At 5:46 PM +0100 4/3/07, Chris Owens wrote:
>Taking Lou's point of "Proper dither is required to reduce the 24 bit file=
s
>to 16 bit for burning or compression."
>
>What settings are suggested for dithering 24 bits to 16 bits? Adobe Auditi=
on
>provides a number of different parameters that can be set.
>
>Can anyone suggest optimum settings in Audition for such a process?
>
>Chris.
Hi Chris--
Dithering: This are the "simplifications" I follow, rightly or
wrongly. Others, please feel free to correct or amend:
A. Dithering "smooths-out" the noise in a recording that can be there
from quantizing. "Quantizing noise" arises mostly in parts of sound
files that are thin (have low volume) whether from low recording
levels in the field or from the "soft" parts of fade-ins and fade
outs-- in mixes. Loud parts are not nearly as prone to audible,
negative effects of quantizing noise.
B. Make sure skinny field recordings get fat. (This applies to files
that are to be compressed as well). Mark and store the precious
original generation, but expand 16 bit recordings to 24 bits* and add
obviously needed EQ and gain in the same step. If your sound app has
reliable metering, don't be afraid to use all 24 bits to a level no
greater than -.3dB. This step keeps your files from gaining
additional quantizing noise while increasing the efficiency of
additional digital processing down the road. No compression. I save
the application/plug-in settings I use for material I'm likely to
return to.
*I _do_ leave the original 16 bit files in the mix timeline when I'm
sub-mastering/mixing to 24 bits all in one fell swoop. I feel EQ can
address some qualities of the quantizing noise in low level originals
at this stage.
C. Don't dither unless its the final step-- that is-- the step right
before the file that will be heard is being made (or the generation
that will be bit for bit "copied" to be heard). This is the least
detrimental generation to "smooth out" quantizing noise. If one is
hearing quantizing noise before this stage, consider step B, above.
The most common situation/concern/application of dithering is with
low (final mix) levels at the head and tail of long fades or very
quiet passages. Different dither settings work better with different
material. I isolate just these quiet parts of my fades and use all
the dither settings in my mix app and output this to play on my home
system for playback with the volume cranked.
D. When the 24 bit sound files in my mix timeline are "fat," I can
hear no difference between making a truncated 16 bit mix-down file to
the proper playback level and adding dither as I mix to 16 bits. "No
difference" I suspect because the bits where the noise would be,
aren't included in the 16 produced. The exception, again, is with
mixes that have long fades or very quiet passages.
Dithering is less a part of "recording basics," than mixing, but step
B can help reduce quantizing noise for files that are to be further
handled or compressed as with mp3 more efficient. Rob D.
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