I think you may be conflating terms. "DialNorm" was something Dolby came up with as a metadata item inside Dolby encoded material. It is not loudness Or even dialogue loudness. The LM100 never measured anything but overall program loudness. It was capable then of giving you a readout in LKFS. It wasn't (yet) smart enough to incorporate further developments in measuring loudness, particularly the BS.1770-2 rec. So LM100 = BS.1770 and then subsequent (smarter) loudness measuring algorithms (BS.1770-2, 3, 4) incorporate a gating measurement to prioritize dialogue loudness, as this is what people are most sensitive to.
CALM started as a way to make loudness normalized between programs and commercials. It relied on BS.1770 at first, and it was clear that was ineffective (hence the revisions). The revisions got incorporated into broadcast specs and measuring devices, but the LM100 is so old it never got there (AFAIK). Everyone had already moved on to plugins and apps to measure, so the revisions were incorporated there. DialNorm was never a part of this, as it was Dolby proprietary metadata and users could only guess at this number, whereas the Dolby head end equipment could assign the number on their own algorithm.
BS-1770-4 is current and very good at measuring loudness with an emphasis on dialogue as a key component. When specs ask for a "DialNorm" number they are assuming that means something to anyone outside of Dolby, and what they really mean to ask for is BS-1770-4. So, for all intents and purposes, read "DialNorm" as loudness measured with dialogue weighting.
I wish the world would stop conflating "DialNorm" (a made up term by Dolby used only in their equipment) and any kind of actual loudness measurement.
On Sat, Aug 19, 2023 at 2:44 AM John Moore <bigfish@pacbell.net> wrote:
That article was very interesting. I think I've had a misunderstanding about Calm and Dialogue Norm. When it all came out and Discovery Channel started rejecting tons of shows that had proven workflow track records I remember attending a meeting to get things straightened out. I have been under the impression that the LM100 box from Dolby was able to discern what was dialogue in the audio signal and that's what was being represented for the dialogue norm reading. This article describes the loudness measurement as the overall perceived loudness without an isolation of what is dialogue in a signal. So did the LM100 actually isolate dialogue in it's measurements or was it just measuring perceived loudness of the overall signal?
The Calm act was explained to me as a way to make dialogue match across different content as one channel surfs and the different dialogue norm specs were to allow for more headroom over the dialogue. IIRC Dial Norm -20 was news, -24 for most content and -27 for Action Movies etc... Later they simplified to making everything -24. I'm not sure where it all stands today so don't trust the figures I just mentioned to be accurate. Can someone clarify this more?
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