The document discusses various types of text, text compression methods, video formats and standards, and video recording systems. It describes unformatted, formatted and hypertext; Huffman coding and LZ/LZW compression; common text formats like TXT, DOC, RTF, PDF and PS. It also explains video signal formats, transmission standards including NTSC, PAL, EDTV, CIF and HDTV, and video recording systems such as VHS, camcorder, laserdisc, VCD and DVD.

1. Unit IV: TEXT
Types of text, text compression: Huffman coding, LZ and LZW, text
file formats: TXT, DOC, RTF, PDF, PS.
Video: Video signal formats, video transmission standards: EDTV,
CCER, CIF, SIF, HDTV, Digitization of video, video recording
systems: VHS, video compact cassette, DVCAN, Camcorder,
laser disk, VCD, DVD-Video, Micro-MV,
Video formats: MOV, Real video, H-261, H-263, Cinepack,
Nerodigital, Video editing, DVD formats

2. Types of text
There are 3 types of text that can be used to produce pages of a
document : unformatted text, formatted text and hypertext.
Unformatted Text – Plaintext. Comprises of fixed sized characters
from a limited character set (ASCII table).
Characters – alphabetic, numeric and punctuation also called
printable characters and control characters – backspace,
linefeed, carriage return, space, delete, escape.
Formatted Text – changes the appearance of characters ie bold,
underline, italics, varying shapes, sizes and colours.
Hypertext – sequential navigation, cross references which lead to
multiple searches by hyperlinks

3. Architecture of Hypertext Document
There are 3 layers.
Presentation Layer : An HTML document displayed in the web
browser.
Hypertext Abstract Machine : It is placed between the
presentation and storage layers. For example interpreting the <a>
Storage Layer : the specific properties of the different discrete and
continuous media need to be considered. Storage of HTML file
along with graphic and audio files can be used to generate a
display of a page containing the graphic and a background music.

4. Text Compression
Compression algorithms are used to reduce the size of the text file
during storage. An algorithm must be applied to decompress the
file before its contents can be displayed on the screen; without
changing the text or character.
There are 2 types of text compression methods.
1. Huffman coding
2. LZ and LZW

5. Huffman Coding
This type of coding is intended for applications in which the text
to be compressed has known characteristics in terms of the
characters used and their relative frequencies of occurrences.
Instead of using fixed length code words, an optimum set of
variable length codewords is derived such that the shortest
codeword is used to represent the most frequently occurring
characters.
Method :
Step 1: Analyze frequencies of the occurrences of each
character.
Step 2: Generate codewords.

6. Huffman Coding Example
A document contains letters A, B, C, D, E, F with frequencies
as indicated :
A : 0.25
B : 0.10
C : 0.20
D : 0.15
E : 0.26
F : 0.04
Solution : Step 1 – store the values in descending order of the
frequency. The last 2 characters (leaf nodes) at the base are
assigned values 1 and 0.

7. Huffman coding example
E : 0.26
A : 0.25
C : 0.20
D : 0.15
B : 0.10 (1) = 0.14
F : 0.04 (0)
Step 2 : Replace the leaf nodes by a branch node whose weight is
the sum of the weights of the leaf nodes. Form a new column to
the right containing the new branch node combined with the
remaining nodes from the first column arranged in their correct
weight order.
Repeat step 1 to 2 till there are only 2 nodes remaining.

8. Huffman coding example...
E : 0.26
A : 0.25
C : 0.20
D : 0.15 (1) = 0.29
: 0.14 (0)
: 0.29
E : 0.26
A : 0.25 (1) = 0.45
C : 0.20 (0)
: 0.45
: 0.29 (1)
E : 0.26 (0)
: 0.55 (1)
: 0.45 (0)

9. Huffman coding example
To derive the resulting codeword for each character, start
from the first column to the left and proceed to the right,
concatenating the values assigned to the character at
each column.
A : (1) (0) ---> 01
B : (1) (0) (1) (1) ---> 1101
C : (0) (0)
D : () () ()
E : () ()
F : () () () ()

10. Text File Formats
TXT : Unformatted text document created by an editor like Notepad on
Windows platform. Encoding – ASCII, Unicode (UTF-8, UTF-16)
DOC : Stores documents created by the MS Word package. Not
considered a document exchange format as it requires propriety software.
RTF : Developed for cross platform document exchanges. The control
codes are human readable similar to HTML code.
PDF : Developed by Adobe Systems for cross platform exchange of
documents. In addition to text, it also supports images and graphics. It is
an open standard.
PS : PostScript is a page description language (to describe the contents of
a page such that it can be accurately displayed on output devices usually a
printer) used mainly for desktop publishing.

