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Fifty Cent Tour: Broadcast Safe Audio
So…I’m trying my hand at producing content for broadcast TV. So far, so good. I have one show on already on a local Fox affiliate and I’m getting lots of encouraging comments.
Now…here’s my dilemma. I’m shopping my show around to other stations. Several stations have expressed an interest, but what I know I need help with is audio. Setting audio levels in Sony Vegas is as clear as mud.
So I understand that every station has its own audio standards and I know I’ll need to ultimately consult with each one on their requirements. BUT! Is there a standard MANY stations go by? I’ve read here and elsewhere about a -12dB rule of thumb. Can anyone tell me about that?
What I want to do is prepare so demo DVDs of the show, but I want to make sure I set the audio to a level that is at least in the ballpark. I put together a demo DVD for one station and the prograaming director said it looked good but the audio was way too hot.
So…is -12dB a reasonable rule of thumb I could follow?
And can anyone give me a quick, down and dirty fifty cent tour of how to establish such an audio standard in Vegas?
Thanks, guys! Thank you so much for all your help.
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18 Replies
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With the help of others on the forum I’m able to produce a PBS television series so I know what you’re going through about the audio.
I’ll tell you what I do and maybe other can jump in.First of all, (at least with PBS) they require that the entire program have an average audio level of -24dB. So how you figure out the average? Well, there’s a free program called “TB EBULoudness”. With that you run the entire show and watch the “intergrated loudness” meter. PBS wants -24dB but allows anything that 2dB either way. If you decide to get this meter, let me know and I’ll try and help you set it up as there are configurations.
But before I do that, on each audio track with voice I set my “track Compressor” for -24.0
Then on my master FX I set the Waver Hammer for -6.0dB. This keeps any audio from going over limit.
That’s about all I know. Hopefully others will jump in. I know it’s a huge issue. At least it was with me getting started.
Roger Bansemer – PaintingAndTravel.com
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Thank you so much, Roger!
So you know my pain.
I’m trying to “fake it ’til I make it.”
I just don’t want to “fake it ’til I blow it.”
So…a few questions:
>> But before I do that, on each audio track with voice I set my “track Compressor” for -24.0.
How do I do this?
>> Then on my master FX I set the Waver Hammer for -6.0dB. This keeps any audio from going over limit.
Isn’t this what the compressor does?
I am so confused.
I am such an audio newb.
Why is audio seemingly so much more complicated than video?
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Whether to apply compression and how much compression to use is an artistic choice. It’s fine for dialog and narration but may destroy the impact of dramatic sound effects and concert music.
-18 dBFS (or -20 or whatever) is a REFERENCE level. That’s where you put your reference tone. Average program material is supposed to peak near this level. Exceptional program material may be much softer or louder. Every distribution channel has its own standards.
In the U.S., average program level is now governed by the CALM Act. It mandates a target level of -24 LKFS for the “anchor element” of a program (normally dialog but could be music in a concert format). LKFS is based on perceived loudness and is not the same as dBFS. You need special meters or analytics to evaluate it.
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>>-18 dBFS (or -20 or whatever) is a REFERENCE level. That’s where you put your reference tone.
Yikes! What does that even mean? This is a language I don’t understand. What is a “reference level”? What is a “reference tone”? How do I “put” one in Sony Vegas?
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Also called alignment level, reference level is a way to match audio levels between programs from disparate sources. In the analog days, the absolute level could be very different depending on the type of tape and recording equipment used. If everyone puts a test tone at the head of the recording, and then their program material relates to it in a predictable way, it’s possible to adjust each playback to the same absolute level.
There is much less need for tones now that we are using a digital scale but it’s still in the specs for some outlets. If you are required to put a test tone on your submission, you will need to generate a file in another program and then bring it into the timeline. I make tones in Adobe Audition; there are freeware program to do it, too.
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The “compressor” … setting the threshold at -24dB is the limit that PBS allows. This means that nothing will be compressed until it goes above -24dB. The “Amount” setting in the compressor sliders should be set from somewhere between 2 (meaning 2 to 1) and 3.5 (3.5 to 1)
The thing to remember is that the higher the compression (3.5) means that louds will become softer and the softs will become louder. Higher compression means less dynamic range.
