32 >16 (Dither)...better results than 24 > 16

Discussion in 'Mastering' started by mark4man, Jun 29, 2009.

  1. mark4man

    mark4man Active Member

    kinda wondering...

    what happens when one dithers a (legal) 32-Bit FP file all the way down to 16-Bit w/ their favorite dither box ??

    reason I ask is...I'd been used to (like everyone else, I suppose) bouncing out of the DAW (SONAR) at 32-Bit FP...then brick walling to legal in the mastering rig (WaveLab) while rendering to 24-Bit at the same time...then, dithering (UV22HR) & rendering to 16-Bit ftom 24.

    [i had been doing this 'cause I assumed (& had heard) that A) the quantization error from 32 > 24 is miniscule & well below the audible range & B) it's a legal file after limiting anyway so I may as well render to 24...why waste bits.]

    I did one today whereby I kept the file size/format at 32-Bit FP during the brick wall phase...(so that it was also 32-Bit FP after limiting)...& then dithered all the way down to 16 from 32 as the final stage. It sounded audibly way better (in comparing both methods) to the old method (24 > 16).

    most notable was a more accurate reproduction of transients (snare, cymbal crashes, et al.) [i had used elephant 2 on clip for the limiting phase].

    guess I'll keep this new (new to me, that is) method...but I'm wondering what's goin on technically w/ it ?

    thanks,

    mark4man
    MoonMix Studios
    ADK Pro Audio Core 2 | Intel DP35DP MoBo/Chipset | Intel Q6600 Quad Core CPU | 4 GB SuperTalent DDR2-800 CL5 RAM | Seagate 160 GB SATA II Primary HD | Western Digital 320 GB SATA II Audio HD | Lynx Aurora8 ~ AES16 | Universal Audio UAD-1 | SONAR PE 7.0.2 | Cubase LE | WaveLab 5.0.1b | NI Komplete5
     
  2. Cucco

    Cucco Distinguished Member

    What in God's name is a legal file? Isn't that when it's 8.5"x14" versus 8.5"x11"?
     
  3. mark4man

    mark4man Active Member

    wow...

    great forum, eh ???

    really serious input, I see


    mf
     
  4. Cucco

    Cucco Distinguished Member

    Well, thanks for answering my question.
    Seriously - what in god's name do you mean by legal file?
    Perhaps if you wrote a coherent post, you'd get meaningful answers.
    You use the term "legal" a number of times in your post and it's a term that I've never encountered after 20 years in the business.
    Now, how about you answer my question and I'll try to decipher the rest of your post.
     
  5. Cucco

    Cucco Distinguished Member

    And yes, based on what I could discern from your first post, a single stage of dithering is always preferred to multiple stages of dither.

    When you record at 24 bit, you're mixing effects and effecting volume envelopes at a 32bit float level anyway (thanks to the 32 bit processing native to your OS, processor and DAW program.) Even if you "record" at 32 bit, you're actually recording at 24 bit and appending 8 '0's at the end of your word. This is due to the limitations of your AD converter. Most AD converters operate at 24 bit (many technically less. Exceptions would be DXD or 1 Bit (DSD or Delta Sigma) converters) and output a 24 bit word.

    When you mix in the DAW, those 8 slots are filled up by valid information. The DAW, if told to render the file to 24 bit, will dither the signal. Then, if you render again, you are adding another layer of dither. This is two separate noise prints laid on the same file at different amplitudes. If you're using the same noise shaping profile, it's likely you're hearing the effects of some bunching up of some noise in key frequencies.

    Short version of the story:
    Dither once.

    Now, seriously - what do you mean by "legal" and "legal file?"
     
  6. MadTiger3000

    MadTiger3000 Active Member

    Let's hope legal in this case means "compliant to the established standard."
     
  7. frnk

    frnk Active Member

    I thought dithering was only when you master in 24bit and then the medium your were transfering the master to was at a lower bit rate
     
  8. Cucco

    Cucco Distinguished Member

    Nope...
    Dithering is changing any bit depth to a lesser bit depth.
    It is the process of adding a base level of (often shaped) noise to a digital signal to mask the presence of digital noise from truncation of a bit length.
     
  9. Codemonkey

    Codemonkey Well-Known Member

    But yes - you need to dither when going from a 24bit master to a 16bit target (CD, etc.).
     
  10. Link555

    Link555 Well-Known Member

    Did he mean legal software? i.e.,that he bought the software he was using?
     
  11. mark4man

    mark4man Active Member

    [forgot to come back...sorry.]

    legal means the signal (of the finished product) is at or below the 0dB ceiling...i.e., not clipping.

    I heard the term once from an engineer at OasisCD...replication houses used to reject premasters that clipped.

    thanks for all the additional info,


    mf
     

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