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AC3Filter is a high quality free audio decoder and processor filter. It allows media players to playback movies with AC3 and DTS audio tracks. Also it can process any audio track, much of processing options allows to adjust the sound in almost any way. It is possible to upmix any audio source to 6 channels. Filter can do multi-channel and digital (SPDIF) output. It can encode any audio source to AC3 on-the-fly and send it over SPDIF to the receiver. The full installation contains OPENCANDY! Use the Lite version

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OS: Win
File size: 4MB
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Latest version

2.6.0b / 2.6.0b Lite ADFREE (April 5, 2013)


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Download AC3Filter 2.6.0b  4MB  Win  Ad-Supported installation!

Download Beta and other versions

Download AC3Filter 2.6.0b Lite ADFREE  1MB  Win

Download old versions

Download AC3Filter old versions

Software License

Free software but ad-supported installation. Be careful when installing it to avoid unwanted addons!

Supported operating systems


More information and other downloads

Download AC3Filter tools here or AC3filter tools 1.0a mirror (direct link) here, command-line tools with AC3 encoder and decoder, SPDIF format converter, parametric filter, graphic equalizer and more.

NOTE! The main version containts OPENCANDY and it may install unwanted addons when you install it. Use the LITE ADFREE version instead(it only contains 32bit filters though).

Complete Version history / Release notes / Changelog

AC3Filter 2.6.0b
Released: 2013-04-05
FFMPEG updated to v1.1.4
Use FFMPEG for AAC decoding (should be less crashes because faad bugs).
SPDIF/AC3 encoder: encode 5.1 with back channels (used by flac for instance) like 5.1 with side channels (standard for ac3).
Serbian language added (thanks to Rancher).
Languages updated: Basque (thanks to Xabier Aramendi), Chineese (thanks to PoYang).
Bug fixed: some languages was reset to english after restart.
Installer: /noicons option works now

AC3Filter 2.5b
Released: 2012-06-17
FFMPEG is used for DTS decoding.
Better decoding quality for EAC3 and OGG Vorbis.
Correct SPDIF output status.

AC3Filter 2.4a
Released: 2012-06-07
No freeze after pause in WMP.
More speaker layouts.
ACM driver crash fixed (thanks to maxsmi).
AC3 SPDIF passthrough fixed.
Basque language added (thanks to Xabier Aramendi!).
Translations updated: Finnish (thanks to Kristian Epäilys), Bulgarian (thanks to Georgi Barzev)

AC3Filter 2.3a
Released: 2012-05-31
Dolby TrueHD support
ACM 64bit works now
Several bugs leading to crash fixed.
Translations updated: Slovak (thanks to Artam), French (thanks to Philippe AGUESSE)

AC3Filter 2.2a
Released: 2012-05-14
Bugfix release
OGG Vorbis support.
ACM driver works again (was broken in v2.0a).
Several bugs leading to crash fixed.

AC3Filter 2.1a
Released: 2012-04-10
Bugfix release
Equalizer crash fixed. Thanks to all who report bugs.
HDMV LPCM support (it was noise).

AC3Filter 2.0a
Released: 2012-04-09
8 channels support
PCM Double output support
DTS-MA (core only), AAC, EAC3, FLAC, MP3 decoding support
Completely new bass redirection:
better filtering (4th order Linkwitz-Riley)
option to redirect bass to front speakers
Single icon per application
Online help
Crash report
Set filter language from the installer
Portuguese, thanks to Manuela Silva
Turkish, thanks to AltanEdip
Dutch, thanks to Ernst Klamer
Bulgarian, thanks to Георги Бързев
Ukrainian, thanks to Michael VigovskyE)

