1-byte/sample, 2-bytes/sample, and 3-bytes/sample.]

Mono means one channel, Stereo means two channels (twice as much data), and multi-channel means 3 or more channels (even more data).

EXAMPLE: Sampling rate: 32kHz, 16-bits/sample, Mono.

How much date per second in bits?

How many kb/sec?

How many kB/sec?

[Make sure you understand the differences between the above questions and their answers.]

Displays and Aspect Ratios.

Standard Television is 4:3 [Width: Height].

"Widescreen" or HDTV is 16:9.

4:3 can also be written as 1.33:1

16:9 can also be written as 1.78:1

Aspect ratio for film called "flat" or "spherical" is 1.85:1.

Aspect ratio for film called "anamorphic" or "scope" is 2.35:1.

Basic Equations for A216.

Video Display Memory

How many MBs of video memory to support a certain resolution and color depth?

EXAMPLE: Resolution = 1024 x 768; Color Depth = 16-bits/pixel.

1024 x 768 = 786432 pixels.

16-bits/per pixel means 2-bytes/pixel.

786432 pixels x 2-bytes/pixel = 1,572,864 bytes of video memory required.

1,572,864 bytes / 1024 bytes/kiloByte (kB) = 1536 kB of video memory.

1536 kB / 1024 kB/Megabyte (MB) = 1.5 MB of video memory.