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Re: information theory?
Posted:
Nov 4, 2011 6:51 AM
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"Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in message
news:I9Psq.13644$Mg.12196@newsfe13.iad...
> On 04/11/2011 09:33, Peter Webb 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.
>>
>
> If Shannon did make the statement attributed to him above (and I seriously
> doubt it) - I would like to see references.
>
>> 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.
>>
>> And how do you define music, except as sound? And random sound waveforms
>
>
> 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.
>
Far more plausible.
If you don't consider singing to be music.
> 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.
>
I wonder what Jimi Hendrix playing Star Spangled Banner would sound like as
a midi stream?
>> cannot be compressed on average at all. To get a smaller figure for
>> music, you have to define what subsets of sounds are music. Lots of luck.
>
> I think that may have been his intention although I don't actually recall
> seeing the 40 bit/s number originally attributed to him above.
>
> 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.
= midi. A very plausible explanation, but one which requires a very limitted
definition of music.
>>
>> The real number probably lies somewhere between 178 kbps and 40 bps. The
>> actual number is the base 2 logarithm of the number of different 1
>> second sound bites that the ear can distuingish and would consider as
>> music. I doubt even Shannon would have known the answer to that equation.
>
> Maybe he didn't consider all the alternative atonal and continuous
> frequency synthesisers of arbitrary waveforms that are possible now - or
> perhaps it was a subtle dig at Stockhausen and Schoenberg as not music.
>
Yeah, I was going to use a synthesiser as an example of an instrument that
couldn't be compressed, but then I realised that Shannon didn't have to
worry about digital synthesisers in his day.
> Be interesting if the reference to this paper can be found to see how he
> allocated those 40 bits/s....
>
> 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.
>
> Can anyone provide a citation to this alleged paper on music bitrate?
>
> --
> Regards,
> Martin Brown
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