Upsampling. Truth vs Marketing

Sean, thank you for all the diagrams, and patient tutoring. It all makes logical sense, sure.

If I had never heard the Audio Note, I would be looking at one of the top up sampling players on the market. Oh well.

More corrections! They don't affect the basic idea, but could easily confuse people. Sorry about that. Hopefully this is it.

If the waveform is sampled at a frequency four times that which corresponds to the uniform time spacing of the example, (44.1 KHz perhaps) the data will look like the following:

Note also that we are now quantized at 1/4, (0+0+0+1)/4 ,instead of 1, which is the quantization of the raw data stream obtained from the disc. A factor of 4. That’s like 2 bits of additional resolution. That’s how Phillips got 16 bit performance from a 14 bit D/A.

OK Sean...Sorry you felt left out because no one jumped all over you. The following is my modification of your statement.

Some digital representations of analog (analogue in England) waveforms are a poor replication of the analog source because they lack the resolution (bits) and sampling rate appropriate for the bandwidth of the signal. Inaccuracy is not inherent to the digital format, but represents a design decision regarding what level of error is acceptable.

As long as human beings are analog, the initial & final music will always be analog. What's in between can be digital. Digital is a compromise for an analog signal - no doubt. How good or bad it is depends on how well the digital system is engineered for the 20Hz-20KHz bandwidth. Digital is chosen mostly for its cost effectiveness (scalability of the DSP engines with shrinking CMOS technology) & what Carver Mead once pointed out - its tremendous noise immunity. Corrupting a stream of digital data to the point of making it useless is very difficult as it requires a lot energy to flip a bit. Some bits do get flipped but the overall context of the message is very much retrievable by using various error correction algorithms. This is hardly the case with a purely analog music signal.

Having more sampling points with an estimation filter allows the digital to better track the analog waveform. Whatever benefits one accured with over/upsampling could be lost by distortions in the analog reconstruction filter. Hence, the above mention of implementation. Having somebody engineer a good re-produced sound CDP solution is priceless (for everything else there's MasterCard!).

Yes, if one converts from analog->digital->analog, one does degrade the original sound. That is to be expected as we take only a finite # of samples (hence the term "quantization"). BTW, if we had infinite # of samples, it would analog! In the redbook CD format, the powers-that-were decided in all their infinite wisdom to Nyquist sample the data onto the CD disc . Thus, no matter how much one oversamples, one can never undo this. Hence the rise of "hi-res" music formats. In fact, if the over/upsampling was A1 perfect, you'd get *exactly* what was on the CD, which is Nyquist sampled!! How good is taking just 2 samples of a dynamically waveform music signal? Not very good I'm afraid!
Eldartford cited his experience: 4 samples was worth every effort. I've found 5-8 samples is worth the effort. The difference is that my work is voice-related. Not hi-res by any standards but when people hear another voice at the other end, they do want to recognize it. Need more samples for this.
FWIW. IMHO.

El: Thanks for correcting my previous errors, your previous errors and then confirming my last statements.

The bottom line is that, as good as digital is and can be, it is still trailing behind analogue as we know both formats today. It is too bad that the decisions foisted upon the audio industry when selecting these design parameters were made by those that don't really listen to the products that they produce. Otherwise, we would have started off with wider bandwidth designs and higher sampling rates to begin with, making conversations like this moot. Then again, hind-sight is almost always 20/20 : ) Sean
>

Bombaywalla...It's an interesting question about whether the world is, at its heart, digital or analog. The electrical signal, regarded as analog, actually consists of discrete packets of charge, called electrons. The human sense of hearing is implemented by the "firing" of discrete cells called neurons.

Of course this digital condition exists at so fine a level that it is entirely reasonable to consider the process as being continuous. But it does point out the fact that at some point, and we can debate where that point is, digital audio becomes, for all practical purposes, the same as analog.