contents l forms of motion picture l multimedia products with motion picture content l motion video...

www.smartphonetech.org

Contents Forms of Motion Picture Multimedia products with Motion Picture Content Motion Video Technology Source for Motion Video Objects Playing Video on PC Video Formats : lines, frames, fields & aspect

Ratio Analog Video Signal Waveform T.V. Broadcast Standards Color of Video Analog Video Camera Principle


Contents (cont.) Luma & Chroma Hue & Saturation Chroma Component Options Video Signals Composite Video Signal Wavwform :Color Digitisation Basics Effect of Low Pass Filters Magnitude Domain Discretisation Color Bitmap Encoding & CLUT Digitised Video Standards


Contents (cont.) Video Compression Motion Compensation Artifacts due to digitisation & compression Video Compression Techniques & Standards Data Rates of Media Analog Video Recording : Tape Formats Digital Video Camera Digital Video Recording : Tape Formats Video File Formats Steps to PC Video


Contents (cont.)

Video Capture : Basics & Platform Video Capture Cards Video Capture Considerations & Procedures Video editing : Primer & concepts Transitions & Superimpositions Non-linear editing Video Editing Tools Shooting Tips


Motion Video Technology for Multimedia

Learning Objectives Appreciation of Technical Aspects of

Full Motion VideoDigital Video Storage and CompressionVideo EditingMultimedia Video Standards

Obtaining necessary background for acquiring and processing Full Motion Video Objects for embedding in Multimedia Contents.


Many Forms of Motion Picture

Films 35 mm , 70mm, 16mm,8mm

Broadcast TV Ordinary DBS TV HDTV (coming up)

Laser Disk (Players) DVD (Players) Video in Cassettes and Tapes Video in computer

Multimedia component Stand alone CD Video Web Content


Why use Motion Video in Multimedia?

Sin qua non in True Multimedia Most effective communication mode Entertains and educates with least audience

initiative Brings realism Multiple views (vista and zoom) Being there - presence People are already sensitised to movies Shows changes - as and when they happen


The downside of Video in Multimedia

Takes two much disk space Needs large bandwidth when transmitted Costly to produce Quality is difficult to achieve and highly

dependent on target machine May easily become the weakest link in the

product


Content is the King

Every king needs subjects - so does video what to show in video

Drama Dances interviews Large artwork or mural architecture Record of events (village fair) and social functions

(marriage) How to do things

Operation Installation Show How is know-how

Internals of a machine You get the idea


Multimedia Products with Motion Picture content As embedded object.

Within an interactive multimedia product (say, web page, encyclopedia entry).

Short length snippets (one or many) Small format (1/4th- 1/16th).

As the primary content Within an interactive multimedia presentation. Good quality, with voice and music At least several minutes long. Rest of contents organised around it . Must be at least 1/4th screen

Stand-alone object Library/depository object Good quality

Stand-alone digital video product Good quality, Longer duration, Full screen preferred


Before you begin

To incorporate video in multimedia, ask the following questions:

Could the video be substituted by still ? If not, why, what is the USP?

Could Animation be better than a video ? What would be the role of the video in the product? ( e.g.

embedded object, album ) Who would provide the footage ? What would be the duration of the video clip(s)? Delivery medium (CD-ROM , DVD ,Internet, LAN) Who would be editing and integrating it (skill level) and

where (facilities)? Does the producer know about the nuances of video

technology?www.smartphonetech.org

Studying Motion Video Technology

All skills are to be converged Many techniques of Multi Media borrowed

from full motion video production methodology.

Possibility of auxiliary services like Desktop Video Editing .

Close kin of Animation. Most complex and jargon ridden


Principle of Motion Picture: Frame Rates

Successive images (frames) of a moving object are

captured in a movie camera at a fixed rate (frame rate)

The frames , when played (projected) at the same

frame rate gives an illusion of moving object.

Frame rate above 20/sec is adequate.

For slow moving objects even 15 frame/sec would do.

Below this rate, jerks are perceived.

Not only object motion but camera -optical motion

(pan, zoom ) is to be considered.

Cine uses 24 frames per second.

Higher frame rates used for special effects.


Source for Motion Video Objects

Computer Files Only form usable in Multimedia. Many formats. Usually compressed.

Analog Video Camera Needs frame grabber for direct storage as a computer file. Equipment technology mature and low cost.

Analog Video Cassettes/Tapes Camera to tapes/cassettes. Different qualities and standards. Generation loss of quality. Needs frame grabber again.


Source for Motion Video Objects (contd.)

Digital Video Camera May be stored in tapes/cassettes or directly stored

as computer files. Technology still evolving. Equipment Costly.

Digital Video Cassettes/Tapes/ disks Surprisingly predates digital video cameras. Old Digital Video Cassettes/Tapes/ disks are not

readable by computers. New Computer readable (compressed) formats are

now available. No generation loss. Best suited for editing.


