You ever have a problem where the audio levels you recorded for your talent are too low, or vary wildly in level? Yeah, me too. All the time. We can add audio keyframes to each clip and try to smooth things out, but, frankly, life is too short.
Depends on your video's final destination. Based on my experiences: If you're making a TV commercial, the standard in the U.S. Is actually -24 LKFS; this is a measurement designed to keep commercials from overpowering program content (look up 'CALM Act' sometime), and isn't measured on the meters in the timeline or the audio track mixer. Radar di Premiere Pro adalah tool yang kurang digunakan, tetapi akan membantu Anda mengukur kenyaringan audio Anda secara akurat, yang tidak bisa dilakukan oleh level dan waveforms. Baik di Adobe Premiere Pro CC dan Adobe Audition, ada filter khusus - yang disebut Loudness Radar. Loudness Radar adalah alat yang memungkinkan kita untuk mengukur.
A while ago, I discovered some audio effects that can make this task a LOT easier. In this article, I’ll show you how they work in Adobe Premiere Pro CC. (In a second article, I show how these work in Apple Final Cut Pro X.) While the concepts of improving audio are the same between the two software, the tools we use and the workflow we create are different.
NOTE: Personally, while the audio processing effects in both FCP X and Premiere aren’t too bad, I find that Adobe Audition is superior to both. While learning an audio app can be intimidating, the time you invest pays major dividends in making your audio sound really, really good. (Here’s a link to my training on Adobe Audition.) ProTools is another excellent audio package, but I’ve never had success working with their iLok copy protection.
EXECUTIVE SUMMARY
The Multiband Compressor effect is my tool of choice in Premiere for boosting and smoothing levels.
In order to process multiple tracks at the same time, we need to combine them using an Audio Submix track.
Also, while it is a good idea to boost and limit dialog and narration, it is generally not a good idea to do the same with either sound effects or music.
NOTE: Here’s a companion article I wrote that is the second half of the “good audio” equation: using EQ to shape your sound to make it warm up a voice and make it more intelligible.
BACKGROUND
The human voice is an unquestionably challenging instrument to record. Whether singing or speaking, it has a huge dynamic range; meaning that it can vary from loud to soft back to loud in an instant. Sometimes, when you are working with professional voice actors, that dynamic range is fully under control.
Most of the time, we’re just hanging on for dear life.
There are two key rules you need to keep in mind about audio when you are mixing:
- At NO time during export should your audio levels ever exceed 0 dB. Not once, not even for “a little bit.” Never.
- Audio recorded on set is always recorded at lower levels so that there’s no risk of distorting an irreplaceable take.
This means that during our final audio mix, we need to boost soft levels, make the levels consistent so that we can clearly hear what’s being said, yet make sure all levels always stay below 0 dB.
AN ASIDE ON MEASURING AUDIO
Audio pros, and those folks that need to deliver audio for professional distribution (broadcast, cable, or digital projection), measure levels using “average levels,” or the new standard of LKFS. Current standards in both the US and Europe mandate that levels not exceed a specific LKFS level for program content; generally around -24 LKFS.
The audio meters in Premiere measure “peak” levels, which are suitable for web posting. However, hidden inside Premiere is a really excellent Loudness Radar which measures average levels. I’ll show you where it is and how to use it in this article.
WHAT THE MULTIBAND COMPRESSOR EFFECT DOES
What the Multiband Compressor effect does is boost softer passages of audio more than louder passages, without having any audio level exceed the maximum level you specify in the effect.
What makes this different from a Limiter is that the Multiband Compressor boosts different frequencies different amounts, while still limiting the maximum volume of a clip. This tends to provide a richer, more “open” sound, when compared to a limiter.
In our example, this has the effect of making all dialog levels louder with more consistent levels, without any risk of distortion.
There are two limit settings that I recommend:
- -3 dB when the audio you are limiting is the only audio in your project.
- -4.5 dB when the audio you are limiting is part of a mix. This lower level allows more room for sound effects and music to be heard in the project.
NOTE: The reason I don’t limit to 0 dB is that I’ve been told that MP3 compression is optimized for levels around -6 dB. Also, leaving a bit of headroom is a good idea in general.
COMBINE AUDIO TRACKS
Here’s a short dramatic scene containing the following:
- 2 video tracks (Main action and B-roll)
- 2 mono dialog tracks
- Stereo sound effects track
- Stereo music track
The first thing we need to do is combine all the dialog tracks into one submix so that we can apply a single effect to control all our dialog. (This audio submix is often called a “bus” because it carries audio from a variety of origins to a single destination.)
NOTE: There is no limit to the number of buses you can create and, creatively, you may want to create a bus for all male voices, and a second bus for all female voices. I’m keeping this example fairly simple to make the technique more understandable.
