The Cat's Alley

NBMA's Developer SIG, October 26, 1999

- Where the Web is Moving!

by Catwoman, roving cat-reporter
(a.k.a. Suzanne Saunders)

Table of Contents
An Introduction to Streaming Media by Ken Colby of INTERVU
About the Firewall Barrier
A little note about musical frequencies
A quick snapshot of video and the history of JPEG's
Back to the Future

An Introduction to Streaming Media by Ken Colby of INTERVU:

Ken began with a brief history lesson, recalling the early days of of video on the internet using Codec technology, through now, when we have video-on-demand.

Video Live Streaming = Webcasting.

A normal Teleconference, he explained, set up by AT&T for a normal conference call works pretty much the same way for video teleconferencing, but now allows internet users to listen in.

INTERVU bought a company to aquire their technology, called Netpodium, to solve problems with timing in voice and slides.

Ken clarified the difference between Streaming versus Live.

• Streaming: waits to finish downloading and plays start to finish.
• Live: works like a Bucket Brigade. There may be a 30-second delay from the time the first bucket is passed to the end of the line, but once the line gets moving, you have continuous play.

When asked about the lowest modem possible to play Live, Ken answered a 56K line is reasonable. You get 6-7 frames per second, you can also start trading down image size.

Microsoft and Real Networks are the top contenders for Codecs. He mentioned Windows Media Player, also Quicktime by Apple making a comeback, and Netshow by Microsoft.

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About the Firewall Barrier:

Firewalls do not allow UDP.

• UDP (Unencrypted Data Protocol) doesn't check back for accuracy, it just sends the data through.
• RTSP, used by Real Networks, is based on UDP.
• HTTP (HyperText Transfer Protocol) on the other hand, checks each frame. Slower, but it will work with a Firewall.

Someone asked about the issue of latency. Put simply, where is the bottleneck in delivering sound in real time? Is it related to encryption?

Ken explained that the ISP (Internet Service Provider) quality determines the delay from the first bucket. There is only a negligible delay from encoding, most of the delay is over the internet and then another delay at the client buffer side. INTERVU uses 8 different ISP's!

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A little note about musical frequencies:

Audio files come in many flavors including AU, AIFF, WAV and MPEG.

Telephone broadcasts at 11kHz in Mono.

High quality music plays at 22kHz in Stereo.

CD quality plays at 44.1kHz in Stereo.

There are 3 levels of compression:

1. RLE: Run Length Encoding. This suffers no loss.
2. Lossy: uses math symbols, reliable and used for video, but for audio at low bit rates, it mixes tones to make the same noise as if they were all original notes, saving time.

On a side note, he mentioned the difference between ProLogic, which has rear and front signals both the same, and DVD which uses separate rear channels, that are not the same.

3. Codecs (Compression Codes): can be generated by software. Drivers on the PC do the translation, or a hardware card installed in the PC.

Thanks to a subcontracting relationship with Encoding.com, INTERVU offers encoding in a number of digital formats, including AVI, JPEG, Microsoft Windows Media, MPEG, QuickTime, Real Audio, and RealVideo.

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A quick snapshot of video and the history of JPEG's:

In the old days, he explained for our edification, there were two scientists having an argument over whether the human eye sees red, blue and green, as opposed to only black and white with only 2 colors. Later, when the technology was developed to answer the question, it turned out to be a little of both! The human eye sees black and white, but then the cone behind the eye adds luminance and saturation.

Relating this story to our current discussion of sound, he compared high-quality sound at a high frequency, versus low sound quality that loses the higher frequency, compared to a JPEG that trades color depth and frequency refresh rate to draw the picture using image compression algorithm.

Fractal compression, he explained, takes big chunks of the picture to copy. HDTV has an aspect ratio of 16 x 9, as opposed to NTSC video at 4 x 3.

A Video Capture Card in the PC translates to digital, designed to work best on a Pentium III.

Digital Video at 320x240 resolution at 15 frames-per-second and 24-bit color depth will equal 3.46MB/sec. which equals 2GB per minute.

He mentioned that a Firewall will permit using IEEE or a video capture card or digital camera and software.

Marilyn from INTERVU Sales, answered a question of cost ratio by explaining the charges are based on bandwidth. For example, a conference stream and numbers of streams or MB/sec rate can pay between $1000/month or $100,000/month.

With Unicasting, she explained, each client gets their own stream.

With IP Multicasting, they use one stream for many clients.

It takes about 3 x PC's to run 1000 streams, about 2000 streams can run on 4 x PC's.

She mentioned CNN has 10 super-computers, but they didn't want to degrade site performance with video, so they link to INTERVU using distributed network servers across the country.

A question of Surestream was asked, with the familiar answer it doesn't work with Firewalls.

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Back to the Future:

Asked about the future of Pay-per-view, Ken responded with some issues of signal drop, E-Commerce partners, Token versus Licenses and mentioned GLID for Rights-management.

Ken created an amusing diversion by explaining about how the human brain does not organize data using search algorithms!

He mentioned their CTO (Chief Technology Officer) Brian Kenner, developing for the future providing the technology to add video for vanity websites.

INTERVU has partnered with Excalibur and Virage and owns patents for some technologies that he could not discuss prior to release, but promised good things to come in the near future.

We will keep our pointy ears peeled Ken, thanks for the peek into the future of video on the web!!

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