Dither

[rick-slo]

Do you use dither when converting from 24bit to 16bit? Personally I don't.

[keith.rogers]

Yes, always.

Can I always hear a difference, probably not, and, yes, I have heard cases where dither does weird stuff (introduced audible clicks once), so I've had to tweak the setting, but I guess I've seen enough videos to show what happens if you don't, and it's a lesser of evils thing, maybe.

[rick-slo]

Once in a while I have used a dither of different types and never heard a difference. If I was to use one in the future I would be a non noise shaping one.
The noise floor of my recordings are above where quantization errors would creep in.

[jim1960]

I don't. I used to spend time doing critical listening to see if I heard anything that needed addressing on that front but I've yet to master a song where I thought it was necessary.

[Doug Young]

I've never noticed any audible difference. These days, there's less reason to convert to 16 bits, with CDs dying rapidly. The last CD I did, I used a mastering engineer, so no idea what he did.

[RodB]

I share my music as mp3 and don’t dither from my 48/24 recordings. In the past I recorded in 44.1/24 as I shared CDs so did dither on final conversion. I did tests and could not detect any difference, but felt it worth doing in case some younger ears did.

[rick-slo]

About the only time I considered it seriously was when I used a long fade out at the end of the tune. Even then I did not hear quantization errors creeping in audibly.

[KevWind]

Like Doug said mentioned, I have not tried to cut a CD and down converted from 24 for oh maybe 3 or 4 years now.

[runamuck]

The one time about 10 years ago I spent to see if I could hear differences I couldn't.

[lkingston]

In photography/videography, you can see dither if you learn how to look for it. It won't jump out at you, but if you look at the gradients, you'll see moiré banding. Look at the blue in the sky as it gradually goes through shades. Without a dither, you can see banding as it always rounds up to the next eight bit representation of the color. You'll also see it on close-ups of the face as it goes through various shades of flesh tones.

What the dither does visually is to add noise into these gradients, which from a distance will look like a smooth color transition instead of a stark line. Zoom in on a gradient in a dithered picture and you will see that the gradient is actually a noise pattern which goes from one shade - to that same shade but with speckles of the next color - to mostly the next color but with speckles of the previous color - to the next color. Yes, there is added noise, but the overall effect from a distance is far more natural.

In audio, the dither does the same type of thing. Listen to the very soft spots: the tail end of notes that are dying out, reverb tails, that sort of thing. What you'll hear without the dither is a sort of zipper effect on the tail ends of notes and reverb tails going into silence. With the dither, you'll hear smoother decay going into a very soft bed of noise.

The difference is very subtle.

Just to be clear. My ears are damaged now and I wear hearing aids. I haven't heard this level of detail in years, but when I was a young audio engineer in the early days of digital audio, I could hear it quite clearly.

[rick-slo]

Sixteen bit undithered noise would begin at about 86 decibels below full scale. Only way you might hear that noise is to highly
amplify the volume near a full fade out on a track (be careful of your ears). For example I have taken part of a recording into a
DAW and cut its amplitude by about 80 decibels. Then saved that as a undithered wav, put that into the daw and boosted the
amplitude back up. That I could hear the noise in.

[keith.rogers]

Originally Posted by rick-slo

Sixteen bit undithered noise would begin at about 86 decibels below full scale. Only way you might hear that noise is to highly
amplify the volume near a full fade out on a track (be careful of your ears). For example I have taken part of a recording into a
DAW and cut its amplitude by about 80 decibels. Then saved that as a undithered wav, put that into the daw and boosted the
amplitude back up. That I could hear the noise in.

Most home recording setups have a noise floor well above that "theoretical zero" of -86dB. That's the noise you are dithering, e.g., on a long fade. Admittedly, few folks can even hear that in today's listening environments (e.g., earbuds, cheap/lo-fi speakers in noisy environments).

My understanding is that if you do higher than 16-bit, don't bother, of course, because then the consequence (described in another post) won't happen at audible levels. (Even if you're converting to a lossy format.)

But if you do bounce to 16-bit, dithering can manage things that might be audible without it. (It can/does introduce its own artifacts, so if used, listening to the result is necessary.) There is no law that says you have to do it, of course.

I suppose I could just stop bouncing to 16-bit. Why I [still] do that is the question I'm not sure I've asked myself recently...

[rick-slo]

Originally Posted by keith.rogers

Most home recording setups have a noise floor well above that "theoretical zero" of -86dB. That's the noise you are dithering, e.g., on a long fade. Admittedly, few folks can even hear that in today's listening environments (e.g., earbuds, cheap/lo-fi speakers in noisy environments).

Yes, that's another reason I question adding dither. The equipment noise floor (mainly mikes normally) is a form of white noise (not triangular admittedly).