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R.I.Feigenblatt - August 2005 (minor edits thereafter)

When the [MIT Media] Lab started fifteen years ago, suggesting that computers should be able to speak and listen and see was a radical thing to do, so much so that it was almost grounds for being thrown off campus for not being serious. It was a battle... that's been won; what matters now is what is done with these capabilities."

- When Things Start to Think
(Henry Holt and Company, 1999) by Neil Gershenfeld


1. Computer application programs in the age of numbers and text
2. Desktop publishing, presentations and videogames
3. Internet audio broadcasting and audio e-books
4. Internet telephony
5. Internet video and digital video time- and location- shifting
6. Digital mapping and design
7. Capturing and manipulating still images electronically
8. Live multimedia, the Internet, and teleconferencing

1. Computer application programs in the age of numbers and text

Originally, computers were just used for performing tedious mathematical operations. But eventually, electronic memory and processing power became cheap enough we could use them to do the prosaic sort of things for which we had previously employed typewriters and filing cabinets - the creation, storage and recall of text.

This type of use is highlighted by the word processor, which we encountered in a previous lesson. Another illustration is offered by the type of application program called a "database processor". Basically, a (flat-model) database is a single computer file which holds information in an especially regular pattern. You can think of it as a giant table with rows called "records" and columns called "fields". But unlike a table on paper, the electronic database is easily erasable and extendable in both dimensions, limited only by the amount of memory you can afford, rather than the size of a sheet of paper.

A common use of a database is as a personnel archive, in which one record is used for each individual and the various fields are used for things we want to remember about each person, like their first and last names, addresses, telephone number, and so on. This suggests an alternate metaphor for the database file - as a collection of paper index cards, with one record per card.

If (as we recall from our third lesson) computer subdirectories (or folders) represent the way we typically group related files together, then database organization is a common way we find it convenient to subdivide the space within a file. But it is not the only way, for every computer programmer is free to use the bytes of storage within a file in any way desired - no matter how confusing, haha! An interesting example (which will only make sense if you are paying careful attention) is the so-called "zip" file, in which a collection of files - even a large tree of subdirectories - is compressed in an orderly manner and packaged within a single, new, archival file, so that it is easy to move as a unit between different computers. A similar file type defined by Microsoft is the CAB file. Yet another related, but distinct type of file, called a "disk image" file, can store the total contents of an entire disk drive - or a major subdivision of it called a "partition" - within a single file. As we discussed before, disk image files are often used to rapidly restore a hard disk to a known state, and are key to PC maintenance today.

While a lot of attention now focuses on the Internet, that does not mean things like the database have lost importance. Most of the so-called "dynamic" Web pages to which we alluded in our second lesson are constructed by searching a database to address a query the Web surfer has entered, and using the results to create a brand-new Web page just for him.

We do not have time for a detailed discussion of the database in this course, but it is a workhorse for all sorts of clerical work - like payroll accounting, postal mailing labels, etc. Nowadays, it is typically sold bundled in with other programs - such as a word processor - in what is called an "office suite" of programs. Microsoft Access is a popular database, part of the suite called Microsoft Office. But there are also acceptable free alternatives, like Open Office.

A special type of computer database called a "spreadsheet" is of great use to people who do complicated sets of interrelated mathematical calculations. The paper spreadsheet was long used extensively by accountants, and its translation to the computer realm is actually what commercially transformed the PC from a hobbyist toy into a serious mass-market office machine.

We call the space defined by a particular row and column in a spreadsheet a "cell". A spreadsheet cell might hold some text, but more typically it holds either a number or an algebraic formula. Such a formula will often refer to one or more other cells using the well-known convention of the algebraic variable. The magical thing about a spreadsheet is that when you change a number in a particular cell by hand, all the other cells which depend on it are automatically updated! That is why accountants fell in love with the computer spreadsheet - all the tedious and error-prone arithmetic involved in updating dependent cells was automated, without the need for the accountant to write a conventional computer program.

Even if you are not an accountant, you will find it useful to know a little bit about handling spreadsheets. That's because spreadsheet processors, like Microsoft Excel, (also bundled into Microsoft Office) include the ability to plot sets of numbers as graphs and charts. As we saw in our first lesson, geometrical representation is a powerful tool to understand, remember and gain insight from large collections of numbers.

2. Desktop publishing, presentations and videogames

Automated image production is older than many people appreciate.

In our first lesson, we encountered what some may argue was the first "computer" graphics display device, the Jacquard loom, which could weave arbitrary patterns in fabrics at the dawn of the 19th (sic.) century, decades before the emergence of chemical photography. But fundamentally, the graphical capability of the loom was not all that different from the centuries-older printing press: both relied on the existence of a pattern which a human being had first created.

In contrast, later in the 19th century, an electromechanical "clockwork" device called a chart recorder began serving in scientific studies to chronicle the variation of a parameter over time on a sheet of paper - using a mechanism to directly transcribe events in the natural world without the intercession of any person. Twentieth-century film buffs are familar with the chart recorder through examples like the seismograph and electroencephalograph.

The chart recorder was mother to a now-rare early computer graphics device called a plotter.

The electronic cathode ray tube or "CRT", invented at the end of the 19th century, was put to work as something of a high-speed successor to the chart recorder, as the oscilloscope - a device familiar to most people through the electrocardiograph.

In the early 20th century, the CRT was recruited to draw imagery associated with RADAR and live all-electronic television. In the late 20th century, RADAR and TV screen devices using CRTs would provide the basis for interactive computer displays.

Non-interactive computer graphics would enabled by re-purposing the teletypewriter, which derived from telegraphic recording machines invented in the 19th century.

As PC processing power and memory size increased in the late 1980s, computer graphics went mainstream, and eventually progressed far beyond the austere business graphics produced by early spreadsheet programs. It became possible to produce ever more complicated graphs, diagrams, charts, maps and even photos in static form. This gave birth to so-called "desktop publishing" by which a PC could be used to digitally perform all the prepress steps previously requiring a professional print and/or photography shop. It was complemented by the cheap new versions of the laser printer which could render masters - or even entire press runs - in the common office, too.

By the late 1980's, as the numbers of PCs multiplied into the millions, the PC graphics display itself became a publication medium target, rather than just an authoring tool. This led to the creation of presentation programs in which the PC would exhibit the sort of material previously common in transparency and film-slide shows - but with digital storage media like floppy disks used to store and transport shows. Today Microsoft Office includes a tool of this sort called Powerpoint.

Desktop publishing and presentation programs acquainted many people with digital publication methods. When the mass-market Internet rolled out in the mid-1990s, these skills were readily translated into those needed to create Web pages. Today a Web page may point to a "PDF" file, a format created for desktop publishing, or it may point to a Powerpoint file, a format created for stand-alone PC presentations. But the type of file used by the World Wide Web itself - the "HTML" or "HyperText Markup Language" file - is a perfectly fine medium itself for publishing a group of pages comprising a traditional linear-page-sequence document. The advantage of using simple HTML is that it is multiplatform - virtually any Web browser running on any type of machine can interpret and show Web pages. You'll note that our first lesson was published in the style of an audio-annotated slide show using HTML rather than Powerpoint or another third-party tool.

