3 Solutions Downmixing 5.1 to Stereo In Adobe Audition
Doing Simultaneous 5.1 & Stereo Exports in Adobe Audition

3 Solutions Downmixing 5.1 to Stereo In Adobe Audition

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Downmixing is the action of taking a surround mix and having it be instantly compatible in stereo. While this is relatively easy to do with judicious routing in 5.1 or 7.1, 9.1 and higher surround formats become prohibitively difficult to allow for easy solutions. In this article I’m going to pull a small section from Chapter 24 of the Mixing Volume from the Pro Member Education and show how we can do downmixing in Adobe Audition three different ways.

The Norm

In most DAWs, there’s a native plugin (usually called downmix) which can be inserted across a 5.1/7.1 mix bus. This plugin then turns that bus into a 5.1/7.1 input – stereo output bus. The plugin has faders on each input channel allowing the user to control how each channel is routed to the stereo bus. This is important, because while the default ITU standard is generally good for most mixes, I’ve honestly never had it work in a way that I thought was successful. Instead, each input channel needs to be tweaked to give the best representation of the surround mix into a two-channel, non AC3/compressed format.

My suggestions are the following:

  • Left = 0 (or full)
  • Right = 0
  • Center = -3 (the reason for this is covered in the article on Pan-Law)
  • LFE = -3 (the default is always “off”, but if you have program material which is only present in the LFE channel, in such a case, it would be completely missing in a stereo mix).
  • Ls/Rs = -6
  • Lm/Rm = -6

96% of the time, these settings make for a great stereo downmix from both 5.1 & 7.1. Channels which may need to be massaged around these settings include LFE (depending on how much exclusive LFE material is present) and Lm/Rm (due to possible phase issues folding them into the surround channels which may have the same material present). You set these up in your output bus and you’re ready to burn. In fact, you can burn these in most DAWs at the same time as you burn your discrete masters to save time. Nice.

The Adobe Audition Way

In Audition you can’t just jump in and do this. Special care must be taken. The video included in this article demonstrates how to set this up in a 5.1 environment, but I’ll list the three ways to do a downmix in Audition here:

Considerations:

  1. the AA downmix plugin isn’t called “downmix” it’s in the plugins/channel effects and located in Amplitude
    Channel Mixer
    The Default AA Channel Mixer Settings are ITU Standard

    and Compression/Channel Mixer.

  2. the AA downmix plugin is currently not shown in dB, but in percentage. Look at the video for what -3/-6 db settings are.
  3. the downmix plugin does not create a stereo output from the bus it’s on – but reather a 6 channel interleaved file with left and right possessing all the program data and the other four channels silent.
  4. choosing to not use the downmix plugin has AA use its built in downmix routing which perfectly emulates the ITU standard which may not give you a good downmix result – but can be used to easily route the 5.1 bus to the stereo master and make a simple downmix.

Suggestions:

  1. If all you need is a simple downmix and you’re sure you have no program material which is exclusive to the LFE bus, then it’s easy: route your 5.1 output to the stereo “master” output. Audition uses the ITU standard to map the 5.1 channels to any stereo bus or output you choose. Once done you can export both the 5.1 bus and the stereo master at the same time using the Export/Multitrack Mixdown command and selecting those two busses. Remember, however, that you need to roll off high frequencies in the surround bus BEFORE you route it, otherwise you’ll have a faulty master/non-Dolby approved and you’ll be getting a call from Quality Control.
  2. If you have a mix where you know you’re going to need more control over the LFE channel, then this video is perfectly made for you. You’ll need to route your 5.1 bus to a stereo bus. Insert the Channel Mixer onto the 5.1 channel. From there, alter your settings to suit. You’ll notice that your 5.1 mix is now only working on the L/R channels and the others are silent. Perfect. From here, the built in ITU routing of AA will happily and correctly route the downmixed 5.1 mix to the stereo bus you’ve created. You’ll be able to Export the downmix on one pass, then remove the channel mixer plugin from the 5.1 bus and then Export the discrete 5.1 mix on the next pass. Nice. But. If that all seems like a waste of time – especially since AA burns final large mix masters at about 1/4-1/10th speed, look to the next method of export to be able to burn both 5.1 and downmix masters at the same time.

    Simultaneous
    Doing Simultaneous 5.1 & Stereo Exports in Adobe Audition
  3. Like in option #2, create a stereo bus, but also create another 5.1 bus.
    1. Call this new bus “Master 5.1” and your other two “Print Master 5.1″/”Print Master Stereo” respectively.
    2. Route Print Master 5.1 to Master 5.1.
    3. Route Master 5.1 to Print Master 5.1
    4. Insert the Channel Plugin as mentioned in #2, but do it on Master 5.1 instead of Print Master 5.1

Now you can have an unmolested 5.1 mix on Print Master 5.1, and the downmixed 5.1 is routed to Print Master Stereo from Master 5.1. To Export both 5.1 and stereo downmix at the same time, simply select Print Master 5.1 and Print Master Stereo in the Export process, and you’ll get both done to your spec flawlessly.

https://youtu.be/UJu8DfqREwE

Have a better way of doing it or have questions? Let us know here, or Tweet about it!

 

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