AC3Filter 1.63b
Release notes:
* AC3 decoding bug fixed (Issue 1)
* Channel order bug fixed (issue 43)
* Remote control using messages
* Write version number to the registry on install (issue 17)
* Command line interface for AC3Config utility (run ac3config /? for help)
* Swedish translation added (thanks to Niclas Burgren)
* French language updated (thanks to Philippe AGUESSE)

v1.62b - 17.07.2009
* Precise PCM passthrough
! Fixed: Noise on LPCM 20/24bit tracks
! Fixed: Delay settings did not work after restart.
+ German translation updated (thanks to Philipp Wode)
+ Japan translation added (thanks to tnetsixenon)

v1.61b - 01.06.2009
* Clear DirectShow filter cache on install and uninstall
! Fixed: Matrix was not saved
! Fixed: Popping sound when seeking DTS/WAV or AC3/WAV file
* Translations updated: Slovak (thanks to Artam), Spanish (thanks to Ferny)

+ 64bit filter
+ Lite filter version
+ Multichannel equalizer
+ Customize equalizer dialog with frequency response of the equalizer
* Spectrum synchronized with audio playback
* Localized installer
! Fixed: ACM driver sometimes crashed
! Fixed: equalizer can mute the sound sometimes
! Fixed: "incorrect value" error message may appear under the settings dialog
! Fixed: tab key now works at edit controls

New Translations:
* Slovenian, thanks to DarkHand
* Greek, thanks to Peter Perdik and Dimitrios Topouzidis

v1.51a - 09.07.2008
* CPU usage takes in account number of processors
* Center, Voice and LFE levels are synchronized across Mixer and Gains pages
* 'Decoder info' box did not work sometimes
* Slovak, Spanish and Italian translations updated

v1.50a - 30.06.2008
+ Equalizer
+ Spectrum analyzer
+ Sample rate conversion
+ spdif_test utility
* New and updated translations
* Old bugs killed, new made :)

v1.46 stable - 09.08.2007
+ AC3 encoder bitrate is now adjustable
+ Korean translation added (thanks to starcodec)
! Upmixing of Dolby Surround files works now (thanks to Stefan Schott)
! MPEG Audio Joint stereo playback fixed (thanks to Daniel Bechter)
! Problem with decimal point in mixing matrix on some non-english Windows (thanks to Marcin Hencz)

v1.45b - 07.06.2007
+ ACM codec is now included into the package
+ Tab labels are now translatable
+ All languages available so far integrated
* Avoid poEdit 'r' warning when creating a translation file
+ Warning messages about dangerous options
! Loud noise was possible after output format switch or SPDIF state change
! Audio skips problem fixed once more

v1.40b - 30.05.2007
+ Localization support!
+ Localization procedure is easy and can by done by everyone!
+ Russian translation
! Fixed bug in AC3 decoder (audio skips). Thanks to Chris Meadowcroft!
! User manual fixed (broken in v1.35b)
* Mixing LFE channel into several channels preserves resulting loudness. LFE level now means gain relative to front channles.v1.40b - 30.05.2007
+ Localization support!
+ Localization procedure is easy and can by done by everyone!
+ Russian translation
! Fixed bug in AC3 decoder (audio skips). Thanks to Chris Meadowcroft!
! User manual fixed (broken in v1.35b) * Mixing LFE channel into several channels preserves resulting loudness. LFE level now means gain relative to front channles.

v1.35b - 24.04.2007
! Fixed a bug in AC3 decoder (decoding of 4.1 and 3.1 AC3 files was affected). Thanks to Dietmar Kleiner for reporting and testing!
! Fixed a bug with fast playback of mono files in WMP
! Delay units works correctly in offline config utility

+ SPDIF page added, all SPDIF-related options are moved there
+ AC3Config utility supports themes
+ Invert levels option to fix a bug with levels display in 3rd-party themes

* Default output format changed to stereo (Much of people with stereo setup cannot hear center channel with default multichannel output)

AC3Filter 1.30b

* AC3 loudness increased by +6dB. Now it matches loudness of other decoders. I was noted about this porblem a long time ago, but I wanted to be sure what I'm doing, because new version produces overflow with LOTS of movies. I checked everything and found that it is not a bug of the decoder, but mastering issues. Other decoders also produce the same overflow at the same places. Therefore, new version works as it must work.