Electronic presentations have displaced those using slide- and overhead-projectors, the universal equipment through the 1980s. Standard business and professional conferencing rooms now include an electronic digital projector (prices for new gear start around $700) for viewing presentations, which allows a visiting speaker to plug in his laptop PC and exhibit his talk. While you can buy a new laptop starting near $500 these days, an even cheaper option has emerged via the consumer electronics market. Many DVD players, including new units costing under $50, have the ability to play electronic slide shows from an optical disk like a suitably formatted CD or DVD. DVD "burner" drives which can create new disks of this type now sell for under $50, including disk creation software - and are commonly bundled with new PCs. These developments make it possible for you to replace your laptop PC with a DVD player costing a tenth as much when travelling to present an electronic slide show - making loss or theft of your gear less painful. But so many people will want to bring their laptop PC along anyway, I'm not sure this sort of substitution will prove popular with any but those of very humble means.

While presenting all-but-simple animation on the very slow PCs of the 1980s was very challenging, the IBM booth at the 1988 ASME convention won an award for its excellence, using a tool called PCMOVIE yours truly authored to exhibit very short cyclical movies on PCs. My favorite movie - obviously not used at the professional show - was a video "yule log": You could even vary the speed at which the movie frames were shown to control the violence of the fire. It was one of the first decorative-genre "screensavers", predating commercial products like After Dark.

As we entered the 1990s, PCs finally had enough power to do a reasonable amount of animation, and dynamic cartoon-based imagery let the PC provide entertainment - as a videogame machine. The first program to broadly demonstrate the simple PC's ability to create heart-in-your-throat "virtual reality" was id Software's Wolfenstein 3D, released in 1992. (It was also a key pioneer of "hookedware" - which offers a limited number of play scenarios for free as a marketing tool, in the expectation you will then be happy to pay money to enjoy more of the same.) Indeed, before the advent of the mass-market Internet in the late 1990s, videogames were the most popular single use of PCs in homes. Today, both PCs with "graphics accelerator" boards and "game console" appliances are supercomputers capable of remarkable photorealism, including live synthesis of highly problematic drawing challenges like hair and foliage. The two have tended to converge in the sorts of hardware used (magnetic hard disks and broadband Internet networking) but game consoles are turn-key zero-maintenance gadgets, unlike the typical PC. Probably that's why they account for vastly more game software sales than PCs.

Early PC-based videogames of the latter 1980s made use of a primitive sound system which included little beyond the ability to beep and play tones. But before the mid-1990s, PCs had enough power that they could easily record, playback and even synthesize arbitrary sounds (like special effects and even the human voice) when equipped with a sound board, such as one using the very popular standard originated by Creative Labs. Together with the CD-ROM drive, this was the birth of the multimedia PC, at which point home purchases of the PC skyrocketed, as they had at the office about a decade earlier.

The combination of the multimedia PC and a decision to allow commercial traffic on the Internet set the stage for the mass-market Internet. When the Netscape Web browser made navigating the World Wide Web simple, use by everyday people exploded.

3. Internet audio broadcasting and audio e-books

Once PCs could measure and produce arbitrary sounds, it did not take long for people to realize the Internet might be used as a radio-like medium - but with no limit on the number of audio feeds or stations it could support - unlike the severe limits imposed by finite amounts of aerial broadcast frequency spectrum. A firm founded by an ex-Microsoft executive called Progressive Media introduced a "receiver" program called Real Player. The basic version was, and remains, free. Its success is why the firm itself is now known as Real Media. Vast numbers of conventional broadcast radio stations now also provide free feeds via the Internet using Real Player and its major competitor, Microsoft Media Player. There are also feeds from many others without broadcast licenses, such as people producing special events, offering educational lectures, or publicizing regular things like town meetings and church services.

And there is yet another advantage offered by escape from limited broadcast spectrum. Often it is no longer necessary to listen to an audio feed live. It is cheap to record and playback audio, and so many audio producers allow you to enjoy a program via "audio on demand" - you can play back the program over the Internet any time at all. Whether live or prerecorded, we call this type of progressively spooled-out audio feed "streaming audio".

Originally, people did not think about sending audio and video media over the Internet. It was amazing enough that one could send e-mail and computer files. Therefore, relatively little thought was given to the question of transmission latency - how long it actually takes to receive a data packet once it is sent - or transmission jitter - how latency can fluctuate because of changing traffic patterns. But these things have important implications for live media like audio and video. If delays are too long or too variable, a raw feed of live material will arrive too late - or worse yet, cause discontinuities in the transmission. Happily, for streaming media, we have an out. Since the communication is one-way, even a long delay is not a showstopper. And by "buffering" a few seconds of the feed before showing it to the user, the media player can deal with a jittery supply of data by "getting ahead" and "carrying an inventory".

When people listen to a live radio program via the Internet, a separate stream of data is generally sent to each individual listener. If say, the transmitter is in London and you have a dozen listeners in Atlanta, this is wasteful. It would be much better if a single stream were sent to a computer in Atlanta, and then a dozen duplicating streams were then created to travel the final short hop to reach the actual dozen end users. This hypothetical scheme is called "IP multicasting". While there have been experiments with IP multicasting networks on the Internet, in general multicasting is not implemented for media broadcasts. (But the type of economy manifested by multicasting is exploited in certain modern "file sharing networks": Users run client software on their PC, so that if they want to get copies of files from the pool of available files, they implicitly agree to provide copies to other users as well.)

While dial-up modem Internet connections in the 1990s provided just enough communications bandwidth to transmit audio like radio programming, now vast numbers of people in rich countries have fast ("broadband") Internet connections at home. A radio program which requires a bandwidth of, say, 32 kilobits per second, can be transmitted at 50 times "live speed" over an ADSL broadband connection that peaks out a 1.5 megabits per second. This makes it possible to "download" a copy of an entire half-hour program in little more than half a minute - and increasing numbers of producers are giving listeners this sort of option.

Why would someone download a program when one could listen to a pre-recorded version via audio on demand? Well, a file copy provides the producer an alternative method of distribution - copying between acquaintances using removable storage media like disks. This was especially helpful when one person had an Internet connection, but maybe his friend did not - or when a person had a connection at home but not at work. The listener might also like to be sure that if the producer stopped publishing online, he would still be able to enjoy and share the audio program in question in the future.

Nowadays, there is an additional powerful reason for downloading entire audio programs whole from the Internet. Flash memory made it possible to make build cheap digital audio players somewhat analogous to the famous magnetic-tape-based Sony Walkman. This allows people to listen to digital audio files anywhere - and even carry hundreds of hours of material in a garment pocket. Since many of these players use an audio compression algorithm called "MPEG-1 Audio Layer-3", or "MP3" for short, they are colloquially called "MP3 players". The first famous player was introduced by Rio in late 1998, but nowadays a hard-disk-based player from Apple called the iPod has a lot of buzz. That's why the publication of audio files for downloading now bears the moniker "podcasting" - a portmanteau of the words "iPod" and "broadcasting."

But the cheapest MP3 players use big-toenail-sized erasable flash memory cards - either built-in or snapped into place as one would a cassette tape. And they can be very cheap indeed. The other month you could purchase an MP3 player without any built-in memory for $10 after rebate. Players that use removable memory have an appeal for those on a limited budget, because the same type of memory might be swapped into a digital snapshot camera, a cell phone, a handheld PC, or simply used to ferry large amounts of data between PCs using so-called flash "card readers". Card readers which plug into the external USB ports found on today's PCs start a little over $10.

