focus fidelity

Copyright © 2021, Focus Fidelity Focus Fidelity Filter Designer of 32

Focus Fidelity

Filter DesignerUser Manual


ContentsContents.............................................................................................................................................................................................................................2

Revisions ...........................................................................................................................................................................................................................2

Contact & Support .............................................................................................................................................................................................................3

System Requirements .......................................................................................................................................................................................................3

Introduction ........................................................................................................................................................................................................................4

User Interface Overview ....................................................................................................................................................................................................5Status Display .......................................................................................................................................................................................................5View Menu ............................................................................................................................................................................................................5Graphs ..................................................................................................................................................................................................................6

Measurements ...................................................................................................................................................................................................................7Hardware...............................................................................................................................................................................................................7Resources.............................................................................................................................................................................................................7

Filter Design Process.........................................................................................................................................................................................................8Measurements Import .................................................................................................................................................................................................8Zero Positions ...........................................................................................................................................................................................................10

Automatic Adjustment ......................................................................................................................................................................................... 11Manual Adjustment .............................................................................................................................................................................................12

Microphone Calibration .............................................................................................................................................................................................14Correction Bandwidth ................................................................................................................................................................................................15Target Magnitude.......................................................................................................................................................................................................16Editing The Target Magnitude ...................................................................................................................................................................................17

Target Level ........................................................................................................................................................................................................17Target Slope........................................................................................................................................................................................................17Low and High Frequency Roll Off Functions ......................................................................................................................................................18Mid Frequency Roll Off Function ........................................................................................................................................................................19Combining Functions ..........................................................................................................................................................................................20Control Points .....................................................................................................................................................................................................21

Target Import and Export...........................................................................................................................................................................................22New Target ................................................................................................................................................................................................................22Filter Magnitude.........................................................................................................................................................................................................23

View Filter ........................................................................................................................................................................................................................24Filter Length...............................................................................................................................................................................................................24Overall Filter Gain .....................................................................................................................................................................................................25

Viewing Results ...............................................................................................................................................................................................................26Polarity Selection.......................................................................................................................................................................................................26

Filter Export......................................................................................................................................................................................................................28

Audio Playback ................................................................................................................................................................................................................29Accurate Sound HLC.................................................................................................................................................................................................29Roon ..........................................................................................................................................................................................................................30JRiver Media Center..................................................................................................................................................................................................31

License Information .........................................................................................................................................................................................................32End User License Agreement ...................................................................................................................................................................................32Licensed Components...............................................................................................................................................................................................32About Dialogue..........................................................................................................................................................................................................32

RevisionsRevision Date Description1.0 12/7/2020 Initial Issue1.1 17/1/2021 Updates for V1.1.10 software1.2 17/3/2021 Updates for V1.1.12 software1.3 05/5/2021 Updates for V1.2.0 software1.4 09/5/2021 Updates for V1.2.2 software1.5 09/6/2021 Updates for V1.4.0 software1.6 17/6/2021 Added HLC Section1.7 23/8/2021 Added note on REW in Microphone Calibration section.


Contact & SupportFor technical support and other enquiries please use the contact form on our website or the e-mail address below.

e-mail: [email protected]

web: www.focusfidelity.com

System RequirementsOperating System: Microsoft Windows 10

Memory: 8GB, 16GB dual-channel recommended

CPU: Quad core x64

Disk Space: 100MB

mailto:[email protected]

http://www.focusfidelity.com


IntroductionFocus Fidelity Filter Designer analyses impulse response measurements taken at multiple positions in the listening area to build a time domain ac-curate mathematical model of the loudspeaker-input-to-listening-area "response" or transfer function. The model enables identification of resonantmodes, phase distortions and reverberant field tonal balance as well as factors that should not be corrected for. The analysis of the model combinedwith the user specified target magnitude frequency response are inputs to the filter design process.

Audio playback through the filter combines with the now known (through measurements) loudspeaker and room characteristics to produce a total re-sult that is substantially closer to the frequency and time domain targets set by the user. The filter is particularly effective at,

reducing the decay time of resonances caused by standing waves (room modes)

reversing loudspeaker phase and impulse distortions

controlling tonal balance

The software does not attempt aggressive correction that would,

be highly position dependent

produce filters with significant "ringing" especially pre-ringing.

drive existing minimum phase behaviour towards linear/zero phase, the target phase behaviour is minimum phase therefore inversion (correc-tion) of some existing maximum (excess) phase behaviour will be included.

