Video Terminology

Clip: source material for a movie. A clip can be a movie, a still image or an audio file.

Frame: basic unit of time– NTSC (TV): 30 frames per second (f.p.s.)

(29.97 for colour television); – motion picture: 24 f.p.s.

Digitisation: Capturing information from a video source for use on the computer

SMPTE Timecode

The Society of Motion Picture and Television Engineers (SMPTE) standard

Describes any frame of video in terms of: Hours:Minutes:Seconds:Frames

So 01:07:34:16 would be:1 hour, 7 minutes, 34 seconds and 16 frames

“Raw” Formats

Different for platforms:– QuickTime (MOV) - native to Mac– Audio-Video Interleave (AVI) - native to Windows

Similar in use and appearance Quicktime has become more flexible and

modern (compression, streaming) Special players required to play on opposite

platforms

Compression

Compression:method by which data is restructured or removed to decrease the size of files.

Decompression: method by which data is restructured after compression to allow use of the files.

CODEC: Compression/Decompression system

Why Compress?

Video files are typically large Internet is (mostly) a low-bandwidth

environment Large amounts of data contained in a

video difficult to transmit on the Internet Therefore, compression necessary to

move the data effectively

Compression Types

Lossless compression– loses no databut...

– small size reduction, max 3:1 Lossy compression

– loses informationbut...

– much greater compression

Compression Formats

JPEG: for stills Motion JPEG: a series of still JPEGs MPEG-1:

– released in November, 1991 – used with CD-ROMs – frame size of 360 x 240 pixels. It has a

VHS-like quality.

Compression Formats (cont.)

"MPEG-1.5": – application of MPEG-1 to full-size video– "pixel-vision" or "chiclet-vision"

MPEG-2: – released November, 1994– full-motion broadcast video version of MPEG, used

by DVD-Video. MPEG-3: never released by the Group. MPEG-4: the HDTV standard

MPEG Format

Motion Picture Experts Group (MPEG)– highly compressed, used on computers

and for broadcast applications, MPG extension

– uses a lossy CODEC

MPEG CODEC

The MPEG CODEC uses this method:instead of saying “A VERY DETAILED FRAME OF VIDEO”“A VERY DETAILED FRAME OF VIDEO” “A VERY DETAILED FRAME OF VIDEO” “A VERY DETAILED FRAME OF VIDEO”etc.

It says:“A VERY DETAILED FRAME OF VIDEO” - KEYFRAME <identical frame><almost identical frame>“A VERY DETAILED FRAME OF VIDEO” - KEYFRAME <identical frame>etc.

MPEG Stats

30 frames per second Audio - CD-quality with full 44 kHz, 16

bit, Stereo Data rate - 140-170 kilobytes/sec or

approximately 10 MB per minute

Internet Video Basics

Video files on the web are either– linked from a page– embedded in the page

Download time depends on – file size– connection speed– general Internet traffic

Basics continued

For “raw” video, every user has a copy of the video on their system

Most common video formats can be played back on a standard system with correct hardware

Some older systems require special hardware for MPEG playback

Internet Video Video Tapes:Standards: MPEG is a global

standard.There are multiple video tape formats.

Linear Presentation:

Great for short video of 10 minutes or less.

Good for longer videos.

Searching Capability:

Excellent - Use of hyperlinks and user directed sequence easy.

Poor - Rewind or fast forward.

Playable by: Those with Internet access. Those with a VCR.

Cost of distribution:

Inexpensive. Involves reproduction and shipping expenses.

Delivery Time: Immediate updates. Lead time necessary for reproduction & shipping.

Maintenance: Single repository. Multiple sites and copies.

Surf Time!

Quicktime and other “raw” video types

Incorporating Video Files In Web Pages Standard Link tag: <A HREF="myvideo.avi">A video clip</A>

EMBED Tag: <EMBED SRC="myvideo.avi" autostart="true" width="176" height="144">

Streaming Video

A number of formats exist today:– RealVideo– Quicktime Streaming– Microsoft MediaStreaming

Today we will look mostly at Real

A RealVideo Demo

http://ots.utoronto.ca/audvid/cat.html

Creating RealVideo

Capture video. – Video tape, TV, camcoder, etc.

Digitize and edit video. – Into a raw (MOV or AVI) format first

Encode RealVideo clip. – Using RealProducer

Deliver RealVideo clip. – From web page - linked or embedded

Using RealProducer

Putting RealVideo on your site

Using Wizards in RealProducer

Using Dreamweaver

Surf Time!

RealVideo Sites

What is SMIL?

The Synchronized Multimedia Integration Language (SMIL)

A recommendation from the World Wide Web Consortium (W3C)

Allows for the creation of time-based multimedia delivery over the web

Based on XML (Extensible Mark-up Language)

SMIL

Currently supported by RealPlayer G2, other systems are adopting it now (including Quicktime)

G2 SMIL includes these media types:– RealText– RealPix– RealAudio– RealVideo– RealFlash

SMIL Examples

Sample SMIL File SMIL including Flash animation with syn

chronized audio and captions SMIL with audio and images created in

RealSlideshow Additional Examples

RealSlideshow

Working on Your Own Site