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Aug 31, 2026
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MPC Audio Decoder is a free DirectShow audio filter for Windows that decodes MP3, AAC, FLAC, Opus, DTS-HD Master Audio and around thirty more formats inside MPC-HC, MPC-BE and any other DirectShow player, with nothing bundled and no paid tier.
Windows plays plenty of audio on its own, right up until the file where the picture runs and the sound does not.
MPC Audio Decoder closes that gap with one DirectShow filter covering more than thirty audio formats, so you are not chasing a separate codec for every file you meet.
It registers itself with Windows and every DirectShow player on the machine picks it up, MPC-HC and MPC-BE included.
What MPC Audio Decoder Actually Does
The filter takes a compressed audio stream and turns it into PCM, the raw form your sound card can actually play. Everything from MP3 and AAC up to DTS-HD Master Audio goes through the same filter, which is the point of it - one install instead of a shelf of single-format decoders.
It ships as a single file, MpaDecFilter.ax, installed to System32 on 64-bit Windows and SysWOW64 for 32-bit players. There is no folder to choose and nothing to configure before it works. The installer takes a /S flag if you are pushing it out across several machines.
It is free, with no paid tier, no trial clock and nothing bundled alongside it. The developer ships it both on its own and inside X Codec Pack 3.0.
Previously known as MPA Decoder. The name changed, the filter did not, and older guides pointing at "MPA Decoder" are describing this same download.
Supported Audio Formats
MPC Audio Decoder covers most of what turns up in real media files:
- AAC (Advanced Audio Coding), including the newer USAC and xHE-AAC profiles
- ALAC (Apple Lossless Audio Codec)
- Monkey's Audio, the APE format
- Dolby AC3, EAC3 (Dolby Digital Plus) and Dolby TrueHD
- Dolby AC-4, still marked experimental by the developer
- DTS, DTS 96/24 and DTS-HD Master Audio
- FLAC, the free lossless codec
- Opus
- MP3 (MPEG Audio Layer III)
- Ogg Vorbis
- WMA (Windows Media Audio)
- ATRAC9 and On2 Audio for Video Codec
- Intel Music Coder and DSP Group TrueSpeech
The DTS side handles full DTS 96/24 and DTS-HD Master Audio bitstreams, which is what Blu-ray rips and high-bitrate surround content need. AAC 22.2 decodes as well, downmixed automatically to 7.1.
Not sure which codec your file even wants? The Codec Finder will narrow it down before you install anything.
How It Fits Your Playback Chain
A DirectShow player does not decode anything by itself. It builds a chain: a splitter pulls the streams apart, a decoder turns the audio stream into PCM, and a renderer hands that PCM to your sound hardware.
MPC Audio Decoder is the middle link. That means it needs the other two to be working, and it also means a silent file is not automatically a decoder problem - a missing splitter looks exactly the same from the outside.
For a video file, pair it with LAV Filters for the video and the container splitting. For bit-perfect output, add MPC Audio Renderer and its WASAPI exclusive mode.
Our guide on Understanding the Roles of Decoders and Renderers walks through how the pieces hand off to each other. If you want to sort out spatial sound at the same time, read Choosing Your Sound - Windows Sonic, Dolby Atmos and DTS.
The easy route. The K-Lite Codec Pack bundles MPC Audio Decoder with MPC-HC, LAV Filters and the rest, already configured, so playback works the moment the installer finishes.
Who Should Look Elsewhere
Here is the tell: open your player's settings and look for an internal or built-in audio decoder list. If your player has one and it is switched on, a DirectShow filter will never get a look in, because the player decodes the audio itself before DirectShow is involved.
VLC and MPV work that way. So does anything built on Media Foundation rather than DirectShow, including the modern Windows Media Player. Installing this filter for those players changes nothing.
It also will not help with DRM-protected purchases, and it is not an equalizer - if you want tone controls, dynamic range compression or per-channel levels, that is a different filter and it is in the table below.
What Changed in Recent Releases
- Updated handling for Dolby AC-4 audio, which also has its own standalone Dolby AC-4 Decoder if you need it outside DirectShow
- Improved TrueHD and Dolby Atmos transmission over HDMI passthrough
- Experimental Dolby AC-4 decoding added
- Fixed decoding of some TrueHD streams
- Better bitstreaming behaviour when the audio device changes mid-playback
- Internal buffer reworked for lower overhead
- Added On2 Audio for Video Codec support (tags 0x0500 and 0x0501)
- Added Intel Music Coder support
- Fixed 24-bit Monkey's Audio decoding, after an FFmpeg update
- Added USAC and xHE-AAC decoding
- Added AAC 22.2 decoding with automatic downmix to 7.1
- Added ATRAC9 support, and fixed a memory leak
Filters That Pair With It
Each of these covers a job MPC Audio Decoder deliberately does not do:
| Filter | What it handles | Add it if |
|---|---|---|
| MPC Audio Splitter | Opens standalone lossless files - FLAC, APE, TTA, WavPack | Your music library is lossless, not just your films |
| Ogg Splitter | Unpacks Ogg and OGM containers | Your files end in .ogg or .ogm |
| LAV Filters | Video decoding and container splitting, with hardware acceleration | You want the video side covered too |
| MPC Audio Renderer | WASAPI exclusive mode output, bit-perfect | You feed an external DAC or an AV receiver |
| Sanear Audio Renderer | Alternative WASAPI renderer with fewer settings | MPC Audio Renderer gives you crackles or dropouts |
| MPC AudioSwitcher | Switching between audio tracks inside MKV and MP4 | Your films carry more than one language |
| AC3 Filter | Equalizer, dynamic range compression, per-channel levels | You want tone control over a home theatre setup |
| DTS/AC3/DD+ Source Filter | Opens loose .dts, .ac3 and .eac3 files directly | You have bare audio files rather than video |
| Dolby Digital Plus Decoder | Dolby-licensed EAC3 decoding for Windows media apps | The app that needs EAC3 is not a DirectShow player |
Still weighing up which player to build all this around? MPC-BE vs MPC-HC: Which Media Player is Right for You? compares the two head to head.
Quick questions
Is MPC Audio Decoder really free?
Yes. There is no paid tier, no trial period and nothing bundled with the installer.
Does it work on Windows 11?
Yes, and on everything back to Windows XP. Both 32-bit and 64-bit builds install together, so 32-bit and 64-bit players are both covered.
Do I need anything else for it to work?
You need a splitter that can open your container and a renderer to send the sound out. LAV Filters covers the splitting for video files, and Windows supplies a default renderer if you do not install one.
I installed it and there is still no sound. Why?
Usually because your player is decoding audio internally and never asks DirectShow. Check the player's settings for a built-in or internal audio decoder list and switch the relevant formats off, or use a player that leaves decoding to system filters.
MPC Audio Decoder or LAV Filters?
They overlap, and both work. LAV Filters is the broader package because it does video and splitting as well, while MPC Audio Decoder is a smaller, audio-only filter you can drop into a chain you have already built.
Where does it install, and how do I remove it?
The filter file lands in System32 and SysWOW64. It uninstalls from Windows Settings like any other program, and removing it leaves no leftover configuration.
Download MPC Audio Decoder 1.9.1.39 and see how it handles your files, or tell us how you got on if you have used it before.