Playing Video on PC

Pentium and Power PC based personal computers are capable of playing full motion video of different qualities.

From Hard Disk (AV, SCSI-II F&W preferable) CD ROM (32x) Intranet/Internet DVD TV antenna or Cable TV (need special cards) VCP (you really do not need a PC)

Quality varies: Full speed , full screen , full colour Small quarter size (Fixed , variable and movable)

windows Smaller frame rates Video Overlay www.smartphonetech.o

rg

Playing Video on PC (Contd..)

Configuration: Pentium-II, 200 + MHz, 32MB Ram SVGA monitor and adapter with required resolution

and colour depth Sound Card and speakers Software Graphic accelerator ( desirable for full speed full

screen) CD-ROM

Configuration: additinally may require DVD (if source is DVD) Hardware assist (For playing MPEG-II) TV tuner Card


Video Formats: Lines , Frames and Fields

Brodcast and VCR video are generally refreshed @ 25/30 frames /sec

Each frame is composed of a large number of horizontal lines.

Each frame is divided into two fields. The even field contains only even lines of a frame. The odd field contains only odd lines of a frame. The two filelds are displayed one after the other :

thus covering the whole frame in two installments. Each field takes half the time of a frame.

This is known as interlacing.


Video Formats: Lines , Frames and Fields


Video Formats: Lines , Frames and Fields (contd)

Interlacing Reduces Broadcast bandwidth (by transmitting only

half the lines per field) Reduces flicker as fields are updated 50/60 fields /sec.

To synchronise the frames and fields , the source supplies vertical synchronisation signal, once per field.

Loss of vertical sync results in jumpy vertical scroll . To synchronise the lines in a field , the source supplies

horizontal synchronisation signal, once per line. Loss of horizontal sync results in loss of picture . Computer Video is progressive i.e non-interlaced.


Video Formats: Aspect Ratio

Films 35 mm 1.85:1(16:9) to 2.35:1 (~19:8) 70mm 2.35 : 1 16mm/8mm 1.85:1

Standard TV Monitors: 5:3 HDTV - 16:9 Computer Monitors : 5:3 (1.67:1) Video in computer (multimedia component)

height -h

width-w

AR=w:h


Analog Video Signal Waveform: Monochrome

TBD


Television Broadcast Standards

Standard Frame rate Resolution Countries

NTS 29.97 fpsinterlaced

525 line USA, Japan, Canada,Mexico, part of Centraland South America,South Pacifics

PAL 25 fpsinterlaced

625 lines India,UK, Germany,Netherlands.

PAL-M 30 fpsinterlaced

525 lines Brazil.

SECAM 25 fpsinterlaced

625 lines France,Eastern Europe,Middle East

HDTV : Coming Up


Color Components of Video

The information of a point in a colour picture may be described in terms of intensities of three colour signals RED , GREEN and BLUE.

Almost all perceivable colours can be described by varying the proportions of the three components.

If we keep the proportions same but change the absolute values of the RGB signals, the colour will remain the same but brightness will change.

However, If we keep the the absolute values of two signals same but change the proportions by changing the third signal, both the colour and brightness will change.


Analog Video Camera Principle

Two basic types of video cameras Tube (e.g videocon, orthicon) CCD (semiconductor)

In a monochrome video camera the external image is focussed on the active surface of the tube or the CCD array.

An electron beam scans the active surface horizontally and vertically just like in a TV monitor.

The scanning action generates the video signal proportional to the luminosity of the points scanned.


Analog Video Camera Principle


Analog Video Camera Principle (monochrome)

The scans are synchronised with V and H sync

signals generated from a stable source.

The stable source may be the camera or another

camera or a studio master sync generator (gen-

locking).

The above video signal is composited with the V and

H sync signals to create the composite video signal.


Analog Video Camera Principle (colour)

In a colour camera The scanning mechanism is identical to that of the

monochrome. An image is optically seperated into R G and B

components using filters and prisms. The three components are focussed into three

different active surfaces which generate corresponding (R,G,B) intensity signals.

In a single CCD colour camera There is only one active surface but containing

three different kinds of active elements, one each for R,G and B.

Each type of active element responds only to its corresponding colour lights.


Analog Video Camera Principle(colour) (contd.)

Depending on the output type desired

The R,G,B signals and the sync signals are

separately ouput

The signals are composited and output.


Luma and Chroma The Luminance or brightness of a small region in a

colour picture is given by:- Y=0.299R+.0587G+0.114B

In black and white TV, only the Luma component is required.

When the Luminance is known, we need two more quantities (say proportions) do describe the colour. These signals are known as chrominance components of the signal.

There are several ways to describe the Luma. Eye is most sensitive to spatial and temporal variation

of the Luma component.


