An Educator's Guide
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Outline of a presentation for colleagues on producing and using digital audio and video (DAV) to support instruction held 31 March 1998, with links to complementary information, manufacturers, and vendors. These pages focus on technologies for creating, editing and delivering DAV on a Windows 95-based platform, and emphasize affordable (not broadcast-quality) MPEG standards. Recommendations assume content distribution via a high-capacity medium (LAN, CD-ROM), and may not be the most appropriate solution in other situations, such as real-time streaming via the Web to modem users.
Rough draft of a work in progress.
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Do you use video, audio or graphics as teaching and learning tools? Would you like your students to access these media themselves, during class or homework time? Does precise control over playback of video or audio in class appeal to you? Are you tired of spending time tracking down videotapes you have misplaced or lent out? Could your students benefit from a self-paced audiovisual presentation of material they must cover, or from a dynamic demonstration of software you expect them to use? Digital media can help you accomplish these delivery tasks more efficiently, and the investment in time and money has become surprisingly modest.
What and Why | Terms | Top
Capture | Playback | Distribution
Copyright | Products | Prices
Links | Linux / Networks | Register First, a Disclaimer
This page is presented for informational purposes only. No claim is made for the accuracy or completeness of the data presented, nor for the availability or performance of any products discussed. All recommendations are strictly the personal opinion of the author, who has no personal or financial interest in any of the firms listed. Under no circumstances should any information found here or at sites linked to from this page be construed as an endorsement or recommendation by the author's employer or any other entity affiliated with the US government. The data and product information reflect the state of the market as known to the author on 31 March 1998.Disclaimer of Disclaimer
Above disclaimer doesn't mean the information here is worthless, only that you shouldn't blame me or my employer if you disagree with my opinions, if your needs differ from the focus of this page, or if new technologies or products have superceded the advice given here.Now, a Warning
Information ages: in this rapidly evolving field of technology, any purchasing decisions should be based on thorough research and hands-on evaluation in your own facilities of the range of products available at the time of purchase.
Digital Audio and Video (DAV) encompasses a variety of technologies to get sight and sound resources into a computer, to distribute them to users, and to replay them on the users' systems. Digital media (a term I use here synonymously with DAV) offer several attractive features:
Despite the advantages of digital media, they do not always provide the most appropriate or most cost-effective solution. Analog audio and video tape, or a closed-circuit video cable system are more suitable when delivery cannot benefit from the advantages of digital media, as in the following cases:
- Copyrighted material for which no prior written permission from the copyright holder could be obtained. Such material may not be reproduced or digitized except in conformance with Guidelines for Fair Use of Copyrighted Material.
- Linear (i.e. playing the clip straight through) digital playback to a number of local users is typically more expensive and resource-intensive than analog alternatives. A closed-circuit TV system and televisions, or video and audio tapes are cheaper than a LAN or dialup or dialup connection. On the other hand, for distribution on demand or to users off site, digital media may be the only cost-effective solution.
- When issues of random access and preservation of audio and video quality are less important than expense is ("analog: affordable portability")
Reason for Focus on MPEG
MPEG (say EM-peg) is a family of ISO/IEC standards for digital video and audio compression which optimize the match between quality and storage requirements. These standards are established and maintained by the Moving Pictures Experts Group. In this paper MPEG is used as a synonym of MPEG-1, the best established of these standards. MPEG-2, targeted for broadcast-quality television, requires significantly higher data transmission rates and is not practical for most instructional use. MPEG-4, a broader standard for interactive multimedia including graphics and text in addition to video and audio and encompassing a greater range of data rates, remains an emerging standard which should be adopted later in 1998.
