[Scott Dorsey]

alex wrote:

This only prevents overs but doesn't say anything about loudness.
Even following this rule i'm still able to produce a very wide loudness
range and the program may appear too loud or too weak compared to other
tapes.

There is in fact now a European broadcast standard, EBU-R128 which tries
to address this. Before EBU-R128 there was only a standard for levels,
not one for loudness.

Note that this is only for broadcast use and if you're delivering an
AC-3 mix to Dolby Digital specs, there are some published DD standards.
The problem, though, is that nobody ever follows them so they don't really
do any good because you are constantly competing with people whose mixes
are too loud.

What i need is to understand where is the common "average" loudness for
a soundtrack and how to achieve it.

My advisor, gus baird, used to have a ten-step "problem difficulty" scale
where a 1 was a question that an undergrad should be able to answer without
thinking and a 9 was worthy of a Nobel prize. The question you have asked
is at least a 7, I think. And the reason it's a 7 is because there does
not seem to be any common average overall, although there might be one in
a single facility or network.

I think that should be a relationship between the program loudness and
the 1kHz tone level, otherwise will be pretty stupid to put the same -20
tone on every digital video tape which is completely unrelated with the
real sound on the track.

The 1KC tone is there to make sure you don't clip anything, it's not there
to make sure that the perceived loudness is the same.

In the old days, there was an control operator at the transmitter who rode
the gain to keep perceived loudness about even. This does not happen any
longer. On top of this, people making commercials always want to be louder
than the programs, and the people making the programs want to be loud enough
that the commercials don't blast viewers during the breaks. In theory
EBU R-128 will help this.
--scott

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