I discover the Digicheck 5.3.
Thank for Smpte channel order (L/R/C/LFE/Ls/Rs), correlation inter channels, LFE display and ITU weighting !!!
About this Loudness measure, i used it a lot, those last years, for dialog level estimation with Dolby products : LM100, DP570, Dolby Media Meter (recent plug Loudness meter + logs, graph).
Key point of the loudness measure, is ITU load ok, but,another key point is that this measure need differents averages time possibilities.
Loudness measure is now being included in spec about 5.1 programs for HD TV but also soon for Stereo pgms.(as very well describe up )
Solution choosed by broadcasters is to fix a Loudness Dialog Level, all programs in the future would have quite the same dailog level (but could have gap of dynamic around this) .
The result is that people at home would get better matching listening levels, when changing channels in their hundreds tv channels(DSL, Satelite, Cable..).
Peak levels was the only parameter checked first, in France -9 dBFs was the max peak accepted for Stereo pgms.
Now, dialog loudnesss is checked also and must be - 25 LKFs(-24 LKFs, -23 LKFs EBU P/Loud group), peak for 5.1 musn't exceed -3dBFs in France. (EBU P/Loud group -1dBFs Max)
So french mixers have to work at -25 LKFs, this value -25 (or else), must be an average of all (and only)the dialogs parts on all the program and summing all channels except LFE (at this time). This must be done at the end of the mix, Dialog detection is needed, and log is apreciate.
If dialog auto detection is not possible, we have to make it ourself, summing the averages of differents dialog parts, this with an "Infinite or Long Term Mode" associated with pause button to "pause" measure when no dialog is present, the system make an average of all the parts measured until u reset it with "reset button" (needed also) and a counter gives u the among of time measured .
The second average time most used (not yet normalised as i know by ITU SMPTE, EBU... but choosed in french specs) is called Short Term Mode and have a 10 seconds average window (EBU P/Loud group talk about 10 or 8 seconds). This one is the most important at this time for TV, DVD,mixers. During the mix when dialog present, we have to be near -25 on loudness meter, and on loud or soft dialog scenes we can reach :-25 +/- 7dB.
Then with this Short Term mode we can checked the "loudness peaks" of the rest of the mix with -25 +/- 12 dB LKFs allowed.
KEY point here : The TV broadcasters will verify those gaps: with Short term 10sec !!
And dialog level with infinite Mode and Dialog Detection auto.
So if u want to be shure, ur production will be accepted by the broadcaster QC control, u need to have the same way of meetering.
Working in Short term mode (10sec) during the mix,checking ur -25 dialog level, matches most of the time with an entire final analyse with Dialog auto detection, the gap allowed is +/-2dB at this point (EBU P/Loud group talk about +/-1dB).
This Short Term Mode would be very usefull in DigiCheck with 10 sec window, and if u can :
- Differents gaps for this window (8, 10...etc infinte)
- A special window with only ITU measure (to have only this process runing and save screen place) shown as meter or as Value Window (3 or 4 cm) with Big Numbers so we can put in a corner to get an eye on Loudness.
Last mode is the shortest one, not present in Dolby Meters, it varies depending on manufacturers,(EBU P/Loud group call this mode: Momentary and talk about 100 to 500 ms, ). This is not normalised yet as i know.
After this short introduction (Sorry) some questions :
- What is the actual momentanary time average of ur ITU loudness meter ?
- Do u think possible to make it work, with 10s average Short term Mode or more ?
- May be get logs and graphics ?
- I noticed a difference on ITU metering between front and rear channels:
Test: Send same sample sound or pink noise, on only one at a time of 5.1 channels Surround audioscope ITU.
You'll notice that measure ITU is about 1.3 or 1.4 dB higher when sound is in one off rear channels than in one of front channels.
Anyway this is already great, even if it stays like that i'm happy with for semi pro use at home ITU metering !
With Some modifications it could be used in Pro environement.
Very Good Job Guys !!