Hue and Saturation

If we (optically) add white colour to another pure colour say blue, what do we get ? Does the colour change (say to pink or yellow)?

Something (tint) remains constant and something (say shade) changes.

What remains constant is the tint or hue. What changes is technically called saturation. If a pure colour does not contain any white

component it is called fully saturated. An image with saturated components looks

bright. Unsaturated components create pastel shades.


CHROMA component options Naive: Y and any two ( not used) CCIR 601

U= (B-Y): -yellow, V= (R-Y) : - cyan PAL (actual)

U= 0.492(B-Y), V=0.877(R-Y) Also known as Y-U-V

NTSC (Y-I-Q) I=0.596R-0.275G-0.321B (orange to blue) Q=.212R-.523G+.311B (purple to green) Eye is least sensitive to Q

JPEG/MPEG Cb=(B-Y)/2+0.5 Cr= (R-Y)/2+0.5 Range is always one.


Video Signals

Component Video RGB and +Hsync (every line) +Vsync (every line)

: 3+2 or 3+1 (combined sync) R,G+ combined sync,B

TV signal and composite VHS Picture info +Hsync (every line) +Vsync (every

line) +chroma burst (every line) Picture info= Luma +chroma Luma + chroma on colour carrier as a combined

signal SVHS (camera and deck)

Luma and chroma on colour carrier as two separate signals


Composite Video Signal Waveform: colour


Digitisation Basics

Lines and frames are first steps of discretisation - already available, even in analog video.

Two dimensions for video data within a line : Time domain sampling, Magnitude domain discretisation.

Both these degrade picture quality to some extent.

Without sacrificing quality How often to sample ? How many bits to discretise the data?.


Horizontal blanking interval

SYNC.WIDTH

BLANKINGWIDTH

BURSTSTART

FRONTPORCH

BURSTWIDTH

EQUALIZINGPULSES

VERTICAL BLANKING WIDTH

EQUALIZINGPULSES

VERTICALPULSES

EQUALIZINGPULSE WIDTH

VERT. SYNC.PULSE WIDTH

Vertical blanking intervalwww.smartphonetech.org

Spatial Resolution and Bandwidth

Consider the figure below which shows an alternate patterns of black and white and the corresponding video signal.

The number of pulses would roughly corresponding to the number of dark bands N.

If the horizontal display line time is Th, then the frequency is f= N/ Th

The frequency content (bandwidth) of the video signal is therefore directly proportional to the horizontal details (resolution) and vice versa.

Thus the bandwidth can be expressed as dots per line (spatially) or alternatively in MHz ( time equivalent) for a given horizontal clock.www.smartphonetech.org

Spatial Resolution and Bandwidth (contd)

If processing, transmission or display bandwidth of the video signal is much below the video signal f generated due to horizontal details, the video signal amplitude would decrease and hence the contrast would decrease and hence details ( bands ) cannot be

distinguished i.e resolution would be lost.

Similar effects may be seen after employing low pass spatial filter in still images.

Due to the limitation of transmission (and display) system, the bandwidth of video signal is (artificially) limited.


Effect of Low-pass filters (spatial or temporal)


Resolution and Bandwidth (contd)

Limiting bandwidth of video signal limits resolution of broadcast / VCR generated images but allows broadcast, reception and processing using

inexpensive equipment allows slower sampling rate.

The vertical resolution is limited by the number of lines. However, the actual resolution perceived by human eye is

a bit different than what the bandwidth calculation would predict.

Due to interlacing, a single pixel width line is displayed only in alternate frames and would tend to blink.

In SECAM a thin line may show two differnt colours (as Cr and Cb are sent alternately)

A projected film has much higher resolution in both vertical and horizontal directions.


Sampling and Nyquist A theorem due to Shannon, attempted to answer the

question “How often to sample ?” Like many other question the answer is “it depends”. The best sampling rate depends on how quickly the signal itself is changing.

The agility of a signal or the quickness of its change is measured by its Bandwidth. For example in broadcast , the TV picture signal bandwidth is less than 6 MHz (6 million times/second).

The sampling rate should be at least twice the bandwidth or a part of the information would be lost and signal may not be reconstructed from its sampled version. This rate is called the Nyquist Frequency.

Nyquist frequency for TV picture signal is 12 MHz.


Sampling and Nyquist (contd.)


Sampling RGB or Composite? Sampling of composite signals are to be avoided

as : Resultant digital signal is difficult to manipulate. The colour subcarrier is also sampled. Artifacts (defects) are introduced.

Sampling of S-Video signal i.e. Luma and combined chroma is slightly better.

RGB is simplest and easiest to manipulate - but wastes bandwidth.

YUV (Luma and separate chroma) are the best as optimal sampling rates and compression are possible.


Luma and Chroma Sampling

The Luma signal changes more rapidly and eye is most sensitive to it. It has a bandwidth of about 4 MHz in broadcast TV.

