On 5/10/2011 8:32, Invisible wrote:
> 1. Why the hell would you put compressed audio onto a CD rather than the
> uncompressed original source?

Because you don't have the original source, or the person mastering the CD 
got the original source over a network and didn't want to spend the 
bandwidth and didn't care?

There are lots of CDs out there that were copied off vinyl albums that 
weren't properly compensated and have the treble turned way up. (Vinyl turns 
the treble up, and the record player turns it back down, to reduce hiss.)

Tomita's "Pictures at an Exhibition" has several tracks where they put the 
same audio on both the left and right channel, just because they screwed up.

> 2. If I can tell that it's compressed, despite not having the uncompressed
> original to compare to, doesn't that mean that there's more redundancy in
> the signal than the codec is taking advantage of?

No. You can tell someone is talking over a telephone by the fact that too 
much information is lost. Same with autotune.

> Now I don't actually know which codec was used here. [Asking whether you can
> tell the codec by the compression artefacts is another interesting
> question.] But in this instance, there are long echo tails which are getting
> audibly chewed up. Not drastically so, but enough to be noticeable.

Sounds like nyquist limits screwing up the codec, to me.

-- 
Darren New, San Diego CA, USA (PST)
   "Coding without comments is like
    driving without turn signals."

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