There I was, sitting in the recliner when the phone rang. My brother-in-law wants to know what an MP3 is. I explain that it is a file that can be played on a computer or MP3 player. He doesn't understand the computer concept of a 'file' and I pretty much failed to enlighten him.
After finally answering most of his questions and hanging up ,
I wondered how to explain a 'file' to someone. The simplest explanation
I came up with is that a file is a number. A one megabyte file is just
an eight million digit binary number. It doesn't matter whether it is a
text file, picture or the Elvis Presley version of
"Baby Got Back" it is just a number.
Back in the early 80s before Compuserve introduced GIF files,
there was a lot of interest in RLE files. An RLE file on Compuserve was
256 x 192 pixels of one bit per pixel. Black or white only. No greys.
The picture of Mona
is actually a GIF file, but could have been an RLE file with no
significant changes. Browsers don't display RLE files very well.
Mona's picture is a binary number 49,152 digits long. Lets say
the least significant digit is the upper left hand corner. We use the
256 least signifcant digits for the top horizontal scan line and repeat
the process 192 times we get a picture of the Mona Lisa.
I wrote a program that cycled this 49,152 digit number through
all of its possibilities in numerical order. I then uploaded it to
Compuserve and descibed it as capable of displaying every possible RLE
picture. I claimed that while it ran it would display the face of every
person ever born or that would ever be born, including beings from
other planets and star systems. All text ever written would be
displayed on the screen, though not necessarily in a useful order. I
suspect that all of these claims were true. There was a catch.
Allowing a thirtieth second viewing time for each iteration
means the top scan line will take 1.2230766306406506982319207312838e+68
YEARS to complete. The second scan line would take quite a bit longer.
The universe may not last long enough for this program to run.
You may be thinking that Elvis died before "Baby Got Back" was
written. It doesn't matter! There is a number that can be fed into an
MP3 player that will play Elvis singing "Baby Got Back". If you find
that number, let me know.
August 6, 2015