With the wide variety of different audio mediums, there are certain requirements expected for each mix. Mixing for television, film and DVD require a different approach than standard music mixing.
Here I will discuss some of the guidelines specific to each medium.
Instructions
1. Movie Theater
There are no guidelines in terms of average loudness, peak or level measurement. You can attain proper levels by calibrating your listening environment so that it resembles the environment of a movie theater.
However, there is a maximum loudness level for theatrical trailers and commercials which is measured with the Dolby Model 737 Soundtrack Loudness Meter.
Trailer loudness should not exceed 85 dB Leq(m), as regulated by TASA.
Commercial loudness should not exceed 82 dB Leq(m), as regulated by SAWA.
2. DVD
The same rules apply as with the theatrical mix with the exception of monitoring (near-field, no X-curve), the room is smaller and calibrated lower and there is the dial-norm parameter if the mix is AC3 encoded.
You have to determine your target dial-norm before beginning the mix, so you can adjust your listening level accordingly. Most DVDs are mixed for dialnorm -27dB (most compatible with the theatrical mix); many will use the full dynamic range (-31dB).
3. TV Commercials
You'll have to get the specifications of your target TV channel, but you will most likely use only the max peak value they provide. With this in mind, you can compress as much as you'd like. TV commercials are very much like pop music CDs. It's a loudness war.
4. TV
Reference level is used for equipment alignment and does not have a direct relation to actual mixing levels.
In EBU countries it is: -18dBFS. In SMPTE countries it is: -20dBFS. This is often refered to as: Zero level, Line-up level, 0VU.
Maximum Peak Level is where you set your brickwall limiter so that it will not allow audio to exceed your calibration level.
What can create confusion is when the average dialogue level is not exactly specified.
In a perfect world, you would calibrate your listening environment to the ITU-R BS.775-1 standard (-20dBFS pink @79dB SPL/C/slow), [or EBU 3276 and EBU 3276-S if you are in Europe] and then mix by ear. In that case you would get average dialogue levels at around -27dBFS RMS.
However, with this method, your mix could turn out too quiet, as there's a loudness war in broadcasting, partly due to the loudness of commercials.