With a PC microphone costing as little as a few dollars, you can record your own audio files for publication on optical disks or via an Internet Web site. For your audio production software, you can use a free, fully-functional, multitrack audio recording and editing program like Audacity. (Just download the installation program file from the Web site and run it on the PC to install the actual program.) It even includes special tools which help clean up corrupted audio recordings. Many people use it to make enduring digital copies of beloved old vinyl recordings, under the shield of the Audio Home Recording Act of 1992, applicable in the USA. (Aside: Note that "burned" optical disks have uncertain lifetimes, as we discussed in our first lesson. Until truly archival low-cost optical disks are developed, one can evade this problem by regular lossless dubbing; it is simple, cheap and quick!)

While MP3 players gained popularity as a means of enjoying vast collections of compromised audiophile music on the go, many podcasts are now used to distribute the sort of talk-based programming one often finds on AM radio in the United States. I think podcasts also have the potential to provide educational and other "narrowcast" programming to busy people who have to work with their eyes and hands all day - doing things like driving, cooking, diapering, and so on - and would be disinclined to pick up a book when they have respite from their workplace and/or commuting efforts.

Indeed, it has long been possible to listen to e-books (that is, conventional books recorded in computer-readable text files) via digital appliances which render the text as synthetic speech. The Road Runner, from Companion Devices, discussed here, was available by 2000, but is no longer made. A modern successor is the BookCourier from Springer Design. But with the availability of cheap MP3 players, many people will prefer to use a cheap ($30) program like Text ALOUD to generate MP3 files from text files, and then download the MP3 files into the player for listening.

E-books are the subject of a Web page here, which lists many sources of free online books. Other types of free online educational material are listed here. Newspapers and magazines, among other things, are listed here.

4. Internet telephony

The great popularity of text-based chat on the Internet begged the question of whether voice-based chat, that is, Internet telephony was possible and advantageous as well. Even when nearly all US Internet users used slow dial-up modems in the late 1990s, people started experimenting with Internet telephony. Multiple makers provided free software which would turn your PC into a free - or nearly free - international telephone of sorts. The principle restriction was that you could only talk with someone else who used the same software. That meant that while you could easily arrange to talk to special communicants with PCs nearly for free, you could not use the system the way you do the conventional telephone system - secure in the knowledge that almost everyone has a telephone through which you can reach them.

While not all that many people took advantage of global Internet telephony, its possibility made it hard to offer long distance telephony at high prices much longer - because a long distance carrier could not let a new technology grow at its expense. Besides, massive deployment of long-haul fiber-optic cables throughout the developed world had made the cost of long-distance communication very cheap from then on anyway.

But the Internet had a more profound impact on long-distance telephony firms than that. As the new century dawned, carrier after carrier announced it would abandon its traditional end-to-end SONET digital telephony technology and replace it with a new network based on Internet-style packet switching, gaining important operational cost economies. These networks would even have an important advantage over use of the public Internet. Because they would belong to a single carrier intending to sell voice service from the get-go, careful attention would be paid to engineering latency and jitter very small.

But it turns out that latency and jitter on the public Internet is not as bad as it might be, and in recent years the public has shown it cares rather little for voice quality, as evidenced by how poor service often is on cellular telephony networks, which have grown massively popular overnight all the same.

Today we call telephony over the Internet and Internet-like digital networks "VoIP", which stands for "Voice over Internet Protocol". In a big business envirionment, it holds out the promise of cheaper communications systems, because workers can be supplied with a single communications channel that supports BOTH voice and data, rather than two systems, such as a conventional "public branch exchange" (PBX) for telephony plus a "local area network" (LAN) for computer traffic. That's why conventional phone companies are starting to offer VoIP service - lest networking companies gobble up their clients.

Millions of people have now exploited VoIP systems for entertainment and social uses, too. Microsoft's video game console appliance, the XBox, eventually added a feature called XBox Live, which lets players cooperating in teams via a broadband Internet connection coordinate their efforts with their spoken remarks - or maybe just taunt their opponents the same way.

Several instant messaging systems, which began offering bilateral or group chat via text alone, have now added support for voice chat. Such systems are getting better at breaking through so-called "firewalls", schemes which try to improve Internet computer security, but often just land up making things inconvenient for novel application programs, without addressing outstanding security problems which trump the ones with which they can indeed help.

A very popular stand-alone VoIP program written in Estonia is called Skype. Basic service, which includes the ability to hold five-party conversations, is free. The company makes some money by offering premium services. One example is SkypeOut, which lets you call out to conventional telephones in much of the developed world for only 2 to 3 cents per minute of conversation. With 50 million registered users only two years after its introduction, it was first rumored that Rupert Murdoch's News Corp. tried to buy the firm for $3 billion. Since the first draft of this chapter, Skype has in fact been acquired - by online marketplace gargantuan eBay for $2.6 billion. A rationale for this purchase is offered here.

I have had good recent experiences with free VoIP software using the public Internet, speaking with people in Europe and Asia at no incremental cost while enjoying a voice quality that rivals that of in-person conversation. That's because we used a broadband connection: it is now cheap to provide much more communications capacity for faithfully reproducing sound than was the case when telephony standards were set down a century ago.

To use VoIP with a PC, you need a headset or handset that includes both speakers AND a microphone. Wired headsets that leave your hands free sell for as little as $7. (You might like to pay somewhat more for gear with a so-called noise-cancelling microphone, especially if you also plan to use it with a speech recognition program to automatically transcribe your speech as text.) If you prefer, you can even buy a traditional-design telephone handset for as little as $13 which can plug into a PC's standard "analog" audio input and output jacks.

If your PC has an electrically "noisy" interior, you may elect not to use the traditional internal sound system bundled with nearly all PCs. Today, PCs sport high-speed digital jacks called USB ports. Into these you can plug external digital audioconverter modules which present standard analog audio input and output for connection with your headset/handset. Such modules start at about $25.

But by now, cellphones and wireless handsets may have made you unwilling ever again to be tethered by an audio communications system wire. If so, you can still enjoy using VoIP on your PC by adding a wireless link between your headset and PC audio system. Logitech introduced its first such product four years ago, offering up to 100 feet of roaming distance, using a 10-channel auto-scan 900MHz band radio unit, for $70 SRP.

It is hard to find them these days - a couple units I encountered had serious problems. But if you can settle for a 10-meter range, you can today instead buy Logitech's Mobile Freedom Headset for $60 SRP. It uses a short-range digital radio standard called Bluetooth (which shares the 2.4GHz ISM band with WiFi) at the Class 2 (2.5mW) power level. (A separate recharger for your car is another $20.) If your PC is not Bluetooth-enabled, adapters that plug into your PC's USB ports start at $20.

I haven't seen any Class 1 (100 mW) Bluetooth headsets, which might operate as far as 100 meters from a Bluetooth-ready PC. But Plantronics has a digital 900MHz band wireless headset with USB-attached base station aimed at the VoIP market called the CS50-USB, with a range of up to 200 feet, at a street price well under $200. One review suggests its audio bandwidth may be as limited as that of traditional telephony. If that is actually the case, one might look to traditional wireless microphone technology for a pair of units to provide a two-way analog audiophile-quality communications link of considerable range.

But don't give up on more VoIP wireless handsets. Cisco's Linksys just introduced the CIT200 which uses a USB-attached base station and provides a wireless link of from 50 to 300 meters span using the 1900 MHz band to communicate 32kbps ADPCM audio. Intended for use with Skype, one source suggests a price of only $130.

Finally, it is not always necessary to own a PC to have VoIP voice conversations. You can even buy handset form-factor appliances that plug directly into a broadband Internet connection and offer you the advantages of VoIP without the burden of PC maintenance.

