LM5D: Correct way to meter a proper dialnorm value

Question

I'm in the middle of a 5.1 channel surround mix which is destined to be encoded to AC3 DD. I'm wondering what is the correct procedure (using LM5D) in metering a proper dialnorm value? Also, how should the LM5D be set in the preferences?

Answer

If your main concern is -

1) To get the AC3 metadata correct, you should load the EBU R128 preset. Note that the unit field on the Radar page should show "LUFS". (You might also load the EBU R128 LU preset, but that wouldn't give you a direct number to enter as the Dialnorm value. The LU preset shows Program Loudness relative to -23.0 LUFS, and the unit field then shows "LU" rather than "LUFS").

  • Reset the meter,
  • Measure the program start to finish,
  • Enter the number shown as Program Loudness as the dialnorm number of that program.

If your main concern is -

2) To comply with EBU R128 based delivery specs, load the EBU R128 LU preset. Note that the unit field on the Radar page should show "LU".

  • Reset the meter,
  • Measure the program start to finish,
  • Gain normalize the program based on the Program Loudness number. If Program Loudness shows, for instance, -1.6 LU, apply +1.6 dB of static gain to the program, and it will now be on target (-23 LUFS).
  • Enter -23 as dialnorm number when transmitting the program.

If your main concern is -

3) To comply with ATSC A/85 based delivery specs and fixed metadata, it gets ambiguous as ATSC currently is not clear on whether to use an ungated BS.1770 measurement (BS.1770 and BS.1770-1), or a gated measurement like EBU, Japan, Brazil and others (BS.1770-2). From a standards point of view, BS.1770-1 is no longer in effect, only BS.1770-2 is.

I would recommend using the best metric from an audio point of view, which currently is BS.1770-2. I would therefore load the EBU R128 LU preset and change target level on the Pref page to -24 in order to have the radar reflect US operating level. Note that the unit field on the Radar page should show "LU".

  • Reset the meter,
  • Measure the program start to finish,
  • Gain normalize the program based on the Program Loudness number. If Program Loudness shows, for instance, -1.6 LU, apply +1.6 dB of static gain to the program, and it will now be on target (-24 LUFS).
  • Enter -24 as dialnorm number when transmitting the program.

If your main concern is -

4) To comply with ATSC A/85 based delivery specs and floating metadata, it's still ambiguous for the reasons given above.

I would again recommend using the best metric from an audio point of view, which currently is BS.1770-2. I would load the EBU R128 preset and change target level on the Pref page to -24 in order to have the radar reflect US operating level. Note that the unit field on the Radar page should show "LUFS".

  • Reset the meter,
  • Measure the program start to finish,
  • Enter the number shown as Program Loudness as the dialnorm number of that program.

Share this page