[vorbis-dev] compressed audio tutorial - 2nd draft

[Graham Mitchell]

> "Extensive listening tests showed that only a small percentage of sound 
> engineers could tell which sound was the original "full-quality" one, and 
> which one was the "CD-quality" one"
> 
> Right. But this is about listeners, isn't it, not about engineers? Why should 
> the opinion of engineers be more important than that of testers with the good 
> ears?

My intent was to imply that if even "sound engineers" couldn't tell the
difference, then the average listener needn't worry that CD-quality is
somehow noticably less good than the original.

Of course, with so many bands compressing the signal to death just to get
an increased average volume for radio airplay, this may not be the case, but
that's beyond the scope of the document.

Anyway, this statement will probably get washed out in the re-working of the
first four paragraphs when I do it tomorrow or perhaps later tonight.

> "Special-purpose compressors (like flac) do exist, which were designed solely 
> for losslessly compressing audio (...)"
> 
> I don't really like this construction with do exist and which.

I do tend to write complex sentences.  I'll try to refactor the information
to be more easily readable.

> Thirdly, it took me a little while to realise why the number 
> 1,411,200 was associated with CD's, while before it was 176,400. Perhaps you 
> could change that sentence in "A bit on bitrates" to "Actual, uncompressed, 
> CD-quality uses 1,411,200 bits (176,400 * 8) bits to store each second".

Good point.  That's what math teachers call "skipping a step".  I'll fix it.

> Other than these minor things I think it's a well-written piece that does a 
> good job of explaining to people how audio compression works, that mp3 is 
> outdated, why using ABR is not as good as VBR, and how to use the quality 
> settings of Vorbis to get good quality .oggs. Well done!

Thanks!  Look for a revised version incorporating these changes later tonight
or maybe Saturday afternoon.

And thanks for good feedback.  The power of "Open Source" is really
improving this tutorial.


--
Graham Mitchell
computer science teacher
Leander High School

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