With the Timeline pane selected, choose Sequence > Add Tracks > Audio Submix. In this case, we’ll just add one track and leave the rest of the settings at their default.
From the Window menu, choose Audio Track Mixer. This displays the mixer built into Premiere. Notice the names of the tracks along the bottom. To name a track, double-click the text and add the name you want; which is what I did here:
- Dialog L. Dialog from one camera channel.
- Dialog R. Dialog from the other camera channel.
- SFX. Stereo sound effects clips.
- Music. Stereo music clips.
- Dialog. What will become a channel containing all dialog from all tracks – this is the submix track we just created
- Master. The master audio output of the project.
NOTE: If you only have one dialog track in your project, or just one narrator, you can skip this Audio Submix section and go right to applying the filter onto the single dialog track. Submixes are only needed when you need to combine audio from more than one track.
To send the entire output of a track, after the fader, to a submix, click the “Master” popup menu and change it to the name of the Audio Submix channel.
Set this channel Master popup menu to Dialog for both Dialog L and Dialog R tracks.
Click the “S” (for “Solo“) button at the top of the two dialog tracks so that you can hear them, but no other tracks. You have now “ganged,” or “grouped,” all similar audio so that it flows though a single channel, the submix channel called “Dialog.”
APPLYING THE FILTER
If the effect section at the top of the mixer is not showing, it’s a series of light gray boxes, click the small white arrow in the top left corner of the mixer to reveal it.
These gray boxes are divided into two sections:
- Effects. Above the dark horizontal line is where you apply effects.
- Sends. Below the line is where you apply sends. We are ignoring sends for this article.
Click the small dot on the right of the Effects section at the top of the Dialog channel and choose: Amplitude and Compression > Multiband Compressor. (To remove an effect, set this to “None.”)
This applies the effect to the Dialog submix.
The name of the effect now appears at the top of the Effects section.
NOTE: You can apply an effect to any of the five slots at the top of each channel. Empty slots are not a problem. However, effects process from top to bottom, so if you are applying multiple effects, the Multiband Compressor MUST ALWAYS BE at the bottom of the stack. Otherwise, you potentially lose its ability to prevent distortion.
ADJUSTING THE FILTER
To display the filter so we can make changes, double-click the phrase “Multiband C” at the top of the Dialog channel strip. (I will confess that the first time I saw this effect, I panicked. However, there are only three adjustments you need to make to this effect for dialog.)
First, make sure the Preset is set to “Broadcast.” This is the default setting and sets all the green numbers in the filter.
Second, in the Limiter section, set the Margin to:
- -3 dB if you are only mixing human speech with no effects or music.
- -4.5 dB if you are mixing speech with sound effects and music.
Mixing to -3 dB makes your narration louder because it doesn’t need to combine with any other audio elements.
Mixing to -4.5 dB leaves room for other audio in the project to be heard without running the risk of exceeding 0 dB and distorting.
Third, if the dialog audio is very low, increase the Gain (in the Output Gain section) until the audio meters are bouncing above -6 dB and the audio sounds good. There is no specific value to enter. Adjust and watch the meters.
NOTE: One of the benefits to using the Limiter effect in Final Cut Pro X is that it provides visual feedback to help you adjust the effect properly.
MAKING LEVEL ADJUSTMENTS
Keep in mind that most of your audio should sound a lot better as soon as you add the effect. However, for those clips that need extra attention, there are several places you can adjust audio levels.
The first is the Dialog submix channel. However, it is considered good practice to leave the submix channel set to 0 dB and, instead, adjust individual elements.
For example, you can adjust the individual channel slider for each track. The numbers on the left indicate the amount of change you are making to the clip. The numbers on the right indicate the absolute audio level of the audio in that track. (Think of the right-side numbers as audio meters just for that track.)
NOTE: Remember to turn off the yellow Solo button when you want to hear audio from all tracks.
Or, go back to a specific clip in the Timeline and adjust the volume line.
Or, add keyframes within the clip to make precise adjustments.
For the purposes of exporting, an audio submix track acts like any other audio track.
MEASURING LOUDNESS
A benefit to mixing audio in Premiere (and Audition) is that both contain a built-in effect called the “Loudness Radar.”
To apply it, go to the Master track in the Mixer, and add: Special > Loudness Radar.
This measures loudness over time. To see the loudness of your project, play the Timeline and watch the meter.
The basic goal, as I understand it, is to get the LKFS reading to hover around -24; it is displayed in the lower right corner of the display.
The polar chart displays average levels over time. Again, the goal is to get the audio to be close to the second-largest circle. Here, for example, everything looks pretty good, except for a spike that reaches out to the outer edge. To fix that, I would go back to the individual clip and tweak the level.
I’m still getting used to using this meter and will share more about it as I learn more.