The design process follows a "wizard" style left to right type workflow beginning with importing measurements and ending with viewing predicted re-sults at each measurement position and exporting the filters.

This user manual is detailed guide of this process. Setup and use of the filters in Roon and JRiver Media Center are also described.

This manual assumes the reader is well versed in the process is taking impulse response measurements.


User Interface OverviewThe user interface follows a wizard type work flow with Import Measurements on the left being the first stage.

Each of the following buttons, Correction Bandwidth, Target Magnitude, Filter Magnitude, View Filter, View Results and Export Filter allow you tojump between stages but typically you would select the next button on the right.

This user manual will take you through each stage of the process.

Status DisplayWhen you select the next stage in the design process there will be some processing that takes place. The state of the processing is shown at thebottom left of the window.

View MenuThe view menu allows preferences to be set.

The frequency axes on all graphs maybe displayed as logarithmic or linear, this is almost always set to logarithmic.

The time range covered by graphs displaying time domain information can be set by selecting Set Time Axes Range from the View menu. This willopen this dialogue,

Use the drop down menu to set your desired range, 15 ms or 25 ms covers a useful range at the start of the impulse or step response. The FullRange option will make the time axes on all graphs show all available data.


GraphsThe user interface employs graphs to display time and frequency data. Some of the features of and basic interaction with these graph displays aredescribed here.

The graph area for each graph is the box defined by the X and Y axes.

Holding down the left mouse button in the graph area will bring up a legend with names and values of each of the traces on the graph. Dragging themouse with the left button held down will update the values to correspond to the cursor position.

Zooming in on an area of the graph is accomplished by holding down the right mouse button and then dragging a rectangle over the desired area,releasing the right mouse button will zoom in on the area.

Zooming out is accomplished by double clicking the right mouse button.


MeasurementsThe Focus Fidelity Filter Design software requires multiple impulse response measurements of the left and right channels taken around the listeningarea. Typically 6 to 10 measurements of each channel. One of the measurements for each channel must be at a central location which is the pri-mary listening position. The remaining measurements should be around this central position covering the intended listening area.

Focus Filter Designer will import impulse response measurements stored as *.wav files.

The files should have a sample rate of 44100S/s, 48000S/s, 88200S/s or 96000S/s and be 1 to 3 seconds in length.

Please note that importing measurements taken at 88200S/s or 96000S/s will significantly increase the computation time to generate the filters,48000S/s is the recommended sample rate.

Focus Fidelity does not provide software for performing these measurements, this will be a future addition. Existing third party software is availableto do this such as,

http://www.artalabs.hr/

http://www.holmacoustics.com/holmimpulse.php

https://www.roomeqwizard.com/

This manual assumes the reader is well versed in the process of taking impulse response measurements.

Instructions for performing measurements with REW can be found here https://www.focusfidelity.com/REWInstructions.pdf

HardwareExamples of suitable measurement hardware,

https://www.daytonaudio.com/product/1116/umm-6-usb-measurement-microphone

https://www.daytonaudio.com/product/911/emm-6-electret-measurement-microphone

https://www.minidsp.com/products/acoustic-measurement/umik-1


https://earthworksaudio.com/measurement-microphones/m23/

https://cross-spectrum.com/measurement/calibrated_umik.html

https://www.cross-spectrum.com/measurement/calibrated_dayton.html

https://rolls.com/product/MP13

https://europe.beyerdynamic.com/mm-1.html

Resourceshttps://www.minidsp.com/applications/acoustic-measurements/umik-1-setup-with-rew

http://www.artalabs.hr/

http://www.holmacoustics.com/holmimpulse.php

https://www.roomeqwizard.com/

https://www.focusfidelity.com/REWInstructions.pdf

https://www.daytonaudio.com/product/1116/umm-6-usb-measurement-microphone

https://www.daytonaudio.com/product/911/emm-6-electret-measurement-microphone



https://earthworksaudio.com/measurement-microphones/m23/

https://cross-spectrum.com/measurement/calibrated_umik.html

https://www.cross-spectrum.com/measurement/calibrated_dayton.html

https://rolls.com/product/MP13

https://europe.beyerdynamic.com/mm-1.html

https://www.minidsp.com/applications/acoustic-measurements/umik-1-setup-with-rew


Filter Design ProcessTo start a new project select New from the File menu. Enter a name for the project in the dialogue and click OK.

