Week 1

8 bits form a

"byte"

most significant bit

(MSB, also called the high-order bit) is the bit position in a binary number having the greatest value. The MSB is sometimes referred to as the high-order bit or left-most bit due to the convention in positional notation of writing more significant digits further to the left.

§Non numeric data types and their representation

Alphanumeric, image (bitmap), image (object), Outline Graphics and Fonts, Sound, Page description and markup, video

Top codecs are

H.264, WMV and DivX

The VOC format is

a general sound format that includes special features such as markers within the file that can be used to repeat (loop) a block or synchronize the different components of a multimedia presentation

Big-endian

an order in which the "big end" (most significant value in the sequence) is stored first (at the lowest storage address)

Bitmap images

are formed of pixels which is the smallest visible representation of a portion of the image

Object images

images are made up of simple elements like straight lines, curved lines (known as Bezier curves), circles and arcs of circles, ovals, and the like. •Object images use lesser space than bitmap images and preserve their quality and attributes •Reducing and enlarging bitmap images will cause loss of detail •Object images can not be directly printed; need to be converted in a bitmap image •Bitmap images are prone to steganography •

Little-endian

is an order in which the "little end" (least significant value in the sequence) is stored first.

GIF format

is limited to 256 colors, which is often inadequate to display the details of a painting or photograph

WAV format is a general-purpose format used

primarily to store and reproduce snippets of sound

The codec is often embedded in a

proprietary "container". The container serves as a superstructure to encode, decode, hold, and stream the video.

least significant bit (LSB)

s the bit position in a binary integer giving the units value, that is, determining whether the number is even or odd. The LSB is sometimes referred to as the low-order bit or right-most bit, due to the convention in positional notation of writing less significant digits further to the right.

PNG format

the best-known less compressed alternative to GIF •PNG can store up to 48 bits of color per pixel, and additionally can store a transparency percentage value and a correction factor for the color in a monitor or printer. •PNG compression algorithm is often more efficient than that used with GIF. •PNG stores only a single image in a file.

"Word" =

the width of the data bus (8, 16, 32, 64) or the maximum number of bits that can be read from memory in one "Fetch Cycle"

.MOD format is used primarily

to store samples of sound that will be manipulated and combined to produce a new sound.

Video codecs use

use both variations on both forms of compression simultaneously

Hexadecimal (Hex) 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F (16 bits) =>

§0xnn

Nybble/nibble?

§4bits)

§Numbers

§In binary the range of numbers stores is higher than in decimal §Integers (signed or unsigned) §Signed integers use MSB for sign "0" for positive and "1" for negative §Signed numbers are represented in 2 complement §Negative number = Inverse (PositiveNumber) + 1 §Ex: §310 = 00112 §-310 = 11002 + 00012 = 11012§Real numbers or floating point numbers are represented as an integer (mantisa) with an exponent of a base. §The base can be 2, 10 or 16 §The range is: §32 bits = +- 3.4 * 1038 64 bits = +- 1.8 * 10308

§Data Types

§Numbers §Alphanumeric Characters §Visual Data §Audio Data §Other

Octal 0,1,2,3,4,5,6,7 (8 distinct values - 3 bits) =>

§nnn

MIDI software can

•"read" the keyboard and can also reproduce the sounds.

Top containers are:

•AVI (audio video interleave) , ASF (advanced system format), MOV or QT (quicktime), AVCHD (advanced video coding HD), FLV or SWF (Flash Video), MPG or MPEG (Moving Picture Expert Group Video File includes H.262), MP4 or MPEG4

•There are two types of images

•Images such as photographs and paintings that are characterized by continuous variations in shading, color, shape, and texture - bitmap images. Ex: Graphics Interchange Format (GIF), Portable Network Graphics (PNG), and Joint Photographic Experts Group (JPEG) •Images that are made up of graphical shapes such as lines and curves that can be defined geometrically - object images or vector images Ex: SVG (Scalable Vector Graphics, Adobe Flash)

The video format is determined by

•a codec, or encoder/decoder algorithm.

A lossless algorithm

•compresses the data in such a way that the application of a matching inverse algorithm restores the compressed data exactly to its original form. •acceptable for files where the original data must be retained, including text files, program files, and numerical data files (PNG, BMP, Raw, ALC, FLAC, WAV and ZIP) •Although there is a debate about it, GIF is considered lossless because of the animation involved.

JPEG format

•employs a lossy compression algorithm to reduce the amount of data stored and transmitted •the algorithm used reduces the image resolution under certain circumstances, particularly for sharp edges and lines. •JPEG more suitable for the representation of highly detailed photographs and paintings, but GIF and PNG are preferable for line drawings and simple

Pixels are organized

•in a matrix that represents the analog image. Each pixel carry information related to the colour, brightness, contrast.

•Data compression algorithms, fall into one of two categories

•lossless or •lossy.

A lossy data compression algorithms

•operate on the assumption that the user can accept a certain amount of data degradation as a trade-off for the savings in a critical resource such as storage requirements or data transmission time •frequently acceptable in multimedia applications (OGG, JPEG, MP3, MP4) •lossy data compression ratios far exceed those possible with lossless compression.

MPEG-2 and MPEG-4 formats

•store and transmit real-time video that produces movie quality images, with the video data compressed to 10-60 MB or less of data per minute, even for high-definition images.

MIDI format is used to

•to coordinate the sounds and signals between a computer and connected musical instruments, particularly keyboards.