Which Dither?

Discussion of music production, audio, equipment and any related topics, either with or without Ableton Live
crumhorn
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Which Dither?

Post by crumhorn » Mon Dec 14, 2009 1:27 pm

Rectangular ?
Triangular ?
POW-r 1 ?
POW-r 2 ?
POW-r 3 ?

I need enlightenment!

I know something of the theory behind dithering but what are the qualities, strengths, and or weaknesses of all these options.

I found some stuff via google but nothing that would really help me choose,

According to wikipedia POW-r 1 is good for low dynamic range material like spoken word, Pow-r 2 is better for Medium dynamic range like Rock Music and Pow-r 3 is better for material with wide dynamic range like orchestral music.

But couldn't find anything comparing these with the triangular and rectangular algorithms.

With my poor, abused equipment and ears I can't be sure I'm really hearing any difference to be honest.

Would love to get some guidance on this.
"The banjo is the perfect instrument for the antisocial."

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33tetragammon
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Re: Which Dither?

Post by 33tetragammon » Mon Dec 14, 2009 2:06 pm

hi,

are you using live's dither or a mastering plugin like Izotope Ozone 4(or similar)?

here's what i do(when using Ozone 4's dither) :

get the Sonalksis free-g plugin(http://www.sonalksis.com).

put one BEFORE the mastersuite,lower the gain to around -40dB.

make sure everything in the mastering plugin is turned off,but leave dither on(obviously).dither is what you should do LAST,and nothing AFTER that(so no normalizing or whatever)

put another free-g AFTER the mastering plugin,and turn up the gain as high as necessary,and listen on a good audio interface with good converters through good headphones.

this allows you to HEAR what dithering actually does.you'll be surprised how much difference you actually hear between the types.one sounds grainy,one distorts,etc etc....

when you found the one you think sounds best(when you don't hear any aliasing or distortion anymore),delete the free-g plugins,and dither your stuff.

hope that helps.

here's some more info on mastering :

http://www.tarekith.com/assets/mastering.html

crumhorn
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Re: Which Dither?

Post by crumhorn » Mon Dec 14, 2009 3:18 pm

^^^

Thanks for the post, and the link

At the moment I'm at the stage where I want to get the best result I can just using Live. Individual songs rather than whole albums. I've got the mix how I like it and want to pass it around for comments or to listen in the car. When I go to export the audio I see all these dither options and have no idea which to choose, but I'd like to get the best result I can.

I'm not really into the whole mastering thing at the moment, just running off demo tracks for burning direct to CD or converting to MP3.
"The banjo is the perfect instrument for the antisocial."

(Allow me to plug my guitar scale visualiser thingy - www.fretlearner.com)

Tarekith
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Re: Which Dither?

Post by Tarekith » Mon Dec 14, 2009 3:36 pm

POW-r2 will likely be the one 95% people need to use, though any of them are better than not using dither at all.
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djsynchro
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Re: Which Dither?

Post by djsynchro » Mon Dec 14, 2009 3:38 pm

POW-R 2 then if you have golden ears and a mastering suite you might be able to hear a difference - just. (I was mastering a record and we had two CD-R copies of my tracks and one copy made the playback CD player go heavier into error correction, and it was audible) just do it Synchro said so. :D
Last edited by djsynchro on Tue Dec 15, 2009 1:36 am, edited 1 time in total.

crumhorn
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Re: Which Dither?

Post by crumhorn » Mon Dec 14, 2009 4:39 pm

Thanks guys,

POW-r 2 is what I've been using, based on what I can find on the web, so thanks for reinforcing that. Just don't seem to be able to get a clue as to when it might be better to use Triangular or Rectangular. Must be good for something otherwise why bother including them.

Anyway it makes no practical difference to my ears, but I'm curious to know what the thinking was behind the different options provided in the audio export dialogue.
"The banjo is the perfect instrument for the antisocial."

(Allow me to plug my guitar scale visualiser thingy - www.fretlearner.com)

djlimbs
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Re: Which Dither?

Post by djlimbs » Mon Dec 14, 2009 5:10 pm

i'm sure there's a thread about it somewhere...but why not a straight 32-bit render?

Nick the Zombie
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Re: Which Dither?

Post by Nick the Zombie » Mon Dec 14, 2009 5:21 pm

Just putting in a placeholder post so I can subscribe to the thread. Dithering is a topic that I really want to know more about.

Tarekith
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Re: Which Dither?

Post by Tarekith » Mon Dec 14, 2009 5:55 pm

I bet most people can't hear the differences in dither, regardless of experience or what gear they have. It can make a difference in certain situations though, so mastering engineers need to pay attention to it. I made some audio examples awhile back that clearly demonstrate the differences between certain dithers and no dither at all. I didn't have the POW-r's at the time, but at least you can hear what it's doing and why we use it.

http://tarekith.com/assets/ditherexamples.zip

All of these files were boosted A LOT to make it easier to hear the effect. The 24bit file is the original, then there's a 16bit file that had no dither applied before truncating, and a UV22Hr dithered 16bit file. You can hear the distortion in the regular 16bit file as the reverb tail toggles the lsb on and off, and how the dithered version is a lot smoother at the expense of a little bit of noise (no pun intended).
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Tone Deft
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Re: Which Dither?

