mkv -> m4v - just can't rap my head around it

Discussion in 'Apple TV and Home Theater' started by kangping, Mar 3, 2011.

  1. kangping macrumors member

    Mar 30, 2010
    hi there,

    i know there are a lot of threads on this, but after reading for hours i still can't rap my head around this theme. i have various mkvs from various sources (i live in deep china, and its tricky to good quality english movies), but they are mostly all h246 and dts or ac3...

    handbrake seems to work very well, but i would rather go for the approach mkvtools uses... but with mkv tools, i only had luck with one movie. the rest just corrupts at some point. either the files are not muxed back together, the sound is totally async or drops out after a while.

    i use the mp4 tab, and either pass through or the other options, if passthrough is red. also i put the hook at "add 2 Ch. track". the last thing is, i just don't understand how to use "turn off mkvs header removal compression" all it does is split the file into these various little mkvs, logs and what not....

    i'd be very thankfull, if someone could kind of "fix" my brain ;)
    thanks for reading up to here.

  2. spacepower7 macrumors 68000

    May 6, 2004
    I'll try to make it simpler. Skip the first part if you already know it.

    MKV is a file container (think of a physical box if that makes it easier)
    MP4/m4v is also a file container (this is based on Quicktime)

    Files within the container usually are:

    h.264 video file

    aac, ac-3, dts - audio files - there may be multiple types and languages in you mkv

    subtitle tracks - there may be several

    chapter track - fi

    Think of using handbrake as converting your mkv video (and most likely audio) to the new mp4/m4v container/box that all of Apple devices prefer.

    Think of mkvtools as software that can take your mkv video and audio out of a MKV container/box and put it into a mp4/m4v box without altering the video and audio.

    Depending on your Apple devices, you may have to alter the MKV when converting with mkvtools.

    Apple devices can't play DTS audio, so this must be converted to aac and/or AC-3.

    AppleTV is the only Apple device to playback AC-3, so if you have an iPad, iPhone, iPod Touch, you need to make sure that your conversion has 2-channel aac sound.

    Second part

    You don't mention what app/device is having problems with audio sync. Most of the time that I have ever experienced this has been on my iPad or Mac with Quicktime. In my experience, the cause of this problem is 6-channel aac sound in the file.

    There's an option in MKVtools preferences that asks if you want to keep temp and log files.

    Another issue if playing on Apple devices is the video from your MKV.

    h.264 video can have various "profiles" and all current devices should lay up to high profile 3.0 (maybe 3.1)

    Some of your MKV files may be using high profile 4.1 h264 video or anything above the Apple limit. MKVtools has the device menu under the mp4 tab. This option tells a file with a higher video profile to pretend to be a lower profile in hopes of working with iTunes and iDevices. This works sometimes but ultimately depends on the options used when the original MKV was encoded.

    Overall, depending on each individual MKV file, MKVtools may be the best option, if you can simply pass thru the video and audio (or quickly convert the audio.)
  3. kangping, Mar 3, 2011
    Last edited: Mar 3, 2011

    kangping thread starter macrumors member

    Mar 30, 2010
    thanks for the answer. i guess i was understanding things, except for the 3.x and 4.x profiles. what i don't understand is why these files are ALWAYS async, or else goes wrong.

    if i convert with handbrake, what would be the way to keep the quality loss at a minimum, and what happens with the sound?

    thanks for helping me out here, really appreciate it.

    edit: usually i check with vlc and quicktime
  4. Rizvi1 macrumors 6502a

    Mar 29, 2006
    Laurel, MD (Baltimore, MD / Washington, DC area)
    Could someone tell me if this is correct:

    If you have a .mkv with dts 6ch and you want to play on a PS3 that's connected to a receiver and home theater system, you can't do audio pass through but you can select AAC 5.1 and the receiver will be able to do the surround sound?
  5. AdrianK macrumors 68020

    Feb 19, 2011
    AAC 5.1 is junk. I don't believe there's a receiver out there that can decode it. The PS3 will simply decode it and spit out 2 channel PCM.
  6. Rizvi1 macrumors 6502a

    Mar 29, 2006
    Laurel, MD (Baltimore, MD / Washington, DC area)
    what should it be converted to then so that you can use the sound with a home theater system?

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