Re: AudioConvertor does dither?
Re: AudioConvertor does dither?
- Subject: Re: AudioConvertor does dither?
- From: Chris Rogers <email@hidden>
- Date: Mon, 3 May 2004 12:13:03 -0700
Ev,
I wouldn't really say dithering is necessary, but it *is* desirable.
As Doug suggested, you could add low-level noise to the floating point
samples before feeding them to the AudioConverter. This noise would
need to be around the level of the least significant bit.
Noise with triangular distribution can be generated by adding two
random numbers together which are uniformly distributed.
This would be a nice feature to add to the AudioConverter, but
currently you would need to do this yourself...
Chris Rogers
Core Audio
Apple Computer
On May 3, 2004, at 12:00 AM, email@hidden wrote:
Ev,
Currently the AudioConverter does no dithering or noise-shaping and
simply rounds to the nearest integer.
Chris Rogers
Core Audio
Apple Computer
When I use the AudioConvertor to blast my buffers from floating
point data to whatever stock bit depth I need, is there any sort of
dithering action done during the conversion?
If so, what kind of dithering is it? Is it noise-shaped at all? Triangular?
OK, knowing that then, is there any need for dithering code anywhere
in this process then? Can/should I modify the results?
I've seen bits of sample code dealing with dither that is all about
the translation from floating point to integer, just adding a
particular noise at the resulting bit depth's lowest level, so the
rounding isn't so expected. I've heard examples of it, and I see the
point.
Should I be doing this to my floating point numbers before I feed
them to the AudioConvertor? Or is the floating point number, by
nature, dithering in itself and it's just not necessary?
Does anyone have any suggestion?
Ev
Technical Knowledge Officer
Head Programmer/Designer
Audiofile Engineering
http://www.audiofile-engineering.com/
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