[vorbis] OT: Ogg Vorbis and Bitrate
Friedrich.Burgwedel at roi.de
Thu Sep 20 09:15:28 PDT 2001
>>>> I've heard lots of discussion about it,
>>>> but what I was taught in school was kilo
>>>> was greek for 1000. In most usages "kilo XXX"
>>>> means "1000 of XXX".
This is correct, but...
>>>> In electronics terms
>>>> I understand we use it collectively wrong
>>>> from a linguistic accuracy point of view
>>>> and define it as a power of 2, or 1024.
...this not! Please distinguish:
k = 1000
K = 1024
So 64 kbps are 64000 bits per second, while 64 KByte are 65536 Bytes.
No such differentiation for the Mega prefix exist; so "M" may be 10^6 or
2^20 -- it depends on the context. On SI units, it's usually 10^6, while
2^20 on computer technology related topic. However, there are exceptions:
Hard disc manufacturers use size tags in MByte, with 1 MByte = 1000000
> Early on in the days of computer memory, it was realized that
> memory is best organized in powers of 2.
> I think that this dates back to the days when "core" memory
> was little ferromagnetic cores (like a 0.1 mm donut) storing
> one bit
It's not that difficult and has nothing to do with history: to address a
couple of memory bits, you have to select an address, and you will have to
use a fixed set of address lines to transmit this address. Now, all these
address lines carry digital signals; therefore, with n address lines there
can be 2^n words in memory (from one to ... bits each). If you do not want
to have valid addresses that do not address real memory within the memory
your memory blocks must have a size that is a power of two.
It was a natural choice to select a new prefix K with a value of 1024.
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