5. Internet video and digital video time- and location- shifting

The success of audio broadcasting over the Internet paved the way for it to be joined by video broadcasting, especially as PC processing power and Internet connection bandwidth increased. The player programs mentioned above, Real Player and Microsoft's Windows Media Player, can handle video as well as audio. As new methods ("codecs") of encoding and decoding audio and video are developed, these players include the ability to automate the download of new codec modules which let them display media encoded using said new methods. (See Microsoft's codec FAQ for more information.) At the Buchanan-Haralson Public Library, the PCs in the main reading room include both the aforementioned player programs - as well as an alternative called Zoom Player. This third program loads very fast, includes nice controls, and is used to show the locally-produced historical film "Buchanan on Parade" from a local disk-based video file. (We use the free version, but paid versions add additional features and better compatability with more types of hardware.)

Improvements in how streaming video is compressed (i.e. how little-visible artifacts are traded for communications-saving removal of rendundancy in approximations of the actual video stream), made possible by the explosion in computing power in recent years, means that remarkably little communications capacity is needed for a watchable video stream. For example, the archived videos in the BookNotes programs of author interviews provided as "video on demand" over the Internet by C-SPAN's BookTV, stream at a mere 128 kilobits per second - because they are basically "talking head" programs. That's almost within the capability of a pair of "bonded" dial-up modems using an old-fashioned telephone line - let alone a low-end ADSL broadband connection with a peak capacity a dozen times as big. Free streaming video on the Internet tends to be encoded at no more than 300 kilobits per second, to save on the cost of transmission. (I have found that even an old-fashioned 350MHz Pentium II PC is capable of rendering such video while supporting a wireless 802.11b "WiFi" connection.) But among the numerous Internet video feeds we catalog here are some that reach 1500 kilobits per second. They are capable of delivering video of wonderful quality indeed.

Internet-based digital video publishers sometimes provide a file for download which encapsulates an entire video program. This not only includes digests of Internet streaming video formats, but other common formats like MPEG. (Various MPEG codecs are used by digital satellite and DVD players.) While nowhere near as popular as digital audio or "MP3" players, portable digital video players are starting to become available, too.

Digital technology now also plays a role in how video is shifted in space and time without use of a general-purpose PC. Originally, people used the analog magnetic tape in a video casette recorder to accomplish this magic. But this was joined by the digital video recorder or "DVR" in 1999 - in the form of the TiVo appliance. The TiVo is actually a special-purpose, zero-upkeep PC with a friendly user interface. Like a PC, it uses a magnetic hard disk (where the TV programs would be stored) and even an operating system originally developed for the PC - the popular UNIX clone called Linux. But unlike a PC, you control it with a wireless remote instead of a keyboard and mouse, and watch your TV set in place of a video monitor.

Because any part of a hard disk can be accessed within a tiny fraction of a second, any portion of any program recorded on a DVR can be called up without delay - quite a different experience from the use of a videotape. And DVRs can now record HUNDREDS of hours of programming with sufficiently large hard disks - quite a contrast to the 6-hour limit imposed on a single VCR casette tape.

Most DVRs depend on a monthly subscription fee and a telephone (or broadband Internet) connection to provide the sophisticated recording services of which their makers are the most proud. For example, you can tell a DVR to record every film that airs in the weeks ahead which includes Katherine Hepburn, and with the help of the service, it will do just that!

DVR providers have deals this summer which give you a machine capable of recording up to 40 hours of programming for under $100 plus the monthly subscription fee. While DVR appliances and services were originally consumer add-ons, DirecTV, the satellite TV provider, now can integrate DVR service with your television programming service, using a pure leasing model.

Unlike a VCR, the original DVR machines did not use removable storage devices. That meant you could never store more video than there was space available on its magnetic hard drive - even though it was equivalent to many, or even very many, VCR tapes.

But when TV-oriented stand-alone DVD video-disk-recorders arrived, some of them soon added the ability to buffer many hours of video on a hard disk before the actual DVD disk was recorded or "burned", giving you better editorial control over exactly what you wanted permanently recorded on a DVD disk. This led DVR makers to respond by adding DVD burning capabilities to their products as well, making the two appliance types more similar.

But one important contrast still typically distinguishes the two products - "DVD recorders" do not usually mandate you subscribe to a monthly service - letting you trade away the DVR's sophisticated automated recording services for freedom from an ongoing expense.

Finally, hobbyists have taken up the challenge of swapping out hard disks, especially from DVRs - or providing a means of extracting video via computer networking from their hard disks, so that it might be transported to the PC world, where all sorts of communications and archiving methods might be applied to the video in question. (Remember that it is now much cheaper to store large amounts of data like a video program on a DVD than on a magnetic hard drive.) DVR makers also make these convenient features available - but only with a monthly subscription fee, as best I know.

One should note that there exist digital devices similar to DVRs for recording broadcast audio as well. It is interesting that most are not much cheaper than DVRs, which record video along with audio. There are also multifunction pocket devices (based on flash memory) that provide multiple functions including two or more of: dictaphone, MP3 playback, and audio ("radio") reception. If you don't need to schedule the recording of more than one radio program at a time, this humble digital audio "swiss-army-knife" might serve you best.

New digital technology has not only changed the way video is broadcast using wired and wireless systems, and how it is stored and time-shifted. It has also changed the means by which it is moved around via the physical transportation of storage media. Because it is much cheaper to transport (e.g. mail) a set of optical disks like DVDs than bulky VCR tapes, a company called NetFlix pioneered a business model (since copied) in which you replace trips to the video rental store for VCR tapes, with use of a Web site to select DVDs which are rapidly delivered to you at no charge. For a fixed monthly fee, you can keep up to three DVDs at a time, as long as you want. When you want new movies, just return the DVDs you no longer need in prepaid envelopes and the no-fee swap is made. Besides saving the cost of travel (all the more valued as gasoline prices rise), you never get slapped with a fee for forgetting to rewind a tape - these are disks!

Ordinary new personal computers are now so powerful that they are suitable for use as digital video editing studios. As we observed, the use of a magnetic hard disk in place of a magnetic tape to record video means that any portion of a large video recording is accessible at once. That is why digital video editing is often called non-linear editing.

Traditional video media based on analog signals, like US NTSC television and VHS VCR tapes, can be digitized with hardware costing well under $100 using PC devices called video capture cards.

Alternately, digital-original equipment, like camcorders based on the DV standard, can be used to automate the analog-digital conversion process at image capture time. DV systems employ a high-speed digital interface standard called "FireWire (also called i.Link or IEEE 1394) to read out its high-bit-rate (25 megabits/second) signal. It is easy to add a FireWire port to a PC lacking one - just be sure the PC and its hard disks are fast enough to record such an incoming signal.

It should be noted that while digital signaling standards exist for flat-panel computer displays, some are still driven from PCs using the analog signaling standards in universal use during the all-CRT age. The VGA standard is the "lowest-common-denominator" variation of this analog family. But none of these analog standards are directly compatible with traditional US NTSC television. Happily, a tiny device called a scan-converter will enable this type of live translation for well under $100. This lets you preview digitally edited video on a conventional large-screen TV set - as well as do things like facilitate computer-based education on the same target device.

Digital video can be published to optical disks like CDs and DVDs, or uploaded to the Internet. Google recently began a free video hosting service as an experiment. Already, a wide variety of fare is available, from a quirky short of a skate-boarding dog, to a computer education lesson, to a full-length historical romance film in Vietnamese, to a tedious 4-hour city council meeting.

