Audio Codec Support

Forgot to mention there's an ACM wrapper that can be used to enable support for audio formats not natively supported by Windows 7.

didn't work

I dont know why but i can't play mkv's on my xbox even tho i did exactly like the tutorial


so i installed new divx7 preview and video is working while playing .mkv file but I have no audio... I tried every link in this thread with no luck, can someone point me in the right direction ?

yes, install &

yes, install & .acm and you will have AC3, which i hope with final build we don't have to do this... and it is still out of sync.. boo...
thank you for all your hard work

OGG tracks does't work

Hi, I have a mkv video with an ogg track so I have tried to install Vorbis OGG ACM codec but it seems it doesn't work.
Topoedit can't resolve the topology "Error rendering media file. No suitable transform was found to encode or decode the content."
I can add the source but "DivX ACM Wrapper MFT" Trasform seems not enough for audio.

please help

Unfortunately it doesn't

Unfortunately it doesn't support the Vorbis mediatype. :(

salamich is right!

salamich is right!

Use "AC3Filter" instead of VAC3ACM 0.3a to enable AC3 / DTS playback in Windows Media Player!

Download AC3Filter here:

AC3 playback

WMP plays back AC3 when it is stored in a m2ts container without the need of any additional codecs. This meens that WMP natively supports AC3.
So why do I have to install an extra codec for AC3 playback with mkvs?

It isn't just a DirectShow

It isn't just a DirectShow vs MediaFoundation question either. Microsoft's AC3 decoder is basically restricted to only work with their components. I believe it has to do with their license from Dolby. Just try using the "DTV-DVD Audio Decoder" in graphedit for AC3. The pins connect but only produce silence.

I think it can play AC3 only

I think it can play AC3 only in DirectShow. The problem is to play in MediaFoundation, then you will need AC3Filter for sure.

This works

After installing AC3Filter I now have audio with my MKV DTS files.

AC3Filter - Why not baked in?

I'm a bit confused. What is the "native" audio encoding as expected by this tech preview in MKV files? Everything I've ever encoded is AC3/DTS. It seems silly that we still have to install a codec on top of the tech preview to get typical MKVs to play properly.

AC3filter FULL

Note: You have to download the "FULL" version.

Is this just for HTPC

Is this just for HTPC playback? Any chance that this might get DTS playing back for me on my 360 extender?

Hi, Is there an ETA on when

Hi, Is there an ETA on when we will get an update with dts support for extenders? Is it even possible for the xbox to decode dts without somehow installing a decoder on the xbox or MS miraculously supplying one through a dash update? Or would the dts audio be decoded on the pc then streamed to the xbox?

I tested a couple mkv's with ac3 audio and everything seems to be working fine but I can't do much more testing since 99% of my mkv's have DTS audio.

I have the same question.

I have the same question. Will we be able to stream MKVs with DTS audio to the xbox 360 without a dashboard update. If not, is there a way to force WMC to transcode the audio to 5.1 AC-3 on the fly?

I have the same question.

I have the same question. Will we be able to stream MKVs with DTS audio to the xbox 360 without a dashboard update. If not, is there a way to force WMC to transcode the audio to 5.1 AC-3 on the fly?

You can download popcorn

You can download popcorn audio converter and convert the DTS to AC3... takes about 10 mins a movie and doesn't alter the video side.


Has anyone tried enabling playback of AC3/DTS audio tracks in Windows Media Player by installing an ACM codec?

Gonna give this a shot:

Not me either

This didn't work for me either.

It worked for me @ Win 7 RC1

It worked for me @ Win 7 RC1 32bit after I installed AC3filter.

MKV with DTS sound now can be played and streamed to Xbox 360

This worked for me also. It works both on extender and on my pc. I am just having trouble on pc to passthrough DTS and AC3 to my receiver. Receiver receives sound as pcm i believe.

AC3/DTS passthrough


First of all, I want to thanks the DivX team for this great piece of software! Really, it does something unique and very useful!

