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List of issues#2653 SEVERE: Uncaught exception in thread: main java.lang.UnsatisfiedLinkError: dev.matrixlab.webp4j.internal.NativeWebP.encodeLosslessRGBA
Author: 
Astariul
AstariulDate created:
Type: bug
Visibility: Everybody
Assigned to:
State: closed 
> What steps will reproduce the problem?
Export sprite with chid=1520 (from the linked SWF) with `-format sprite:webp`
> What is the expected output? What do you see instead?
Expected the export to work correctly
> What version of the product are you using? Is it "nightly build"? Which operating system
do you have?
Windows, v25.1.2 nightly build 3440
> Please provide any additional information below. If the problem is related to a SWF
file, attach it here, otherwise we can't help you.
Low-priority (for me), I don't use `webp` format but I just came across this when running
the commandline and wanted to file an issue for the record.
o1.swf (3,075 KiB)
Please check the lib directory if there is only single "webp4j-1.4.0.jar"
and not other versions of it.
This may happen if you download/unzip ffdec in the same directory as previous version for
example.
Also WEBP could be not available on your platform - probably you got 32 bit Java (?).
In upcoming nightly 3443, I will add a check for the availability in CLI rather than the
Exception.
Stack trace :
```
PS C:\Program Files (x86)\FFDec> ./ffdec-cli.exe -format shape:png,script:as,sprite:webp
-zoom 2 -selectid 1520 -export sprite out_folder o1.swf
JPEXS Free Flash Decompiler v.25.1.2 nightly build 3440
-------------------------------------------------------
Exporting sprite...
Exported frame 1/1 DefineSprite (chid: 1520, exp: "325")
Mar 04, 2026 9:27:15 AM java.util.logging.LogManager$RootLogger log
SEVERE: Uncaught exception in thread: main
java.lang.UnsatisfiedLinkError:
dev.matrixlab.webp4j.internal.NativeWebP.encodeLosslessRGBA([BIII)[B
at dev.matrixlab.webp4j.internal.NativeWebP.encodeLosslessRGBA(Native Method)
at dev.matrixlab.webp4j.WebPCodec.encodeWithNativeLibrary(WebPCodec.java:230)
at dev.matrixlab.webp4j.WebPCodec.encodeImage(WebPCodec.java:121)
at dev.matrixlab.webp4j.WebPCodec.encodeLosslessImage(WebPCodec.java:159)
at
com.jpexs.decompiler.flash.exporters.FrameExporter.lambda$exportFrames$8(FrameExporter.jav
a:613)
at com.jpexs.decompiler.flash.RetryTask.run(RetryTask.java:60)
at
com.jpexs.decompiler.flash.exporters.FrameExporter.exportFrames(FrameExporter.java:617)
at
com.jpexs.decompiler.flash.exporters.FrameExporter.exportSpriteFrames(FrameExporter.java:1
93)
at
com.jpexs.decompiler.flash.console.CommandLineArgumentParser.parseExport(CommandLineArgume
ntParser.java:2417)
at
com.jpexs.decompiler.flash.console.CommandLineArgumentParser.parseArgumentsInternal(Comman
dLineArgumentParser.java:689)
at
com.jpexs.decompiler.flash.console.CommandLineArgumentParser.parseArguments(CommandLineArg
umentParser.java:475)
at com.jpexs.decompiler.flash.gui.Main.main(Main.java:3618)
at
com.jpexs.decompiler.flash.cli.CommandlineInterface.main(CommandlineInterface.java:32)
```
Ah thank you for the answers !
What does nightly 3443 say to you?
Does it produce different message?
The library should be named webp4j-core-2.1.1.jar now.
Using the latest release (v25.1.3), I now get a proper error message :
WEBP format is not available on this platform
Error: Bad Commandline Arguments!
followed by the help 👍
Thanks ! We can close this issue
State: new→closed