Originally Posted by NismoZ
When I switch inputs or sometimes when you FWD, Pause or play again, the receiver says "Dial Norm +4" for a second. Have you guys seen a definition of what this does in the manual?
Dial Norm is a feature of the encoding codecs, both DTS and Dolby.
It was designed to allow content mixed at various levels to be played at closer to relative volume so there aren't great swings in volume between different titles, or shows and commercials...
If you see Dial Norm +4, it means that the volume should be raised 4 db at your calibrated reference to get it back to the level where it was encoded at (the track is attenuated 4 db post decoding.)
The dialog norm metadata doesn't effect the encoded signal, and the way to "offset" (some manufacturers label it at "Dial Offset") the attenuation is to raise the volume 4db (in this case.)
Why use it for films? There really is no reason to use it as there is a strict monitoring standard for mixing films.. so if you play all titles at your preferred reference level, you should get back to the directors intention on any given title. However, the dialog norm setting determines the metadata used by the dynamic range compression technologies ("Midnight Modes") in your receiver when you activate them, so it is important in this respect. (There are also provisions in the metadata to have a title activate DRC automatically, but it's rarely used.)
In practice, very few content providers use the feature accurately (you are supposed to run the track and analyze the average dialog level and generate the dial norm setting from that...) Most people, unfortunately, leave it at the default setting of -27 (the range is from -31 towards zero, hence -27 is 4db away from -31.)...
If used properly, it would be a great asset for television broadcasters as it would equalize the programs from the commercials... but the industry is woefully uninformed in how to properly use it, and it has lead to technologies such as Audyssey Dynamic Volume and Dolby Volume.