I have no doubt that once it will be released it will have a huge success!

There are still 2 things annoying me:

- I was unable to have any 5.1 sound on my computer. AC3/DTS pass-through in AC3Filter seems to be ignored when reading a MKV (I don’t get any AC3Filter icon in the system tray in fact). If I play a normal DivX AC3Filter works as expected though. If I uninstall AC3Filter I don’t get any sound at all when reading a MKV.

- I am missing subtitle, I know; this is a known issue, I just really hope that this will be included in the final release because I really miss those.

Any hint about the release date (Windows 7 release date maybe)?

Keep on the hard work,

Thank you,

AC3 problem

I have the exact same AC3 behavior with Media Center / Windows Media Player. I am happy to see that I am not alone. I have tried very hard to fix the situation. Hopefully it can be fixed. I get no system tray icon and the sounds always comes out stereo, no mater the AC3 filter settings.

I am running W7 RTM x86.


Can you tell me how?

I have installed the AC3Filter 1.60b. I have enabled the options exactly the same way as in this tutorial:
With the AC3Filter, the SPDIF tab, all are unchecked as well.

When using the Divx MKV Preview, the audio only plays in PCM 2 Channel, so the best I can do is make Dolby Pro-Logic out of it. I really want the audio to work on all 5.1 channels and have Dolby Digital.

Atleast I did find a work-around for now. I installed Sharky's codec ( and enabled Gabest for MKV.

Realtek 2.25

Read this:

"The new Realtek R2.25 drivers have a tab for dd/dts through HDMI, it works and says *for Windows 7*"

It's worth a try!

Awesome tip!

Thanks for the help on that one. I finally can get AC3 and DTS working on my HTPC over HDMI. That had been driving me crazy since that worked fine under Vista.

Now that I could get that to work I decided to do some testing doing audio pass-through in Media Foundation and it looks like there are some problems. As far as I can tell MF doesn't do pass-through at all. I can pass-through AC3/DTS in DirectShow no problem, but I get 2-channel PCM in MF. This happens even for .AVI files with DivX and MP3 which are all handled by Microsoft components in MF.

My investigation into this isn't done yet though so hopefully we can figure something out. Fortunately I still get AC3 pass-through on my 360. :)

VAC3ACM didn't work for me

I'm using Windows 7 RC (7100) x64 and only want to play MKV on the machine itself.
VAC3ACM didn't work for me but AC3 Filter 1.60b did. Have not tried streaming to extenders.
You can get it here:

Gonna give this a

Gonna give this a shot:

Is this the current recommended method to allow .mkv AC3 playback?

I tried AC3 filter, but my audio on regular HD TV was WAY out of sync...

I'm also getting massive

I'm also getting massive sync issues with ac3filter. All of it's settings seem to only affect the DShow filter, not the ACM one.

Btw: That "VAC3ACM" is an old version of the ACM filter that comes with AC3filter.

resolved sync issues

Hi, has anyone succeeded with getting ac3 sound in sync with mkv's?

I have tried ac3filter (about a second out) and VAC3ACM (half a second)

using Win 732bit RC 7100.


What worked for me.

I found that on the system tab of the ac3filter config window if I set a time shift of -100ms it appears to be in sync. I have used this same setting on multiple computers. I don't use any extenders so I have no idea if it will help with an extender setup.

Are you trying it with the

Are you trying it with the latest release of the MKV Tech Preview?

Yes the latest release and 7 x64

I'm using the latest release of the MKV Tech Preview (R3) and Windows 7 x64.

Trying ac3filter and it's

Trying ac3filter and it's out of sync still, using Win7 64 RC 7137. Might try the FFDShow x64 tryouts for audio.

I have tried this vac3acm

I have tried this vac3acm file but still no luck.

Sorry replied to the wrong post...

No luck here with the

No luck here with the vac3acm. I can hear audio after I install it but my video gets super choppy in WMP.