Luma signal needs to be known for every pixel. Chroma signal changes more slowly and can be

sampled less frequently. Good quality may be obtained by sampling the colour

components at half the frequency. (4:2:2). Reasonable colour rendering is obtained by 4:1:1

sampling. Colour signals may also be sampled in alternate lines

(4:2:0)


Luma and Chroma Sampling(illustration)


Magnitude Domain Discretisation

For Digitisation the sampled magnitudes or values need be converted into binary integers.

For a black and white image, we would require only 1 bit (0 or 1) per pixel.

For grey scale image, the number of bits required would depend on the number of grey shades desired. For example, with 6-bits, 64 different shades may be

distinguished. with 8-bits the shade count would be 64


Magnitude Domain Discretisation (contd.)

The total number of bits employed in RGB component video would determine the varieties of shades.

For RGB component video, the number of bits employed are usually identical for each channel.

For Chroma-Luma component video,the Luma channel may use more bits than the Chroma

Employing more number of bits per pixel would increase the fidelity of the picture, but increase file size and play banndwidth requirement.

Some lossy compression techniques may reduce the bit depth


Colour Bitmap Encoding

Colour of a point (pixel ) may be described by the quantities of the R-G-B components.For computer ,the quantities would be described by digital numbers- say integers.

So we need three integers for every point to describe the image .

For the image, the sets of numbers for all points is called the Colour Bit Map.

For true colour representation , each such numbers should be of 8-bit size. So we need 24 bits , giving Millions of shades.

We may not need such huge varieties of shades for every single picture.


Bitmap Encoding and CLUT (contd.)

If our requirement for shades is modest , say 200 shades only, we may reduce the number of bits required. Example: night scene, sky, buildings...

This is done by using a palette or a colour look-up table (CLUT).

A colour look-up table contains entries of RGB components against shade numbers. (we may throw- in a colour sample strip along, just like the shade cards available in paint shops)

As there are less than 256 numbers, an 8-bit integer would be adequate.

We may then represent each point with just one 8-bit number. Of course we knew this while studying still image and graphics. What we did not know is that for a video, the 256 shade

CLUT limitation may be applicable for the whole clip.www.smartphonetech.org

Digitised Video Standards Studio Quality

NTSC PAL CIFpels/line 720 720 360Active lines 485 576 288LumaSampling

485 576 288

Chroma SubSampling

4:2:2 4:2:2 4:2:0

Fields/s 60 50 30Interlace 2:1 2:1 1:1Aspect Ratio 4:3 4:3 4:3


Pixel Arrays

120

240

483

600

720

900

1080

160 352 720 800 1152 1280 1920

QSIF(19kp)

SIF (82 kp)

601 (300kp)

SVGA (500kp)

ATP (1Mp)

Workstation (1 Mp)

HDTV (2Mp)


Rationale for Compression

Example : 640x240 (full screen) , 24 bit full colour, 30fps 221 M bits/s (~ Indian Internet BW) 28 M Bytes/s 15 s file takes 420 MByte space (about 1 CD)

Storage Streaming rates Distribution Transmission


Data rates/BW of Medium

Medium Bitrate/BWOrdy Telephone 0.3-56 Kb/sDS-0 Telephone 56 Kb/s

ISDN px64 Kb/s

T1 1.5 Mb/s

Ethernet 10, 100 Mb/sBISDN 100-200 Mb/s


Compression Basics

Redundancies Exist Spatial (subsampling, subband)

neighbouring pixels tend to have very similar brightness and colour, except for the edges.

Temporal (predictive) Successive frames have many pixels identical to

those of previous. Intraframe Vs. Interframe

Spectral (subband) Not all shades of colour appear in a clip

lossy Compression may destroy information

Also called source encoding !www.smartphonetech.org

Lossless Encoding & Compression No loss of information Compression depends on content. Low compression fast encoding and decoding Run length encoding (RLE)

Simplest form of compression Usually intraframe, also used in fax, zip etc. Example: aaaaabbbccccd=5a3b4cd

Huffman Encoding Determine the most frequently occurring pattern,

give it a short code and so on. Dictionary is required.

Transform Encoding (some)


Lossy compression Enforces ‘almost similar ‘ things to be similar and

then compress. Large compression ratios may be obtained. Quality may suffer Trade-off may be done between compression ratio

and quality. When applied spatially , reduces levels of

contrast Hue

Almost similar successive frames are treated as similar

May be carried out without notice (Backdoor Compression) When you reduce size When you reduce colour depth When you reduce frame rates


Transform Encoding: The basic idea

Similarity is not always obvious. By transforming the original data, the

similarities are revealed.

In the above picture, the horizontal lines are not similar.

If we rotate the thick line (i.e. mathematically transform it) to be horizontal, similarity is revealed.