MPEG-1 Video and Audio
- Provides very acceptable ("VHS-quality") full-motion video (Standard Image Format [SIF] is 352 x 240 pixels for NTSC, rescalable to full screen, at 30 frames per second) with stereo audio at data rates up to 1.5 Mbits/s, which permits storing an hour of video on a CD-ROM, or real-time delivery over a LAN via ethernet connection
- MPEG-1 audio can be used alone, without the video; "audio layers 1, 2, and 3" refer to encoding schemes with increasing degrees of compression (in fact, currently the vast majority of MPEG sites on the Web seem to be devoted to questionable copies of popular music in MPEG-1 Layer 3 stereo)
- MPEG playback software is typically included with today's graphics cards and web browsers
- MPEG conversion and capture tools are now abundant and affordable
- MPEG is an open standard, not subject to arbitrary changes in the marketing strategy of a single firm
Lower-bandwidth DAV technologies are less suitable than MPEG for most instructional purposes, and are appropriate only when dictated by limitations in storage capacity or distribution channels (e.g. via the web to users with slow modems). They typically lack the quality of MPEG video (small image size, often 160 x 120, with insufficient visual detail to be resized to full screen, low frame rates which result in jerky motion, tinny-sounding audio). Uncompressed alternatives (e.g. WAV audio and AVI video) are unnecessarily wasteful of bandwidth resources: the perceived quality is not enough better to justify the tremendously greater storage requirements. On the other hand, higher-bandwidth alternatives such a broadcast-quality MPEG-2 simply exceed the requirements of typical instructional applications, and impose an unnecessarily high cost for storage and distribution.
RealAudio is the only exception to my claim of MPEG's greater suitability for instructional use. This proprietary technology is so widely distributed that one can count on its being installed on the machine of any user who has a recent-generation web browser. For audio-only (or audio with stills) applications, RealAudio's many compression levels can provide a match between quality requirements and bandwidth targets. The free Real Encoder Audio and Video Encoding Tools and Software Development Kit (SDK) put this technology within any content developer's reach. (Under the terms of the license when I downloaded the SDK, one can develop and distribute software which incorporates RealAudio non-commercially without paying fees to Progressive Networks as long as the users have already installed the free RealAudio players on their system.) Caveat: there have been several generations of Real players, so some users will not be able to play the latest formats with downloading new playback software.
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TLAs (Three-Letter Acronyms) and FOMLAs (Four- Or More-Letter Acronyms, say FOM-luhz)
Following general technical English usage, acronyms of three or fewer letters tend to use the names of the letters, while those of four or more letters typically are said as words. Pronunciation guidance is given except where the letter names are pronounced.
Tip:
Search PC Webopaedia or the Glossary of EMedia Technology
for further detail and for terms not found here.
Audio File Types, by Filename Extensions
Video and Audio File Types
Storage
Other Technospeak Acronyms and Concepts
Bandwidth
Streaming
Broadcasting on Demand
Artifacts
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One-Pass / Two Pass Capture / Compression
As Jan Ozer says in his article Leading Low-Cost MPEG Encoders, "... with software MPEG encoding, spending time takes on a whole new meaning."
SIF / QSIF 352 vs 320
AVI size and limits
10-50x real time to convert
Editing
Linux / Unix servers
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Software-only Playback
Hardware-Assisted Playback
Add-In Boards
Cyrix MMX-enhanced Media GX: integrated support for audio, MPEG video, and graphics. A single mainboard with onboard sound, video, and MPEG decompression, as well as optional composite output for recoding or displaying on standard TV set. Pentium 200 equivalent costs under $200 for processor and all this functionality.
Rough guide to the order of magnitude of storage required per minute
Actual results will vary by quality of input and output
| NTSC Full-Motion Video (352 x 240 pixels W x H at 30 frames per second) | |
| AVI file (uncompressed) | 80-100 MB per minute |
| MPEG Video (compressed) | 8-10 MB per minute i.e. about an hour of video on a single CD-ROM |
| Music Audio | |
| WAV file (top-quality stereo, uncompressed) |
about 10 MB |
| MP2 (reasonable-quality stereo) |
about 1 MB |
| MP3 (acceptable-quality stereo) |
as low as 200 KB / min. |
| RealAudio (acceptable mono) |
about 100 KB / min. |
Note that UPPER / lower case matters when reading product specifications, which can be expressed either in terms bitrate or in byterate. In the PC-world, each byte consists of 8 bits.
