Dithering Question....

Posted: Sun Sep 28, 2008 4:46 pm

ok, so i'm using Adobe Audition 3 for all of my recording, mixing, and my somewhat rough, improperly trained attempt at mastering. - but hey, i'm doing it all to learn from anyway.

after adding some limiters and stuff and i get my level fairly hot, i was wondering....should i dither?

cause when i'll use the program to burn it to CD, it says "converting from 32 bit to 16 bit" during the burn process. - does that mean it's automatically dithering for me?...or do i actually need to dither to 16 bit before i burn. - i tried this and it still will say "converting from 32 bit to 16 bit" - if i dithered, wouldn't it already be 16 bits???

idk... i get easily confused when it comes to bits and all that jazz Smile

sorry if this was kind of a dumb question.

i know i should leave this to the pros, but i just want to learn about this and understand as much as i can.

any input would be greatly appreciated!
thanks!
-jordan

Moderator Joined: Sep 12, 2002 Posts: 1865 Location: NYC

If Audition dithers when it burns, then you don't need to dither before hand. I'm not sure if it does but I would image it does.

Posted: Mon Sep 29, 2008 12:14 pm

Dithering is the process of adding low level random noise. It is separate from the conversion process even though they are usually done at the same time. So it is possible to convert without dithering and dither without converting (which is what it sounds like you did).

Posted: Mon Sep 29, 2008 5:47 pm

I seriously doubt that dither is being applied during this process. It's more likely that your audio is being truncated. The reason for this leap of logic is simply that dither requires shaping, and there is no way for any application to determine how your dither noise should be shaped during bit depth conversion.

Also, I use several applications for audio, and none of them dither without your say-so, they only truncate. You should definitely be appplying dither in this case.

Posted: Tue Sep 30, 2008 7:10 am

thanks guys. yeah, i looked into it, and no, i don't believe it's automatically dithering for me.....however, wouldn't i notice some pretty audible distortion if i have not dithered???
i've obviously been skipping this step for quite some time, lol, and haven't really been noticing any unplanned distortion....hmmm? idk.

although i know somewhat what dithering does (i don't know it fully. i just know it adds low level noise to get a fuller bandwidth coverage at lower bits...right?), would it also help with getting louder levels with the end product? -that might have been a dumb question....

Posted: Tue Sep 30, 2008 7:27 am

jordy wrote:

wouldn't i notice some pretty audible distortion if i have not dithered???

Not really. When dithering from 32 bit or 24 bit down to 16 only the least significant bit is in question. This corespondent to a -96dB amplitude change compared to full volume. If you don't dither, your audio is truncated (or it could be rounded)

A dithering algorithm will smartly alter the least significant bit to fake a higher bit depth. It's equivalent to a laser printer using very small dots of black and white to make shades of gray. If you truncate a photo, it would be just blotches of black and white. If you dither, you can see grays. Although with audio 16 bit allows 65536 shades of gray, and dithering allows you to fake it to make it seem like you have more.

Quote:

would it also help with getting louder levels with the end product? -that might have been a dumb question....

Not a dumb question, but the answer is it does not.

Posted: Tue Sep 30, 2008 7:45 am

thank you gecko!
that explains things alot better for me. i'll do some more research on it and start dithering my stuff.

Moderator Joined: Sep 12, 2002 Posts: 1865 Location: NYC

hackenslash wrote:

I seriously doubt that dither is being applied during this process. It's more likely that your audio is being truncated. The reason for this leap of logic is simply that dither requires shaping, and there is no way for any application to determine how your dither noise should be shaped during bit depth conversion.

Also, I use several applications for audio, and none of them dither without your say-so, they only truncate. You should definitely be appplying dither in this case.

Lots of programs I know of dither while burning. Dither does not require shaping either. There is usually a selection in the preferences to or not to dither. You can select the type of dither, shaped or unshaped. It's not rocket science. Shaped dither is random noise that is shaped. Looking in the manual should tell you if your program is capable of dithering during the burn.

Posted: Tue Sep 30, 2008 11:27 am

I stand corrected.

I still highly doubt that Audition dithers automatically. Wavelab certainly doesn't.

Moderator Joined: Sep 12, 2002 Posts: 1865 Location: NYC

From the Adobe website

"If you begin at 24 bit or higher, do not convert your material until the final stage of production"

"The preset dither depths and noise shaping curves (pdf=triangular, Noise Shape A) are usually adequate"

So, find the dither presets in the program and you should be good to go.

Moderator Joined: Sep 12, 2002 Posts: 1865 Location: NYC

From Wavelabs website.

"We must mention the dithering options which include WaveLab's dithering algorithm and Apogee's highly-acclaimed UV22"

Posted: Tue Sep 30, 2008 6:08 pm

Just to extend the discussion a bit (if not hijack the thread) - Do any of you have strong opinions about the type/shape of the noise in the dithering process? I understand the theory behind the differences, but I frankly can't hear any obvious difference between the few options that I have.

Posted: Tue Sep 30, 2008 6:22 pm

Essentially, it moves the dither noise to different areas of the frequency spectrum. Since the noise itself is meant to be difficult to hear, it's hardly surprising that the differences are even more difficult to hear. If my understanding is correct, and it may well not be, it's so that you can hide the noise in different places, depending on the actual content of the recording.

Posted: Wed Oct 01, 2008 7:50 am

Interesting question Mr. Bob.

I have seen the shape options but the default sounded good so I didn't mess with anything.

Next time I get a chance I will have a listen. Cheers for the fun mission.

Moderator Joined: Sep 12, 2002 Posts: 1865 Location: NYC

I'm sure there will be smart dither in the future, but right now I only know of fixed dither shapes. flat dither is just that, low level broadband noise that is relatively flat across the spectrum. noise shaped dither tends to dip the noise at the ears most sensitive midrange and boosts it in the not so sensitive ranges. Some say it excites the content in these boosted frequency ranges, others say not. I feel it's not important as to what kind of dither you use, just as long as you use it. Keep an ear on it and check to make sure you aren't hearing any funky stuff if you're using exotic shaped dither's .

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