AC3 audio and mkv files broken in Mountain Lion?

Discussion in 'OS X Mountain Lion (10.8)' started by zen, Jul 29, 2012.

  1. zen macrumors 68000


    Jun 26, 2003
    I have a bunch of mkv files that I usually run through Quicktime 7 as a pass-through to turn them into .mp4 files which my PS3 will recognise (and Apple TV).

    With Mountain Lion, all of these files are now silent - each has AC3 audio, and a quick Google tells me that AC3 audio no longer works in Mountain Lion.

    Is this the case, or am I doing something wrong? Because I now have a whole lot of mkv files that I can't play or convert to watch via the PS3 and Apple TV.

    This is in addition to avi files no longer playing in Quicktime, which I guess is due to Perian being dead.

    Anyone found any solutions?
  2. kamuix macrumors regular

    Feb 9, 2011
    If you're open to using other players, VLC basically can handle all your media types. Avi, MKV, you name it, it has the ability to play them. It works perfectly fine on mountain lion as I'm using it.

    For the conversion, Handbrake is a free app that can handle your encoding needs. Here's a link:

    Hope this helps.
  3. Feed Me macrumors 6502a

    Feed Me

    Jan 7, 2012
    Location Location
    If your mkvs are just H.264 you can use an app called Subler to repackage the video into .mp4.

    Takes about two minutes and there's no artefact or quality problems since there's no transcoding going on. Handbrake can take hours to do a large movie so I highly recommend Subler.
  4. zen thread starter macrumors 68000


    Jun 26, 2003
    I was using Quicktime 7 for remuxing, but Subler seems to have solved the problem, thanks! I can pass-through audio and video with no issue, and the sound is present! Thanks!
  5. nakedbear macrumors newbie

    Jul 29, 2012
    VLC still no sound

    I upgraded to Mountain Lion, have the latest VLC and still have no sound on my MKV files. This really stinks as I have tons of MKV files with AC3 audio. There has to be a solution without having to convert them.
  6. bushido Suspended


    Mar 26, 2008
    holy **** this is amazing, now i can turn all my mkv into something that plays natively in iTunes in no time. thx :D
  7. ac3320, Jul 29, 2012
    Last edited: Jul 29, 2012

    ac3320 macrumors regular


    Aug 20, 2011
    Yeah, just know that the audio will be degraded when going from mkv to m4v using Subler, if you choose to . The video is passthru'd but not the audio. Check the Subler pref's. You will see that the highest audio bitrate/channel is like 160 Kbps or something. That is why, after comparing the mkv to the final m4v, the final m4v can be up to ~2 GB smaller (since Subler truncates the audio streams). I didn't know this originally. It is still worth it to use Subler for quickness, but I wish they would write in some code to passthru the audio :/

    Edit: I was wrong about this. You can passthru the audio just fine. I had not noticed when adding a file manually that there are options in regards to the audio. For instance, if it is DTS, you can pass it, but will probably have trouble with ATV. So what you can do there is change the DTS (AC-3) to AAC, Stereo or multi-channel, up to 160 Kbps. This is probably higher that whomever encoded the audio to anyways, so no big loss there. Just wanted to clear this up for everyone. I did some research after posting and realized I had been incorrectly remuxing all this time (essentially throwing away the multichannel stuff in most of the encodes I had).
  8. Alrescha macrumors 68020

    Jan 1, 2008
    Use MP4Tools instead of Subler to remux MKV to m4v. It will pass through H.264 and AC3 audio and generate a stereo AAC file for Apple TV compatibility.

  9. bushido Suspended


    Mar 26, 2008
    hmmm it just stopped working for unknown reason

    the files are all H.264 with AC-3 but it just turns to a red error in the queue
  10. scottperezfox macrumors newbie


    Jul 27, 2011
    I've had the same problem with playing back my MKV files, which seem to all have AC3 audio encoding. I've also had the same problem with the occasional AVI file. I suppose it depends on how it was created. My problem specifically is one of personal preference...

    I prefer to use Movist to view video files since it A.) can play back damn near everything much like VLC, B.) has a great interface and toolbars, etc. and C.) Has the best options for adjusting playback speed. This last one is key since I, like some others out there, prefer to watch my videos at an adjusted playback speed — usually 1.3x or 1.4x.

