[haiku-development] Re: Mixer resampler API

  • From: Ingo Weinhold <ingo_weinhold@xxxxxx>
  • To: haiku-development@xxxxxxxxxxxxx
  • Date: Wed, 18 Aug 2010 18:35:36 +0200

On 2010-08-18 at 16:35:34 [+0200], Stephan Assmus <superstippi@xxxxxx> 
> Am 18.08.2010 15:02, schrieb pulkomandy:
> > Some days ago I introduced a new resampler that uses interpolation in
> > the media kit. I'm still not happy with it, so I'm going to write
> > another resampler, this time using a Lanczos filter, which should give
> > much better results.
> I would guess something is wrong with your filter, but some months ago
> (years?) I also wrote an uncommited resampling version and was also
> wondering why it didn't seem to have any affect on the quality. I did
> not trust my implementation though, just curious that you also seem to
> be unhappy with your resampling. In theory, it should already have
> enough quality.

One problem with simple interpolation is that it introduces high frequency 
noise, so it has to be followed by a low-pass filter. I haven't looked at 
the code, but if you haven't done that, it would explain the poor quality.

A quick look at Wikipedia suggests that the Lanczos filter is a low-pass 
filter, so I guess better quality can be expected when using it.

CU, Ingo

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