A project maybe saved at any stage in the design process by selecting Save Project from the File menu.

To open an existing project select Open Project from the File menu.

Measurements ImportWith a new project created the Import Left Speaker Measurements and Import Right Speaker Measurement buttons will be displayed on the ImportMeasurements page.

Click the Import Left Speaker Measurements button. The following dialogue will open,

Click the Import Measurements button at the top left.

In the Open file dialogue select all of the left channel measurements you wish to import.

The measurements must all be of the same length and sample rate.

Click Open/OK in the open file dialogue.


The imported measurements will be displayed as step responses,

In each group (Left and Right) of measurements there must be one measurement that was taken at the central/primary listening position.

Using the drop down menu labelled “Center Position Measurement” select the measurement which was taken at the central listening position.


Zero PositionsEach impulse response has a time delay before any sound arrives at the measurement microphone. This is due to the distance between the loud-speaker and measurement microphone.

The imported measurements will show different delays for each position due to differing distances.

The purpose of this stage is to align the measurements close to a time of zero effectively removing most of the delay.

This aligns the impulses with the software’s internal processing and “windowing”. Note that the alignment done here does not determine final accu-racy of this processing.

The imported measurements are displayed as step responses and will look something like this (zooming in on the start of the step in the top graph),

The adjustment is done in the bottom graph of the import measurements dialogue.

The check boxes on the right hand side of the bottom graph toggle the display, show or hide of each of the measurements.

Clicking the Select Single button ensures only one measurement is shown at a time. After clicking Select Single the button function will switch to Se-lect Multiple to allow switching back to viewing multiple measurements at once.

The Set Time Axis Range button allows adjustment of the time range displayed on the bottom graph, you can also zoom in as required.


Automatic AdjustmentClick the Auto Set Zero Positions button.

This will automatically align the measurements with the time delay reduced to a target of 1 millisecond.

This process searches for the start of each step response and assumes the measurement does not contain significant noise or distortion prior to themain impulse from the loudspeaker.

Zooming in around time of zero in the bottom graph should show,

The Reset Zero Positions button will revert the measurements back to original imported state.


Manual AdjustmentAlthough not normally required the time alignment maybe adjusted manually.

Hovering the mouse over one of the traces will show a vertical line with left / right arrows along with a legend box displaying the name of the selec-ted trace. The trace closest to the mouse pointer will be selected.

Press and hold the left mouse button to move the trace left or right, release the mouse button when the trace is in the position you require. Note thatit is only possible to move left from the initial imported position.

Set the start of the step somewhere between 0 and 1 millisecond. They do not need to be all perfectly aligned with each other so long as the start ofeach one is between 0 and 1 millisecond.

It is easier to do this when displaying only one trace at a time. Click the select single button on the right hand side to view one trace at a time.

It will be necessary to zoom in as shown above.

Click OK to close the dialogue.

Click the “Import Right Speaker” button and repeat the process.


Your display should now show a list of the imported measurements,

The first row (Central Position) of the table will be the measurements previously selected as the ones taken at the central listening position.


Microphone CalibrationIf the loaded measurements do not already include compensation for the measurement microphone then the microphone calibration can be loadednow. If you do not have calibration data for your microphone this step can be skipped.

If you have performed the measurements with Room Eq Wizard (REW) and loaded the microphone calibration in REW then you still need to loadthe microphone calibration in the filter designer. This is because REW does not include the calibration in the exported impulse response.

Select Microphone Calibration from the tools menu. This will open the microphone calibration dialogue box.

Click Import File and select your calibration file. The software supports the most common formats and will import the magnitude frequency responsedata above 10Hz. Importing a 1/3 octave smoothed response is sufficient, higher resolution is not required.

The green dots are the imported points,

The software requires the microphone response be extended to 0Hz and up to half the sampling rate (the sampling rate being set by the previouslyimported measurements). The response below 10Hz is set as a flat line with constant gain over frequency rather than as a high-pass slope. This isto prevent the compensation for the microphone response from producing excessive gain at very low frequencies.

The low frequency gain and gain at half the sample rate can be adjusted with the blue dots located at 10Hz and half the sample rate. These can bemoved vertically.

Zoom in on the appropriate area of the graph and adjust the gain so it smoothly transitions to the imported points,

In the example above the sample rate is 44100 S/s, the blue dot at half the sample rate is therefore located at 22050Hz. One of the imported micro-phone points is above this frequency and has to be ignored in this case.