Transform Encoding: The basic idea (continued)

A picture may be transformed into components which

may be easily and compactly expressed.

A picture may produce very large number of components.

One may discard the insignificant components.

Discarding component implies loss of information- but

this may not be perceptible.

By varying the number of components retained, one may

trade off between quality and compactness.

The trick is to find the right transformation which would

produce a small number of significant components.


Transform Encoding(contd.)

Available Transforms Direct Cosine Transform (DCT) Fractal transform

Fractal Transform Highly asymmetrical Needs huge time during compression proprietary

Discrete Cosine Transform Popular (MPEG, JPEG) Well understood Good trade off 1:200 compression feasible


1-D Cosine Transform Example

The following waveform represents the luminosity distribution along a 180 pixel line.

A cosine transform of this would need ~ 180 components

sigma

-2

0

2

4

6

8

10

12

0

10

20

30

40

50

60

70

80

90

10

0

11

0

12

0

13

0

14

0

15

0

16

0

17

0

18

0

sigma


1-D Cosine Transform Example (contd): total Vs 30s ig m a

- 2

0

2

4

6

8

1 0

1 2

0 10

20

30

40

50

60

70

80

90

10

0

11

0

12

0

13

0

14

0

15

0

16

0

17

0

18

0

s ig m a

-1

0

1

2

3

4

5

6

7

8

9

01 8 0

3 0 C o m p o n e n t A p p ro x im a t io n

2 0 C o m p o n e n t A p p r o x i m a t i o n

0

1

2

3

4

5

6

7

8

0 1 8 0


1-D Cosine Transform Example (contd): 40 Vs 30

-1

0

1

2

3

4

5

6

7

8

9

0180

30 Component Approximation

40 component Approximation

-2

0

2

4

6

8

10

0 180


1-D Cosine Transform Example (contd): total Vs 20

s ig m a

- 2

0

2

4

6

8

1 0

1 2

0 10

20

30

40

50

60

70

80

90

10

0

11

0

12

0

13

0

14

0

15

0

16

0

17

0

18

0

s ig m a

2 0 C o m p o n e n t A p p r o x im a t io n

0

1

2

3

4

5

6

7

8

0 1 8 0


1-D Cosine Transform Example (contd): 30 Vs 20


0

1

2

3

4

5

6

7

8

0 180

-1

0

1

2

3

4

5

6

7

8

9

0180



1-D Cosine Transform Example (conclusion)

If we retain just 50 components there is almost no loss of information, except some noise .

If we retain just 40 components, we get a reasonable replica

We may try going down to 30 or even 20 components. One may observe the rapid deterioration of details.

We see the trade-off between compactness and loss of detail.

The above concept may be extended to 2-D as well.


8x8 Discrete Cosine Transform

Popular 2-D transform with 64 coefficients


Interframe Compression

Temporal redundancy is eliminated by interframe compression.

Consider a title page, which have to be shown for 3 seconds (i.e 75-90 frames) Each such frame is absolutely identical Sending one frame and N-1 ditto’s are good enough and

non-lossy. In general, successive frames may be very similer. Compression could be obtained by sending a

reference frame and then sending only the changes or differneces. In order that the differences do not become too big,

reference frames may be sent periodicallywww.smartphonetech.org

Motion Compensation

A special case of interframe compression Applicable with camera pan or moving subject A part of the picture remain same but move

as a group (translate) By supplying only the motion vector (direction

and amount) the pixels concerned may be defined.

Macroblocks (16x16) between successive frames are compared for close matches.

Differences are computed after considering the motion vector.


Why filtering is required

With spatial filters we may limit the details and levels of contrast

Limiting the details reduces bandwith and sampling at lower frequency is possible without violating Nyquist limits.

Bandwidth and contrast limited pictures compress well.

Lossy compression will reduce bandwidth and contrast in any case

Artifacts may be introduced if filtering is not performed.


Artifacts due to Digitisation and Compression

Pixelisation Jagged edges Moiré fringe Contouring Colour seepage and smear Palette Flash Jerky movement Salt and pepper


Video Compression Techniques and Standards

JPEG & M-JPEG (intra frame) H.261 (intra frame) MPEG-1 MPEG-2 MPEG-4


JPEG and M-JPEG

JPEG (Joint Photography Expert Group) Recommended standard for digitisation and compression

of still images May be used for frame by frame compression of MP.

