On Nov 4, Martin Brown <|||newspam...@nezumi.demon.co.uk> wrote: > > He estimated music contains 40 bits/second entropy. > > How close is MP3 to that? > > >___________________________________ > >I doubt surprised Shannon said that, and if he did its > >somewhere between meaningless and wrong. > > >CD quality mp3s are roughly equivalent to 178 kbps, > >over 4,000 times his estimate. But then you can > >encode a lot of sounds that most people would not > >consider music. And it stereo, so you can halve it > > if Shannon was talking about mono. > > Have you never seen sheet music? That is what > Shannon was estimating - the bitrate for describing > music in the abstract. > There are a finite number of notes, durations and > amplitudes in a classical composition.
I suspect that's the case.
> I suspect 40 bits/sec is still far too tight, > but a midi stream using a high end reconstruction > codec represents a pretty good > example of what is possible by way of compression > for *music* as opposed to voice or a random noise > stream. > > > To get a smaller figure for music, you have to > > define what subsets of sounds are music. Lots of luck.
Not so hard, if you analyze samples of what we label 'music'.
> I think that may have been his intention although > I don't recall seeing the 40 bit/s number > As I said if he did anything I think he was estimating > the information content of music in the already > concise form of an orchestral score.
That appears to be the case.
> I reckon at a bare minimum about 7 to the note, 8 to > amplitude, 6 duration, 5 to the instrument - and it > is already obvious that you cannot encode more than a > single note per second at this bitrate.
You fail to account for the essential concept of correlation.
> Can anyone provide a citation to this alleged paper > on music bitrate?
I found the reference in John Pierce's book. It's not attributed to Shannon. My boner. He claims a humans can absorb information, e.g. reading or music, at 40 bits/second. He also cites a paper where it's claimed that sheet music contains 2.5 bits entropy per note. This supports the MIDI model, as opposed to digitization of a recording. In that case, what is the bit rate? Though the question of chords arises, with much redundancy there.
It also raises the possibility that recorded music might be adequately represented by a MIDI stream.