Click OK to close the dialogue box.


Correction BandwidthClick the Correction Bandwidth button to move to the next stage.

The high frequency content of the impulse response which parts of the filter generation algorithm include decreases with time. This prevents the re-sulting filters from being overly position dependent as would otherwise be the case due to the short wavelengths at high frequencies and variabilityof reflection timing relative to the direct sound.

The correction bandwidth is set at this stage of the design process, the graph shows how correction bandwidth decreases with time. The measuredimpulses are shown on the graph so that the bandwidth can be viewed relative to the impulse response measurements.

The rate at which the bandwidth decreases is determined by the “Bandwidth Multiplier Direct Sound” setting at the top left. A smaller multiplier givesa faster decrease in bandwidth. This will be shown by shape of the purple trace shown above which will change when the multiplier is changed.

The vertical marker line with left and right arrows determines the time at which the bandwidth begins decreasing. This should be set to after the di-rect sound.

The horizontal market line with up and down arrows determines the bandwidth which the filter generation process always includes.

Hovering the mouse cursor over the marker line will highlight the line and show a legend box with the line’s current position. Pressing and holdingthe left mouse button with the line highlighted allows the line to be dragged, release the mouse button when the line is in the desired location.

It is recommended to initially leave these settings at the defaults shown.

The settings on this page can be set back to the default values with the “Set To Defaults” button at the top right.


Target MagnitudeClick the Target Magnitude button to move to the next stage of the design process.

Moving to the Target Magnitude stage will start the “Calculating Model...” process with this state shown at the bottom left of the window. This maytake a couple of minutes depending on how many measurements you have loaded and the speed of your PC.

Once the calculation is complete magnitude vs frequency responses will be shown for the left and right channels.

A Target Curve with slope and level best fitted through the left and right channel responses will also be shown.

The best fitted target is intended to be an initial starting point which retains the current tonal balance of your system and room.

The correct target curve is the one that sounds right to you and several iterations over a few listening sessions maybe required to arrive at yourideal target.


Editing The Target MagnitudeThe target magnitude editor includes several features for editing the shape of the target magnitude.

The overall level, overall slope, high pass slope, low pass slope and mid range slope are all adjustable. In addition there are control points on thetarget curve for finer adjustment if required.

While the editor provides an extensive set of features it is generally best to keep the target magnitude shape relatively simple.

Target LevelThe overall level of the target is initially set as a best fit, this may then be adjusted by hovering the mouse over the target curve between the controlpoints. Up and down arrows will appear. Drag the target vertically by clicking and holding the left mouse button.

Target SlopeThe overall target slope is adjustable by changing the number (dB / Octave) in the Target Slope box at the top left of the window. The initial value isthe best fit to measurement data.


Low and High Frequency Roll Off FunctionsLow and high frequency roll off functions can be set if required, the low frequency roll off is a high pass filter and the high frequency roll off is a lowpass filter.

The slopes are adjustable by changing the number in the Low Frequency Roll Off Slope and High Frequency Roll Off Slope boxes. For illustrativepurposes the image below shows high and low pass slopes set to 24 and 60 dB / Octave respectively.

The corner frequencies of these functions are adjusted using the vertical marker lines shown with left and right arrows either side of the line. Hover-ing the mouse cursor over the line will highlight the line and show a legend box with the line’s current position displayed in Hz. Pressing and holdingthe left mouse button allows the line to be dragged horizontally, release the mouse button when the line is in the desired location.

In the image below the Low Frequency Roll Off function has been positioned at 25Hz.


Mid Frequency Roll Off FunctionAn additional low pass function is available to aid in shaping the target curve. The corner frequency is adjustable with the middle vertical markerline.

In the example below the corner frequency has been set to 200Hz and the slope 1.5dB / Octave.

The overall Target Slope has been set to 0 and the overall target level has been manually adjusted by moving the whole target vertically as pre-viously described.


Combining FunctionsThe image below shows how the various functions can be combined.

The overall Target Slope is set to 1.5 dB / Octave.

The Low Frequency Roll Off set at a corner frequency of 100Hz and is also set with a slope of 1.5 dB / Octave. This cancels the overall Target Slopebelow 100Hz creating a flat target.

Similarly the Mid Frequency Roll Off Slope is set at negative 1.5 dB / Decade and cancels the overall Target Slope above its corner frequency of1500Hz resulting in a flat target.