JPEG Modes: lossless sequential progressive hierarchical

JPEG lossless mode : pixel-wise predictor encoding using neighbours

Sequential Mode each image component encoded in a single left to right,

top to bottom fashion.www.smartphonetech.org

JPEG and M-JPEG (continued)

M-JPEG JPEG extended for motion picture and animation,

still intraframe Sequential JPEG applied to each frame

JPEG progressive : image quality improves as more data arrives Suitable for web images

JPEG hierarchical Code and compress a down-sampled image Upsample it and take the difference with original, send the down sampled and difference may be repaeated multiple times


MPEG

MPEG (Motion Picture Expert Group) Recommended encoding and compression

standard. Accepted by ITU and ISO

Three different standards MPEG-1 (for PC Video, near VHS) MPEG-2 (for HDTV and Broadcast studio) MPEG-4 (primarily for video telephony)

MPEG-1 and MPEG-2 are already available and popular


MPEG standards Overview Three layers or streams

System Audio Video

System = Info regarding synchronisation random access, management of buffers time stamp

State of the art compression Flexibility for optimisation Software Decoders available

Quicktime Xing Mediamatics with windows Media player


MPEG-1

1991 Vintage For CD-ROM video and Audio Audio is near studio quality Video is near VHS Targeted frame rates ~ 1.5 Mbits/s lossy & asymmetric compression

Intra frame spatial redundancy crunch using DCT (6:1)

Interframe ,temporal redundancy elimination, using P (predictive) difference

A number of RLE and compaction steps Software coding and decoding possible.


MPEG-2

For higher data rates (4 to 9 Mbits/s)

For better picture quality and HDTV (US and Europe)

Would play MPEG-1 objects

Used in DVD video and DBS (hughes)

Interframe ,temporal redundancy elimination, using

P (predictive) and B (bi-directional) frames

Seq: I-P-P-P-B-I-P-P-B-I

4:2:2 Chroma subsampling


MPEG-2 (continued)

10-bit DCT DC precision non linear qualtisation Other compression steps Optional time stamp error and transport control Hardware codec recommended Don’t expect MPEG-2 to be better than MPEG-

1 at lower bit rate.


MPEG-2Standards and levels

Level Sample xLine

Framesper sec

Bit rateMbps

Quality

Low 352 x258

30 4 VHS

Main 720 x576

30 15 CCIR 601,Studio

High1440

1440 x1152

60 HDTVStudio

High 1920 x1152

60 80 Filmproduction


MPEG-4

Expected to be formalized in Nov 1998 Targeted bit rate 4.8 to px 64 Kbps (p <80) Suitable for

Video phones Video conference Internet video Mobile video Computer generated animation

Object based encoding


Data Rates of Media

Media Data Rates (KBytes/sec)

CDROM-2X 300 (theor)CDROM-8x 1,200 (theor)CDROM-32(SCSI)x

4,800 (theor)3,500 (typical)

F & W SCSI &AVI HardDisk

6MBps- 10MBps

SCSI & AVIHardDisk

2.5MBps- 6MBps

IDE HardDisk 1.5MBps- 2MBps

DVD-R 2.5MBps- 6MBps

Striped Disks 10MBps- 20MBpswww.smartphonetech.org

Analog Video Recording:Tape Formats

VHS (1/2”: Consumer, composite) 8 mm ( Consumer camcorder, composite signal) S-VHS ( improved VHS, S-Video, midrange) Hi-8 ( improved 8 mm , S-Video/RGB,midrange) Betacam 1/2”(high end, studio, RGB and other) Betacam-sp (high end, studio, RGB and other) U-matic-3/4’’ - now obsolete Tapes (1’’) : Broadcast and studio

Type -B Type-C


Digital Video Cameras

Type Price Note

SonyDSR-200

$6,400 DVCAM tapeFireWire Conn.

SonyDSR-130

$19,400 Multiple backs(tape formats)

PanasonicAJ-D700

$22,000 DVCAMAnalog feed-in

IkegamiHC-5900

11,106

JVCENG-1910

$11,000


Media For Storage and Distribution

Considerations Capacity Streaming rates erasability transportability

Types Hard Disk Zip disks (between stations or for back up) Tape (between stations or for back up) CD-ROM

Writable for small volume Mass produced

DVD www.smartphonetech.org

Digital Video Recording:Tape Formats

Type ColourDepth

Sub-Sampling Compression

SonyDVCAM

8 bitcomp

4:1:1 5:1Intra-

Pana VisionDVC Pro

,, ,, ,,

Pana VisionDVC Pro-50

,, 4:2:2 3.3:1

JVCDigital-S

,, ,, ,,

SonyBetacam-SX

10 bit ,, 10:1interfram

D1 10 bit ,, Uncompressedwww.smartphonetech.org

Media For Storage:DVD

DVD = Digital Video/Versatile Disks The Latest Storage Medium, capable of

storing multiple full length feature films. Songs (multiple albums) Data (4 GB- 16 GB)

Standards still evolving Different Capacities

Single/double layer Single/double side(may require manual flip) Typical capacity of single side-single layer 4.7 GB


DVD(contd.) Different Versions

DVD-Video DVD -Audio DVD-ROM DVD-R (write once-by user) DVD-RAM (rewritable)

DVD -Video and DVD -Audio may be played in dedicated players.

