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Old April 13th, 2005, 11:31 PM   #1
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What is "0 tone" (for broadcast)?

I'm preparing to shoot my first broadcast spot. A TV station has the following requirements:

"Lengths:
30s should be 29.5
10s should be 9.5 to avoid possible downcuts.

Tapes should have bars for :60, 0 tone, slate for 10, black for 10, followed by spots.

Multiple spots should be proceeded by slates with spot numbers and length info."

Is 0 tone a frequency, audio level in dB, or both?
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Old April 13th, 2005, 11:49 PM   #2
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1- 0 tone probably means that whatever tone you put on the tape, they will use that as a reference level for 0VU (analog). Typically tone is at 1000hz, although sometimes you will run across 400hz. (I could be wrong though... I've never made a broadcast master. But I don't see what else they can mean by '0 tone'.)

2- What format are you mastering on? (What formats do they accept?)
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Old April 14th, 2005, 07:53 AM   #3
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Tim: I've moved your thread to our audio forum since I think you'll get a better response there.

My knowledge of audio is extremely limited, however I think they want a 1000hz tone as Glenn describes which will be used to calibrate their analog equipment. The level of this tone on your tape will require a judgement call based on the nature of the audio. As I understand, the standard would be to set it at -12dB in your NLE software. However, if your program has a large dynamic range then -18dB or -20dB may be more appropriate.

If you're using FCP then have a look at the audio section in the user manual. It discusses this in some detail and offers good suggestions. FCP - and other software I'm sure - should provide a way to insert "Bars and Tone" into your video. Using this feature you should also be able to set the volume of the tone to the desired level.
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Old April 14th, 2005, 08:24 AM   #4
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I think they mean "Zero" analogue level. Since most TV stations are still utilizing analogue masters, then the 1000hz tone is set to Zero for level calibration.

On most digital systems, that would be 14, but on some, 20.

At least, that's the way it worked 'back in my day'.
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Old April 14th, 2005, 10:23 AM   #5
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Thanks

Thank you, everyone, for your prompt replies.

Glen, oddly enough they didn't tell me which media they accept. I asked but they didn't answer. I'll ask again.
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Old April 14th, 2005, 11:52 PM   #6
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In your NLE, it's very important to set your levels right for tone and for everything else.

You should do your mix so all the important sound falls within a narrow-ish dynamic range. This is so everyone in your audience can hear the dialogue and music. Keep in mind:
A- A majority of your viewers can only hear mono sound. Ideally you could build yourself a mono test switch... see Jay Rose's book Audio Postproduction for Digital Video. Or a not-so-elegant workaround is to export a mono mix and just listen to it quickly. Check that sound elements haven't disappeared because they are out of phase, or that there isn't flanging/phasing (if you don't hear anything weird, then you're set).
B- Many people's TVs have crappy speakers. They may not be able to hear low bass or high treble.
C- Many people have background noise while watching TV (i.e. dishwasher). This is why you need to have the important sound fall within a narrow-ish dynamic range. One way to check this is to step outside your room and listen through the door.
D- Don't use headphones for mixing. They can be useful for noise reduction, dialogue editing, maybe EQ/compression, live recording, but never for mixing (for audio post).

Once you got your mix right, you need to have it at the right level for output. What level you set tone at in your editing system depends on your output format. It's usually -12dBFS OR -20dBFS or it doesn't matter too much if it's betaSP/analog. dBFS refers to decibels within digital formats, and doesn't apply to the analog domain.
Whatever you set tone at, generally the average volume level should be hitting around there and peak audio should not be 10dB more than tone.

i.e. digibeta and other pro digital formats: -20dBFS tone, -20dB nominal level, peaks should never exceed -10dB (peaks should probably be lower).
mini-DV: -12dBFS tone, -12dB nominal level, peaks should never exceed -2dBFS.
analog: Different animal.
delivering for theatre is different. the figures above are for broadcast.

Most but not all editing programs have decent audio metering. There should be a line that only gets pushed up but never falls down. That line indicates what level your peaks are.
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Old April 15th, 2005, 12:36 AM   #7
 
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http://www.creativemac.com/2003/02_feb/tutorials/analog_dv_levels.htm

The ATSC standard for tone is 1K, -20dBFS. Length is determined by the broadcasting station standard.
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