[MPlayer-dev-eng] Re: bug repport with surround

[Anders Johansson]

> Stephen Davies wrote:
> 
> > I'll update and have a look.  ANyone else is welcome to fix it, of course.
> 
> I've just commited a port of pl_surround.c to the new audiofilter layer.
> However I think the fir filter is not working properly, maybe I'm doing
> something wrong, it'd be nice if Anders could have a look at that
> part... At least when I tried a very low cutoff frequency (700Hz) it did
> not sound much different to me...
> 

Hi nice work, I did some speed optimizations (and changed some
variable names, sorry) I also fixed the filter, and did some other bug
fixes.

Check if the change made in the way the sound is delayed is OK?  I
delay the sound after it has been filtered but I assume that will give
the same result?

BTW: what would be required to enable the active matrix? Do you have
any docs on it?

Also: I have started to write a filter for adding a sub-woofer
channel. What stop-band attenuation and steepness are required? The
pasband ripple is almost of no consern (I havent seen a phase linear
sub ever) I think I'll use a IIR Buterworth filter (the ear is not so
sensitive to phase errors in the low frequency region and so I think
it is an OK tradeoff), but I am not sure I I'll need a 2nd, 3rd or 4th
order filter. Any clues?

Cheers,
/Anders