Overview: How streaming media works

COM 597 Streaming Media Lecture 1 June 21, 2007

What the heck is today’s drill? My background Definition of Streaming A little data to get you started A discussion of terms Why compress media Workshop setup

The class website can be found here: http://courses.washington.edu/smedia/2007/index.shtml Review the Syllabus

What is streaming media? • Data that is transferred in an orderly and logical fashion. • For this class it will be defined as audio and video media that is interpreted in real time by a player application on a computer. • This will also include media that is handled in something called a “progressive download” • Streaming is often confused with media that is downloaded to a hard drive for later use. That is just saving a file.

Why use streaming media? • Cost effective way of • Tracking and communicating profiling • Faster time to • Global delivery market • Use infrastructure • Create more options more efficiently for communication

More or less memorable media Some Personal Favorites: Paul Potts Flagpole Sitta Pandora Yes, even my kids

Who should be concerned about the nuances of streaming? • Web designers • Educators • Web programmers Communications • Videographers and journalism Distance learning • Audio engineers Computer science • Media producers • Business leaders • Post-production interested in new managers opportunities

Media compression is all about trade-offs Variables to consider when considering a compression strategy: • Image quality • Sound quality • Frame rate • Disk space • Bandwidth • Platform --- how will it play on older processors • Portability and cross-platform compatibility • Licensing for tools • Digital rights management • Labor costs (time and money)

Consider the context of how it will be used… UI, environment (TV, computer, portable device)

What is a media player? • Television • Radio • CD player • DVD player • TiVo • VCR • Movie projector

If you think about it, Thomas Edison created a media player that transformed the peaks and valleys in the groove of a wax cylinder into electronic signals that moved a speaker, creating pressure waves we could hear. The principal is essentially the same with today’s players.  Click Me! http://www.tinfoil.com/ The Melon Patch Schottische A snappy band number from 1895, The Melon Patch Schottische, played by the 23rd Regiment Band of New York

Where are we today? How are on-demand media devices such as the TiVo/DVR and the iPod, along with Video On Demand and other digital media delivery platforms, continuing to alter the traditional media landscape?

Some implications of the Arbitron|Edison research • Content producers will need to track the “Heavy” on-demand media consumers closely. The growth in this arena are showing that these new broadcasting platforms are not just a fad. • As media becomes ever more portable and flexible, it will require new advertising approaches. Shorter spots, testing of new approaches

Some implications of the Arbitron|Edison research • Video on demand is ever expanding and approaching critical mass • More information at: www.edisonresearch.com

What the heck is a “Codec”? • A Codec is a device or program capable of performing encoding and decoding on a digital data stream or signal. The word "codec" is a portmanteau of any of the following: 'Compressor-Decompressor', 'Coder-Decoder', or 'Compression/Decompression algorithm'

What really is a codec? • It is the software and/or hardware that squeezes video and audio down and then expands it back out so it can be viewed on playback.

Codecs need to be the same on both point of origin and reception. In other words, you will need the proper software to uncompress and view a file. Codec families include the big five, QuickTIme, Real, Windows Media, Flash and MP3. There are countless other codecs, and specific iterations within different families.

What are you after when encoding? • Make the file as small as possible with the least quality loss. But this is a judgment call, and just like art, somewhat subject to interpretation what is best. What follows are some common terms we will need to commit to memory:

How big do you want to be? B byte One KB Kilobyte Thousands MB Megabyte Millions GB Gigabyte Thousands of Millions TB Terabyte Millions of millions PB Petabyte Thousands of terabytes

How fast do you want to go? •bps  Bits per second •Kbps  Thousands of bits per second (“kila-bits”) •Mbps  Millions of bits per second (“mega-bits”) •Gbps  Thousands of millions of bits per second (“giga-bits”)

How loud do you want to be? dB Sound is measured in tenths of Bels, better known as decibels.

What is your speed? • fps • Super 8 is 16 fps (frames per second) • Film is 24 fps • European standard definition video is 25 fps • North American standard definition video is 29.976 fps • High definition video can be 23.9, 24, 25, 29.976, 30, 59.9 or 60 fps

What is your speed? • ips Used for analog audio tape (inches per second) Magnetic tape speeds are commonly an even fraction of 30 ips: 30 ips: The highest professional speed. 15 ips: The most common professional and studio speed for reel to reel including multitrack. 7 1⁄2 ips: The lowest professional speed, The most common speed for pre-recorded reel to reel tapes. 3 ¾ ips: Used on later single speed domestic machines 1 7/8 ips: The standard speed for compact cassettes

How big do you want to be? dpi dots per screen resolution inch dots per film resolution dpmm millimeter

Can’t we just all get along? Some codecs that we will review have several names for the same thing. • Exhibit A: MPEG-4 part 10 This is usually referred to a H.264, but can also be called AVC (Advance Video Coding) • Exhibit B: Windows Media 9 or WM9 The format started life as WM6.5, then WM7, then WM8 before landing on WM9. Because it is becoming a standard for more than just Microsoft products (HDVD) it is officially known as VC1.

Evolution of a codec MPEG-1 The first compression codec in this family MPEG-2 Probably the most popular. This is what a DVD is made of MPEG-4 part 2 The first of the MPEG 4 standards. Supports an alpha channel MPEG-4 part 10 A more recent standard, and a significant improvement in compression

Why do we compress our media? More than just keeping files small It is about optimizing throughput on a network.

The process of compressing a file from 40,000 feet up (the big picture)

What is Video? Video is basically a three-dimensional array of color pixels. Two dimensions serve as spatial (horizontal and vertical) directions of the moving pictures, and one dimension represents the time domain. A frame is a set of all pixels that (approximately) correspond to a single point in time.

Digitizing • This is the process of taking an analog signal and turning it into an approximate digital representation of the original image and sound. • Examples of digitizing: scanning a photograph, capturing video into a computer, capturing a recording • Ripping a CD is not technically “digitizing” because it is already data. It is usually referred to as “capturing”

Compression in simple terms is reducing the data used to display an image, play an audio file or present video. It is used throughout the industry. • Cable TV • Editing platforms • DVD • TiVo / PVD • Video Acquisition Data can not be put back once it has been removed.

Spatial Compression • Spatial encoding is performed by taking advantage of the fact that the human eye is unable to distinguish small differences in color as easily as it can changes in brightness and so very similar areas of color can be "averaged out" • Common image file examples are .jpg, .tiff, .gif and .png

Spatial Compression Points are usually described with Cartesian values (X-Y) • X side to side • Y up and down • Z close and far away

Temporal Compression With temporal compression only the changes from one frame to the next are encoded as often a large number of the pixels will be the same on a series of frames Low motion example 276 Kbps Medium motion example 344 Kbps Fast motion example 354 Kpms

When not to compress • Acquisition and origination • Archiving • Mastering You (your client or boss) have to decide what is an acceptable level of compression based upon the variables we will be discussing in class.

Other nifty terms we will be using: • Metafile: A small file on a web server that includes information (metadata) that informs a player where to locate a file on a media server. A roadmap, if you will • Encoder: a software or hardware application that transforms a source media file into a file that can be streamed efficiently. • FTP Client: software on a client computer or server that uses File Transfer Protocol to upload or download files from another computer at a remote location.

Additional websites for reference: http://www.streamingmedia.com/magazine/ http://www.digitalproducer.com/ http://www.streamingmediabible.com/ http://www.w3.org/AudioVideo/

Overview: How streaming media works

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