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Audio reference tone

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John Hammond
Audio reference tone
on Jul 13, 2009 at 12:23:11 pm

Hi,

I am sending an uncompressed image sequence and a .WAV file to a post house to get it transferred to DigiBeta tape.

My Channel 4 Delivery Guidelines are asking for an audio reference tone at 1-kHz at 0dBu (-18 dBFS, PPM4).

In Adobe Premiere there is a reference tone effect, but the help states that it is: 1-kHz, 12dB referenced to 0 dBfs.


What should I do - Should I change the level of the Premiere tone? Do you know anywhere where I can download a correct tone, or instructions for making one in Premiere?

Pointers appreciated,

John






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John Hammond
Re: Audio reference tone
on Jul 13, 2009 at 1:00:15 pm

Quick update:

I have found what seems to be the right audio signal.

http://www.stevengotz.com/referencetone.htm

For now I am going to trust this.

So, now I need to adjust the audio file I have been given, changing it's level so that it matches the reference tone (else the ref tone is pointless, right?)...

Forgive me, I am new to preparing things for broadcast. Also, I am not in control of the audio - I have just been given a finished track and I know the people that created it aren't familiar with making sound for broadcast, so I will probably need to level it..


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John Hammond
Re: Audio reference tone
on Jul 13, 2009 at 2:51:10 pm

Ok I have set my audio levels to peak at -10 dB.

The channel 4 spec sheet states:

"Tapes must start with a line-up signal consisting of at least 1 min of line-up reference comprising: Video: 100% colour bars"

100% colour bars? this seems to contradict what a lot of googling says, which is to use 75% as standard in PAL countries.

I guess if the delivery spec sheet says 100%, use 100%. Not sure what the native color bars in Premiere are supposed to be. I think I read somewhere though that they were rubbish and shouldn't be used...?

I'm slowly working through all this stuff but could do with someone telling me if I'm on the right lines!


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maurice jansen
Re: Audio reference tone
on Jul 13, 2009 at 4:51:48 pm

well

let the posthouse do the lineup part and let it normalize your audiotrack. they have the tools to do this if you don't have good meters don't burn your fingers !!
if they specify 100%bars give them 100%bars. i guess the PostProduction company can help you give them the channel 4 spec sheet and ask for a Broadcast master. yes they ask more money for that but doing things twice will cost you more.

greet
Maurice


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