Part 3 - Digital Media Flashcards
What does the term Digital Media mean?
It is the tools we use to create media such as text, images, audio and video and also the the idea of communicating and sharing through the internet and web.
What is Discrete data?
Discrete data is digital data which can be represented by a finite number such as the number of people in a room or the price of petrol. fundamentally analogue means the value can be any number e.g. the speed of a car.
What is a Bitmap? What is the file extension for a Bitmap file? What is a constraint of a Bitmap file?
.bmp’s are files for coding images which assign a binary code to each pixel to determine colour and brightness. They are often very large files which creates a problem when sending or storing them.
What is a Vector graphic?
Instead of using a binary code to define each pixel, straight lines are used and the code will define the start and end point of a line or the middle and radius of a circle to create the image. This uses much less storage however isn’t very effective for photographs or motion pictures.
What is a bit?
It is a switch which can be on or off and represents a 1 or a 0.
What is a byte?
It is 8 bits.
How many bits are in a kilobyte (KB) of storage?
1024 bytes (2^10) = 8192 bits (2^10 * 2^3)
How many bits are in a megabyte (MB) of storage?
1048576 bytes (2^20) = 8388608 bits (2^20 * 2^3)
What is sound?
Sound is the vibrating of particles in the air which is interpreted by peoples ears as sound.
When looking at a sound wave, what determines the volume of the sound?
The amplitude of the wave correlates to the volume you hear the wave at - the larger the amplitude, the louder the sound
When looking at a sound wave, what determines the pitch of the sound?
The frequency of the wave controls if the pitch is high or low
Describe different compression techniques.
Lossless compression techniques such as using runs or assigning codes to certain repeating words reducing storage space.
Lossy compression techniques which take out data which is not required but then cannot be recovered.
How can sound files be compressed?
A lossy technique involves understanding the frequencies and amplitudes at which the human ear can’t hear noise and to remove all data outside this range.
Another technique involves removing noises where two noises of differing volumes pass over each other - only keeping data for the louder noise.
What is MP3?
It uses lossy compression techniques and 32 bands of frequencies to compress files to a ratio of around 11:1.
Is JPEG a lossy or lossless compression method?
Lossy - it actually loses some data when it takes a block of pixels and groups them together which can never be recovered however this is often not visible to the human eye.
