actually, i believe that the fhg encoder uses joint stereo for anything
below 192kbps
----- Original Message -----
From: "Mark Taylor" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, February 04, 2000 11:10 PM
Subject: Re: [MP3 ENCODER] LAME in the PRESS
> >
> > > > I agree in that encoding in CBR opposed to VBR gives me a feeling of
being
> > > > more safe :)
> > > I wonder where the myth that joint stereo would somehow adversely
affect
> > > quality comes from. Was it the web pages from the BladeEnc guy?
> >
> > Actually, it was this mailinglist. I think Mark Taylor (correct me if
I'm dead
> > wrong!) said something like:
> > "at high bitrates, joint stereo can do more evil than good, because the
algorithm
> > [of detecting similarities in the left/right channels] is not perfect".
> >
>
> we all know this, but just to clarify: jstereo means the encoder
> is free to choose between regular (l/r) stereo or mid/side stereo
> for each frame.
>
> I think mid/side stereo will always improve quality when the left and
> right channels are similar. In that case, the mid channel is more
> important than the side channel and allocating more bits to the mid
> channel will effectively increase the bandwidth. But there are two
> problems I've seen with mid/side stereo:
>
> If the L and R channels are very different (and thus there is a lot
> of information in the side channel), encoding in mid/side
> stereo will creates problems, since noise in either mid or side
> channel will be spread to both the L and R channels. Check out
> mstest.wav on the lame web page for an example. If this is coded with
> mid/side stereo, you will get some very noticeable artifacts. So lame
> only tries to use mid/side stereo when the L and R channels are very
> similar.
>
> The second problem I've seen is too much switching:
> if lame switches back and forth between mid/side and regular L/R,
> the switching itself can create artifacts.
>
> The question is, when do the benefits of mid/side stereo
> outway the negatives? Until someone figures out the answer
> to that question, we'll just take what the FhG encoder does
> as the gospel truth: use mid/side stereo only for 128kbs and less.
>
> Mark
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