Registry Locations for Codecs and Media Foundation

Windows manages audio and video decoding pipeline components through distinct Windows Registry (regedit) pathways, separating legacy Video for Windows (VFW) and Audio Compression Manager (ACM) codecs, DirectShow filters, and modern Media Foundation Transforms (MFTs). This guide outlines the exact registry paths used to register, store, and manage these multimedia decoders and filters across 32-bit and 64-bit environments.

1. Media Foundation Transforms and Handlers

Media Foundation is the primary multimedia framework for modern Windows versions. Its transforms (MFTs), byte stream handlers, and scheme handlers are registered in the following locations:

• Media Foundation Transforms (MFTs):
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Media Foundation\Transforms
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\MediaFoundation\Transforms
• Byte Stream Handlers (File extensions mapping to parsers):
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Media Foundation\ByteStreamHandlers
• Scheme Handlers (Protocols such as HTTP/RTSP):
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Media Foundation\SchemeHandlers
• Hardware-Accelerated MFTs:
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Media Foundation\HardwareMFT

2. DirectShow Filters

DirectShow filters are registered as COM objects under the standard CLSID hive and categorized under specific filter categories:

• DirectShow Filter Category:
  • HKEY_CLASSES_ROOT\CLSID\{083863F1-70DE-11d0-BD40-00A0C911CE86}\Instance
• WDM Streaming Filter Category:
  • HKEY_CLASSES_ROOT\CLSID\{DA4E3DA0-D07D-11D0-BD50-00A0C911CE86}\Instance
• Video Compressors Category:
  • HKEY_CLASSES_ROOT\CLSID\{33D9A760-90C8-11d0-BD43-00A0C911CE86}\Instance
• Audio Compressors Category:
  • HKEY_CLASSES_ROOT\CLSID\{33D9A761-90C8-11d0-BD43-00A0C911CE86}\Instance

3. Legacy Codecs (VFW and ACM)

Legacy 32-bit and 64-bit system codecs (Video for Windows and Audio Compression Manager) are listed as driver values under the Drivers32 keys:

• 64-bit Native Codecs:
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Drivers32
• Installed Audio/Video Drivers Registry Cache:
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\MediaResources

Inside Drivers32, entries prefixed with vidc. represent video codecs (e.g., vidc.h264), and entries prefixed with msacm. represent audio codecs (e.g., msacm.mp3).

4. 32-Bit Codecs on 64-Bit Windows (WOW64)

When running 32-bit media players or frameworks on a 64-bit Windows installation, Windows reads codec entries redirected under the WOW6432Node:

• 32-Bit Media Foundation Transforms:
  • HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows Media Foundation\Transforms
• 32-Bit DirectShow Filters:
  • HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Classes\CLSID\{083863F1-70DE-11d0-BD40-00A0C911CE86}\Instance
• 32-Bit Legacy Codecs (Drivers32):
  • HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows NT\CurrentVersion\Drivers32