Some notes about how to handle these overflows you may read here: Overflow in movies

* Some Vista compatibility issues fixed (matrix editing works and gains are saved correctly). But problem with SPDIF output stays. I did some reseach and almost sure that problem is with sound card drivers.

* A small issue with WMP fixed: sometimes it made 2 tray icons.

AC3Filter 1.20b
* Now we can play multi-channel audio CD without any conversion! Just insert multi-channel CD into CD drive and open it with Windows Media Player or Media Player Classics. (Or you can use any other DirectShow media player that can playback AudioCD. Winamp IS NOT DirectShow player and does not work!)
* Also, we can playback .wav files ripped from multi-channel CD (that produced just noise before) without any conversion!
* New method of DTS over SPDIF passthrough allows to transmit DTS streams that was impossible to transmit before!
* Fixed work with 14-bit DTS files that was played back incorrectly (like fast forward).
* SPDIF input support. This will allow to decode external SPDIF source at future...

AC3Filter 1.11. Stable release.
* Now filter saves output settings to preset. So now you can create presets with different output configurations.
* Tray icon and some other options display fixed
* Fixed crash with TMPGEnc

AC3Filter 1.10b. Tray icon added!
* Tray icon to access filter's settings from players that do not allow to configure filters.
* Sometimes SPDIF mode cannot be set because of post-processing filters that do not support SPDIF output. Now it's an additional option to force this problem. Read here for more info. (Thanks to LESAGE Aurelien for testing)
* DivX player now works with SPDIF

* DivX Player compatibility
* Audio/Video sync option works again

* More work with player compatibility.

* BSPlayer crash fixed
* No sound in some players fixed
* AGC fixed: was limited to -6dB

AGC fixed: overflow check did not work sometimes

Extended AC3 sainty checks disabled. How it recognizes AC3 files produced with buggy encoder (see more at forum). All projects updated.

Bugfix release
* SPDIF passthrough did not work with Program Stream (DVD)
* SPDIF had jitter with DVD
* Cannot enable SPDIF with some sound cards (found on HDSP 9632)
* Uninstall now deletes pis folder

- As-is output mode (without change of number of channgels)
- SPDIF output options:
· Enable/disable AC3 encoder
· Enable/disable encoding of stereo PCM
· Option to output SPDIF stream as PCM
· Sample rate check
- Option to check output format support
- Sound card reinit after pause
- Extended decoder inforation
- SPDIF disabled reason indication
- Time shift and jitter correction work with SPDIF output
- Extended jitter statistics
- Attack/Release speed adjust

* First working alfa for new filter generation
* Totally rewrited
* 10%-20% faster
* Level meters are now syncronized with playback
+ DTS decoding support (including AVI/DTS and WAV/DTS)
+ MPEG1/2 Audio Layer I/II decoding support
+ DVD/LPCM decoding support
+ Audio processing for any kind of audio track
+ AC3/DTS/MPEG Audio SPDIF passthrough
+ Real-time AC3 encoding for multichannel SPDIF output
+ More powerful dynamic range compression
+ Bass redirection crossover frequency
+ Per-channel gain control
- equalizer
- save configuration to file

0.70b - 18.07.2003
! Serious bug in decoder fixed. Sound is _much_ better now especially on low bitrates.
* Some optimizations.
* Updated DPLII downmix matrix according to (thanks to bleo!)

0.69b - 09.07.2003
+ Jitter correction (more smooth playback)
+ Italian translation added
! Sometimes sound disappeared in MPC.
! 'File' button now works at stand-alone configuration.

0.68b - 03.04.2003
! Speaker configuration switched to spdif with auto load of config file enabled. Fixed

0.67b - 31.03.2003
- Auto switch to stereo was a bad idea... Removed.
+ Delete preset buttons added for all preset boxes.
+ Save/load settings to file.
+ Auto load setting from file with the same name as media file (so it is possible to create individual settings for each movie).
+ System configuration property page.
+ Output levels indicate overflow.
+ Time shifting for audio/video sync.
! Video stuttering again. Now it is possible to choose sync method between v0.63 method and v0.64 method.

0.66b - 19.03.2003
! Switch from SPDIF to stereo after seek fixed.