    The problem is that watching with VLC, or viewing a video with Movist but using the FFMPEG playback instead of Quicktime, does not allow for adjustments to playback speed. I'm stuck at 1.0x, but the sound works fine.

    So far, I've been using Handbrake to create a new video file formatted for Apple TV (using Handbrake's included setting for Apple TV). I'll try Subler as a faster alternative.

    But these are all workarounds. We haven't solved the actual problem — that AC3 doesn't play back in Mountain Lion. Does anyone have insight into a permanent fix? It would seem that installing a system-level tool like Perian would be the fix, but in reading this it seems nothing has yet appeared.
  11. zen thread starter macrumors 68000


    Jun 26, 2003
    Subler does a passthrough, so it takes seconds, versus hours for Handbrake to re-encode.

    The lack of AC3 support is a little peculiar. I used to work with DVD Studio Pro, which used AC3 a lot of the time. I presume Apple's current pro apps still support AC3?
  12. matrix07 macrumors 601


    Jun 24, 2010
    Yeah, if ML doesn't support AC3, how can it play DVD?
  13. scottperezfox macrumors newbie


    Jul 27, 2011
    I just downloaded MPlayerX from the App Store and it works perfectly for playing back all the problem files. MKV and AVI files that are silent in Quicktime or Movist now have sound. From a technical point of view I don't know what's going on, but it seems that the problem of playback is solved.

    I still prefer Movist for viewing file. It has a playlist, which almost no other players do. MPlayerX also has playback speed, which is nice, but having to start a new video after the previous one finishes is kind of annoying if you're like me and you have dozens of short videos to watch rather than full-length movies.
  14. Mackan macrumors 65816

    Sep 16, 2007
    Strange enough, I can play mp4 files with only AC3 in QuickTime X. And I don't have Perian installed.
  15. ellawhiteg macrumors newbie

    Aug 12, 2012
  16. Bombermac macrumors newbie

    Apr 16, 2010
    I just got a 2011 iMac (with Mountain Lion) to use as an HTPC. It's taking the place of our MacBook Pro (with Lion) which was filling the same purpose (when I wasn't taking it places, that is). On the MBP I'd been using the method outlined here to get 5.1 surround when watching MP4s, M4Vs, MKVs, etc.:

    Now I have to admit that I don't know why the above method worked (I don't even fully understand what I did, I just basically followed the steps), but work it did.

    I downloaded Perian for the iMac, but I've yet to use the Terminal command. I was thinking about finally doing that when I came across this thread. Am I to understand that if I use that Terminal string and load a movie in VLC I'll no longer be able to hear anything? Right now I'm getting (non) surround sound and I'm a little worried I might break something. Should I leave well enough alone, or will completing the entire method at the site I linked to do anything useful?
  17. nyolc8, Aug 15, 2012
    Last edited: Aug 15, 2012

    nyolc8 macrumors regular

    Jul 20, 2012
    I tried this method, and now I can play every avi files properly with sound in quicklook, but Quicktime player won't let me play it. It's just opens the file up, and when I click on play button, nothing happens. Console says "prime failed". I don't understand why it works in quicklook but not in quicktime player.:confused:

    edit.: I just figured out that it plays perfectly in quicklook without any modifications, just installed perian. But how to get it working in quicktime player??
  18. Alrescha macrumors 68020

    Jan 1, 2008
    iTunes (probably because of QuickTime) handles AC3 in supported files (like m4v) natively. In my experience, Perian breaks this functionality. The trade-off may be worth it for some people.

  19. Menneisyys2 macrumors 603

    Jun 7, 2011
    Have you tried it? Unfortunately, it requires the now-abandoned Perian for both DTS and AC3 to AAC conversion, independent of the number of channels etc. of the target AAC. (No such problems with MKV's purely with AAC / MP3 tracks like ).

    There's a dedicated thread on this at

    All in all, if you do want to remux but don't want to install Perian because of its side-effects, only partial ML-compatibility and now-abandoned status, you'll need to choose something else.
  20. tangles macrumors member

    Jul 1, 2008
    I can't remember the last time I launched QT...


