Dithering Question....

Discussion in 'Mastering' started by jordy, Sep 28, 2008.

  1. jordy

    jordy Active Member

    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 :)
    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
     
  2. Michael Fossenkemper

    Michael Fossenkemper Distinguished past mastering moderator Well-Known Member

    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.
     
  3. BobRogers

    BobRogers Well-Known Member

    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).
     
  4. hackenslash

    hackenslash Active Member

    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.
     
  5. jordy

    jordy Active Member

    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....
     
  6. GeckoMusic

    GeckoMusic Guest

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

    jordy Active Member

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

    Michael Fossenkemper Distinguished past mastering moderator Well-Known Member

    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.
     
  9. hackenslash

    hackenslash Active Member

    I stand corrected.

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

    Michael Fossenkemper Distinguished past mastering moderator Well-Known Member

    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.
     
  11. Michael Fossenkemper

    Michael Fossenkemper Distinguished past mastering moderator Well-Known Member

    From Wavelabs website.

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

    BobRogers Well-Known Member

    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.
     
  13. hackenslash

    hackenslash Active Member

    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.
     
  14. Greener

    Greener Guest

    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.
     
  15. Michael Fossenkemper

    Michael Fossenkemper Distinguished past mastering moderator Well-Known Member

    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 .
     
  16. hackenslash

    hackenslash Active Member

    Thanks Michael. A great explanation, and clarified for me what I was only wandering around the edges of blindly before.

    Incidentally, I can confirm that there is no auto dither in Wavelab, and it must be applied in the master section.
     
  17. music_guy

    music_guy Guest

    I am not familiar myself with this program but it should give you a dithering plugin separately. I doubt it would dither as you convert...

    Some limiters offer dithering and noise shaping options all in one plug. Does yours have it?

    Edward Vinatea
     
  18. jordy

    jordy Active Member

    hey thanks, Edward!
    yes, some of the limiter plugins i've been using do have a dithering option. - there's just so many options on dithering it seems. -there's doesn't seem to be a "stock" dithering plugin with Adobe Audition, but there's options under the file and edit tabs at the top. i guess i'm just kinda uneducated in this area. the replies seem to have cleared it up for me. i just have to read up on how my program handles dithering. - it seems there may be sort of an auto- dither option that can peform right as i'm converting the 32bit file down to 16 during the burn process, however, i'm not quite sold on that idea seeing that some are saying each song may benifit from different dithering options- such as the shape of the noise and what frequency etc....

    i haven't got to check though, if the program has indeed been dithering my previous material....if i load a song and look at the waveform, do you think i would be able to see the dither noise at the beginning or end of the song if magnified?

    thanks for all the help guys

    -jordan
     
  19. music_guy

    music_guy Guest

    You won't see anything. Dithering is a very subtle effect/process, somewhat arcane and thus you probably won't even hear a difference in the sound quality, certainly not a high amplitude.

    Dither with a peak limiter when "bouncing" or mixing to 2 track stereo deck (for example a MasterLink ML9600) from high word length values to low, i.e. from 24 to 16.

    So, always dither when changing word lengths. And, if you happen to save a lot of money to buy DAC/ADC pair of converters like the Lavry Golds, you would have world class dithering built right in. The price tag is about $15K

    Edward Vinatea
    Mastering Engineer
     
  20. Michael Fossenkemper

    Michael Fossenkemper Distinguished past mastering moderator Well-Known Member

    All converters have "dither" built in.

    You may or may not be able to see the signs of dither depending on what kind of tools you have. If you have spectrafoo, they have many tools that you can use to visually see it. But you are more likely able to hear it on the fades of songs if it was truncated. it will sound "grainy" as it fades out.
     
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