0.65b - 18.03.2003
! DVD playback is back

0.64b - 17.03.2003
* Much of testing
+ Speaker configuation can be changed when playing (no more need to stop playback). Thanks to Gabest for ideas
+ Bass redirection option
+ 100Hz-7000Hz filter for Dolby Surround/ProLogic downmix
+ Automatic switching speakers to PCM 16bit stereo if selected mode is not supported. ('Some streams are in unsupported format' error message)
+ Time delay can be specified as diatance to speakers
+ You can now switch using ac3filter or other installed decoder (for NVDVD)
! Reject to work with SPDIF on some systems bug fixed. ('Some streams are in unsupported format' error message)
! Video stuttering with SPDIF fixed
! Silent center/surround (-3dB gain removed for center/surround)
! Surround decoding matrix changed
! W98/ME config crash fixed
! W98/ME ControlPanel icon is working now
! W98/ME 'Use WaveOut' & 'Use DirectShound' files fixed.

0.63b - 23.12.2002
! fixed SPDIF mute issue

0.62b - 22.12.2002
+ Signal clipping on overflow
+ Auto gain control can be turned off now
* filter_merit now accepts common abbrevations for root registry keys instead of senseless codes
* More error-tolerante

! Seeking bug fixed.
! Bug fixed: sometimes timestamps may be lost.
! Bug with SPDIF output fixed (incorrect frame size)
! WaveOut/DirectSound switching is now working more correct in W98 (thanks to Mario *LigH* Rohkramer!)
! Fixed little bug in uninstaller

0.61b - 20.12.2002
+ Installer
* Changed syncronization algorithm
! Crash with WaveOut and ReClock renderers fixed

0.6b - 17.12.2002
+ Equalizer
+ Audio delay adjust
+ Support for different output sample formats: PCM16, PCM 24, Float
+ Dolby Surround/ProLogic/ProLogicII downmix.
+ Control Panel icon
! Mono output bug fixed
! Bug with WMP9 playback fixed
* Mixer page is redesigned
* Made filter code smaller

0.55b - 25.11.2002
! Bug fixed: surround and voice gain controls did not work in 5 channel mode
! Bug with decoding stereo files fixed

0.54b - 01.10.2002
+ SPDIF pass-through output.
+ Preset loading and several standart presets added.
* Speaker configuration is now saved to registry.
+ Speaker configuration program added.
+ Patch for dialog size in Win98 Chieneese
! Bug filxed - in some cases filter settings was not saved.

0.53b - 14.09.2002
* Filter is distributed under GPL lisence now.
+ Save settings to registy.
+ Mixer control page with mixer matrix added.
* LFE channel is now mixed only to front speakers.
* 'Normalize' checkbox on main page means now one-pass normalization.
! Some bug fixed and new added.

0.52b - 01.09.2002
! Bug fixed - hang on corrupted PES streams.
+ Sound volume increased.
+ Overflow control and automatic gain control added.
+ Master gain control added.
+ DRC power control added.

0.51b - 18.07.2002
! Bug fixed (crash on some ac3 formats)

0.5b - 07.07.2002
* AC3 decoder code was fully rewritten
+ PES support added.
+ Levels for LFE, Surround and Voice locked to BSI by default.
+ CPU usage indicator
+ Input and output levels inidicators.
+ DRC level indicator.
+ Some information about stream added.
! Some bug fixes.

0.4a - 23.06.2002
+ LFE support and LFE gain added.
+ Added buttons for reset all gains to BSI values.
+ Stereo now transmitted in standart format, so now filter can work with sustems with no multi-channel support (Win9x/WinNT).
+ DVD decoding added.
! Syncronization problem fixed.
+ Option to enable/disable dynamic range compression added.

0.3a - 03.04.2002
+ Volume gain for central (voice) and surround channels.
+ Speaker configuration change support added. Only works when all intermediate filters support dynamic reconfiguring and only in stopped (not paused!) state.