So, in other words, if someones talking sort of loud and then their voice drops off to sort of quiet, the compressor will boost that low voice up and drop the loud voice down to even them out. I use to adjust all my volume levels with the volume envelope but this basically does that for you. Then the “Wave Hammer” keeps anything from going over a certain level so you are assured that nothing ends up with a volume over a certain limit. I put the compressor on the track level. Then the wave hammer goes on the master track.
This is how I have mine set up and I can thank John Rofrano for all the help that I’ve gotten about this and I’m just trying to pass some along.
Roger Bansemer – PaintingAndTravel.com
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I’m confused on some of this as well.
Can someone explain to me in the Track Compressor dialog the following:
1) What does Input Gain mean?
2) What does Output Gain mean?
3) If I take the Threshold to say, -24db, what does that do? Do that mean that whenever the sound level goes ABOVE -24db that it will compress (ie, lower) the sound? If so, is it the INPUT or OUTPUT level that determines when the sound gets compressed?
4) What exactly does the Amount (x:1) mean? If I set it to 2 or 3, that means 2:1 or 3:1 of what?
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Input Gain is a constant level adjustment made before the compressor does any work. Output Gain is a constant level adjustment made after the compressor does its work. The threshold is the level at which the compressor begins to squeeze the dynamic range by the amount specified.
For example, if you set the threshold to -12 and the amount to 5:1, any audio below -12 will be unaffected. A peak of -7, 5 dB higher than the threshold, will be reduced by a factor of 5 and become only 1 dB higher, or -11.
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[Norm Kaiser] “I’m trying to “fake it ’til I make it.””
With all due respect, there is no “faking it” in the broadcast industry. They are going to put your submission under a microscope (literally using scopes and meters) and reject it if it’s out of compliance. They will send you a report with lots of numbers on it and expect you to know what to do to fix it. If you don’t know what you’re doing, you might want to hire someone who does until you learn. You’re asking the right questions, but unless you understand audio, you might not understand the answers. That shouldn’t stop you from asking more questions.
Every station is going to expect your show to start with bars and tone. They will tell you what level the tone must be, how much black should be before it, how long the bars and tone should be displayed for, and how much black should be between the bars and tone and the program content, and how much black should follow the program content.
Broadcast Audio is measured by average perceived loudness and peak levels. You need to handle both. Vegas Pro does not have a loudness meter so you’ll need to buy one or use the free tool Roger uses. Audio is also additive but not in a linear fashion. You asked why do you need a compressor on the master audio bus if you have one on the track. If you have more than one audio track (e.g.., dialog and music), they will be added together and get louder and nothing will control the overall volume unless you also handle it at the master audio bus. It’s a delicate balancing act.
You might want to read the PBS Technical Operating Specifications to get an idea of what broadcast stations expect. The main take away from that particular document is that PBS expects a -20dBFS reference tone with no peaks to be above -10dB and your average program loudness to be -24 LKFS +/- 2dB. You’ll need a loudness meter that can read ITU BS.1770-3 levels (Vegas Pro doesn’t have one). Also, if you have any audio that is out of phase your show will be rejected so you’ll need a phase meter as well (but most good loudness meters include this).
Why is audio so complicated you may ask? Because you’re not an audio engineer! lol Audio is quite simple to an audio engineer. It’s complicated for a Videographer, but then I wouldn’t hand my audio engineer a video camera and ask him to shoot a documentary either. 😉
~jr
http://www.johnrofrano.com
http://www.vasst.com -
John, your right about all of that for sure. The good news is that I not knowing anything about producing a television series have done so with the great amount of selfless help from everyone on this forum, especially you. Without all that it would never have happened and now we’ve produced over 80 PBS shows. Amazing!
So Norm, don’t give up. It takes a lot of persistence. I can tell you that.Roger Bansemer – PaintingAndTravel.com
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