Stumper of a Question about 5.1 Mixdowns in Foobar

Discussion in 'Audio Hardware' started by tmtomh, Apr 18, 2013.

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  1. tmtomh

    tmtomh Forum Resident Thread Starter

    [Didn't turn up the answer to this via search; apologies if I missed it...]

    I'm doing a stereo mixdown of 5.1 DVD-A files. (I legally own the DVD disc.)

    The problem I have is that the stereo mixdown is majorly clipped.

    In Foobar, I select the 5.1 files, select "mixdown to stereo," and output to 32-bit.

    But it appears Foobar is mixing down all six tracks at 0dB, so when they get combined into a two-track stereo file, they clip.

    I've solved this by also applying EQ during the processing - and simply moving every one of the EQ sliders down by 7dB. The result is a stereo file with no clipping.

    But I am concerned that moving all the EQ sliders down like that could produce some frequency non-linearity. I'd much rather be able to tell Foobar simply to attenuate every track by 7dB during processing. However, I don't see a DSP option for that - and when I right-click on the DVD-A tracks, I also don't see any option to edit the ReplayGain info.

    Does anyone know of a DSP plugin or other solution that will allow me to tell Foobar to attenuate all the tracks, instead of attenuating via EQ?

    Or, alternatively, does anyone have any insight on whether or not using the EQ this way will screw up the frequency spectrum/profile of the tracks?
     
  2. tmtomh

    tmtomh Forum Resident Thread Starter

    D'oh - never mind, figured it out. Sorry for the bother.
     
  3. rockclassics

    rockclassics Senior Member

    Location:
    Mainline Florida
    Could you enlighten us on what you ended up doing? This sounded interesting. Not sure I'll have the need to do this, but you never know.

    Thanks
     
    chilinvilin likes this.
  4. tmtomh

    tmtomh Forum Resident Thread Starter

    Sure, no problem. In the Processing window, where I selected the "downmix 5.1 to stereo" DSP, there's a "ReplayGain" section at the top. I didn't notice it initially; and even when I did notice it, I thought I couldn't use it because the tracks had no ReplayGain values. But it turns out when you press the little "..." button, you get two different preamp sliders. One is meant to be used with RG, while the other allows you to attenuate (or amplify) the tracks even if the tracks have no ReplayGain tags in them. Here's a screenshot of the Processing window, after I'd fiddled with the sliders in the RG popup window, and returned to the main Processing window with my 7dB attenuation set:

    [​IMG]

    It's a "destructive" volume change in that it alters the data - but heck, so does downmixing to stereo. And if you export in 32-bit mode (the original files are 24-bit), you've got plenty of headroom to do the processing without losing any real resolution.

    As an FYI, I did this with Beck's Guero, Deluxe Edition. The CD is hyper compressed, and (while my Deluxe Edition was on order) I'd gotten ahold of a DTS mixdown that sounded very good. But AFAIK the DTS files are lossy and not hi-res (or at least the form I got them in wasn't high-res). So I wanted true lossless, high-res mixdowns of the tracks, which is what I've now got.

    At any rate, hope this helps!
     
  5. ElevatorSkyMovie

    ElevatorSkyMovie Senior Member

    Location:
    Oklahoma
    Yes, you found what you need to do. Mixed down the 5.1 of my Porcupine Tree dvd-audio discs because the stereo is so compressed. I think I had to lower the volume 7 to 9 db, depending on the disc. "In Absentia" didn't turn out well, no bass for some reason. "Deadwing" and "Stupid Dream" sound great though. Much more dynamic than the hi-rez stereo tracks.
     
  6. rockclassics

    rockclassics Senior Member

    Location:
    Mainline Florida
    Thanks. I appreciate it.
     
  7. coyot51

    coyot51 New Member

    Hi, there!
    Sorry, I'm a newbie... and above this... I'm freeeeeeeeeeeeeeeeench... :)
    Well, I decided to write here because this forum seems to be the most active among those I visited regarding "downmixing 5.1 to stereo".
    I want to downmix AC-3 5.1 audio streams from a MKV movie file (Dances with Wolves to tell everything).
    I chose to use FooBar2000 and managed to find 2 DSP plugins, i.e. DownMix and Channel_Mixer.
    Then come the questions:
    - can I use the MKV file within FB? seems not
    - I tried to demux the audio part using MKVTools... I obtained 2 MKA files (french and US) but it seems FB can't use MKA files
    - tried to extract the audio files using MediaCoder (I failed) then FormatFactory (you already guessed it)

    Using MediaCoder to convert 5.1 audio to stereo audio doesn't downmix but make "raw" stereo... low voices, music breaking the wall of sound... :)

    Please, I need your help. I'd like to remux my MKV movie adding audio in stereo, downmixing it properly. I just need to obtain a stereo downmixed version of the FR AC-3 5.1 audio part and a stereo downmixed version of the US AC-3 5.1 audio part. Then I remux with MKVTools... easiest part, actually! May you take a little time to tell me how I could do this, please?

    Thanks a lot, anyway!... and happy 2014!
     
  8. Vidiot

    Vidiot Now in 4K HDR!

    Location:
    Hollywood, USA
    Play the original disc in a DVD-A player and take the analog stereo downmix out of the player, then feed that to a decent soundcard in a computer. I don't think doing it in the analog domain is going to buy you anything, not with files that have already been compressed.
     
    QBNCGAR likes this.
  9. coyot51

    coyot51 New Member

    Hehe... thanks. But are we talking about the same thing, actually? MKV vidéo file, DVD-A player... player doing automatic downmix... ^^
    Thanks, anyway. It's good to smile a bit in the morning.
     
  10. Vidiot

    Vidiot Now in 4K HDR!

    Location:
    Hollywood, USA
    My way, it's never gonna clip.
     
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