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Topic: Fidelity potential index (Read 4364 times) previous topic - next topic
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Fidelity potential index

[a href="http://www.newformresearch.com/fidelity-potential-index.htm" rel="nofollow"]http://www.newformresearch.com/fidelity-potential-index.htm[/a]

Moderation: Changed link so that it doesn't increase search engine rankings.

Fidelity potential index

Reply #1 –
It's pretty meaningless. According to the index, cassette tapes and FM radio sound better than 320kbps mp3...
Not really sure what the point of it is?

Fidelity potential index

Reply #2 –
"Meaningless" is understated. Through all the crap that sometimes came up here in the last few weeks this belongs to the TOP 3.

The "Fidelity potential index (FPI)" is just the rounded raw bitrate of an undithered(!) digital stream. In the case of analog its the bitrate of an "equivalent" PCM stream for a given frequency response and dynamic range.

That's how it's supposed to "help" comparisons:

Don't compare dynamic range and frequency response of two systems, compare FPI.

In fact FPI for analog systems isn't anything else than those two values merged into one metric (with only 50% loss of information).

If you want to compare the potential sound quality of an analog system, e.g. an extremely wobbling tape recorder with a FPI of 3.5 to a LAME encoded 320kbps MP3, don't be fooled by obvious differences. Just compare FPI.

See how easy it is to simplify your life and see tape win by 0.3 points! What, the whole Stereophile editorial team failed an ABX test for the second? Must be cabling issues. After all this is about potential! And according to FPI it's simply an irrefutable fact that wobbly tape has more potential than 320 kbits MP3.

I would really like to introduce a new metric: the bullshit potential index (BPI). It's word count divided by sense in percent. In this case

BPI: 1687 / 0.00001 = 168700000!!!

Fidelity potential index

Reply #3 –
Bronson

Thanks for posting it.  I assume it went up on the 23rd or there abouts?  If you'd post this, I would appreciate it as I can't log on.

Anyway, the three responses were pretty hostile and some hostility was expected as clearly there can't be a precise numerical representation of the perceived fidelity of different formats.  People don't like technical things which are imprecise.  So we have to get out in front of their expectations with an explanation of the limits of the tool.  Understanding what a tool can't do is just as important at the beginning as learning what it can do.

What the Fidelity Potential Index is designed to do is establish an order and a set of ranges for the different formats.  It also draws together the specs for the different formats and comments on their various strengths and weaknesses all in one place.

A listing of performance specifications for the older formats doesn't exist to my knowledge and the FPI page should be a useful research tool for those looking for this information.

The Fidelity Potential Index serves as a basis for discussion.  Just as important as the specifications and the mechanism to generate a relative fidelity scale is the discussion of the index itself and the larger, fidelity-of-mediums topic.  Anyone reading the entire page will have a better understanding of this area and that is the whole idea.

Cheers,
John Meyer

Hi John,

It dawns on me that I should inform you that I have posted your Fidelity Potential Index on Hydrogen Audio.  See link here http://www.hydrogenaudio.org/forums/index....showtopic=70725

Bronson

Fidelity potential index

Reply #4 –
Quote from: forum neophyte on
Anyone reading the entire page will have a better understanding of this area and that is the whole idea.

Cheers,
John Meyer

No they won't.  They will be confused by meaningless numbers.  Any scale on which lossless compression would score (significantly) lower than uncompressed audio is deeply flawed.
Creature of habit.

Fidelity potential index

Reply #5 –
"The ongoing debate over the past 25 years as to which format - analog or digital - "vinyl or CD" - sounds better has been conducted in the fog of ignorance and marketing hype. The first digital format, the CD, was billed as "Perfect Sound Forever" - fidelity so high no one human could perceive anything better.

Many people knew at its introduction this was marketing hyperbole and now everyone knows it. Despite the many hoary flaws in analog playback that the public found extremely frustrating, the new CD system clearly had limitations of its own and they weren't all due to poor implementation."

Right from the start he shows his bias and his ignorance. Need we read any further?


Fidelity potential index

Reply #6 –
The idea that mp3 really doesn't belong in such a ranking is only shown at the end as an afterthought written by someone else.

The ranking is misleading and useless.

I challenge the author to distinguish higher-definition PCM from properly dithered 44.1/16 PCM of real music that uses all 16 bits played at a level that does not cause pain during the loudest part.

I also think the author should open an account in order to discuss the table rather than give us a cowardly reply through a proxy.  There should be no reason why he "can't log on" unless he's been banned (TOS #8 or TOS #14?).

Fidelity potential index

Reply #7 –
Quote from: forum neophyte on
A listing of performance specifications for the older formats doesn't exist to my knowledge and the FPI page should be a useful research tool for those looking for this information.


Calling this a research tool is pathetic. It the same approach American banks used for risk management: reduce complex correlations to a single score, that even idiots are able to "understand".

In audio it's even easier. We have two meaningful metrics, dynamic range and bandwidth, and FPI reduces them to one not meaningful.

Take an imaginary recording system, Pathetic Audio System (PAS) with a dynamic range of 12329 db (2048 bit) and a bandwidth of 250 Hz (500 Hz sample rate). At a fraction of a telephone's bandwidth PAS would not even be able to comprehensively record/playback human voice. Still its "FPI" (1024000) would surpass that of CD-Audio by ~30%.

Looking at just two values, a consumer can instantly see, that PAS is not suitable for audio reproduction. Looking at just one crippled value as FPI, he would think that PAS has a higher potential for "fidelity" than CD audio, what's clearly not the case.

And that's all even before psycho-acoustical matters.

Fidelity potential index

Reply #8 –
Quote
The bit depth times the sampling rate per second equals the number of bit per second the medium can deliver. This number divided by 100,000 for brevity is its Fidelity Potential Index.


So, 176kHz/8bit PCM file has the same FPI as 22kHz/64bit?   

Added: rpp3po was faster...