Bit-Depth Converter controls
The following controls are located in the Bit-Depth Converter dialog.
Control
Description
Bit depth
Choose a setting to specify the number of bits that should be used to store each sample.
Dither
This control allows you to specify the randomness of the dither (generated noise) used to mask quantization
distortion resulting from conversion to a lower bit depth. You can select from several shapes, each roughly
describing the pattern that would be produced if you plotted a graph with the dither amplitude on the X-axis
and the probability of the dither values on the Y-axis.
As is frequently the case when working with audio, experimentation with dither values yields the best results;
however, keep the following information in mind:
•
Half Rectangular
Eliminates distortion resulting from conversion to a lower bit depth, but the noise level is
more likely to be dependent on the signal. This setting uses a maximum dither noise amplitude of 0.5 LSB
(least significant bit).
•
Rectangular
Identical to
Half Rectangular
, but with a maximum dither noise amplitude of 1 LSB (least
significant bit).
•
Triangular
Eliminates 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
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.
High-pass contour
noise shaping attempts to push all quantization noise and error into high frequencies.
Equal loudness contour
noise shaping attempts to push the noise under an equal loudness-type of curve.
More
Click this button to view additional options that you can use to adjust your data window selection.
Adjusting the data window selection
Noise shaping dangers
Noise shaping places quantization noise near the audio’s Nyquist frequency, a value equal to one-half of the file’s sample rate. Consider
the following information:
•
A file with a sample rate of 44.1 kHz has a Nyquist frequency of 22.05 kHz (at the high end of human hearing). Applying noise
shaping to this file results in audio perceived to be cleaner than it actually is.
•
A file with a sample rate of 22 kHz has a Nyquist frequency of 11 kHz (well within the sensitive range of human hearing). Applying
noise shaping to this file results in audio that is perceived to be noisier than it actually is. Ironically, this defeats the entire purpose
of the
Noise shape
control.
For this reason, we do not recommend using noise shaping on files with sample rates less than 44.1 kHz.
PROCESSING AUDIO
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Summary of Contents for Pro 10
Page 1: ...Pro 10 Sound Forge User Manual ...
Page 2: ......
Page 26: ...20 CHAPTER 1 ...
Page 60: ...54 CHAPTER 2 ...
Page 152: ...146 CHAPTER 8 ...
Page 166: ...160 CHAPTER 9 ...
Page 176: ...170 CHAPTER 10 ...
Page 200: ...194 CHAPTER 11 ...
Page 220: ...214 CHAPTER 12 ...
Page 236: ...230 CHAPTER 13 ...
Page 266: ...260 CHAPTER 16 ...
Page 278: ...272 CHAPTER 17 ...
Page 312: ...306 CHAPTER 20 ...
Page 346: ...340 APPENDIX C ...
Page 366: ...360 APPENDIX E ...