[MPlayer-dev-eng] [PATCH] Audio balance feature

[Zuxy Meng]

Hi,

2007/6/17, Reimar Doeffinger <Reimar.Doeffinger at stud.uni-karlsruhe.de>:
> Hello,
> On Fri, Jun 15, 2007 at 05:53:51PM +0800, Zuxy Meng wrote:
> [...]
> > +    if (af->data->nch >= 2) {
> > +      s->level[0][0] = min(1.f, 1.f - val);
> > +      s->level[0][1] = max(0.f, val);
> > +      s->level[1][0] = max(0.f, -val);
> > +      s->level[1][1] = min(1.f, 1.f + val);
>
> Btw. where does this "formula" come from? I think at least my hardware
> balance control would only adjust [0][0] and [1][1].

Hmm...that's why I wanted pan; I hope sounds from FL and FR can be
mixed into both speakers, instead of adjusting their volumes only.

>
> > +    if (af->data->nch < 2)
> > +      *(float*)arg = 0.f;
> > +    else if (s->level[0][1])
> > +      *(float*)arg = s->level[0][1];
> > +    else if (s->level[1][0])
> > +      *(float*)arg = -s->level[1][0];
> > +    else
> > +      *(float*)arg = 0.f;
>
> Not very important, but I don't think these many else cases make much
> sense, I'd suggest just doing always e.g.
> > *(float*)arg = s->level[0][1] - s->level[1][0];
> If you want keep the special af->data->nch < 2 case but not the others.
> Though I'm not sure if some other AF_ return might make more sense in
> that case (but then you have to make sure it doesn't cause the control
> code to insert yet another af_pan ;-)

Thanks! level[0][1] - s->level[1][0] actually works for all the cases.

>
> > +// Number of outputs from pan, arg is float*
> > +#define AF_CONTROL_PAN_BALANCE               0x00002500 | AF_CONTROL_FILTER_SPECIFIC
>
> The description is wrong, and I'd name it just AF_CONTROL_BALANCE, there
> is no reason to keep it af_pan specific forever.

The description will be corrected. As for the name, currently it's a
filter specific control, and the tradition is to prepend the filter
name. Were u suggesting making it a general control option like
AF_CONTROL_REINIT or AF_CONTROL_POSTCREATE?

-- 
Zuxy
Beauty is truth,
While truth is beauty.
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