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I tried, Lord knows, I tried...

Posted by Charles Hansen (M) on April 15, 2009 at 21:17:34

In Reply to: TCP/IP posted by Old Listener on April 15, 2009 at 14:44:29:

There was a brilliant opportunity about 10 years ago as DVD came along with its higher sampling rates.

At that time, UltraAnalog wielded quite a bit of influence in the high end market. They made 20 bit DAC modules that a lot of people used, along with a low-jitter S/PDIF receiver module. There were quite a few high-end companies that knew *nothing* about digital, so they had UltraAnalog make them an OEM solution.

Then UltraAnalog tried to introduce "I2Se", where "e" stood for "enhanced". It used ECL devices for the receiver and transmitter to keep the speeds up and the edges sharp. The cable was a mildly rare bird, a special computer video cable with 3 extra impedance-matched co-ax lines.

Most of these ideas were stolen from a meeting they had with Kevin Halverson of Muse Electronics. But they forgot to steal the most important part -- support for any data rate other than 44.1 kHz. Since DVD with 96/24 was literally around the corner, the proposal was doomed from the get-go. The only company that used it was Assemblage, the kit division of Sonic Frontiers. Muse went ahead and made a similar system, using the same exact cable although it would handle different sample rates. Nobody else adopted it.

So I made a plea. I sent an open proposal to Theta, Wadia, Levinson, Muse, Resolution Audio, Audio Research, and others. I explained that we needed to make a system that was high-performance, handled high sample rates, and was open. The problem was that the specialty manufacturers were getting squeezed out by the Japanese giants who were inventing ever more complex schemes that required outlandish licensing fees. (Anybody remember iLink?)

I got exactly three responses. Theta said they didn't want an open scheme. They wanted something proprietary so that they could lock their customers into their own system. (This was announced many years later, but never actually released.) Muse and Resolution were interested, but all three of us insisted on slightly different details. So nothing ever came of it.

Now we are stuck with HDMI. S/PDIF is going away. The license fees for HDMI and HDCP are "only" $30,000 per yaar. And the performance is limited. During the development, a friend at Silicon Image (one of the main forces behind HDMI) called me up and explained the problem they were having with audio. I told him that everything would be easily solved if they added one more line to carry the audio clock.

He said they couldn't. Because...(get this)...the *connector* had already been designed and all the pins were allocated!

So the audio clock is derived from the video clock by the sink (receiver). So let's say that you are watching an NTSC BluRay disc with a 96 kHz soundtrack. The link tells the PLL to divide the audio clock by 23296 and to divide the video clock by 140625 and then it can sync up to the rate at which the audio data is being sent. Such a *stupid* system!

But that is what we are stuck with from the Japanese giants if you want video. Aaahh, progress....

For audio-only, S/PDIF is the only standard interface, and it is inherently flawed. The only quasi-standard way around this is to go to computer audio. Then you can use USB or FireWire in "asynchronous" mode, where the DAC is in charge and the transport (computer) is slaved to it. But as a glance at any post on this forum will tell you, we are a long way from reaching "plug'n'play" operation with computers!

This post is made possible by the generous support of people like you and our sponsors:

Sonic Craft

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