Computer may play all. DVD-R : Best suited for small volume multimedia content

distribution. DVD-RAM : Useful for object capture and edit Data rates 2-5 Mbytes /s (video)

Supports MPEG-II


Video File Formats

Video For Windows AVI (Audio- Video interleaved) QUICKTIME

A very popular PC-Video format from Apple for Mac ,PC, Internet

Mature and open standard. Play backs most forms of files (CODECs). Suitable for virtually all forms of multimedia objects like

video, sound animation stills, MIDI,VR. Scaleable - quality adjusted automatically to suit

platform. Latest :- real-time support and Vector graphics in QT3.

Special Animation files (FLI, FLC)


CODECS

Cinepack Most widely used and supported. Software and hardware versions available. Best for 320x240 @ 15 fps,180 KBps 10:1 achievable compression Shortcomings : pixelisation, chunky, poor colour

saturation. Indeo

From Intel (Hardware and software) 3x version good for talking heads, poor colour

saturation. 4x and 5x versions comparable to MPEG-1 Realtime adjustment of brightness and contrast


Steps to PC Video

Plan Content Decide Target platform , run length and quality. Shoot and Grab or otherwise Acquire (vide

Video tips) Prepare Edit Decision List (EDL) Edit and Compose Dub Clean and Compress Store in CD or Distribute via Net


Video Capture: Basics

Required for analog sources like . VCP VTP Laser-Disk players Camera

Requires Special Hardware (frame Grabber Cards) which Samples the video signal Digitise the chroma and Luma components Stores them in disk files Optionally compresses the data Displays while grabbing


Video Capture Platforms.

Should be the highest performance machine affordable.

Would serve as video editing and compressing stations as well.

Windows NT Pentium-II, 128 MB memory, SCSI-Disk 4GB

AV, RAID is better. Separate disk for software and data storage

recommended. Zip drive for transportation of large files or 100 Mbps

fast Eathernet and of course the frame grabber card .... ...


Video Capture Cards

Also called frame grabbers Some popular cards

Megamotion (JPEG) Broadway (MPEG-1) Video Blaster (Creative) Video Spigot (Creative) Matrox Illuminator


Video Capture Cards :check list

Input Signal types Composite, S-Video, RGB Whether Audio channels supported NTSC/PAL/SECAM

Sampling rates supported Colour resolution (8/16/24) Whether full screen frame grab possible. Maximum frame rates Video Overlay, whether needs special video

cards. Whether saves in raw or compressed mode. Software Provided


Video Capture Cards :Typical Specs Data Translation- Broadway

32 bit PCI master NTSC or PAL capture Frame Size: 352x288 (240) Colour: 16bit,YUV 4:2:2 SVideo and Composite Preview (15 fps typical ) Overlay (full fps) Capture to AVI (uncompressed) Capture to MPEG (compressed) 16 bit audio Bundled

Edit Software (Ulead Media Studio VE) and Compress Software (MPEG-1)


Video Capture Cards :Connection

RGB or Composite orS-Video connectors

Feature connector

I/O bus connector

To mother board

To video source

To video Card


Video Capture- considerations.

In house or outsource? Budget Type of capture CODEC Quality

Equipment availability High end camera/VTP/VCP Video capture platform , card with appropriate CODEC. Example

QUICKTIME Time required to perform the job.

Asymmetric Encoding Operator skill Do not use lossy compression if editing is envisaged(MJPEG-ok)


Video Capture- considerations(contd.).

Two Approaches Best Capture Just Capture

Best Capture Capture with the highest screen size, colour depth and frame

rates Same for audio Better safe than sorry : you can always reduce information Huge file sizes Requires the most expensive boards

Just Capture Why bother for full frame and true colour when the target

machines cannot display them? Use the target screen size, colour depth and frame rates Save time and money


Video Capture procedures

Estimate the file size. Create a blank file and defragment the disk. Check the settings Trial run

Electrical Settings Palette


Video Editing Primer

Contents: Concepts Tools Adobe Premiere Story board


Video Editing Concepts

Edit Decision List Linear and non linear editing

Edit like serial tape or Edit Like disks File edit

Just cut and paste True Edit

File edit and more Transition Conversion Superposition Picture edit

Filters, Colour correction &cwww.smartphonetech.org

Video Editing: Conversions (continued)

Cropping Resizing Pan & Scan

For 70 mm format Performed often at telecine stage.

Frame Rate Conversion More : duplicate frames Less: discard frames CAUTION !

Pace Slow motion Fast Play

Colour Depth www.smartphonetech.org

Transitions Dissolve

Gradual superposition of the incoming clip on the outgoing

May ustilise other subtechniques also. Fade-out

The ongoing clip gradually turns into black Fade-in

The incoming clip gradually turns from black to normal Wipe

A line divides the frame into the outgoing and incoming clip areas.