SUMMARY
The audio mixing capability inside Premiere is really very nice. I like the ability to create sub-mixes and, given all the regulations surrounding audio levels these days, I’m very impressed with the Loudness Radar.
However, the big benefit to using these effects is that they take the worry out of getting your audio to sound good. The Multiband Compressor boosts soft audio and corrals excessive audio, all while guarding against distortion.
It will take a bit of time to get comfortable using these filters, but I guarantee that your projects will be better for it.
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Any time you’re working on a mix that’s going to broadcast, it’s important to ask for specs. Specs are essentially a set of rules for each broadcaster, such as:
- How loud content can be (overall average and peak levels)
- What format to deliver (files – including file type and bit depth; or tape)
- Specific mix requirements (such as “no music in the center channel”)
Generally there will be a spec sheet for each broadcaster (i.e. ABC, CBS, BBC, etc) that your client will provide when asked. Spec sheets aren’t necessarily public or available online but some are (such as NBC Universal). Some online content providers (like Amazon), movie theater chains, and movie distributors also have specs, so it’s always good to ask.
Background on the average loudness spec
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Before 2012, there used to only be one loudness spec: peak loudness. This was a brickwall limiter placed at the end of the chain. Back then, most television networks (in North America) had a peak level of -10dBfs. From the outside (especially coming from the music world) it seems like an odd way to mix – basically you’ve got 10 dB of empty headroom that you’re not allowed to use.
As long as your mix was limited at -10dB, it would pass QC even if it was squashed and sounded horrible. That’s what was happening, though, especially with commercials that were competing to be the loudest on the air. If you remember running for the remote every commercial break because they were uncomfortably louder, that was the issue.
Average Loudness Level & Audio Plugins That Measure It
In the US, Congress enacted the CALM act which went into effect in 2012 and required broadcasters to reign in these differences in loudness between programs and commercials. The spec that evolved from this was “average loudness level.” A loudness measurement covers the length of the entire piece, whether it’s a 30 second spot or a 2 hour movie. Average loudness is measured through a loudness meter. Popular measurement plugins are Izotope Insight, Waves WLM and Nugen VisLM. Dolby Media Meters was a standard for many years but is no longer being supported.
Important terms and concepts
To understand some important concepts, we’ll take a look at PBS’s most recent specs (2016), found here.
For PBS, it’s a 21-page document that includes requirements for video, audio, how to deliver, file naming, closed captioning, etc. It gets pretty detailed, but it’s a good example of what a spec sheet looks like and the types of audio requirements that come up. The information in the spec sheet will dictate some details in your session, such as track layouts for 5.1, where your limiters should be set, dialog level, bars and tones, etc. We’ll break down a few of these important elements.
PBS Technical Operating Specification 2016 – Part 1, Page 6 Sections 4.4.1, 4.4.2 – Audio Loudness Requirements
The three most important details to look for on a spec sheet are peak loudness, average loudness, and the ITU BS 1770 algorithm. These will be explained in detail below. In this case, the PBS specs are:
Peak Loudness: -2dBTP (“true peak” or 2 dB below full scale). This is your brickwall limiter on the master buss/output of the mix. In this case, it would be set to -2dB.
Average Loudness: – 24dB LKFS +/-2 LU. LKFS is the US standard (under ITU BS.1770) and LUFS is the European standard (EBU).
ITU BS 1770 Algorithm: ITU-R BS.1770-3. This is the algorithm used to measure average loudness.
The ITU developed an algorithm (ITU BS 1770) to calculate average loudness. The latest algorithm is 1770-4 (still used in 2018). In technical terms, loudness is an LEQ reading using a K-weighting and full-scale; the designation for this reading is “dB LKFS”. In the PBS spec sheet, section 4.4.1 and 4.4.2 say mixes should use ITU BS 1770-3, which is an older algorithm. This is an important detail, though, because when you’re measuring your mix, the plugin has to be set to the correct algorithm or the reading may be off. The PBS specs were written in 2016 (before 1770-4 came out). Broadcasters update these every couple of years, especially as technology changes.
In this PBS spec, the optimal average loudness is -24dB LKFS, but there is an acceptable loudness range (LRA) above and below +/-2 LU (“Loudness Units”). Basically that means your average loudness measurement can fall on or between -26dB LKFS and -22dB LKFS, but ideally you want to mix to hit at -24dB LKFS. The measurement plugin will probably show a short term and a long term value. The short term reading may jump all over the place (including beyond your in-spec numbers). The overall (long) reading is the important one. If the overall reading is out of range, it’s out of spec, won’t pass QC and will likely be rejected for air. Or, it may hit air with an additional broadcast limiter than squashes the mix (and doesn’t sound good).
As HD television has become more popular, broadcasters have loosened up on the peak loudness range. PBS is pretty liberal with -2dBTP (or -2dBfs); some broadcasters are at -6dBfs and occasionally some are still at -10dBfs.
