Multimedia Flashcards
What is multimedia?
Multimedia is a combination of two or more categories of information
having different transport signal characteristics
Typically, one medium is a continuous medium while another is discrete.
Image, audio, video and graphics are examples of media
Five main elements of multimedia?
Multimedia combines different types of media such as text, audio, video, graphics, and animations to deliver information or entertainment content.
What are the steps from analog to digital conversion?
Analog to Digital Conversion consists of three
steps to digitize an analog signal:
1. Sampling
2. Quantization
3. Binary encoding
What is sampling?
Sampling is the process of capturing and digitizing analog data signals such as audio and video. The process involves measuring the amplitude of the analog signal at specific intervals of points and converting the measurements into digital data.
What is the standard sample rate for analog?
It depends on the device for the telephone it is 8Khz ,for voice over 16Khz and for audio CD and mp3 44KHz and some even go to 1MHz (blu-ray disc).
Quantization is
Refers to the process of reducing the precision of equality of digital data such as images audio video to make it manageable to store. It takes infinite points and turns them into finite number of points.
Binary encoding is
representing info into ones and zeros.
What is PCM?
Pulse Code Modulation
(PCM) a method used to
convert analog signals to
digital signals
Nyquist’s Sampling Theorem is
fundamental concept in the field of signal processing and digital communication. It says that to not lose data from continuous signal from its sampled version the sampling rate should be twice or equal to the highest frequency component in the signal.
DAC is
DAC- A digital-to-analog converter takes digital audio data and transforms it into an analog signal to send to
headphones or speakers.
Sample rate is
Sample Rate- Measured in Hertz (Hz), this is the number of digital data samples captured every second.
SNR is
SNR- Signal-to-noise ratio is the difference between the desired signal and the background system noise. In a
digital system this is linked directly to the bit-depth.
Text data is (how is it stored)
is stored when typed, and then there is software that converts text into normal code. From ASCII to binary code.
Audio data is (how is it stored)
we store it according to its frequency, every frequency has its code, when we compile it and turn into machine code.
How do we know the difference between frequencies in audio data?
We store the analog sound waves info in digital signals then we take in the info with different voltages of 0 and 1.
Analog signal path is
when the audio stays analog from input to output.
Image sampling is
is the process of converting a continuous two-dimensional image into a discrete grid of pixels.
Image quantization is
turns the intensity value of each pixel into a finite set of discrete values using a specific bit depth.
Pixel (how is the word made)
(Pic)ture (el)ement
Image compression
trying to reduce the size while keeping the quality
What is an Image?
an image is a two-dimensional array or matrix of pixels (picture elements), each containing color and brightness information
Why do we compress data?
To save storage;
to save time;
optimize resources;
reduce memory requirements;
improve the data access rate;
faster transfer;
Redundancy is
refers to the amount of wasted space consumed by storage media to record picture info into digital image.
What are the 3 types of image compressions?
Spatial redundancy: elements that are duplicated within a structure,
such as neighboring pixels in a still image. Exploiting spatial
redundancy is how compression is performed.
Spectral redundancy is due to correlation between different color
planes.
Temporal redundancy: pixels in two video frames that have the
same values in the same location. It is due to correlation between
different frames in a sequence of images such as in
videoconferencing applications in broadcast images. Exploiting
temporal redundancy is one of the primary techniques in video
compression
What is revisable compression
- Reversible compression
(loss-less compression)
– Decoded data is the same as original
– Applied for computer, medical data
What is non-revisable compression
- Non-reversible compression
(lossy compression)
– Decoded data is not the same as the original
– Compression ratio is better than reversible
compression
– Applied for audio and video
Run- length
is a reversible compression
easy to implement
it is not fit for data in 0 n 1
Huffman coding
assigns shorter words for frequent patterns
Arithmetic coding
adaptively assigns words according to the statistics of objects data.
Jpeg is
compressed picture or graphics
Mpeg is
compressed video
MP3 MP4 is
compressed audio
Lossless methods are
Run-length
Huffman
Lampel Ziv
Lossy methods are
JPEG MPEG MP3 MP4
We use lossless when
we cant afford to lose any data, such in medical or legal data.
We use lossy when
when we want to save on storage, also out eye can not notice the difference in the image or video.