Post by Tone Deft » Mon Dec 14, 2009 7:10 pm

Bob Katz blew my mind with dither. I know more now but also less. quoted from page 55 of "Mastering Audio."

"Dither's resolution enhancement is a truly physical/mathematical phenomenon, not simply a means to fool the ear or "to mask the low level digital breakup." In addition to being able to record and reproduce all the analog values at high high and medium levels, dither lets us encode low level signals below the -96dB limit for 16 bit! We can digitally measure undistorted test tones lower than-130dB in a 16 bit system. These results - increased resolution and the elimination of quantization distortion - cannot be achieved by adding noise after the A/D conversion. So dither must be added at the proper point in the circuit: adding noise after quantization is not the same as dithering and is as effective as locking the stable door after the horse has escaped."

he goes on about shaping the dithering signal's frequency content to dither different regions of the audio spectrum, laying off dithering at 3kHz because that's a frequency that our ears are sensitive to. lots of great info but of course he never says which option to use in Ableton Live. ;)

IMO, try each method, listen for what works for you. I might blindly follow advice from someone like Tarekith who knows his shit and is known to be OK with saying he doesn't know (a trait I highly appreciate in people) but most forumites don't really know the answer.


use your ears!!! my bet is that you won't hear a difference. you could phase cancel each of them, if you compared three or more dither processes you could deduce which has more or less frequency content in each range but would that tell you if more or less frequency content sounds better? I wonder if we took your song and put another song on top of it at -96dB if you could hear the other song.

it'd be interesting to read from REAL studio whores how they've come to know dither over the years. I take it to be a very inexact science and an art.
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davepermen
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Re: Which Dither?

Post by davepermen » Mon Dec 14, 2009 7:14 pm

yeah, dithering can enhance the resolution by spreading information over another dimension.. depending on how they spread it, they create different artefacts. as always, me, the dave, loves to intepret it visually.

here are ditherings of dave :)

Image

as everyone can see, the last 3 pics are only black and white, so they are 1 bit per pixel information. still, the IMAGES contains much more information about shade, as our brain doesn't interpret each pixel individually.

same happens for audio.
http://davepermen.net my tiny webpage, including link to bandcamp.

Tone Deft
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Re: Which Dither?

Post by Tone Deft » Mon Dec 14, 2009 7:19 pm

davepermen wrote:yeah, dithering can enhance the resolution by spreading information over another dimension...
not to start the whole nit picky bullshit, but did you really mean another dimension?
In my life
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At people who I'd much rather kick in the eye?
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Tarekith
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Re: Which Dither?

Post by Tarekith » Mon Dec 14, 2009 7:20 pm

Dither is extremely scientific, and very reproducible. It's also a highly complex subject that makes most people's eyes (including mine) gloss over once you get into the details. Saying use your ears is a good thing usually, but with dither we're talking about something that's sooooo quiet compared to the music that like I said I doubt most people can even hear it, let alone the differences between the versions. Certainly worth a try though, don't get me wrong. This might help people with what to listen for:

The POW-r Dither plug-in provides three types
of noise shaping, each with its own characteristics.
Try each noise shaping type and choose the
one that adds the least amount of coloration to
the audio being processed.

Type 1 Has the flattest frequency spectrum in
the audible range of frequencies, modulating
and accumulating the dither noise just below
the Nyquist frequency. Recommended for less
stereophonically complex material such as solo
instrument recordings.

Type 2 Has a psychoacoustically optimized low
order noise shaping curve. Recommended for
material of greater stereophonic complexity.

Type 3 Has a psychoacoustically optimized high
order noise shaping curve. Recommended for
full-spectrum, wide-stereo field material.

OR:

POW-R #1: optimized for simple program of average dynamic range, such as spoken word.
POW-R #2: optimized for low dynamic range program, such as rock music.
POW-R #3: optimized for complex, high dynamic range program, such as orchestral music."


If you really want to know more, make yourself some popcorn and do a search on dither at Gearslutz. Take some aspirin in advance too for the inevitable headache.
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davepermen
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Re: Which Dither?

Post by davepermen » Mon Dec 14, 2009 7:29 pm

Tone Deft wrote:
davepermen wrote:yeah, dithering can enhance the resolution by spreading information over another dimension...
not to start the whole nit picky bullshit, but did you really mean another dimension?
yep. as the amplitude at an individual sample has too less information in this dimension (vertical if you plot out an audio-wave), the information gets spread over several samples, that means, over time.


as f.e. (if you have only whole numbers), you can not represent a continuing signal of 1/5th, you spread it over 5 samples, each being 0, one being 1. and repeat.

so you spread it over another dimension. yes.

same happens on the picture. as the individual pixel doesn't have enough resolution anymore in the colour-dimension, it spreads over the two spacial dimensions it's information.

dimensions in the mathematical sense.
http://davepermen.net my tiny webpage, including link to bandcamp.

Tone Deft
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Re: Which Dither?

Post by Tone Deft » Mon Dec 14, 2009 7:30 pm

nice explanation. 8)
In my life
Why do I smile
At people who I'd much rather kick in the eye?
-Moz

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