11. Video
Video Signal Formats :
1. Component Video – A video signal which is stored or
transmitted as three separate component signals. The simplest
form is the collection of R, G and B signals. Three separate wires
and connectors are usually used to convey such signals from the
camera to another device for storage or playback. In situations
where the same set of signals are required to drive both a color
monitor as well as a B/W monitor, RGB signals are replaced by Y,
Cb and Cr signals, also delivered along three separate wires.

12. Video signal formats
2. Composite Video – Composite video is the most
common type of video interface for sending or receiving
an analog video signal to or from a television set. A
composite video interface might connect a VHS tape
player, DVD player or game console to a television.
Composite video is a yellow, RCA jack, normally found
next to two audio jacks, one red, the other white. The
three jacks together provide an interface for audiovisual
connections. A video stream is composed of a Y signal
for luminescence or black and white values and a C
signal for chrominance or color. The Y signal provides
brightness and contrast, allowing for deep rich blacks and
startling bright whites.

13. Video Signal Format
3. S-Video – Super Video is an analog signal
format where the luminance and chrominance
portions are transmitted separately using multiple
wires instead of the same wire as for composite
video. The picture quality is better than that of
composite video because of reduced interference
but the cable is more expensive and is usually
found in high end VCRs and capture cards.
1. Ground
2. Ground
3. Luminance (Y)
4. Chrominance (C)

14. Chrominance
Chrominance (chroma for short) is the signal used in video systems
to convey the color information of the picture, separately from
the accompanying luma signal. Chrominance is usually
represented as two color-difference components: U = B' − Y'
(blue − luma) and V = R' − Y' (red − luma). Each of these
difference components may have scale factors and offsets
applied to it, as specified by the applicable video standard.

15. 4. SCART Connector – (Syndicat des
Constructeurs d'Appareils
Radiorecepteurs et Televiseurs) is a
French standard of a 21 pin audio and
video connector. It can be used to
connect VCRs, DVD players, set top
boxes, game systems and computers to
television sets. SCART attempts to
provide a standardized connector
containing all the signals for audio video
applications.

16. NTSC
National Television System Committee (NTSC) is a television
broadcasting system used in a number of countries. It specifies
a standard using:
- 525 horizontal lines,
- 30 frames/sec,
- an aspect ratio (image width : image height) of 4:3,
- 2 interlaced fields /frame (also called 2:1 interlacing),
- 262.5 lines per field,
- 60 fields per second and
- frequency modulation for the audio signal.
In video, a field is one of the many still images which are displayed sequentially to
create the impression of motion on the screen. Two fields comprise one video
frame.

17. NTSC
Colour information was added to the black and white image by adding a
colour sub carrier to the video signal.
Of the 525 horizontal lines, only 480 are actively used for generating the
picture on the screen, the rest being used for synchronization and
vertical retrace.
In colour transmission the luminance signal takes the place of the original
monochrome signal used for B/W TVs. The chrominance part of the
signal is represented by two sub components known as I(in-phase) and
Q(Quadrature).
A television channel occupies 6 MHz of bandwidth; majority of which (0-4
MHz) is occupied by the luminance signal Y (brightness information),
1.24 MHz for video carrier frequency, 1.5 MHz for colour information.
NTSC has some colour problems because of which professional also call
it “Never the same colour”

18. PAL
Phase Alternation (or Alternating) Lines (PAL) is a TV broadcasting
standard used in a number of countries. The PAL system uses 625
horizontal lines (gives better quality picture) at 25 frames / sec, 2:1
interlacing with 2 fields per frame, 4:3 aspect ratio and a chroma sub
sampling scheme of 4:2:2.
PAL also uses a colour sub carrier signal with 2 amplitude modulated Q
components, however its location is different compared to NTSC.
PAL is also called “Perfect At Last”. Out of the 625 lines, only 576 lines
are actively used to display the image on the screen, the remaining
lines being used for synchronization and vertical retrace.

19. video transmission standards
1. EDTV – Enhanced Definition Television Systems
They are conventional systems modified to offer improved vertical
and horizontal resolutions. An emerging system is known as
Improved Definition Television (IDTV) which improves NTSC
(National Television Systems Committee) image. By using digital
memory to double the scanning lines from 525 to 1050. The
pictures are only slightly more detailed than NTSC images
because the signal does not contain any new information. By
separating the chrominance and luminance parts of the video
signal, IDTV prevents cross interference between the two.

