Summary / Introduction
There is a known compatibility issue affecting Pro‑Codec and Codec Toolbox plug‑ins when used in certain Steinberg hosts such as Cubase and WaveLab.
In these cases, the host is unable to locate a required library file, which prevents the plug‑in from loading correctly.
This guide explains the cause and provides a temporary workaround until a permanent fix is released.
Affected Products
- Pro‑Codec
- Codec Toolbox
Affected Hosts
- Steinberg Cubase
- Steinberg WaveLab
Cause
The issue is due to the host being unable to locate the mmtisobmff.dll dynamic library in its default system folder.
Without this file in a location the host can read, the plug‑in fails to load.
Workaround
Important: This is a temporary solution. We plan to address compatibility in a future update.
- Close all Steinberg applications before making changes.
-
On your system, open the folder:
C:\Windows\System32\
-
Locate the file:
mmtisobmff.dll
-
Copy (or move) this file to the Sonnox VST3 plug‑in directory:
C:\Program Files\Common Files\VST3\Sonnox
- Relaunch your Steinberg host and check that your Sonnox Codec plug‑in now loads correctly.
Notes & Safety
- Copy vs Move: We recommend copying rather than moving the file, so it remains in its original location for other applications that may rely on it.
- Permissions: You may need Administrator rights to copy files into Program Files directories.
-
System File Warning: Do not rename or delete
mmtisobmff.dll. This is a valid Windows system component.