[speex-dev] Way to measure loss of quality

Thomas S thomas9920 at yahoo.com
Wed Aug 20 00:39:12 PDT 2003

I think you misunderstood my quality measurement idea.
I mean if you subtract the original and the one after,
the LESS voice that is less over or the LESS you can
tell when someone is speaking, the better the
compression. This is still subjective but I think its
easier to tell this way because its easier to tell how
much voice is remaining than to tell how much the
compressed voice is missing from the original.

Quick analogy, if you have 3 huge piles of apples (one
being the original), of various colors. It is very
difficult to tell which of the other 2 piles is
closest to having the same proportions of each color
BUT, if you subtract them out, it becomes very easy to
look at it and see which is closest to the original.
Hope that makes some sense, but I fully admit it,
until I give it a try some day down the road, I can't
be confident in this idea.

<p>> What do you prefer: a codec that sounds good or one
> for which
> subtracting the original gives a better signal? 

> > I find it difficult to hear 2 voice samples and
> tell
> > which is nearer the original, especially if the
> > background hiss is slightly different. So what if
> you
> > actually subtract the post-compression sound from
> the
> > original and then listen to the DIFFERENCE. If you
> > can't hear any voice except background noise and
> some
> > hiss from "s"'s and "d"'s and such, that means
> most of
> > the actual voice has been maintained. If you can
> hear
> > someone speaking, that means there is leftover
> voice.
> > If you can actually understand what that someone
> is
> > saying, the difference is great. Thoughts?

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