Audio Standards for Broadcasting

[Ryan]

I know that Dolby Digital has set standards for the film industry.
-20dBFS = 0VU = 85SPL

Is it true when delivering final mixes (assuming the editor is laying
back to tape), there must be a -20dBFS 1kHz tone in the final mix
(whether digital or not) in order to calibrate the layback machine?

My follow up question is: Are there broadcast standards for audio?
I've heard that it depends on the station. Where can these be found?
And what's the general work flow in terms of delivering audio for
broadcasting?

Thanks in advance

[Mike Rivers]

Ryan wrote:
> I know that Dolby Digital has set standards for the film industry.
> -20dBFS = 0VU = 85SPL

I'm not sure about Dolby, but SMPTE has a standard that calls for
-20 dBFS nominal level with no peaks above -10 dBFS. Monitoring
level is supposed to be calibrated so that -20 dBFS gives an SPL
of 83 dB per channel (which works out to 85 dB with both channels
running pink noise).

> Is it true when delivering final mixes (assuming the editor is laying
> back to tape), there must be a -20dBFS 1kHz tone in the final mix
> (whether digital or not) in order to calibrate the layback machine?

With digital, dBFS is absolute. It doesn't matter where the recording
came from, If it's recorded at -20 dBFS it'll play back at -20 dBFS. That
can represent any analog level to which the playback end is calibrated,
so a -20 dBFS tone is not really necessary.

It's not like an analog recorder where the magnetic field strength at
the record head can be adjusted to wherever the user wants it (as
long as the recorder works that way). We put a calibration tone
on an analog tape at the nominal reference flux level (what equals
0 VU) so the playback electronics can be calibrated to match.

> My follow up question is: Are there broadcast standards for audio?

Oy! If only stations would follow standards! There are FCC regulations
saying how much you can overmodulate, but that's about it.

> And what's the general work flow in terms of delivering audio for
> broadcasting?

These days, usually e-mail them a link to a file or send a CD.


--
If you e-mail me and it bounces, use your secret decoder ring and reach
me here:
double-m-eleven-double-zero at yahoo -- I'm really Mike Rivers
)

[Scott Dorsey]

Ryan > wrote:
>I know that Dolby Digital has set standards for the film industry.
>-20dBFS = 0VU = 85SPL

This is actually a SMPTE standard.

>Is it true when delivering final mixes (assuming the editor is laying
>back to tape), there must be a -20dBFS 1kHz tone in the final mix
>(whether digital or not) in order to calibrate the layback machine?

It's a very good idea, and I recommend it. In some shops, it may be
the standard policy. In others, it won't be. I'd do it anyway, because
it doesn't take much effort and it can prevent finger pointing.

>My follow up question is: Are there broadcast standards for audio?
>I've heard that it depends on the station. Where can these be found?

Ask the station, or the network. A lot of them have actual standards
on paper. Others do not, and have only oral tradition.

Nobody ever got fired for providing a test tone and a tape at 48 ksamp/sec.

>And what's the general work flow in terms of delivering audio for
>broadcasting?

That's also very site-specific. In lots of cases these days, everything
goes into the AVID and then stuff comes out the other end, like a kind
of sausage grinder for video....
--scott



--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Ryan]

Thanks Mike and Scott! Very helpful. If only there was a true standard
life would be sorta easier...

[Scott Dorsey]

Ryan > wrote:
>Thanks Mike and Scott! Very helpful. If only there was a true standard
>life would be sorta easier...

Don't think about it that way. Think instead, "How can I use this confusion
to bill my customer more?"
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[John Williamson]

Ryan wrote:
> Thanks Mike and Scott! Very helpful. If only there was a true standard
> life would be sorta easier...

You could look through this site:-

http://www.bbc.co.uk/guidelines/dq/contents/radio.shtml

Possibly not terrifically relevant if you're in the USA, but the BBC
have been doing this for over fifty years.

For final delivery, you need to liaise with your client as to which
format they want.

--
Tciao for Now!

John.

[Geoff]

John Williamson wrote:
> Ryan wrote:
>> Thanks Mike and Scott! Very helpful. If only there was a true
>> standard life would be sorta easier...
>
> You could look through this site:-
>
> http://www.bbc.co.uk/guidelines/dq/contents/radio.shtml
>
> Possibly not terrifically relevant if you're in the USA, but the BBC
> have been doing this for over fifty years.
>
> For final delivery, you need to liaise with your client as to which
> format they want.

I recall hearing about another dialogue normalisation standard of -23dB
averaged over the course of a whole program ...?

geoff

[Ryan]

On Jul 29, 11:09*pm, John Williamson >
wrote:
> Ryan wrote:
> > Thanks Mike and Scott! Very helpful. If only there was a true standard
> > life would be sorta easier...
>
> You could look through this site:-
>
> http://www.bbc.co.uk/guidelines/dq/contents/radio.shtml
>

Thanks John! Yea I AM in fact looking for something like that BUT for
the USA. That's nice of the BBC to do that :)

[John Williamson]

Ryan wrote:
> On Jul 29, 11:09 pm, John Williamson >
> wrote:
>> Ryan wrote:
>>> Thanks Mike and Scott! Very helpful. If only there was a true standard
>>> life would be sorta easier...
>> You could look through this site:-
>>
>> http://www.bbc.co.uk/guidelines/dq/contents/radio.shtml
>>
>
> Thanks John! Yea I AM in fact looking for something like that BUT for
> the USA. That's nice of the BBC to do that :)

The advantage of having a state controlled broadcaster that used to be a
monopoly. Most of the commercial stations here use the BBC standards for
source material (In theory, anyway.)

The BBC were told to open up to receiving material from independent
producers a while ago, so they published their internal documents to
help keep up standards, saying that if programming didn't comply with
their technical standards, it wouldn't be accepted. At one point, they
even refused to accept programming on CD-R not written to their own
approved discs.

--
Tciao for Now!

John.

[Peter Larsen[_3_]]

geoff wrote:

> I recall hearing about another dialogue normalisation standard of
> -23dB averaged over the course of a whole program ...?

That's in the ballpark - perhaps on the high side - for natural vox humana.
I posted something on this a loooong time ago.

> geoff

Kind regards

Peter Larsen