REW Beta Release REW API beta releases

thothsong · Jul 23, 2026

I have what I hope is a small FSAF feature request. When using FSAF with a File source, it appears that the dither REW adds in varies across instantiations of REW. That is, if I use the Generator to generate and save an FSAF file from a File source, exit and restart REW, and then generate and save again, the two files are rather different. Would it be possible to have an option to make the dither consistent?

I'm trying to make offline FSAF measurement work, by using a virtual cable audio device to feed measurement files back in to REW's Measure, and it appears I can make it work if I do things in a single REW session, but it fails miserably if I use the Generator to create an FSAF file in one session, make offline measurements, and then try to use those measurements in a different REW session.

John Mulcahy · Jul 23, 2026

thothsong said:
When using FSAF with a File source, it appears that the dither REW adds in varies across instantiations of REW.

I'll make a change in the next build so that the added TPDF dither always uses the same sequence.

thothsong · Jul 23, 2026

John Mulcahy said:
I'll make a change in the next build so that the added TPDF dither always uses the same sequence.

Thank you!

John Mulcahy · Jul 26, 2026

Builds updated today (beta 131) with these changes:

Changed: Updated Windows and Linux bundled runtime to Java 17, linux without JRE requires Java 17
Changed: As a partial workaround for a bug in the macOS Java runtime blank input or output names show "No name" and an index
Changed: When FSAF file processing adds triangular noise it generates the same sequence for every file
Changed: There are new entries in the applications, audio, graphs, infopanel, measure, measurements, roomsim, rta, scope, siggen, soundcardprefs and viewprefs properties files
Fixed: When saving new measurements on exit if the filename existed choosing not to overwrite would exit without saving
Fixed: The Overlay offset t=0 dialog did not update when its measurement was deselected

TWO_ND · Wednesday at 8:14 AM

REW V5.40 Beta 131 running Eclipse Adoptium JRE 17.0.17 64-bit on Windows 11 Language en, country US, keyboard US, windows-1252 Screen 1536 x 864 at 240 DPI Running in C:\Program Files\REW
Message:
java.lang.NullPointerException: Cannot invoke "java.util.ArrayList.get(int)" because "this.p" is null
Stack Trace:
Cannot invoke "java.util.ArrayList.get(int)" because "this.p" is null
roomeqwizard.H.A(y:1622)
roomeqwizard.H.B(y:630)
roomeqwizard.H.A(y:3367)
roomeqwizard.H.A(y:280)
roomeqwizard.H.A(y:1881)
roomeqwizard.H.run(y:1200)

Glitch i encountered with the new Beta version...

John Mulcahy · Wednesday at 9:32 AM

TWO_ND said:
Glitch i encountered with the new Beta version...

Thanks, fixed for the next build. Occurs when trying to generate a warning that the timing reference level is low.

HD MOVIE SOURCE · Thursday at 12:09 PM

John Mulcahy said:
Not a bug. If you want REW to retain your manual filters uncheck the "Auto EQ" box for those filters.

Will try, thank you.

navid0308 · Thursday at 9:59 PM

Not sure if the root cause is the same as the other null ptr exception provided above, but running into this quite frequently with beta 131.

REW V5.40 Beta 131 running Eclipse Adoptium JRE 17.0.17 64-bit on Windows 11 Language en, country US, keyboard US, windows-1252 Screen 1463 x 823 at 168 DPI Running in C:\Users\navid\AppData\Local\Programs\REW

Message:
java.lang.ArrayIndexOutOfBoundsException: Index 4 out of bounds for length 4
Stack Trace:
Index 4 out of bounds for length 4
roomeqwizard.graphgroup.b.A(y:1092)
roomeqwizard.graphgroup.b.ɑ(y:3254)
roomeqwizard.graphgroup.b.ȅ(y:1733)
roomeqwizard.graphgroup.b.A(y:1368)
roomeqwizard.graphgroup.b.valueChanged(y:2107)
roomeqwizard.graphgroup.n.valueChanged(y:1504)
ca.odell.glazedlists.swing.DefaultEventSelectionModel.fireSelectionChanged(Unknown Source)
ca.odell.glazedlists.swing.DefaultEventSelectionModel$SwingSelectionListener.selectionChanged(Unknown Source)
ca.odell.glazedlists.ListSelection.fireSelectionChanged(Unknown Source)
ca.odell.glazedlists.ListSelection.listChanged(Unknown Source)
ca.odell.glazedlists.event.ListEventAssembler$ListEventFormat.fire(Unknown Source)
ca.odell.glazedlists.event.ListEventAssembler$ListEventFormat.fire(Unknown Source)
ca.odell.glazedlists.event.SequenceDependenciesEventPublisher$SubjectAndListener.firePendingEvent(Unknown Source)
ca.odell.glazedlists.event.SequenceDependenciesEventPublisher.fireEvent(Unknown Source)
ca.odell.glazedlists.event.ListEventAssembler.commitEvent(Unknown Source)
ca.odell.glazedlists.BasicEventList.remove(Unknown Source)
roomeqwizard.measurements.B.H(y:3388)
roomeqwizard.measurements.B.A(y:856)
roomeqwizard.measurements.B$_B$1.actionPerformed(y:1513)
java.desktop/javax.swing.Timer.fireActionPerformed(Timer.java:311)
java.desktop/javax.swing.Timer$DoPostEvent.run(Timer.java:243)
java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:318)
java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:773)
java.desktop/java.awt.EventQueue$4.run(EventQueue.java:720)
java.desktop/java.awt.EventQueue$4.run(EventQueue.java:714)
java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:742)
java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

