Audio Level Metering Calibration On ATEM Mini Pro

I'm trying to calibrate line level signals coming into an ATEM Mini from a mixer, but I'm unsure about how the metering levels displayed on the multiview and in the ATEM software relate to input signal levels.

According to the ATEM Mini Specs, the maximum input level for the 3.5mm inputs is +6dBV and based on other forum posts from Gary, the nominal level when set to line is -15dBu, but the meters just show a scale with 0 at the top. Is this a dBFS scale? How does this relate to the input voltage levels? Also, the faders have +6dB of gain above unity, is that pushing the level above digital full scale? Essentially, if I want to calibrate a level from a mixer, where should the meters be on the ATEM side?

Any help would be greatly appreciated.

Thanks
Alex

Yes, I believe the ATEM audio meters use a dBFS scale which show the digital audio levels after any analog to digital conversion of the inputs.

With dBFS, you can't exceed a level of 0, and if you reach it, it indicates that clipping has occurred. But if you are working with signals that you know are going to be consistently below this level, you could probably boost them to get closer to the target range.

Television broadcast specs typically use an alignment level of -20 dBFS or -18 dBFS (depending on the country), but for web content people will often use higher levels, I believe to compensate for the fact that people are often watching on laptops or mobile devices with relatively weak speakers.

Some additional discussion in this thread:
viewtopic.php?f=4&t=87826

My experience with the Mini Pro is different for voice than music. For voice the meter seems reliable. For music, the meter is erratic and the max level to run at and prevent clipping is the yellow/red boundary. If we go much into the red, even without maxing out, I can hear distortion in the output.

I have sat and watched the meter many times during music, it often misses obvious music peaks but not so for voice peaks.

HTH

Essentially, if I want to calibrate a level from a mixer, where should the meters be on the ATEM side?

Short answer, 0db on audio mixer's meters = -18dbfs on the Mini's.

The Mini's inputs are line level -10 versus the mixer's +4. If you make the adjustment on the Atem Mini side, signals coming from the desk that meter over roughly -8db will clip. The attenuation must come from the mixer side to prevent clipping. Using pink noise to calibrate will avoid any issues with the attack speed or differences between meters.

Good Luck

Thanks for all the helpful info. All ATEM meters are definitely dBFS meters and reducing the input gain to -12 (coming direct from a +4dBu XLR with a max output of +18dBu and all signals at unity) seems to align to just about full scale. However from a listening point of view, it does sound like the ATEM is starting to distort a little before that point. Admittedly there's no impedance matching or other level matching beyond setting the mixer fader levels in my tests so far. I've got a high quality transformer and am going to pick up an electrically balanced matching converter to test more.

I suppose for what we're doing (which will alas involve pushing music that's been limited and peaking just under full scale, way above traditional broadcast standards, in peak terms anyway) it's a bit tricky.

A S/PDIF input would have been great. Or at least, adding audio delay controls to the HDMI inputs so that AES or S/PDIF could be embedded into the HDMI feed without the need for an external delay unit.