Topic: Dither in Sound Forge 8

[cd2go]

Hello,

New to 24-bit and using SF 8 for the time being. Can anyone tell me what settings I should use in the bit-depth converter box for 'Dither' (None, Half Rectangular, Rectangular, Triangular, Highpass Triangular, or Gaussian) and 'Noise-Shaping' (Off, Equal loudness contour, High-pass contour)? Thanks.

--james

[Brian Skalinder]

Does the Help file offer any useful information?

From Adobe Audition's manual:

p.d.f.

(probability distribution function) Controls how the dithered noise is distributed away from the original audio sample value.

Usually, Triangular p.d.f. is a wise choice because it gives the best tradeoff among SNR (Signal-to-Noise ratio), distortion, and noise modulation. Triangular p.d.f. chooses random numbers that are generally closer to 0 than to the edges -1 or +1 (that is, the chance of 0 being chosen is twice as great as the chance of 0.5 or -0.5).

Noise Shaping

Determines the placement when you move noise to different frequencies. The same amount of overall noise is present, but you can place less noise at one frequency at the expense of placing more noise at another. You may also specify that no noise shaping is used.

Different curves result in different types of background noise. The type of curve to use depends on the source audio, final sample rate, and bit depth. By introducing noise shaping, you may be able to get away with a lower dither depths to reduce the overall background noise level, without introducing a lot of unwanted harmonic noise.

FWIW, as with most things taping and recording, I've found it's best to use one's own ears.  At any rate, when I'm not using MegaBitMax or some other, fancier dither, I typically use AA or Audacity's triangular dither with no noise shaping (I didn't especially care for any of the stock noise shaping options in AA, so give the ones in SF a listen to see if you prefer one over the other).