Monday, March 26, 2018

FCPX Audio Meters

 FCPX has a particular audio metering. It scales from minus infinity to +6dB, with intermediary marks at -50dB, -40dB, -30dB, -20dB, -12db, -6dB and 0.
FCPX audio meters showing a 1kHz tone played at -20dB.



FCPX audio meters showing a 1kHz tone played at 0dB.
According to Apple:
"The audio meters show the audio levels of clips in Final Cut Pro and warn you if a particular clip or section of a clip reaches peak levels, which may result in audible distortion.
When an audio clip is approaching peak levels during playback, the level color changes from green to yellow.
When an audio clip exceeds peak levels, the level color changes from yellow to red, and the peak indicator turns red for the respective audio channel or channels. The peak indicators are reset when you stop and start playback.
To avoid having clip volume exceed peak levels, adjust the volume. Although the proper level for a clip depends on the mix, it’s important to make sure that the combined level for all concurrent clips doesn’t exceed 0 dB during the loudest sections."
The Zero being the actual 0dB MAX FULL SCALE. In other words, FCPX has a +6dB buffer up there. Obviously, the absolute loudest sound in your program should not go above zero, even though we have this +6dB buffer for occasional - to be dealt with, or not - incursions.

For film work the median level for dialog is -23dB Full Scale (EBU) or -24dB Full Scale (ATSC-85), on the FCPX meter this translated to a position in-between marks as seen below:
FCPX audio meters showing a 1kHz tone played at -23dB.

A specialized meter display like the YouLean Loudness Meter has  different display for film work, here marking -23dB (the marking can also be set to show -24dB.) Note the YouLean meter has no headroom above zero. That's the absolute max.
YouLean audio meter showing a 1kHz tone played at -23dB.

In practice FCPX meters are fine. Note that they are the PPM kind, not the VU kind. Meaning they show instant Peak values, as opposed to averaged values. For a constant volume sound (like the tones shown above) it's all the same. For dialog which is inherently varying in volume all the time, that's a different story. See below for the same speech displayed on FCPX meter and on the YouLean meter.
FCPX (PPM) meter showing speech played at an average of -20dB.

YouLean (VU) meter showing values for the same speech played at an average of -20dB.

FCPX meters are much more "alive" jumping up and down with huge variation. The YouLean is more tame and tranquil, with limited incursions. Same signal, PPM vs. VU representation.

Starting with a proper range will make the transition into mixing easier. While editing in FCPX it is good practice to have most dialog levels in the -20 to -6dB range, visually "dancing" most of the time in the -12dB vicinity.

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