Mixing a Surround Sound Project in Vegas Pro and ACID Pro, Part I: Basic Setup and Controls

by Gary Rebholz

Both Vegas Pro™ and ACID Pro™ give you the ability to mix your project audio in 5.1 surround sound and deliver 5.1 files. This month, we'll look at how to set up your default surround audio routing and explore the basics of placing your audio in the surround spectrum with the Surround Panner window. In a future article we'll talk about surround sound automation, busing, and other more advanced topics. I'll use Vegas Pro 11 in this discussion, but the techniques we cover here are very similar to the tools in ACID Pro 7, so users of both applications will learn how to use these tools in their projects.

Since we're talking about 5.1 surround sound, I'm going to assume that if you're creating a surround mix, you have a 5.1 surround sound speaker setup in your studio or office. If you don't, you'll want to get something in place before you start mixing. Theoretically, you could create a mix with a stereo monitoring system since the software provides the tools to do so whether you have a surround sound setup or not. However, you certainly can't make the best mix if you can't actually hear it as you're creating it!

The first step to creating a surround sound mix, is to let your software know that you want to work in surround sound. To do this, choose File | Properties. In the Project Properties dialog box, click the Audio tab. From the Master bus mode drop-down list, choose 5.1 Surround.

You'll probably want to leave the Enable low-pass filter on LFE checkbox selected. Only frequencies that fall below the Cutoff frequency you set here will be fed to the LFE channel.

Choose the appropriate frequency for this setting from the Cutoff frequency for lo-pass filter (Hz) drop-down list. Some DVD and Blu-ray authoring applications require a specific cutoff frequency and rolloff. Your application may also not allow a filter to be applied before encoding, so make sure to check your authoring application's documentation to see if it requires specific settings here. If the frequency your software needs does not appear in the drop-down list, type the required frequency directly into the Cutoff frequency for lo-pass filter (Hz) text field.

Choose the option you want from the Low-pass filter quality drop-down list. Best produces the sharpest curve for the filter's rolloff. This means that with the Best setting, the cutoff engages more quickly when sound frequencies rise above the cutoff. Lower settings may be useful for slower computers, but with modern PCs, Best is probably fine.

When you're done setting these options, click OK. Depending upon how you have your Vegas Pro window configured, you may not notice it, but your Master Bus controls are now expanded and presented as Surround Master controls. To see this, rearrange your workspace so that you can see the entire Master Bus window. For instance, if you're using the default Vegas Pro window layout, drag the Master Bus window and dock it over the Trimmer window as I have in Figure 1.

Figure 1: Click for a larger view

The Master Bus window has been moved and docked over the Trimmer window so that you can now see the expanded controls for each surround sound channel.

Once you can see all of the controls in the Master Bus window, you see that you have meters and volume controls for each of the six channels in the 5.1 system. The Front and Rear channels are presented as stereo pairs for right and left, while the Center and LFE channels are presented as mono channels.

Now that you have your channel controls available to you, you need to make sure that you have your routing properly configured. In other words, you need to make sure that the audio signal you want to come out of the front/left speaker in the 5.1 system is routed to the Front/Left channel and that that channel is, in turn, routed properly to the speakers that you'll use to monitor your mix.

To make this all work properly, you'll need a 5.1 speaker system and an audio interface device (sometimes referred to as a sound card) that features enough line out jacks for you to feed each of the six speakers in the system. I'll proceed under the assumption that you have such a hardware system already in place and we'll concentrate strictly on the software setup that you need to establish in order to feed the hardware.

To route your audio to the proper channels, choose Options | Preferences and click the Audio Device tab. Here you can set the default routing for any surround sound projects that you start. Choose your audio device drivers from the Audio device type drop-down list. When you switch this setting to a device that supports multiple outputs, the next three drop-down lists in the Audio Device tab become active. Set each of these drop-down lists so that they point to the proper outputs on your audio device.

For instance, you can see in Figure 2 that I've set my Audio device type to my FirePod ASIO x64 drivers. My FirePod audio device features eight analog outputs and you can also see in Figure 2 that I've designated outputs 1 and 2 as my default front playback devices, 3 and 4 as my default rear playback devices, and 5 and 6 as the default Center and LFE devices. Once you've set your default devices, click OK.

Figure 2: Click for a larger view

The audio device type has been set and each channel pair has been routed to specific hardware outputs on the audio device.

Now that you've got your default audio routing in place, let's add some audio to the project. Since you'll be routing this audio to the 5.1 space, it makes sense to start with mono audio files, but that isn't strictly necessary. I'll assume here that you're using all mono files for your mix.