6. Digital mapping and design

Perhaps you are not surprised to hear that computing machines are used to manipulate geometric information, because geometry is as much a part of mathematics as is counting. But recall also that geometry literally means "measurement of the earth". So computers make a natural platform for manipulating maps - as well as other spatial designs.

Photography and other types of realistic image representation are the most faithful and complete simulations we have of the human visual experience. But because of the way our visual system works, we have another respresentation which is almost as popular - the drawing. Drawings, by which we mean the use of lines to represent the boundary between objects, "work" because edges play a key role in how our brain deciphers the meaning of what our eyes perceive. (One might suppose children like cartoons better than adults because drawings are easier for an immature brain to decode than is the actual real-world view it represents!)

So drawings and images are the two major alternate methods we use to represent visual information. Now, if digital memory is very expensive, as it was until recent years, it is far more practical to use a digital video display for making (line) drawings than it is for showing images - because then only a very tiny subset of the positions on the screen contain information which the digital memory must store: most of the screen is blank. Therefore, in the old days, computers graphics systems used "vector" graphics. ("Vector" is basically a fancy term meaning a line aligned in a particular direction.) When memory became cheap enough that it became easy to record the color and intensity of every distinguishable location on a screen, we flowered into the more general "bitmap graphics" (once called "raster graphics") in universal use today. (A "raster" is a pattern of adjacent parallel lines which completely covers a surface - like hoe rows completely cover a garden field.)

But bitmap graphics, since it can represent anything, can also portray vector graphics patterns. And as we pointed out, for some purposes, we like drawings (vector graphics) better than images (bitmap graphics)! Take, for example, text. Handwritten text is formed by making strokes of a thin line. Or consider the floor plan of a house. That too, is basically created by using line segments, rather than contiguous areal patterns. Finally, consider the road map. We mark the location and directions of roads with lines as well.

While line drawings economically capture the essence of many things, it is sometimes of value to supplement them with the richness made possible by the use of complete imagery. For example, we may want to use serifed fonts to beautify our text. Or we may want to show the color of carpeting and furniture in a floor plan. Or we may want to show how different lands areas on a map are put to practical use: as lake, forest, field or town.

A wonderful free facility which shows how to use both drawings and images well is Google Maps. As the name suggests, this is a map of the world, but one that is much more impressive than the paper maps with which you are no doubt familar. Not only does it show you mapping information, but you can also overlay detailed, registered aerial photography as well! For many places in the United States, including a lot of Haralson County, Georgia, you get detail down to the level of about a yard - you can even see the rooms of houses and any cars parked out front.

Now you may wonder how you can see cars on a map that covers the whole world. How big a screen do you need to hold such a map? That's where the advantage over paper of an electronic version becomes clear. You can use a normal computer display to see such a map because you only look at a portion of it at a time. When you want to look at another portion, you can use your mouse to drag the map area exposed, and the new material comes into view. If you want to change scales, that's easy as well - you can zoom in and out at will. Of course, to get the full benefit of this interactivity, it is important to use a broadband Internet connection.

But this facility is even richer yet. You can query for a particular type of store - say restaurants - and the locations of all restaurants within the field of view are marked with virtual push pins, each of whose details you can view one at a time by clicking on same with your mouse. We call an electronic map that integrates with databases holding geographically indexed information a "geographical information system" (GIS).

GIS programs with application programming interfaces, which allow programmers to augment existing functionality with new capabilities, are especially powerful. For example, if you are providing police protection, you might want to integrate your call and arrest records with the GIS. When a new type of crime occurs at three new places on the map, you might like to be able to click on those locations and ask the computer to see what factors those locations have in common - like the age distribution of the population living within a ten-minute walking distance of each, or the last five citizen complaints called in within a three-minute drive of each.

Some example real-world derivatives leveraging Google Maps as the base GIS, open to use by anyone, include a crime map of Chicago, a US apartment-hunting map, and a global camera snapshot map.

Google Maps provides aerial views which comprehensively tile the earth's surface. Another photographic catalog scheme is provided for a limited number of cities in France and Spain by France's Pages Jaunes ("Yellow pages" in French), which lets you look at streescapes from the pedestrian's perspective. Take for example Cannes, site of a famous annual film festival in the late spring. Sadly, only ONE side of the street is shot at any one location, for example this view of 59 boulevard de la Croisette looking from the Mediterranean beachfront. (Click at the center of the red circle to view the photo; more on this later, below). Closer to home, now Amazon is developing a service called A9, which provides streetscapes of selected US cities. Check out Atlanta here.

Some GIS programs even allow you to combine elevation data with the other types of data we've mentioned and create a three-dimensional perspective rendering of the area you are examining. This might be useful for planning military campaigns, realty development or resource management. Because you are looking at a malleable digital model and not the real site, you can even do things like vertically exaggerate the terrain to bring out subtle topographical details that have important consequences (like drainage paths) which you would not see with a naked-eye inspection. Indeed, you could even artificially "flood" the whole area with water of an arbitrary level to see the very phenomena which we cite. The use of synthetic animation - in which you "fly through" the scenery at any altitude or speed, unrestricted by the performance limits of a buildable real-world aircraft or the high cost of aviation fuel - can also help the human eye pick up details it would otherwise miss.

Perhaps the most dramatic example of this type of system is a marvelous three-dimensional model of our entire planet, called Keyhole, which was acquired from its creators by Google, and used to create Google Earth. Resolution of detail varies over the globe, but is rarely worse than 15 meters. In important areas like major cities it is typically 1 meter and sometimes even as good as 15 centimeters (or 6 inches)! The basic system is a free "beta" (or testing) version which works extremely well almost all of the time. (Albeit I've found a large lake with a bump in its water surface!)

A small program runs on the PC with which you view the Earth, and additional mapping detail is sent as needed from Google's central computers via a requisite broadband Internet connection. A limited amount of this data is stored or "cached" on the local PC, so that it need not be resent when you return to viewing a previously examined portion of the globe. Depending on how many people on the Internet are using Google Earth simultaneously, and how fast you move across the Earth, you might see coarse details emerge before fine details are added as you change views.

Unlike Google Maps, described above, with Google Earth you can view our planet's surface from an arbitrary glancing angle to observe the irregular surface height depicted. In some cities, individual geometrical building models are also added to the photographic decoration of the topography (to compensate for the fact that the lateral topographic resolution is coarser than the width of individual structures.) Google Earth shares with Google Maps the ability to search for and mark particular facilities in the displayed area (e.g. schools). Web sites associated with such landmarks can be accessed by clicking on the hyperlinks featured in the flags which locate them. Among the ways to navigate the globe is to drag the surface - or even give it a spin - in a very natural way, using the computer mouse. You can also take imaginary automatic "helicopter rides" between arbitrary locations using an optimized trip path.

Google Earth currently depicts eastern Haralson county in acute detail, but the western portion - including our town of Buchanan - only appears in coarse 15-meter lateral resolution. Of course, urbanized metro Atlanta is rendered in exquisite detail.
This is a view of Stone Mountain Park. You can even discern the monumental (90' x 190' figures) bas relief on the side of the eponymous Stone Mountain, originally a cenotaph memorializing war leaders of the Southern Confederacy. Stone Mountain Park
This is a view of Kennesaw Mountain National Battlefield Park, run by the victors of the aforementioned struggle. Here, resolution is so good that you can see the width of the lines separating the bus parking spaces! But the terrain model is not good enough to accurately represent how the terminal bus stop and access road are cut into the side of the mountain top to remain as level as possible. And the direct-overhead photography of the (poorly-parked) bus is naturally painted onto the lot as if squashed flat. Kennesaw Mountain National Battlefield Park

GIS features are essential to realistic vehicle simulations, such as the airplane, automobile and ship examples in today's video games. One such game is Microsoft Train Simulator, currently installed on one of the PCs at the Buchanan-Haralson Public Library. The best thing about this "toy" is that it is open to "modding," i.e. modifications. You can insert routes of your own design, with terrain of your own design, featuring buildings and sounds of your own design, which you can view from trains of your own design!

