http://www.aes-media.org/sections/pnw/ppt/jj/adc.ppt Once again offered. Sadly, no recording that I know of.
a small question regarding dither.
You say its a requirement, is this also true for 24bit PCM, say 24/96 ?
I would argue the dither would be lost in real world noise.
Technically it will be better but in practice will it have benefits ?
Not JJ, so PMFJI, but the "real world noise" actually is dither. This is something we discovered in FT infrared measurements when I was fresh out of school and working at Nicolet- the detector noise was an excellent way to increase apparent resolution.
I thought dither was shaped in spectrum and can only be dither when it is 1LSB in size, otherwise it is just noise even though it works a bit like dither.
edit: ahh.. was crossposting with J_J
At 24 bits it's a philosophical question, really. Do you want to capture the system noise from before the ADC?
For whatever it's worth, SoX automatically dithers the output only if it is less than 24 bits. I don't know what the reasoning was behind this decision.I have been pondering the question of dithering a 24 bit audio signal too.
Take the scenario of a convolution engine, processing a 16 bit, 44.1kHz input signal with some FIR filter(s).
If the engine works internally at 32-bit floating point by first normalizing its input signal to +/- 1.0, convolves the input and filter(s), then de-normalizes to a 24 (or 32 bit) integer for output (non-truncating rounding method), is there anything to be gained by applying dither to the output?
Me thinks not, but I would be grateful to have my notions reinforced or destroyed
I have been pondering the question of dithering a 24 bit audio signal too.
Take the scenario of a convolution engine, processing a 16 bit, 44.1kHz input signal with some FIR filter(s).
If the engine works internally at 32-bit floating point by first normalizing its input signal to +/- 1.0, convolves the input and filter(s), then de-normalizes to a 24 (or 32 bit) integer for output (non-truncating rounding method), is there anything to be gained by applying dither to the output?
Me thinks not, but I would be grateful to have my notions reinforced or destroyed
Dithering is meant to reduce, or rather spread, quantization noise. In your example if everything were done at 32 bits right up to the DAC, the 16-bit DAC still has quantization noise at the 16-bit level, so yes you'd want to dither that.
Dithering is meant to reduce, or rather spread, quantization noise. In your example if everything were done at 32 bits right up to the DAC, the 16-bit DAC still has quantization noise at the 16-bit level, so yes you'd want to dither that.
Posting whilst working, bad idea.
No, actually, it slightly increases total quantization noise, but totally decorrelates it from the signal, making quantization a linear system with a noise source, rather than a nonlinear source.
That linearization is why it's so important on 16 (and less) bit signals.
And, yes, if you reduce to 16 bits at the output, indeed you )&(*& well dither!
May be semantics, or different definitions, since my data converter designs were not audio... I would
..
And yes I know you know all this!
May I stir up the discussion a bit? NOS DACs need no filter because there always exist two filters: number one is the speakers/phones that shut off around 20 kHz. Number 2 are our ears.
Of course that won't prevent me from doing it right in the first place, but....you get it.
Is there a way to measure how well a DAC recreates recorded reverb? I got to thinking about this when reading an article by Herb Reichert in Stereophile about the R-2R Denafrips DACs' handling of reverb in recordings.
The one thing that appears to be consistent about subjective reviews of R-2R DACs is a sense of “soundstage width”, or “space”, or “three-dimensionally”. I interpret this as reverb. I’m not sure how the reproduction of this specific aspect in the recording is reflected (pun intended) in any one measurement.
Humans seem to have a strong attraction to and sensitivity to reverb. I wonder how this translates to the digital realm.
Any thoughts on this?