New Transport Approach

This is a great idea and I am all for it!! Heck I'll even help write the software if I have time. However what about encrypted CDs and anti-piracy concerns? In the not distant future I think we can assume the RIAA will force us all to listen to encrypted CDs. There are CDs on the market today that are already watermarked. :-(

- Dan

As someone who designs Digital record and playback systems, I can tell you that this is done all the time, but for commercial applications. The problem is that for CD music, people want real-time playback. This just wouldn't be feasible for that. In addition the power required for refreshing the RAM would prohibit portable players. A better idea but one which also has drawbacks for real-time applications is to prefetch some fixed amount of data. Of course all of this is moot because even if you produce these transports, you'd have to redo the CD spec as it's designed for real-time reading and not bulk I-O.

I only envisioned this as a high-end application - hence, no need for portable players, etc., and an acceptance of the initial delay for the improved performance, since audiophiles are the type that are willing to go to these lengths. I'm not sure about the power requirements prohibiting portable players anyway, though - we already have portable MP3 players which are the same thing with compression, though the goal is ease of use and amount of music as opposed to better audio performance.

I'm definitely NOT a designer of digital recording and playback systems, but I've integrated lots of related but unconnected systems in my professional life. It would seem here that you already have a functional (and cheap!) design for reading a CD into RAM, and as others have noted, it's already incorporated into many high-end players to cache data in RAM and re-clock it out to the DAC. I don't want to over-trivialize it, but it seems like a little "glue" to put the two together would suffice.

I agree with everyone that in the "I want it NOW" environment we currently live, the loading delay would be unacceptable for a mass consumer version of this, even if it was cost-effective. -Kirk

It's a LOT more than a little glue. Do NOT compare time for reading a CD ROM with an audio CD. They have different data formats. Have you ever read an entire CD for the purposes of burning. That's the load time we're talking about. To do what you want you would need a new format or greatly increase the CD read time. Caching a SMALL amount is different than reading a whole disc. On one system I know of it takes 3 seconds to cache 10 seconds of audio. Extrapolate that out to 80 minutes. This isn't practical. That's why commercial digital systems don't use the CD format. It's based on technology that's 20 years old. The CD format was designed to be efficient with the state of the art data retrieval and processing in 1981. Besides most of these ram reclockers aren't as good as the better CD playback systems. Your final product could be worse. It wasn't a good engineering solution when I looked into it 10 YEARS AGO, and it still isn't.

From the Meridian website:

In the 800 Reference CD Machine, the audio data is read asynchronously in blocks using high-speed, high-integrity CD ROM drives. This data is checked for integrity, corrected and triple buffered to ensure that the audio output timing is independent of the drives for the first time.