The Internet makes it possible for people with a common interest - like this particular videogame - to use groupware to meet online and work together. Fan sites for Train Simulator are listed here. They often include digital files which you can download and use for free (they're donated by fellow hobbyists) to implement virtually any type of modification you like. One can even finally learn enough to author one's own "mods" and thereby pick up useful vocational experience in "computer aided design" (CAD).

7. Capturing and manipulating still images electronically

Digital (electronic) imaging is displacing old chemical-film based photography, even for still images. That's because electronic photography now can match what one can do with film and offers additional advantages as well: even professional photographers are going digital. The only real consumable in digital electronic photography is the battery, and even that might be rechargable. Goodbye to buying film, and waiting for it to be developed after the shoot - or paying a premium for instant film. Also, because digital memory is erasable, you don't have to think twice before taking a shot to ration your film for later opportunities: you can always replace one less-wanted shot with one you simply must have. And it is very easy to do experiments with still life or panorama shots - if you don't like the snapshot you just took, overwrite it with a new shot: you get an artifact-free palimpsest every time.

Some electronic cameras are combination movie and still-shot cameras, but for the greatest snapshot detail it is reasonable to invest in a separate still camera. Today you enjoy excellent color balance and reasonable shutter delays. One popular online guide to digital cameras is Steve's Digicams. And extensive guides to model specifications and both professional and consumer reviews are available for digital cameras (as well as almost anything else you buy!) via the online resources tabulated here.

The other year the Haralson County Historical Society bought an entry-level 2-megapixel still camera which has served all of its needs, indoor and outside. It only cost $60 and the $4 battery lasted over a year. A tripod costing under $20 is used when one wants to steady the camera to achieve the greatest image detail. Like almost all digital cameras, it uses a flash memory card to record photographs. The card can be popped out of the camera and into a card reader on any of the PCs in the main reading room of the Buchanan-Haralson Public Library. Doing this makes it look like just another magnetic hard disk drive to the computer, with each snapshot represented by its own JP(E)G file.

There are many tools available for post-processing a digital photograph, mimicking and even transcending the sorts of tricks once pulled only in the chemical film darkroom. A free basic tool for doing this is Picasa, brought to you by the folks at Google. With the click of a button you can turn a color photo into a black-and-white one, crop the edges the way you like or readjust the lighting of the shot, among many other things. You can even use Picasa to create PC screensavers or render photos via computer printers, tiling the image among multiple pages to create a giant-sized version you use as a poster.

But Picasa has limited functionality compared to other image processing tools, often called "graphics editors" or "painting programs", of which Adobe's Photoshop is among the most famous - and the more expensive. A popular cheaper alternative is Paint Shop Pro, now sold by Corel. A free tool crafted to look like Photoshop is GIMPshop. Find a comparison of many bitmap graphics editors here and some tutorials in their use here.

The aformentioned programs are used to edit or create two-dimensional imagery, but many support the concept of independent (flush, parallel) layers in the third dimension, to help keep different design elements separate.

True three-dimensional graphics tools are another program category. CAD tools, which we met in the previous section, support the design of three-dimensional objects for use in programs like simuations. But sometimes it is simply enough to create fixed visual renderings including such objects, whether static or dynamic (animated). One powerful, free, 3D modeling and rendering program is Blender.

Some sophisticated "image understanding" programs can extract 3D geometrical information from multiple photographs of a real-world scene captured from different perspectives. They are useful for importation into modeling programs. By "texture-mapping" the captured photographic detail to the extracted 3D model, it becomes possible to simulate continuously "flying through" the scene via any specified trajectory.

A more modest example of the power of technology to combine multiple digitized photographic images is a program which can use overlapping snapshots to automatically assemble a panorama - even one with the capability to let one seamlessly turn around a full 360 degrees at will! As an example of this, vicariously visit romantic Budapest, Hungary via this map. Click on any of the red dots with your mouse cursor and then enjoy a wonderful interactive panorama of the place chosen, using your mouse to control where you look.

While stand-alone digital snapshot cameras have become wildly popular, they are now starting to be overshadowed by cellular telephones which include such cameras, as well as the ability to transmit the images they take via the wireless communication link. Perhaps a quarter-billion camera cellphones were sold in 2004! While high-end stand-alone cameras take better photos, cameras of ever-increasing resolution are being incorporated into cellphones.

The light sensor arrays in digital cameras, which capture the individual picture elements of a photograph, are sensitive to the broad range of colors visible to humans. To record color information as well as light-intensity information, digital color cameras almost always use a reseau of color filters in front of these elements which periodically tile the viewing field of the camera. But the unavoidable result is that the spatial resolution of the captured photograph is compromised.

This is unfortunate when one is actually taking a photograph of a black-and-white object, like the writing in a precious historical book. Cameras without color filter reseaus are manufactured, but very low production volumes mean they are very much more expensive than pedestrian mass-market full-color digital cameras. In such circumstances, depending on the number of images to be captured, it may make a lot more sense to use an old-fashioned film camera with monochrome film, and have the film digitized when it is developed. Such services are readily available these days.

But because of the falling price of flash memory, some digital cameras now give the photographer the option to record the unprocessed intensity values recorded by each and every of the sensor elements, rather than only a (lossy) compressed version, using a non-standardized format baptised "raw". In principle, such a format allows one to reconstruct the monochrome image intensities of each pixel, even with the interference of a periodic color reseau.

Finally, a revolutionary breakthrough called "Foveon" technology had promised to cast off the tradeoff between multicolor support and resolution by capturing images WITHOUT a mosaic color filter, using instead the fact that light of different colors produces electrons in the sensor chip at different depths. Sadly, however, the products made so far have all been recalled on account of problems.

With photographs in digital form, it is simple to publish them globally with no out-of-pocket expense. As we will discuss in the next lesson, one can easily add photos to World Wide Web pages of one's own design. And to make exhibition even simpler, a number of parties help one publish digital photos online without learning anything about Web publication technology. This simplified approach began with the "photoblog". (You will recall "blog" is short for "Web log".)

When someone's home is on fire, people will race into the burning building to rescue the people and pets, and then often return to retrieve critical records as well. Not among the least important of these records is the family photo album. Digital photography holds out the promise that fire, flood and other calamity can never again destroy a "lifetime of memories" is a few minutes. That's because it is now so cheap and easy to make and store "perfect" copies of photographs digitally - even photographs captured and printed long decades ago. By storing copies of the whole collection at multiple locations (e.g. safe deposit boxes, homes of relatives and friends) destruction of any single copy due to diasater at its storage location does not mean the collection is lost. (And fewer people will die risking life and limb retrieving paper records from dangerous locations!)