Would the ACM wrapper allow playback of DTS on an extender or did I miss the point?

I have gotten an MKV with

I have gotten an MKV with DTS to play on the xbox with AC3Filter 1.60b installed. However the audio has been down converted to 2.0 PCM. I'm assuming this is the best that we are going to get unless Microsoft gives the Xbox the ability to decode DTS or at least accept 5.1 PCM. I do not believe that a workaround is going to be possible in windows. Can someone from the development team confirm that I am correct?

Shouldn't the xbox have the

Shouldn't the xbox have the ability to decode a DTS stream already?? It seems to spit out a DTS stream to my receiver when I put a DTS DVD in the drive...

This is my experience with

This is my experience with X360 as an extender, DTS doesn't normally work only until you invoke a crash, sounds a bit farfetched but hear me out.

MKV's with DTS audio don't work and pop up with an error message video cannot be displayed but if you play a couple of compatible files and skip forward and backwards until it freezes, it's a bit tedious, but eventually it should freeze then all you have to do go to x360 dashboard and startup media center again. Now if you startup a MKV with DTS audio it should work. I don't know why or how but it works. As long as you don't close that session of media center all your DTS files will work.

I know it's not a proper solution but sometimes it does work. But I'm waiting for a better solution.

@saleem09. Sounds odd but......

.... I'll see if I can re-create it on my setup.

I can confirm that the

I can confirm that the ACMWrapper does indeed allow AC3/DTS support for the X360 Extender. Thanx DivX!!

Are you getting all channels

Are you getting all channels from DTS playback on your extender?

5.1 DTS does not work on

5.1 DTS does not work on extenders. You only get 2.0 (PCM?). I've been converting files with DTS to AC3 with the Popcorn Audio Converter. It pretty easy and only takes 10-15 minutes for a 2 hour movie. The sound quality seems to be very good.

i only have stereo output so

i only have stereo output so i don't know

sync problem

I'm also getting massive sync issues with ac3filter, too bad.
tried ffdshow tryouts but nothing new.
W7 seems the perfect media center for my HTPC, just need to get rid of the 2 major problems (no 5.1 passthrough & out of sync)...

I'm having the same

I'm having the same problem,
I have an Asrock ion 330 with the nvidia ion processor and this seems to be the only solution for DVXA hardware acceleration. I've installed AC3 codec and I get the out of sync issue for my MKV movies.. I guess its transcoding the audio when I specifically set it to passthrough my receiver via spdif for the RAW dts tracks.. but theres no way of me knowing since the AC3 info box doesn`t work properly in windows 7.

I`m currently using Windows 7 RTM. Other then the sound issue, the video plays back flawlessly, keep up the good work team!


For those who have problems with dts not being multichannel on extenders, use mkv2vob it takes less then 5mins per movie, and sound and video(untouched) are great. Hopefully with a later beta of the preview we will not have to do this.

In mkv2vob's configuration set the check mark "always transcode dts", and output type as "file", everything else can stay the same because the only thing being touched is the audio.

This is by far the easiest solution and can do batch transcoding. Also if you dig further into the software there are other cool things possible.

I've updated to the latest

I've updated to the latest build and alas, the sync issue is fixed.
But I haven't been able to get DTS output.. just AC3 to my digital receiver. Could this be a problem with the AC3 Filter?

Hi I am also having issues


I am also having issues with the audio pass-through not working. I've installed the DIVX Tech Preview for the first time on a clean install of Win7 RTM 32bit. I've also installed the latest version of the AC3Filter. However I am unable to get 5.1 audio on MKV files, when playing them on the PC in WMP/7MC. I only get 2 channel PCM.

I started a thread about the problem on the green button here
And a new thread here on the DIVX Forum.

How do I configure AC3Filter to get 5.1 audio when using the DIVX Tech Preview?

Or is there another way to get this working are there any step by step guides?



Microsoft Media Center MVP