Dirac's graphical user interface allows adding points to a target curve and manipulating their frequency and decibels position, but there is no way to select a group of points and move all of them together, like what typical function of software digital audio workstations.
This python script allows you to apply gain, attenuation, compression, expansion, and limiter
to all breakpoints within a frequency range you define. Then you can output the new *.targetcurve file, import it to Dirac
and continue tweaking the target curve by individual points using the GUI.
Note: My Dirac device is an NAD T778. Please enhance this script with a pull request to be useful for other systems.
$ python dirac.py "/source/of/file.targetcurve"
Choose Target curve Modification:
1. Gain
2. Attenuate
3. Compress
4. Expand
5. Limit
6. Graph
7. Write to new .targetcurve file
8. Quit
| Mode | Description |
|---|---|
| Gain | Add dB equally to all breakpoints within the desired bandwidth |
| Attenuate | Subtract dB equally to all breakpoints within the desired bandwidth |
| Compress | Multiply the breakpoint values by a factor < 1 to proportionally "shrink" (decrease) the dB. E.g. for 10% compression, a 4 dB point will become 3.6 dB and a 2 dB point will become 1.8 dB. |
| Expand | Multiply the breakpoint values by a factor > 1 to proportionally "stretch" (increase) the dB. E.g. for 10% expansion, a 4 dB point will become 4.4 dB and a 2 dB point will become 2.2 dB. |
| Limit | Breakpoints are not modified unless they are over a limit, in which case they are set to that limit. E.g. Limit = 0 dB: -1 dB -> -1 dB but 2 dB -> 0 dB |
The default bandwidth range is 0Hz - 20kHz but this can be changed by the user.
Low Frequency cutoff for transformation [0 Hz]:
High Frequency cutoff for transformation [20 kHz]:
Attenuate by __ dB [0]:5
Matplotlib is used to graph the new breakpoints. Close the graph window to continue the script.
Choose 7 to create a filename and write this transformation to the new file.
Import the new file into Dirac Live to continue building your filter.
Here is the structure of the TargetCurve module Usage
from TargetCurve import TargetCurve
# file is loaded and parsed to instance properties
target_curve = TargetCurve("path/to/your/file.targetcurve")
# print of properties
target_curve.description()
# transform curve
target_curve.transform_breakpoints(operation, dB_change, bandpass_low_freq, bandpass_high_freq)
# write new file
target_curve.write_transformed('target/filename.targetcurve')
| parameter | description |
|---|---|
| operation | Operation.Gain Operation.Attenuate Operation.Compress Operation.Expand Operation.Limit |
| dB_change | value to add in .Gain or subtract in .Attenuate modes (use positive values for both) Percent change in .Compress and .Expand modes. Upper limit in .Limit. |
| bandpass_low_freq | lowest frequency cutoff in Hz for transformation to have effect |
| bandpass_high_freq | highest frequency cutoff in Hz for transformation to have effect |