The easiest way to create a digital copy of a photograph is from the start: Use a digital camera or get digital copies made from chemical photographic film at development time. But it is not impossible to create digital versions of photographs when all you have are film negatives or paper prints. The image scanner is a cheap digital device which plugs into a PC and helps create a "high-resolution" (detailed) digital file which records the image on a paper or other flat surface. The most common type is the flatbed scanner. It is really just a special type of digital camera which trades speed and depth-of-focus for thrift, detail and accuracy. When buying one these days, make sure it uses a USB interface so that the connection speed to the computer is not the speed bottleneck.

An image scanner is also useful in digitizing the sort of material traditionally used to populate scrapbooks. But think about copyright implications when you scan a printed object, rather than store it physically: just because the physical copy is your property, it is absolutely not necessarily true that you enjoy copyrights to the intellectual property it embodies.

Nowadays general-purpose digital snapshot cameras are acquiring such filigree acuity at modest price that they can function as low-end scanners if mechanically or electronically stabilized. When incorporated into cellphones, this provides a means of automatically rendering printed text as spoken language through the use of off-site computers, a potential boon to those with limited vision or some other barrier to the ability to read. New Scientist currently reports:

"Commuters in Japan already anger bookstore owners and newsagents by using existing cellphone software to try to take snapshots of newspaper and magazine articles to finish reading on the train to work. ...some phones now offer very rudimentary optical character recognition (OCR) software which allows small amounts of text to be captured and digitised from images.

"...[But] new software, developed by NEC and the Nara Institute of Science and Technology (NAIST) in Japan, goes further than existing cellphone camera technology by allowing entire documents to be scanned simply by sweeping the phone across the page...

"Using the new software with a 1-megapixel camera held at least 20 centimetres away, an A4 sized page takes about 3 to 5 seconds to scan. This produces between 21 and 35 images which the software merges together to extract the text and record any images."

Electronic images can also be applied to paper by means of a computer printer, for distribution by traditional means. But you might not have to own such a device to make use of it. Modern printshops stay in business by providing access to specialty tools like high-quality or large-format printers, and many of them can print images you transmit via the Internet. Indeed, many photoblogging services bundle in the ability to order paper-based prints for a fee, as a source of revenue.

Now there are also dozens of millions of DVD players deployed in homes. Electronic images can be rendered to a DVD blank (and sometimes a CD blank) for playback on DVD players without benefit of computer skills. The biggest drawback is that current one-off optical disk production results in a product that fails to work on an arbitrary player a significant minority of the time. This is more an issue of compatibility than inherent quality. One solution to this problem is to dub a magnetic videotape from a DVD showing of an optical disk, as VCRs do not have compatibility limitations; but quality will be compromised in the process, and each playback will degrade the recording. One advantage of an electronic slide show is that it is easy to provide an audio track which annotates each image - something beyond your old photo album.

No matter what display medium one uses, visual fidelity to the original is not perfect. The real issue is how imperfect it is compared to a human being's ability to discern (or even care about) the flaws. (cf. above: Sometimes a drawing is better than a photograph.) Paying for excessive fidelity is wasteful anyway.

As we discussed earlier, digital graphics started out with line drawings rendered on CRT screens or on paper via plotters. Multiple pens made it possible for plotters to help distinguish lines by use of multiple colors from a small palette.

In the 1970's, primitive all-pixels-addressable graphics - included limited greyscale - were possible via computerized impact printers, by using different characters to fill all the locations on a sheet of paper. Held at a distance, the page manifested a continuous-tone image in the way long accomplished at much higher resolution by half-tone photographs in newspapers.

When digital memory plummeted in price through the introduction of integrated circuits, greater electronic image fidelity became practical. Bitmap graphics replaced vector graphics on CRTs and eventually color was no longer considered a luxury. Finally, full-color (i.e. the use of a palette with milions of entries) became pedestrian and we arrived at the situation common with electronic displays today.

The ability today to interactively pan and zoom electronic images rapidly (e.g. Google Maps) often obviates the need for a display of great physical area, and we can function well using electronic displays of limited size. And new, lightweight head-mounted displays potentially enable more natural modes of interaction with a visual world (and least in part) created by a computer. We use the terms virtual reality and augmented reality to refer to such modalities.

The main feature limiting the verisimilitude of computer imagery to that of natural life is the absence of stereoscopy. While we don't have time to talk about it here, progress is quite possible in the years to come. In the meantime, humble stop-gap measures, like the use of animation and cheap anaglyphic glasses, allow one to communicate stereographic information intuitively with ordinary contemporary displays.

8. Live multimedia, the Internet, and teleconferencing

While the masses have long enjoyed the ability to capture still photos via chemical photography and speak with distant parties in "real time" via wired telephony, we are now in an age where multimedia teleconferencing is a practical reality for the average person. As the end of cheap oil and other environmental, economic and population pressures build in this century, we will look to the Internet and successor networks as a giant "nervous system" which allows us to manifest our personal presence enormous distances away without the need to physically transport our bodies, advancing ever closer toward full telepresence. In the meantime, there are plenty of opportunities to use this capability for all sorts of (extremely economical) technologically conspicuous consumption.

Twenty years ago, when I was exhibiting (at an IBM technology exposition in Monte Carlo) a prototype portable computer I had designed, one weekend I took a railroad trip to Cannes and ate lunch at a charming beachside restaurant called the Plage Royal. (It is from this eatery that we viewed the streetscape from France's "Pages Jeune" above.) This was just before the US dollar's value collapsed and I enjoyed courtly and attentive service from an elegantly clad waiter for a modest US$10. (I guess I should have eaten less for the sake of our balance of payments.)

I did not snap any photos during my meal, but technology has caught up with the old memories I keep. The restaurant Website reveals the waitstaff dresses far more causually now - but no one should believe the sea is that noisy. And now there is a Wifi "hotspot" so today a business traveller could use her laptop computer and transmit a live video feed - thereby sharing lunch with her husband back at home in the States.

Actually, many places now provide (nearly) live imagery of their environs - picturesque or not - via the so-called Webcam. In contrast to teleconferencing cameras which provide live feeds between actively communicating persons, Webcams tend to provide snapshots that are automatically updated every few minutes or hours - and sometimes, on demand.

One fixed-view Webcam I favor, which archives its periodic snapshots for review, is this eye on the Traunsee ("Lake of Dreams") from Ebensee, set in the northern foothills of the Alps. (Enjoy a current, large-format snapshot by clicking on the link labelled "Bild vergrößern".)

Originally, Webcams were attached to the Internet via computers like PCs, but now you can buy Webcam appliances, which plug directly into a broadband connection, starting under $200. There are models which attach via a WiFi radio connection, as well as those which allow you to pan, tilt and zoom the camera from your viewing location anywhere in the world. These devices make possible a convenient way to provide security for a remote unoccupied home: some of them bundle a motion detector that snaps and e-mails a photo immediately, which could potentially place a cellphone call.

One of the most earnest applications of teleconferencing is telecommuting, or telework, as it is called in Europe. One example with which we are already quite familiar is the call center, which now includes the at-home single-person micro-call center, as well as the overseas facility performing offshore outsourcing. Call centers range from simple appointment clerking to high-end functions like technical support and academic tutoring. In the simplest and most common form, contact with the client is by audio only, but Internet connections make shared (synchronized) white/blackboards and other media contact (e.g. live video) between worker and client eminently possible when desirable. One useful application is remote configuration of a client's PC from the call center.

Recent government efforts to encourage telecommuting in Georgia are discussed here, with the current status of the referenced House Bill 194 of 2005 here.

