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And for my last trick, to hopefully turn some of you non-believers, I will turn to some rudimentary ASCII art.
The Original File looks like this:
AIIIIIIIIA
BIIIIIIIIB
CIIIIIIIIC
DIIIIIIIID
I'm making it real easy there. The sound starts all the way on the left, and ends on the right. Treat all four lines of I's as one sound.
Here is what happens when you compress it into a music file, for example WMA:
BIIIIIIIIB
CIIIIIIIIC
DIIIIIIIID
What happened? We stripped off a "layer" of the music to turn it into a compressed file. In this case, the new file is about 75 percent as good as the original. We can pretend that this is mid-range quality on wma.
Now, we are going to convert it to mp3. But first, lets listen to it.
BIIIIIIIIB
CIIIIIIIIC
DIIIIIIIID
Hmm, yes, this is what we hear. The part that was stripped off does not magically re-appear. It is gone forever, unless you go out and buy an official copy. Official meaning- Not Bootlegged, Downloaded, Taped by a friend, etc. Official stands for- What the music guys put on CD/Medium for my consumption.
Anyway, lets convert the wma to mp3 now.
CIIIIIIIIC
DIIIIIIIID
Using what we saw when we listened to it, we see that again, the top layer did not magically reappear. The conversion took what it was given, the BCD file, and uncompressed it. The uncompressed BCD file will sound the exact same as the compressed BCD file, except that it will be very large in file size. The conversion then goes to the next step of recompressing the new uncompressed BCD file. That is when it strips off the B layer. Why? Because it is doing the same thing it did the first time when we made the WMA file. Only, because we do not have the A layer, it removed the B layer.
This new mp3 file is about 50 percent as good as the original, and about 66 percent as good as the WMA file.
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