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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
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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
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“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
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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
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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
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Compression Types
Lossless compression– loses no databut...
– small size reduction, max 3:1 Lossy compression
– loses informationbut...
– much greater compression
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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.
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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
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MPEG Format
Motion Picture Experts Group (MPEG)– highly compressed, used on computers
and for broadcast applications, MPG extension
– uses a lossy CODEC
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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.
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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
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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
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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
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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.
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Surf Time!
Quicktime and other “raw” video types
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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">
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Streaming Video
A number of formats exist today:– RealVideo– Quicktime Streaming– Microsoft MediaStreaming
Today we will look mostly at Real
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A RealVideo Demo
http://ots.utoronto.ca/audvid/cat.html
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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
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Using RealProducer
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Putting RealVideo on your site
Using Wizards in RealProducer
Using Dreamweaver
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Surf Time!
RealVideo Sites
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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)
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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
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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
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RealSlideshow
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Working on Your Own Site