Control PointsThe control points on the target curve allow finer editing of the target. Hovering over the control point will show left / right and up / down arrowsalong with a legend showing the point’s frequency and level.

Moving a control point is accomplished by pressing and holding the left mouse button while hovering over the point. Drag the point to the desired lo-cation and release the mouse button.


In the example below 5 control points have been moved to create a dip.

The points can be set back to their original positions by clicking the Reset Points button at the top right.

Target Import and ExportTarget curves maybe exported and saved. The saved file can then be imported into other projects if required.

The Import Target and Export Target buttons will show file open and save dialogues respectively.

New TargetClicking the New Target button will reset all your changes and set the target to a level and slope best fitted through the measurement data.


Filter MagnitudeClick the Filter Magnitude button to move to the next stage of the design process.

Moving to the Filter Magnitude stage will start the “Evaluation Model...” process with this state shown at the bottom left of the window. This may takea few tens of seconds.

Once the processing is complete the target magnitude response for the left and right channel filters will be shown.

The filter’s frequency range, maximum gain, maximum attenuation, low frequency gain and high frequency gain are adjustable in this stage.

It’s important to note that excessive filter gain may over drive loudspeakers.

The top horizontal marker line allows adjustment of maximum filter gain, the lower horizontal marker adjusts maximum attenuation.

The left vertical marker line sets the low frequency limit of the filter, this is the frequency at which the filter starts transitioning to a constant gain, simi-larly the right vertical marker line adjusts the the filter’s high frequency limit.

Set the low frequency limit to a frequency that corresponds to the capabilities of your loudspeakers.

The high frequency limit can typically be left at 20 kHz.

The filter gain at low frequencies (below the low frequency limit) is adjustable with the moveable point control located at 10Hz in the graph.

Similarly the filter high frequency gain is adjustable with the moveable pointed located at half the measurement sample rate.

Typically these points are set to 0dB.

The Set To Defaults button at the top right sets all the settings on this page back to default values.


View FilterClick the View Filter button. This will start the final stage of the filter calculation process. Once complete the filter time and frequency domain proper-ties can viewed.

Filter LengthThe length of the generated filter is selectable by selecting one of the 5 check boxes. Two times are shown for each check box, the first number(e.g. 0.743 seconds) is for filters with a sample rate that is a multiple of 44100 Hz and the second time for multiples of 48000 Hz.

Longer filters provide greater frequency resolution but require more processing to apply to the audio signal. Typically processing is not an issue onmodern PCs. The default selection shown of 0.743 / 0.683 Seconds should be suitable for most applications.


Overall Filter GainIt is important to note that to prevent digital clipping a digital filter can only attenuate the audio signal. The gain of the filters is therefore scaled ap-propriately.

The frequency domain view of the filter shows the gain never exceeds -1.0dB at any frequency.


Viewing ResultsTo view predicted results click the View Results button.

The predicted “corrected” response at each measurement position can be viewed. The predicted response is arrived at by applying the filter to eachof the original measurements.

The check boxes on the right hand side of the screen select which positions are currently displayed.

Polarity SelectionThe software will select the filter polarity so that the step response is positive.

The Left Channel Polarity Flip and Right Channel Polarity Flip check boxes shown above the impulse and step responses allow for this to be inver-ted.


In the Magnitude view the average for all measurement positions can be displayed. The target is also displayed for reference.

Smoothing options are available, these only affect the displayed data, they do not change the generated filters.


Filter ExportClick the Filter Export button. The following dialogue will open,

The defaults shown above will be suitable for the most common audio and media playback software with a filtering (convolution) feature. The filterswill be exported as *.wav files with left and right channels in a single 2 channel *.wav file. If you require the left and right channels in separate fileschange the Right Channel File Index to zero, leave the Left Channel File Index also set to zero. The files will have LEFT and RIGHT automaticallyincluded in the file names.

Click OK.

A file save dialogue will open with file name set to the project name,

Click save in your desired location. If you will be using JRiver Media Center the location should be the same location you will point JRiver to, youshould not need to move the files. Using JRiver with the exported files is described later in this manual.

The software will export eight *.wav and *.cfg files for each sample rate automatically adding the sample rate to the file names,

This completes the filter design and generation process.

Using the exported *.wav files with audio playback applications is detailed later in this manual.