- Storage capacity of hard disk drives and CD-ROMs is specified in bytes, abbreviated with upper-case B
- Data transfer rates of networks, modems, and usually, disk drives, as well as DAV datarates, are typically given in bits, abbreviated with lower-case b
- "Mbps" thus means "megabits (i.e. million bits) per second", as opposed to MBps, which means "megabytes (i.e. 8 million bits) per second".
- In addition, K "kilo" and M "mega" are often used in two very different ways; while not as striking as the contrast between bits and bytes, cumulatively the difference between them can add up:
- Binary or digital thousand and million, 1024 and 1,048,576, based on 210 and 220
- Decimal or traditional thousand and million, 1000 and 1,000,000, based on 103 and 106
Server RAID
CD-Rom Recordable
LAN / Server
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Copyright resources
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Most cost-effective (two-pass) solution for capture and playback known to me:
Matrox Mystique Graphics Card with the Rainbow Runner Studio daughter board. Available from CDW at around $300; compare also this alternate source: NECX - Matrox Showcase. Top-quality bundle for graphics-card, AVI capture with conversion to MPEG, and TV tuner. Supports output of computer display to TV, both NTSC and PAL. PCI-bus board with two daughter cards. Powerful video editing software bundle included. Check out complete specifications for Matrox Mystique and Rainbow Runner Studio here. Product review PC Magazine: Matrox Rainbow Runner Studio (10/07/97) Additional reviews Matrox Rainbow Runner (Doceo). The ATI All-In-Wonder Pro Graphics offers a similar range of capabilities (capture, MPEG playback, TV out) for less money (currently $160-180); I have not evaluated it personally, and product reviews (e.g. PC Magazine) mention limitations in capabilities and bundled software which appear to make it a less attractive alternative than it may seem at first glance.
Worthwhile addition: Xing Technology Corporation's MPEG encoder software (about $90). Latest version claims real-time or better performance on MMX machines, and is significantly more expensive ($250). Darim's encoder software is slower, but also supports the MPEG-2 (broadcast-quality) standard.
Best low-end one-pass solution for capture known to me:
MPEGator MPEG-1 Encoder (PCI-bus; $1425) with M-Filter video filter board (ISA-bus; filters impaired-quality or VHS video for better, more compact MPEG capture; about $600). Review of Leading Low-Cost MPEG Encoders. Another review: PC Magazine: Darim MPEGator (10/07/97).
Low-end one-pass MPEG1 external capture system which I have not had the opportunity to evaluate:
- PC Magazine Editor's Choice 7 April 98 and newMedia's "Awesome" rating for real-time single-pass full MPEG 1 video (352/320 x 240 at 30 fps) and/or audio capture system (unlike many systems includes audio capture for better sound/image synchronization); also offers JPEG still-frame capture
- Costs about $350
- Complete software bundle, including frame-accurate MPEG editor
- Does not support AVI out, which theoretically could provide better-quality editing and effects
- External device with parallel port interface:
- Does not require opening the computer to install
- A single unit could be shared among multiple users (legally, software would have to be installed and uninstalled each time)
- Could be used for recording classroom interaction with inexpensive analog video camera and microphone
- Capture to a laptop is now feasible (laptops lack the PCI or ISA bus expansion slots required for most capture cards)
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Capture Hardware and Encoding Software
Requirements
- Fast Pentium or equivalent system with sound card, copious RAM (at least 32 MB) and hard-disk storage (how much? say at least 2 GB free space -- the more the better)
Cost: $1000-1500 at today's prices- Desirable: CD-ROM recorder for distribution and archiving
Cost: $250-500For capture add one of the following:
- Matrox Mystique with Rainbow Runner Studio, about $300
More versatile than the Videosphinx, this Matrox setup does require two passes for MPEG- Futuretel Videosphinx Pro at $350
- Darim MPEGator, about $1500; add M-Filter video filter board for about $600
Price range for entire capture setup, including computer but excluding video equipment: $1250-3500
Playback Hardware and Software
Rough-estimate budget for a networked system for classroom or learning laboratory based on Cyrix MMX-Enhanced MediaGX processor (components only, straight-forward DIY assembly)
Components Estimated Price
(US dollars)Case, Floppy, Keyboard, Mouse 80 System board with CPU, fan, cables
Includes on-board sound, video,
MPEG decompression180 32 MB RAM 42 2 GB hard drive
stores up to 3 hours of MPEG video130 16x CD-ROM Reader 50 Network Card 20 Windows 95 (academic license) 60 Monitor and Speakers/Headphones 200 Total (US$) $762
Storage and Distribution
CD-ROM for archiving and off-line distribution
Raid
Linux Network Server
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General Information
On-Line Glossaries and Quick-Reference Sources
Technical Information
If you care to know how the sausage is made and
served...