The challenges of working with loudness specs
When the CALM Act went into effect, re-recording mixers thought loudness metering would be restrictive to creative mixing. Average loudness is measured across the entire program so there’s still room for some dynamic range short term. Loudness specs can be a problem for certain content, though. For example, if you’re mixing a show with a cheering audience, the cheering is still picked up as dialog by the loudness meter. You could have a spec of -24dB LKFS (+/-2), mix the show host at -24dB LKFS (in spec), but every time the audience cheers the short term measurement is -14dB LKFS. The overall loudness measurement might be -18dB LKFS – which is way out of spec! So sometimes you end up mixing dialog on the low side or bringing down an audience more than feels natural to fall in spec.
Another difficulty of mixing with a loudness spec is making adjustments when your overall measurement is out of spec. A dB of LU (the unit of measurement for average loudness) is not the same as 1dBFS (full scale). If you drop the mix 1dB by volume automation, it’s not necessarily a 1dB change in average loudness. If you’re mixing a 30 second promo and the loudness level is out of spec it’s easy to adjust and recheck. If you’re mixing a 90 minute film, it takes a bit more work and time to finesse the mix and get a new measurement.
There’s software that will make these adjustments for you – basically you can tell the software what the specs are and it’ll make small adjustments so the mix will fall in spec. While this is a good tool to have in the toolbox, I encourage mixers to first learn how to adjust their mix by hand and ear to understand how loudness measurements and metering works.
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Loudness Over Time
When a mix gets QCed, it’s measured for loudness over the entire length unless the spec sheet says otherwise. For a 30 second commercial, the loudness reading will be one value for 30 seconds. A tv show might be the whole program (like 42 minutes) or it might be each act (from commercial break to commercial break). The spec sheet will give that info. A movie will have a single reading based on runtime, etc. So, it’s ok to have dynamic range over the content as long as the overall loudness level is within spec. There will be some dynamic range naturally especially if you have action scenes, music with vocals, and so on. If you weren’t looking at a meter and just mixing, you might mix as loud as -14 and as low as -30 (for short periods of time). The spec sheet dictates the range – like “-24LKFS +/- 2dBLKFS” or -27 +/- 1dB. Usually there’s a couple dB of range around the main number and they measure with decimal points (so -22.0 could be in spec but -21.9 would not).
Tips for working with loudness specs
I find in general if dialog is sitting between -10 and -20dBfs (instantaneous highs and lows) and not over-compressed, the average loudness reading should fall pretty close to -24dB LKFS. When I first started mixing to an average loudness spec, my mixes were often averaging hot (-20 to -22dB LKFS) when spec was -24. My ear had become accustomed to the sound of compressed dialog hitting a limiter on the master buss. What I’ve learned is that if you’re mixing with your dialog close to -24 dB LKFS (or -27 for film) you can bypass the master limiter and it should sound pretty seamless when you put it back in. If you’re noticing a big sound change with the limiter in, the overall reading will probably fall on the hot side.
I’ve tried mixing a few different ways with meters – leaving the meter up all the time, for a while til my ear gets dialed in, or just checking from time to time during a mix. When you have the window up all the time, you do risk making choices based on metrics and not on your ears. At the same time, if you’re just mixing a scene of simple dialog (people having a conversation, no yelling, normal level background noise) having the meter up can help train your ear what that pocket sounds like. Now, when I start a long-form mix (or if I’m working in a room I’m not familiar with), I usually dial in my dialog with a loudness meter visible. I’ll pick a scene or a character and set my channel strip (compressor, EQ, de-esser, noise reduction etc) so the dialog mix lands right on -24dB LKFS. I do this to “dial in” my ear to that loudness. It then acts as a reference, essentially.
One thing I like about mixing with a loudness spec is you don’t have to mix at 82 or 85 dB. While a room is optimally tuned for these levels, I personally don’t always listen this loud (especially if it’s just me/no client or I anticipate a long mixing day). Having a loudness meter helps when jumping between reference monitors or playing back through a television, too. I can set the TV to whatever level is comfortable and know that my mix is still in spec. When I’m mixing in an unfamiliar room, seeing the average loudness reading helps me acclimate, too.
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When there’s no loudness spec
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I mix most projects to some sort of spec, even if the client says there are no specs. For indie films, I usually mix at -27dB LKFS and a limiter set to -2dBFS or -6dBFS (depending on the content). If an indie film gets picked up for distribution, the distributor may provide specs. Sometimes film festivals have specs that differ from the distributor, too. If you’ve already mixed with general specs in mind, it may not need adjusting down the road, or at least you will have a much better idea how much you’ll need to adjust to be in spec.
Article originally featured on Soundgirls.org