    I would like to share my setup and workflow.

    I've had a Mac Mini in the lounge for years now and I seriously cannot remember the last time I launched QuickTime. As good as Perian is, I haven't even bothered to install it on ML yet, and I don't think I need to anymore.

    The Mini is connected to my Sharp 42" display via HDMI and a Yamaha 5.1 am via toslink.
    I have 3 Elgato tuners hanging off the back of the Mini being the Diversity USB twin tuner and my original Firewire C410 tuner. I have a single antenna feed that is simply split 3 ways to feed the tuners.

    I have an AFP file server hiding away in another room that's running macZFS with my iTunes and iPhoto Libraries on it. These libraries can be used by any Mac in the house that has iPhone/iTunes installed. The server also shares out a video library comprising of movies, tv shows, documentaries, sport and misc. (I use soft links on the Mini in the lounge to reference the iTunes and iPhoto libraries as I used to use NFS back in the early days)

    For those who have "lots" of video, I strongly recommend It's brilliant and will even support hardware decoding on certain/modern macs, so a 25GB BluRay RIP is no probs!
    Secondly, XBMC has a neat feature where you hit "a" on the keyboard and you can correct any audio/video sync issues by using the left and right arrow keys! Great if you can be bothered with Telecine for cam efforts floating around...

    Just point/configure XBMC to your repository and away you go!

    As mentioned before, for any other video outside of XBMC I want to watch, it's all the way! AVI, MP4, MT2S, MKV and WMV all play perfectly fine whether these containers have AAC/AC3 or DivX/AVC inside them. I think XBMC piggybacks on top of Mplayer from memory too.

    I don't touch VLC anymore. I understand VLC to be "designed" to drop frames (if need be) because it's roots lie in network/packet based supply of video. I'm sure I haven't described that part of VLC quite right so please don't flame me about it... I like VLC but I don't have a place for it anymore in my setup.

    I clean up and rename the video files using (I donated $50AUD to the developer, she's that good) and then remux everything to MKV using before I add it to my library for XBMC to see/play it.
    I can do this with the GUI for a couple of files or I can batch entire nested folders with MKVtoolnix using the command line.

    Oh, one more thing about XBMC and this is a biggy!
    If I watch a movie that's ripped as 24p, XBMC will even change my Mac Mini's video output to my Sharp panel and drive it at 24Hz so that I don't experience that annoying 3:2 pulldown jitter effect! It will do the same and jump to 60Hz for NTSC formatted video. (I live in Aus, so PAL (50Hz) is the norm/standard here)

    This is an unfortunate thing about the iMac and the 27" displays – they're stuck at 60Hz. So if you're into your movies and get into the technical side of things a bit, you want a display/panel that can receive a 24Hz/24p signal natively and not shoe-horn the feed and render it back out at 50/60Hz. (hint, a 120Hz capable display can receive a 24p signal, and simply fills each frame with 3 extra fields (i.e. the same frame 4 times) to pad it out, thus 24 is divisible into 120 without any remainder ;) )

    Once the renaming and remuxing is all done, I can opt to use on my server that also knows where my video repository lives, and MediaCenter transcodes all my MKV in realtime back to any iOS device on my wireless network.

    I love my setup:
    all movie files are in the same format/container;
    everything is in the same place; and
    I don't have to piss-fart around re-encoding/re-muxing files and transfer via iTunes for iOS devices.

    Well, I've rambled on enough. I hope someone can take something away with them from my Mac HTPC experience.

    Cheers all,

  21. Lancer macrumors 68020


    Jul 22, 2002
    I know this thread has not been used in a while but is there any change the AC3 issue will be fixed with the next OS X due out later this year.

    Its annoying my old G5 can play these video files but my shiny new iMac can't (with QT) I have VLC and MPlayer both of which work fine, also installed Perian which helps with some files but I have some AVIs with AC3 which refuse to play the audio in the Finder/QT which is a shame as I often like to preview a clip before opening it in VLC or MPlayer.

    Hope Apple fixes this issue in 10.9.

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