Best audio quality when rewrapping MKS to m4v

Discussion in 'Digital Video' started by absolut_mac, Aug 24, 2014.

  1. absolut_mac macrumors 6502a

    absolut_mac

    Joined:
    Oct 30, 2003
    Location:
    Dallas, Texas
    #1
    As someone who doesn't know too much about video editing and conversions etc, I've done a lot of reading on the subject on these forums which have been most helpful.

    It seems to me that the easiest way to convert Blu Ray mks files to m4v is clipwrap or subler. I tried subler and was most impressed by its ease of use, speed and the fact that there's no re-encoding so there's zero loss of video quality.

    Now the audio options are different nightmare. After reading about Dolby Pro Logic 1 & 2, AAC, AC-3 etc. I'm still no clearer in understanding which one offers the best sound quality for people like me - i.e. the highest available sound quality for regular stereo sound systems.

    I understand that the various Dolby options offer better or worse implementations of surround sound etc. I'm sure that the vast majority of home users don't have 7 let alone 5 speaker surround sound systems, so I'm sure that I'm not alone in just wanting the absolute best available stereo sound option from my Blu Ray movies.

    Hopefully some of our resident video experts can weigh in and offer suggestions for highest quality audio options needed for regular stereo.

    If I understand these things correctly I believe that converting Blu Ray DTS 7.1 audio to stereo should also greatly reduce the file size without sacrificing audio quality. Or is that another mistaken assumption?

    Thanks in advance for your help on this confusing topic.
     
  2. phrehdd macrumors 68040

    phrehdd

    Joined:
    Oct 25, 2008
    #2
    I admit I get a bit lost in your post. I'll offer up some thought on this in general and pick and choose what is useful -

    Often Blue Ray discs offer a stereo stream. This would be your best choice for stereo playback. Alternatively, many Blue Ray players can downmix Dolby and DTS multi-channel to stereo. Let the hardware do this for you. In my estimates, if a hardware device can do a down mix for you, it is worthwhile to keep the best audio (surround) for future use if you decide to go to surround or even add just a center channel. So what you would have would be the highest quality audio stream plus the video stream. You would remove any extra streams you don't need such as foreign audio tracks, subtitles if they are not needed etc.

    Without knowing what you are using for a playback device to your receiver/AVR or having your AVR do the work, you will remain unclear as to which options are best for your needs. Many Blue Ray discs offer DTS-Master or similar (Dolby counterpart) and within the DTS Master is DTS core. It gets a bit messy for many to understand but DTS core is lossy and DTS Master is supposedly lossless. When you use DTS to convert, you are taking an already compressed lossy file and doing more 'damage' to the audio track and thus, opting to use out the door the audio stream that is already stereo should ideally sound better than generating it yourself. There are of course exceptions.

    Hopefully others will chime in and lend an opinion or two here.
     
  3. absolut_mac thread starter macrumors 6502a

    absolut_mac

    Joined:
    Oct 30, 2003
    Location:
    Dallas, Texas
    #3
    Thanks for your response phrehdd. I'm sorry if my post wasn't clear enough. I'm using Subler to rewrap the mkv container to m4v. There are various audio options in there for downsizing the 7.1 and 5.1 surround sound audio to regular stereo, which I assume is what the vast majority of people use both on their iPads and home TVs etc.

    I also have Compressor for downsizing the files if they're still too large. The latter has virtually the same audio presets as Subler, but neither make it clear to an inexperienced user like me which is the best option for the highest quality stereo output.

    i.e. Which of these presets will deliver highest quality accurate audio reproduction good enough for top quality stereo components and speakers. Or for those on a budget like me a top notch set of headphones like my V-Moda XS driven by the Cambridge Audio DacMagic XS.

    Most users like myself obviously have zero use for 7 channel surround sound, but we still want the best stereo sound available from the original source.

    My knowledge in this area is woefully inadequate, but I assume that Subler, Compressor etc mix the various surround sound channels down to stereo using their own proprietary algorithms or something along those lines.
     
  4. phrehdd macrumors 68040

    phrehdd

    Joined:
    Oct 25, 2008
    #4
    Since MKV is just a wrapper, what is the original source of the files? Sadly, there are only a few tools for MAC but lots for Windows (free or near free). In your shoes, I would check to see if your MKV file has already a stereo stream. Do you have access to Windows (even a virtual windows would work such as Win7 under Fusion or Parallels)? I gather most people wanting to compress use items such as Handbrake.
     
  5. absolut_mac thread starter macrumors 6502a

    absolut_mac

    Joined:
    Oct 30, 2003
    Location:
    Dallas, Texas
    #5

    As mentioned in my original post above the source is my collection of Blu Ray movies which I want to transfer to my HD.

    Yes, I do have access to PCs. My son has an HP laptop with Windows 7 and my younger son has a home built desk top with Windows 8.1. I'm not sure how these would deliver superior sound quality compared to comparable Mac programs seeing as they're both down mixing from the same surround sound source material. Unless of course there's a Windows program out there that has a superior algorithm.

    I can't believe that I'm the only one looking for help with this issue. I guess excellent sound quality is not that important to most people.
     
  6. phrehdd macrumors 68040

    phrehdd

    Joined:
    Oct 25, 2008
    #6
    The reason I mentioned PCs (Windows) is that there are some really excellent free or near free software that you may want to investigate using.

    As example - assuming you "archived" your entire disc, you could use tools such as Clownbd, or TSmuxer and select the video stream, then look for a stereo stream. The latter will prove far easier to deal with than a 5.1 or 7.1 stream. What you are left with is a file with exactly the streams you want. There are other software that can help with creation of a stereo stream that started out as a 5.1 or 7.1 surround stream. Not all software works the same with respect to generating a stereo file/stream from a surround source.

    Sadly, Apple only has a few apps available that are free or near free that are worth bothering with. We all pretty much are familiar with Handbrake which is a good tool for file conversion for creation of a file to play on an iPad or iPhone and just a handful of other software options.
     
  7. absolut_mac thread starter macrumors 6502a

    absolut_mac

    Joined:
    Oct 30, 2003
    Location:
    Dallas, Texas
    #7
    Thanks!!

    That's exactly the info that I was looking for. I DO archive the entire Blu Ray movie. I usually only watch the extras like alternative endings and behind the scenes only once, so I don't bother saving them.

    As I mentioned earlier, I use both Subler and Compressor and both seem to offer the same and very limited options as far as audio output is concerned.

    I do use Handbrake to convert and downsize my regular DVDs, but much prefer Subler and Compressor for Blu Ray.

    I'd appreciate if you can think of any other options. I don't mind paying for any apps that do the job well as they're usually money well spent in the long run.

    Thanks once again for your help.
     

Share This Page