John Mulcahy · Friday at 5:05 AM

navid0308 said:
running into this quite frequently with beta 131.

Unintended side effect of trying to keep the offset t=0 dialog updated, fixed for the next build.

John Mulcahy · Saturday at 7:29 AM

Builds updated today (beta 132) with these changes:

Added: ETON Audio equaliser entries
Added: MiniDSP Tide-16 equaliser entry
Changed: The full paths to mic and soundcard cal files are no longer saved in the mdat file to address any related privacy concerns
Fixed: NPE when generating a warning about the timing reference level
Fixed: Index out of bounds could occur after removing a measurement
Fixed: Requesting a log spaced frequency response with smoothing set to None via the API could produce slightly different phase values than a text export

pmar4015 · Saturday at 1:29 PM

Is there a bug in the Mac version of Beta 132 in terms of the Channel Mapping found in the Sound Card preferences tab? No matter what I do, only the SBL and SBR speakers/channels as well as the subwoofer speaker/channel provide any output. Please note I am using the 7.1 rear surround format in the Audio Midi Setup setting with a 9.1 setup, I have tried remapping the speakers several times but to no avail.

For example, I have the Front Left speaker mapped to Channel 1 but yet when I select Channel 1 the SBL speaker plays. If I select the Right Speaker (channel 2) the SBR speaker plays, If I select the SBL the SBL speaker plays and I select the SBR the SBR plays. Even more strangely is when I select the Center speaker the SBR speaker plays.

Apologies in advance if I have made a stupid mistake by inadvertently changing a setting but I don't believe such is the case (admittedly I have been wrong before!). I have never had this issue before.

Thanks in advance for looking into this matter

John Mulcahy · Saturday at 3:04 PM

pmar4015 said:
Is there a bug in the Mac version of Beta 132 in terms of the Channel Mapping found in the Sound Card preferences tab?

Not that I'm aware of, works OK for me. Bear in mind that REW is generating multi-channel linear PCM, it is not a compressed format.

pmar4015 · Saturday at 3:33 PM

John Mulcahy said:
Not that I'm aware of, works OK for me. Bear in mind that REW is generating multi-channel linear PCM, it is not a compressed format.

Thanks John,

Must be an issue on my end.I will reset my Denon X-8500HA and see if that solves the problem.

pmar4015 · Saturday at 8:11 PM

John Mulcahy said:
Not that I'm aware of, works OK for me. Bear in mind that REW is generating multi-channel linear PCM, it is not a compressed format.

Yep, it was a setting. Somehow the receiver got switched to Multi Ch Stereo as opposed to Multi Ch in 7.1. kids (hahaha)

Apologies for wasting your time

moij · 2026-08-03T14:12:13-0500

I find RTA can analyze also wav files. This is very good option, other analysers are missing many options what REW RTA have. But one feature is missing. Is possible to wind file back and forward on RTA analysis? Currently is only possible to stop the file loading and not continue after that or go back in file. Or even better is to have some time slider for analyzing wav file.

dcibel · 2026-08-03T15:21:03-0500

moij said:
I find RTA can analyze also wav files. This is very good option, other analysers are missing many options what REW RTA have. But one feature is missing. Is possible to wind file back and forward on RTA analysis? Currently is only possible to stop the file loading and not continue after that or go back in file. Or even better is to have some time slider for analyzing wav file.

Instead of RTA, try using file -> import -> import audio data, then go to the spectrogram tab. Enable "show slice at cursor" and you can view FFT of any specific location in the audio. REW allows 30s maximum file legth for this import if I recall.

REW Beta Release REW API beta releases

thothsong

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