The line moves to increase the incoming clip area . Many more


Superposition

Whatisit Many layers of picture with transparent and opaque

regions, superposed together Kinds

Picture +Text Matte + Text Video +Video Picture + Animation Video +Animation (Spilberg)

Keying Chroma Keying Alpha Channels: pixel by pixel transparency control


Traditional Non-linear Editing! Tradition goes back to

Music Channels. “Jurassic Park” “Who framed Roger Rabbit”

Used Silicon Graphics High End Work stations Composite or RGB digitised Random Access Abekas Disks and Exabyte digital

tape drives Digital Edit and special effects including animation Tape to film

Not been a cup of tea for the PC’s But stay tuned


Non Linear Editing using Model

Instead of an “edit decision list” on paper, one or more story boards may be created using compressed (lower quality) clips.

Such “dummy” products are called models of the final. We would call them prototypes.

Models may be iteratively improved. Compressed, smaller screen , slower frame

rate and lower resolution content allows quick prototyping and improvement.


Video Editing Tools

VidEdit Comes Free with Video for Windows and many

frame grabber cards. From the stable of Microsoft.

Adobe Premiere Most popular


VidEdit Features

Basic Video File Edit Tool. Input may be .AVI file, Autodesk Animator .FLI

or .FLC file. Cut , Paste and Insert of Video and Audio

components. Frame rate convert Colour Depth convert Crop and Resizing Palette building compression

RLE, Indeo, Microsoft video-1 Custom settings based on target (CD-ROM etc.)


Adobe Premiere: Features

Fairly Comprehensive Video Clip Editing Wide selection of picture edit Conversion applied on whole clip Drag and Drop Wide selection of Transitions Film Strip metaphor Super Audio edit Compression


Adobe Premiere Windows

Preview

Clip

A

B

Super

Videos

Transitions

Audios3 of

Construct

ProjectSources of all clips

Info

TransitionPalettes

Premier


Adobe Premiere Construction Window


Media Merge

Simpler video editor Uses story board metaphor Sequence of clip and transition boxes Text superposition Drag and drop Three components

Story board editor Scene editor Audio Editor


Video Compression Techniques and Standards

JPEG & M-JPEG (intra frame) H.261 (intra frame) MPEG-1 MPEG-2 MPEG-4


Tips for Video in multimedia

Shoot or Acquire Lights more Lights Shooting Ancillaries More tips


Shoot or Acquire

Don’t shoot if good quality “footage” is available.

Employ a professional for shoots if fund permits.

Choose the best available camera (SVHS and High-8

recommended).

Tripod is equally important.

Lighting can make or break.

Choose a simple background.

Check if direct storage to PC is feasible.

See ‘tips’ at the end.


Lights... more lights

Eye is more forgiving than camera, which needs better lighting.

At least three light sources (including natural light). The main light from front but a bit left (or right). The key light from up and behind. A compensatory light to reduce stark shadows

from the main Don’t neglect the background:

The background and the foreground should have difference in illumination.

For bright background , exposure should be adjusted or the subject would look too dark.


Shooting Ancillaries

Reflectors Thermocol on masonite backing Aluminium foil White board

Halogen main light Halogen “table lamps” and stand Turn table (for machine parts and small

objects) Back screen

Remember chroma key Prompting stand Mike boom


More Tips for Video in multimedia

While shooting landscapes and large buildings, use slow pans. It would look good, compress well.

Use shooting notes - detailing location, date, event , shot number, identity of persons etc.. Do not rely on memory.

Always capture audio along with video. It would back up your shooting notes.

Take shots that may be used as the back drop of titles for long clips.


More Tips

For indoor objects experiment using short clips with back ground lighting shooting techniques filtering rate conversions compression.

This extra trouble would be rewarded. Cuts take less disk space than transition . Use

transitions judiciously. Use fonts specially designed for video (e.g.

sans serif faunts) in titles.www.smartphonetech.org

The Future :

DVD video’s at Indian homes and libraries. CD-ROM social function video a must for

Indian middle class. DVD-video of museums Indian Cartoon films (Amar Chitrakatha) on

CD-ROM’s and DVD. Amature film directors. Spielberg from India Desktop Editing of Broadcast Quality Software Video on demand


Desktop Editing of Broadcast Quality Content

Favourable Factors: Digital Camera, DVD Players and HDTV Increased Processing Power at the Desktop at

affordable price. Cost 1/100 th of present analog edit station cost Emergence of MPEG-II

Special Equipment would still be required Media

Tape .. Computer .. Tape Analog Tape or Digital ? DVD.. or Tape ? Camera to Computer ?

India- the destination ? Labour intensive Special Care, Closer control


Thank You


contents l forms of motion picture l multimedia products with motion picture content l motion video...

Documents