20. video transmission standards
2. CCIR – (ITU-R) Recommendations
The International Telecommunications Union –
Radiocommunications Branch (ITU-R) formerly known as the
Consultative Committee for International Radiocommunications
(CCIR), defined a standard for digitization of video signals known
as CCIR 601 Recommendations. A colour signal has 3
components – a luminance component and two chrominance
components. The CCIR format has 2 options :
one for NTSC TV and another for PAL TV.
(Both of them being interlaced formats)

21. CCIR ...
Each TV channel occupies a maximum bandwidth of 6 MHz. To digitize
the entire information, a sampling rate of 12 MHz needs to be chosen a
per Nyquist's postulate, though a higher rate of 13.5 MHz has been
proposed by CCIR in order to take care of the imperfections of the filter
due to which some high frequency component always percolates
through the filter.
The frame size for digital NTSC is fixed at 720 by 480 pixels whereas the
size for digital PAL is fixed at 720 by 576 pixels (based on
specifications).
CCIR proposes using two chroma sub sampling schemas – 4:2:0 and
4:2:2

22. Video trans. std....
3. CIF – (common intermediate format) it is non interlaced format.
Its luminance resolution has 360 x 288 pixels / frame at 30
frames / sec and the chrominance has half the luminance
resolution in both horizontal and vertical directions. It is a
common intermediate format for both PAL and NTSC systems.
In the NTSC system only a conversion of line number is needed
while in the PAL system only a picture rate conversion is
required.
4. SIF – Source Input Format has luminance resolution of 360 x
240 pixels / frame at 30 frames / sec or 360 x 288 pixels / frame
at 25 frames / sec. It is usually used for video conferencing. For
both cases, the resolution of the chrominance components is
half of the luminance resolution in both horizontal and vertical
dimensions.

23. 5. HDTV – High definition TV is a new standard for digital video for
improving picture quality compared to the standard NTSC or PAL
formats. They require a high definition monitor or TV screen to be
viewed and have been defined as the ITU-R recommendations. There
are 2 alternate formats one relating to the standard 4:3 aspect ratio
screen with 1440 x 1152 (1080 visible) pixels and the other to the 16:9
aspect ratio wide screen with 1920 x 1152 pixels (1080 visible).
Both use either 4:2:2 sub-sampling scheme for studio applications
with 50 / 60 Hz frame refresh rate or 4:2:0 scheme for broadcast
applications with 25/30 Hz refresh rate.
Video trans. std....

24. Analog video has been used for years in recording / editing studios
and television broadcasting which needs to be converted to digital
format for incorporating it in multimedia production.
Digitizing reduces the file size due to compression.
Digitizing video in general requires a video capture card and
associated recording software. The capture card is usually
installed at the PC end, which accepts analog video from a source
device and converts it into a digital file using a recording software.
Alternatively the capture card can be inside a digital video camera
which is capable of producing a digital video output and recording
it onto a tape.
Digitization of video

25. video recording systems
VHS – The Video Home System is a recording and playing
standard for Video Cassette Recorders. Early VHS machines
could rewind and fast forward the tape considerably faster. It
contains a 12.7 mm (½ inch) wide magnetic tape
wound between two spools allowing it to be slowly
passed over the various playback and recording
heads of the video cassette recorder.
Super VHS and VHS C (compact) and S-VHS-C and D-VHS were
some of the improved versions of VHS.

26. video recording systems
video compact cassette – VCC was the first practical home video
cassette recorder system. The system used ½ inch tapes coated
with chromium dioxide available in three versions : 30, 45 and 60
minutes. To prevent cross talk between adjacent
video tracks it used an unrecorded guard band which is
essentially a small space between tracks to prevent
interference when reading data.
DVCAM – it is a variant of the Digital Video (DV)
format which uses the same DV cassettes but
uses greater track widths in SP mode (standard
play), EP (extended play) is not supported. Greater
track width makes the tape more robust.

27. video recording systems
Camcorder – it is a generic term for a portable device for recording
of audio and video onto a storage device within it. The term is a
combination of camera and recorder in one unit. Prior to the
introduction of the camcorder, the video camera needed to be
connected to a separate device the VCR
for recording video footage. Sony introduced
its model known as handycam. Initially
camcorders used the VHS or Betamax tapes
and were quite bulky, but later with the
introduction of 8 mm tapes, they reduced in
Size. Now a days, digital camcorders use
MiniDV or DVD for storage.

28. video recording systems
laser disk – it was the first commercial
optical disc storage medium and was
used primarily for the presentation of
movies. Originally was called Reflective
Optical Videodisc System. Video was stored on LD as an analog
signal, while audio could be stored in either analog or digital
format and in a variety of surround sound formats. Like on a CD,
the surface of the disc is an aluminium foil covered by pits and
lands, but on a audio CD or DVD the pits and lands will signify
binary codes, on an LD, the pits are created using frequency
modulation of an analog signal.