Audio PlaybackAudio and Media player software with a FIR filtering (convolution) feature is required to apply the filters to the audio signal.

Setup with Accurate Sound HL Convolver, Roon and JRiver Media Center is described here.

Accurate Sound HLChttps://accuratesound.ca/products.html

The Accurate Sound Hang Loose Convolver operates as a VST plug-in or as a stand-alone application. It enables seamless switching between upto six filters along with a bypass mode and all with level matching. You can easily compare filters to filters to bypass mode.

When run stand-alone HLC can be used with VB-AUDIO Software’s Virtual Audio Cables ( https://vb-audio.com/Cable/ ) which allow the audio out-put of one application or system wide audio to be routed HLC’s audio input. You can therefore apply Focus Fidelity filters to any audio stream.

This section of this manual is not intended to be a complete guide to HLC, the full operations guide for HLC is here

https://accuratesound.blob.core.windows.net/hlconvolver/Hang_Loose_Convolver_Operations_Guide.pdf

To use HLC with the Focus Fidelity filters zip all the previously exported filter *.wav files into one zip file. Do not include the *.cfg files in the zip file.

To load the filters into one of the six filter bank slots click the magnifying glass icon in that slot.

Select the zip in the dialogue that appears and click open. The slot in HLC will show the name of the filter, the current sample rate and filter length.

Selecting Audio/MIDI Settings from the options menu (top left of the HLC window)will open the audio IO setup.

The example to the left shows the output of VB-AUDIO’s Virtual Cable set as theinput to HLC, Windows Audio Exclusive Mode is used to provide bit perfect con-nections between HLC and the audio devices.

https://accuratesound.ca/products.html

https://vb-audio.com/Cable/

https://accuratesound.blob.core.windows.net/hlconvolver/Hang_Loose_Convolver_Operations_Guide.pdf


Roonhttps://roonlabs.com/

To use Roon with the Focus Fidelity filters zip all the previously exported filter *.wav files into one zip file. Do not include the *.cfg files in the zip file.

Open Roon and select the audio zone you wish to use the filters in.

Click the loudspeaker icon in the lower right hand corner then click the DSP icon which appears.

Select and enable the convolution filter.

Click Browse and select the zip file.

Your zip file should show as the Currently Selected Filter.

During audio playback the signal path view in Roon should include the Convolution Filter as shown below,

https://roonlabs.com/


JRiver Media CenterTo enable filtering in JRiver Media Center select DSP Studio from the Player menu which will open the dialogue shown below.

Enable Convolution by ticking the box next to Convolution on the left.

Browse to the YourFilterName2.0_441.cfg file which was previously exported.

The *.cfg files follow the naming convention required by JRiver, JRiver should search the same location and use the file which matches the currentsource material sample rate.

Ensure the Normalize filter volume and Automatically switch filter based on input format are selected.

Playing audio in JRiver should result in the Status of the convolution filter being updated as shown above. In the example above the 2.0_192.cfghas been selected by JRiver.

The *.cfg files contain absolute paths to the *.wav filter files i.e. C:/Filter Export/Living Room Filter 192000.wav. These were generated when the fileswere exported from the filter design software using the location the files were exported to. The cfg files would need to be manually edited if the loca-tion of the *.wav files is changed.

More details on convolution setup with JRiver Media Center is described here https://wiki.jriver.com/index.php/Convolution

https://wiki.jriver.com/index.php/Convolution


License Information

End User License AgreementA copy of the End User License Agreement is provided with the software and is located here

License_Docs\EULA.rtf

which is located in the software installation directory typically,

C:\Program Files\Focus Fidelity\Focus Filter Designer\License_Docs\EULA.rtf

Licensed ComponentsFocus Fidelity software uses the Qt ( https://www.qt.io/ ) cross platform user interface and application framework, it is licensed under the GNU Les-ser General Public License (LGPL) v3 license ( https://doc.qt.io/qt-5/lgpl.html ).

Copies of relevant licenses for Qt and other components are distributed with this software, these are stored in the

License_Docs\Licensed_Components\

directory which is located in the software installation directory typically,

C:\Program Files\Focus Fidelity\Focus Filter Designer\License_Docs\Licensed_Components\

About DialogueThe about dialogue can be viewed by selecting About from the Tools menu. This provides software version information and a list of licensed compo-nents.

https://www.qt.io/

https://doc.qt.io/qt-5/lgpl.html

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