On Sunday, 2 July 2017 0:31:03 ACST Rodolfo Medina wrote:
But suppose you have a song, or any piece of music... a certain particular precise recording, just that one... and that you find in internet two mp3 different files of that song, from two different web sites, both same size in megabytes. Suppose that the test with Audacity, which we have earlier much spoken of, reveals a difference between them: this means that a portion of the original WAV file during the MP3 conversion has been discarded in more quantity in, say, file1.mp3 than in file2.mp3 (in fact it can be heared). Or also suppose that both files are in wav format but still Audacity reveals a difference between them (because one of them could be - as far as we know - the result of a previous unknown conversion). Then I expect if would be technically possible that we could give an algebraic plus or minus sign to that discarded portion and tell - objectively and not by a simple personal listening feeling - which of the two is the one that contains more information and which less - that's what I would reasonably expect.
It's as if in Algebra we can do |a - b| but don't know wether it's a < b or b < a...
Rodolfo
What about an FFT analysis? -- ============================================================== Rodney Baker VK5ZTV rodney.baker@iinet.net.au ==============================================================