0.2a - 01.04.2002
* LibA52 code was rewritten for multitasing, so now possible to create many instances of the filter in a filtergraph. It is primary used for multi-language films.
+ Information panel added (but settings are not working now).

0.1a - first working alfa
Hide changelog

All features


* Watch movies with AC3 and DTS audio tracks
* Listen multi-channel (AC3/DTS) AudioCD
* Playback WAV files with AC3/DTS content, ripped from multi-channel AudioCD without any conversion of these files.
* Playback raw .AC3 and DTS files (with help of AC3File filter)


* Up-mix any audio track (even plain stereo) up to 6 channels
* Down-mix any audio track to any number of channels (to match your speaker configuration)
* If you have an external Dolby ProLogic decoder, you may use ProLogic down-mix to help DPL decoder to extract surround information
* Watch movies under poor hearing conditions (noisy environment, weak speakers, ...)
* Decrease dynamic range to watch movies at night
* Apply time shift to the audio track to synchronize audio with video.
* Adjust gain of every input/output channel independently to compensate loudness differences
* Adjust time delays for every channel to compensate different distances to loudspeakers.

SPDIF output:

* Passthrough AC3 and DTS over SPDIF without any change to external decoder
* Encode any audio to AC3 and transmit it over SPDIF
* USB sound cards supported

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Acronyms / Also Known As

ac3filter, ac3 filter, ac3filter tools, ac3 filter tools

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7 reviews, Showing 1 to 5 reviews

The filter merit choices are broken (for me) in version 2.3a, so I've had to go back to version 2.2a.

Review by mike20021969 on May 31, 2012 Version: 2.2a OS: WinXP Ease of use: 5/10 Functionality: 5/10 Value for money: 10/10 Overall: 7/10

with this update the filter no decompress ac3 audio in virtualdub or virtualdub mod.

Review by LUCHOO on Apr 26, 2012 Version: 2.1a OS: WinXP Ease of use: 5/10 Functionality: 5/10 Value for money: 5/10 Overall: 5/10

Tuesday, 17 April 2012

What a class release, What a perfection! - perfect 7.1 (8) channels surround sound decoder, and it's FREE plus Open Source!
I LuV this Developer.

Recently I was fixing my buddy's Windows system and came to know about features in this latest release. We literally started dancing when we blasted 8 channel video.

I would like to consider this release either as a Mile Stone or a Hammer Blow b'coz "The World" of Encoders and Rippers is yet not ready for 7.1 channels
Surround Sound. I am still fumbling for audio and video sync even in tuking two channels stereo. Here this decoder is 8 channels ready. Grrrrrrr!

However few things about this release...
1) Sensitivity of LFE channel in Mixer Level Bar indicator seems little bit higher than other channels, or it may be my buddy's system residual noise.
2) It would be great if Mixer Input and Output indicator Bars are provided a separate tab (page) with half-half, so sensitivity and size of bars can be higher. At present tabs are Mixer, Gain, but Mixer, Level, Gain would be better, I guess.

We already started enjoying this decoder up to maximum capacity.
Bunch of Thanks!

Review by Bonie81 on Apr 17, 2012 Version: 2.1a OS: Other Ease of use: 10/10 Functionality: 10/10 Value for money: 10/10 Overall: 10/10

It requires 5.1 channel sound card to play 5.1 (6ch) surround sound.
Otherwise set media players in stereo (2ch downmix) mode.

If any one wanna test correct hook-up of surround sound speakers. Download following DD5.1 AC3 Test file
download link :
(I can appreciate if above file can be hosted on VideoHelp itself in a section.)

Review by Bonie81 on Apr 11, 2012 Version: 2.1a OS: Other Ease of use: 10/10 Functionality: 10/10 Value for money: 10/10 Overall: 10/10

I had this problem of volume way too low on my DVD playback. Finally, found the cure ! I'll make sure the word gets out !

PS Only problem is with the loads of functionnality that you can adjust for people who do not know much about it ;)

Review by jackeric on Nov 5, 2006 Version: 1.1 OS: WinXP Ease of use: 4/10 Functionality: 10/10 Value for money: 10/10 Overall: 10/10

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