You add audio to a 5.1 project just like you add audio to any other (stereo or mono) project. You can record the audio into your project directly, or use the Explorer window or any of the other tools to bring in an existing file. Thus, if you add a video file to your timeline, the audio comes in as usual onto an audio track. Notice in the track header that instead of the normal Pan slider control, your new track's header contains a Surround Pan control. With this control you can place the output of this track into any position within the surround audio field. To see a larger version of this Surround Pan control, double-click the control in the track header area. This opens the Surround Panner window that you see in Figure 3. To make the window even larger, drag one of the window's corners until you're happy with the size of the controls within the window.

Figure 3: Click for a larger view

The Surround Panner window gives you a large view of the 5.1 audio field and enables you to place the audio signal from any track anywhere within that field.

The orange diamond in the middle of the field indicates the audio placement for that track within the field. The speaker icons give you a couple of clues as to where the audio is placed. Notice that with the orange diamond in the center of the field, each speaker icon shows a value of -6 dB. Since equal volume is coming from each of the five speakers in this case (note that the LFE speaker is a special case which we'll talk about in a few moments), the listener perceives the audio as coming from the very center of the room. Notice also that the audio field graphic in front of each speaker contains two shades of gray and at the moment, the dark gray in each extends to the white arc. This white arc represents -6 dB and as we discussed, that's the readout of all speaker icons when the audio is panned equally to all speakers.

To adjust the placement of the audio for this track, drag the orange diamond to a new location. For instance, say you want a sound effect on this track to occur to the left and behind the listener. Drag the orange diamond toward the left/rear speaker. As you do so, notice (as in Figure 4) that the values in each speaker icon change. Some of the values grow smaller as you move the diamond away from them while the left/rear value grows larger as you get closer to it. The gray shading in each speaker icon also shrinks or grows accordingly, so you have a couple of handy visual clues as to what the final audio will sound like.

Figure 4: Click for a larger view

The orange diamond indicates that this track has been panned so that its audio appears to come from behind and to the left of the listener.

There may be times when you want to move the diamond horizontally without changing its vertical position, or vice versa. To accomplish this, use the Move button, which you can see in the upper-right-hand corner of the window. By default, the button shows up in Move Freely state. In this state, you can move the diamond up, down, right, and left. Click the Move button to change it to Move left/right only state. Now you can move the diamond only left and right. Click the button again for Move up/down only state and one more time to cycle back around to Move Freely state.

To reset this track's panning so that the audio appears centered in the room, double-click the orange diamond. Now drag the Center slider to the right. This slider enables you to boost the signal to the center speaker by as much as 12 dB.  This is helpful to bring a little extra something out of a sound that you want to come from directly in front of the listener. You can drag the Center slider all the way to the left to remove the center channel output completely for this track.

You can also mute any speaker in this window. So, say for instance you don't want any sound to come out from behind the listener and to the right. Click the lower-right speaker icon. This mutes that speaker from the system and now no audio from this track can route to that output and, in turn, to that speaker. Click the speaker icon again to unmute it.

You can also choose between several different panning modes. Right-click the Surround Panner window and choose the mode you want from the menu. If you're mixing for film, you may want to use Film mode. The Application Help file contains a good technical discussion of the differences between each of these modes, so you can consult that to decide which mode you want to work with. Or, do a little hands-on experimentation to see which mode gives you the results you're looking for. 

Finally, if you want to send the output of this track to the LFE channel, click the LFE button. This is a toggle switch, so click it again to bring the track back into the regular mix. You'll use the LFE channel to enhance the very low end of your audio. For instance, if you have an explosion in your video, you may want to send the explosion audio to the LFE to create an enhanced rumbling during the explosion. You may also want to have another copy of the explosion on a different track that you're mixing into the regular mix so that your listener can hear the high-frequency sounds within the explosion.

Now that you've routed each channel to the appropriate output on your audio device and you've panned each track to where you want to place those tracks' audio, you can further adjust the audio level from each channel with the controls in the master bus. If you've panned a lot of audio to the left/rear speaker and you like the mix in that speaker, but that speaker is generally too loud in the overall mix, you can use the Left/Rear Surround Master fader to adjust the overall volume of everything (from every track) that's panned to that speaker. Remember, you can always click the Unlock Rear Fader Channels button to adjust the left rear channel volume separately from the right rear.

This article should get you up and running with surround sound mixing. With what you know now, you can create a basic surround sound mix. In Part II of this series (which will appear in a future issue of this newsletter) we'll go beyond these basics to explore automation and other advanced techniques. We'll also discuss the techniques involved in delivering the final 5.1 mixed file for use in your DVD or Blu-ray authoring software.

For more training resources including free training videos, webinar archives, article archives, and more, visit the training section of our website at www.sonycreativesoftware.com/training.

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