Trade Publications
Check these out for product reviews and to
help anticipate future trends
Related Articles and Product Reviews
Manufacturers
MPEG / Digital Video Capture Hardware
- Darim Vision MPEGator, highly-rated single-pass MPEG capture board for about $1500; encoding software (MPEG1 & 2) for about $100.
- Broadway good single-pass capture board under $1000
- DV Studio also priced under $1000
- Optivision MPEG Digital Video high-end capture products ($5000+)
- FutureTel Inc.: Video Sphinx Pro
- Hitachi MPEGcam is a small [3.3" x 5.6" x 2.2" (83.8 x 142.2 x 55.9 mm), 19.3 oz (547 g) with battery and PC card] stand-alone device to record up to 20 minutes of MPEG video (or 3000 JPEG stills or up to 4 hours of MPEG digital audio, which can be used to annotate the stills); street price about $1500; read review from New Media
- Hauppauge Computer Works offers various video capture boards for two-pass MPEG encoding and MPEG playback
- Video Capture Devices listing of products and manufacturers, with links, but no commentary
MPEG Playback Software
- Xing Technology Corporation Pioneer in affordable MPEG products; excellent player, powerful MPEG encoder software; MCI support
- SoftPEG ZORAN software playback; excellent performance even under Win 3.1; MCI support; also available from Visible Light
- CWSApps - 32-bit Multimedia Viewers lists and reviews several players
- MPEG MCI Command Set documentation for programmers who wish to control MPEG playback from their software
- MpegTV - real-time MPEG software for Unix
- MPEG Software Sources
- InterVu EyeQ Multimedia Manager free plugin for Netscape that appears to include an MPEG player; available for both Win 3.1 and 95; not evaluated.
- See also ActiveMovie under "Other Product Links"
MPEG Playback Hardware
- MPEG Plaza has numerous products in this category with notes and links to manufacturers
- Cyrix MediaGX Processor Technology on GCT - GCT-MGXm Baby-AT Motherboard Mainboard incorporates on-board stereo audio, SVGA graphics, and hardware MPEG-1 decompression; optional TV out; price under $200 including processor
- Darim Vision has MPEG playback boards (can also run under DOS for excellent performanc eon a low-cost platform)
- Matrox Mystique with Rainbow Runner Studio combines a graphics card with add-on daughter boards for excellent hardware-assisted MPEG playback (Matrox MJPEG AVI capture with conversion to MPEG, and TV tuner. Supports output of computer display to TV, both NTSC and PAL. PCI-bus board with two daughter cards. Includes comprehensive video editing software bundle.
Storage Hardware
- Promise IDE RAID Controller Controls up to four IDE drives as a RAID, with performance comparable to SCSI. With this product one could configure a 44 GB RAID (enough on-line storage for 75 hours of video) for $1700
- Promise iRaid External IDE based Raid; about $3500 plus drives complete; supports up to 10 drives (11 GB drive costs about $400)
- Transitional Technology, Inc. offers well-designed SCSI RAIDs
Vendors
Other Product Links in Random Order
Copyright Issues
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WRITTEN BY: William H. Fletcher
REVISION: 28 April 1998
URL: http://miniappolis.com/mpeg/mpeg.html
©1998 by William H. Fletcher. All rights reserved by the author.