29. video recording systems
VCD – with a display resolution equal to 352 x 240 (NTSC) pixels
or 352 x 288 (PAL), a VCD holds about 74 minutes of
compressed video. It is in MPEG-1 format; audio is encoded as
MPEG layer 2; video is stored at 1150 kilobits per sec, audio at
224 kilobits per sec. Overall bit rate of VCD is approx equal to
the bit rate of ordinary audio CD, the length of video that can be
stored is similar to the length of audio in an audio CD.
The following folder structure is used on a VCD : MPEGAV
(contains main movie), SEGMENT (contains optional still
pictures), EXT (contains optional list of I frames), VCD (contains
album and disc identification information), CDDA (contains
optional audio files).
SVCD (Super VCD) is a format used for storing video on standard
CDs. Picture and audio quality is higher than VCD but lower
compared to DVD.

30. video recording systems
DVD-Video – DVD video was the first DVD format to be launched.
It uses the MPEG2 data compression algorithm to encode the
video data. It uses a display size of 720 x 480 pixels and instead
of encoding RGB components uses a YcrCb representation. It
may include one or more subtitle tracks in various languages
including those made especially for the hearing impaired.
DVD has 4 complementary system designed to restrict the DVD
user in various ways : Macrovision (analog anti copying
mechanism), Content Scrambling System – CSS (discourages
people from making perfect digital copies), region codes
(denoting the areas of the world in which distribution and
playback are intended), and disabled user options (UOP) –
specifies whether the user may perform any operations like
selecting menu, forwarding etc on remote control.

31. video recording systems
Micro-MV – it was a proprietary videotape format introduced in
2001 by Sony. This cassette is physically smaller than a Digital8
or DV cassette. In fact, MicroMV is the smallest videotape
format — 70% smaller than MiniDV or about the size of two US
quarter coins. Each cassette can hold up to 60 minutes of video.

32. Video formats
MOV – Quick Time Movie requires a program called Movie Player
for playback which is freely downloadable.
Real video – the RM file format was developed by Real Networks
for playing video files from web pages. It supports straming
which means that the video file starts playing even before they
are fully downloaded from the Internet.
H-261 – developed by ITU-T for videotelephony and video
conferencing applications in a ISDN environment.
H-263 – it was designed for very low bit rate applications like
videotelephony, videoconferencing, interactive games,
surveillance video.
Cinepack – its greatest strength is its extremely low CPU
requirements.

33. Video formats ...
Nero digital – is a software product that uses MPEG 4 conforming
compression technology with support for two MPEG 4 video
coding algorithms and two forms of MPEG 4 audio.

34. Video editing
Online and Offline editing
SMPTE (society of motion pictures and television engineers) Time
Code – time code defines how frames in a movie are counted
and affects the way you view and edit a clip. Frames are
counted differently when editing video for TV than when editing
for motion picture film.
Time Base – when editing a video, several source clips may need
to be imported to create the output clip. The source frame rates
of these source clips determine how many frame rates are
displayed per second within these clips.
Edit Decision List – when an offline edit is completed on a low end
system, a table of scene sequences called an edit decision list is
created.

35. DVD formats
DVD – video : requires a DVD drive.
DVD – Audio : describes a high quality audio storage format. They
employ a robust copy prevention mechanism called Content
Protection for Prerecorded Media (CPPM).
DVD – R : is composed of 2 0.6 mm thick polycarbonate discs
bonded with an adhesive to each other. It is approved by DVD
forum. It is supported by 90% DVD players.
DVD + R : not approved by DVD forum. It is a writable disc with 4.7
GB capacity.
DVD - RW : is a rewritable optical disc with capacity like DVD-R ie
4.7 GB. Main advantage is to erase and rewrite. It is approved
by DVD Forum.

36. DVD formats
DVD + RW : is a rewritable optical disc with 4.7 GB capacity. It is
not approved by DVD Forum. They are commonly used for
volatile data such as backups or collections of files.
DVD – RAM : they are used in computers as well as camcorders. It
is more closely related to hard disk technology as it has
concentric tracks instead of one long spiral track.
DVD+R DL (dual layer) : also called DVD+R9. It uses discs with
two layers of writable polycarbonate thereby doubling the
storage capactiy.
MiniDVD : it was developed for use in camcorders and holds 30
min of video.
DualDisc : is a combination of CD & DVD with one format on one
side of the disc and the other on the opposite.