85
Decreasing bit depthTo maximize storage space, larger sound files (24- and
Note: The maximum
Screenblast Sound Forge is
1.Open a
2.From the Process menu, choose
3.From the Bit depth
4.If desired, choose an option from the Dither
5.If desired, choose a Noise shaping type. For more information, see Noise shaping on page 85.
6.Click OK.
Note: There are no rules regarding maintaining audio quality when decreasing bit depth. Experiment with the Dither and Noise shaping controls to determine the optimum settings for each audio file.
Understanding dither and noise shapingYou can adjust Dither and Noise shaping settings when decreasing a file’s bit depth.
Dither
The Dither value determines the randomness of the dither (generated noise) used to mask quantization distortion resulting from conversion to a lower bit depth. This
As is frequently the case when working with audio, you should experiment with dither values to yield the best results. However, keep the following information in mind:
•Rectangular eliminates distortion products caused by conversion to a lower bit depth, but the noise level is more likely to be dependent on the signal.
•Triangular eliminates the distortion products as well as any noise floor modulation, but results in a slightly higher noise level. The option typically works well in conjunction with noise shaping.
•Highpass Triangular behaves like triangular dither, but shifts its noise into higher frequencies. This is typically the best option when used in conjunction with noise shaping.
•Gaussian does not perform as well as Rectangular and Triangular dither, but may be suitable for certain audio.
Noise shaping
The Noise shaping value determines the aural positioning of quantization noise. Using this control, you can shift the noise into audio registers that are less perceptible to human hearing. This lowers the perceived noise floor and creates the illusion of cleaner audio.
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CHP. 6 | CHANGING FILE ATTRIBUTES AND FORMATS |