The DialNorm value of the AC3 stream for a commercial should be the positive integer of its LKFS reading, as set out in section 4.
At some point, you’ll need a metering solution to measure LKFS so might as well sort that now. That is laid out in section 5 of ATSC a/85. For commercials, that doesn’t work so the overall level in dB LKFS is the level used to set it. Originally, you’re supposed to set it to the average dialog level of the encoded program, as read in dBFS. It’s a boring but important read.Īs Wikipedia will tell you, Dialnorm is the meta-data parameter that controls playback gain within an AC3 stream. All the theory is laid out in this year’s most gripping thriller read, ATSC a/85 ( ).
#Air video server hd ac3 tv#
Broadcasters, set-top box manufacturers and TV manufacturers are all at a slightly different step of this process and the results can be quite unpredictable, as you’re learning. We’re in a bit of a transitional period with regards to broadcast digital audio right now with the imminent implementation of the CALM Act in the US. I think all the troubles are related to the Dialog Normalization (DialNorm) data point of the AC-3 mixes. I wondered if the reason the same ad on the same network having two different output levels might be because the file that is airing has more audio information/channels than some TVs (mine) can output.ĭoes that make any sense? Might Dolby files have that ability? There are, as you listed, a LOT of factors between the head end and that TV. In my office, the ads are exactly the same level.Īt the customer’s home, the ads on the same network are much louder. The frustrating thing is, the relative volume of our inserted ads compared to the programming (cable shows) on the networks is different. As well as searched their TV menus to see if there were any audio settings that may fix the issue. I have visited a few and heard the problem. The loudness reports are coming from customers and some employees who are seeing the ads at home. I am working on getting a flat screen in my room so I can test multiple monitors on one box. One other point to consider is what connections are being used and how the signal gets into the TV, is processed, and gets to the speakers.Ī number of things, I know, but I figured I would try to put them all on the table for you. If it doesn’t, then you know it’s the TV. If the issue transfers with the box, you know where the problem is. Try hooking up the CRT TV’s cable box to the “modern” TV and then vice-versa for that TV’s box (but only test them one at a time). Also, realize that sometimes these settings are source-dependent and are independent of each other.ģ. Make sure these aren’t set to one extreme or the other. All the “modern” televisions I know of allow for some adjustment of the volume and rudimentary EQ adjustment.
Take a look into the settings to see which is selected for each box.Ģ. First, a question: when viewing program material (not commercials), is there still a disparity in levels between the two tv sets? If so, then you’re got a few more places to check.ġ.Most set top boxes allow the user to select fixed volume (used when there’s a central receiver unit) or variable volume control (when the TV is already set).
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