An early experiment to bring online education to Georgia high school students is chronicled here. This summer saw the roll out of the home-grown Georgia Virtual High School. Twenty other states already provide similar efforts. Deeper reporting by the Atlanta Journal-Constitution which appears here cites as key motivation

"...the potential to give rural students the same access to advanced-level courses as students in larger or wealthier school systems"
The Governor's press release describes the institution as
" internet-based public high school housed in DOE that will give students in any region of the state access to Advanced-Placement (AP) courses, summer school courses, and other advanced science and math courses."
The technological ambitions appear modest. It describes the contact between students and teachers as mediated "via email and telephone" (but presumably will use the World Wide Web to deliver materials, too). But as we have seen, tools like groupware (in both synchronous and asynchronous versions) already provide the means for assembling a "traditional" (if virtual) classroom for those occasions where free-ranging discussion aids the learning process. Isn't it just bizarre that teams of youngsters from ordinary homes play massive multiplayer online games with one another across the globe using zero-maintenance appliances which cost a low single-digit percentage of what their public schooling does in a year, while critics fret over whether something like Georgia Virtual High School can work?

Distance education became important at the university level long ago. Of course, correspondance courses date back to a pre-electronic age. Today, colleges like the State University of West Georgia (SUWG) make distance learning an important part of their offerings. SUWG is even editorial home to the Online Journal of Distance Learning Administration, "a peer-reviewed electronic journal offered free each quarter over the World Wide Web... [welcoming] ...manuscripts based on original work of practitioners and researchers with specific focus or implications for the management of distance education programs."

Telework need not be restricted to employment which merely involves the manipulation of symbols or discourse with other people. Prof. Rodney Brooks, Director of the 230-person MIT Artificial Intelligence Laboratory and a principal of proxymobile manufacturer iRobot, offers a radical vision for the future. In "Flesh and Machines : How Robots Will Change Us", he writes:

"Here now is the killer app for robots in the short [sic] term. Physical work [performed by machines, but directed by people] can be done from any place in the world. The implications of this will be profound on the world's economy."
He fleshes this out by looking at how rapidly aging Japan, opposed to immigration, which will turn to workers in other countries to telework in such fields as agriculture, construction and nursing. (In the meantime, iRobot has done more pedestrian things like sell over a million units of its consumer-product Roomba autonomous vacuum cleaner. And even today, its staff in three locations do work intimately with one another all the time.)

Telework of a physical nature is even easier to implement in a highly controlled environment like a factory. The factory itself can be sited in a location which optimizes transportation of incoming and outgoing goods - as well as freedom from war, crime and political instability - while most of the workforce can be located anywhere in the world there is good telecommunication and able workers. One flexibility of this scheme is the ability to run the factory 24/365 (including nominal "downtime" for maintenance and repairs) by using shifts of workers from all over the globe. Sunk costs are consumed much more rapidly, making accurate prediction of future trends much less important. "Industrial actions" become much harder because the geographical monopoly of local labor is broken. Likewise, a worker need not move to take a better job with a remote employer using such technology. And when someone does move because his/her spouse need relocate (perhaps for more old-fashioned-style-work reasons), he/she need not quit employment at a factory run in the way proposed.

There are numerous tools for implementing multimedia teleconferencing.

The Video Development Initiative (ViDe) "promotes the deployment of digital video [and bundled audio] in research and higher education." They author a very useful free how-to manual, the Video Conferencing Cookbook, for getting started with Internet videoconferencing.

On April 7, 1927, a group of newspaper reporters and dignitaries gathered in the AT&T Bell Telephone Laboratories auditorium in New York City to communicate with then-Secretary of Commerce Herbert Hoover in Washington, D.C. via live picture and voice over telephone lines - the first videoconference in the United States. But it would take very many decades of progress before it became practical to put live multimedia telecommunication like videoconferencing to economical, everyday use.

The history of videoconferencing since the 1960's, which begins long before microprocessor-based computers became the everyday tools they are today, is summarized in an article and a timeline (1964-1999).

An early PC-based videoconferencing tool was Cornell University's CU-SeeMe. It came out for the Apple MacIntosh in 1992 and for Microsoft Windows in 1994.

In early 1996, Microsoft released NetMeeting, which runs on Windows 9X and later operating systems, including PCs which are extremely modest by today's standards. This free tool features audio and video communication with a single other party, and up to eight-way conferencing using text chat, a shared whiteboard, application sharing and file copying. "Remote desktop sharing" allows one party to perform maintenance of another's PC with the permission of its owner.

Microsoft "retired" NetMeeting in late 2003, but that doesn't mean you can't still make use of it, or even newly download a copy. If you want to give it a try, be aware that firewall "port blocking" may undermine your efforts; you might look here for some additional information.

When it bought PlaceWare a couple years ago, Microsoft refocused on Office Live Meeting instead of NetMeeting. A company presentation earlier this year is available here. Microsoft made a significant move shortly thereafter, buying Groove Networks, founded by the famous groupware pioneer, Lotus Notes creator Ray Ozzie in 1997 (when he and his team departed IBM, who had engineered a hostile takeover of Lotus). Ozzie is now one of three chief technology officers at Microsoft, reporting to Microsoft Chairman and Chief Software Architect Bill Gates. Additional information is available here.

But you don't need to use Microsoft teleconferencing software just because you run Microsoft Windows. So-called Instant-messenger programs now often bundle in support for audio and video, such as the free client from Yahoo!.

A favorably regarded simple videophone application with multipoint potential is SightSpeed. You can make limited use of it to call one person at a time for free. [In 2006, Skype added videoconferencing to its bag of tricks. Basically, image update rate is slower, and quality higher, in comparison with SightSpeed.]

Novamens makes available a free version of its teleconferencing software, neos mt, which provides a shared whiteboard, along with audio, video and file transfer capabilities. You can download software that runs on Microsoft Windows 98 or later. This product is based on the Jabber standard, "an open, secure, ad-free alternative to consumer IM services like AIM, ICQ, MSN, and Yahoo... a set of streaming XML protocols and technologies that enable any two entities on the Internet to exchange messages, presence, and other structured information in close to real time." Other Jabber client software is listed here.

In 1998, a research lab in Britain's Cambridge (then the Olivetti & Oracle Research Lab, later the AT&T Laboratories) released an "open source" version of VNC (Virtual Network Computing). This popular free remote control software allows you to view and interact with one computer (the "server") using a simple program (the "viewer") on another computer anywhere on the Internet. The two computers don't even have to be the same type, so for example you can use VNC to view an office Linux machine on your Windows PC at home. There are clients and servers for almost all operating systems and for Java. The system allows several connections to the same desktop, providing a tool for collaboration in the workplace or classroom, too.

While teleconferencing has been preoccupied with transmitting information using the human senses of sight and hearing, other modalities are not beyond contemplation as well.

Haptic output devices, which engage the sense of touch, are already present in the form of force-feedback joysticks, but have the potential to go much further, as long suggested in fiction by the example of the "feelies" in Brave New World. Tactile feedback has obvious applications to remote medicine, such as the first major trans-Atlantic surgery, conducted in 2001.

People have even entertained the notion of telecommunicating odors in ways that go far beyond so-called "scratch-and-sniff" cards. One modern effort, which did not pan out, was undertaken by DigiScent.

While many speculate about how robots might assist - and even replace - people in tasks they alone can undertake today, the potential for transporting unique human skills across the globe at the speed of light through the man-machine synergy enabled by teleconferencing, is among the most inspiring possibilities of the years to come in the digital revolution.