Meter clipping doesn't go red

[jarvic]

Hi Pro Toolers

I just downloaded pro tools 11 few days ago and I connected to it a Zoom H4n portable audio interface (by USB) with a condenser mic connected to the input number 1 of the H4.
The issue is that on protools I can't see actually the red clipping on the track linked to the mic. Instead, I can see on the H4 when is clipping.

How can I see when is clipping by the track's meter of pro tools?

Thank you

[albee1952]

I believe this is a known bug. With digital recording, you should NOT be recording hot. Set levels so the track meters just hit the yellow, and you will be fine.

[jarvic]

Oh! I see.
thank you very much for your suggestion!

[Carl Kolchak]

I don't think it's a bug - it's a technically accurate feature (can't remember if it's new to Pro Tools 11, or goes back maybe as far as PT9).

As you no doubt know, Pro Tools HDX did away with the fixed point mixer, bringing all version in line, with a floating point mixer.

In such an environment, it's possible to exceed the headroom of a fixed point system (whilst "in the box"), and still recover the signal without any degradation.

Again, in a floating point system, depending on where abouts in your signal path the overload is occurring, will determine whether that overload is "virtual" or actual.

For example, if you were to route every individual track of your song to a single Aux channel, it's possible you may be summing so many tracks together, that they eat up all the equivalent fixed point headroom, and overload the Aux channel...

But as we're in a floating point system, you can show the Master Fader for the buss that is inputting the Aux channel, and pull it down until the signal is no longer clipping - without degrading the signal.

In this case, as the clipping is only "virtual", the clip light shows AMBER, as a warning (overloading is occurring, but at this point in the chain is not fatal. Just watch out for it further down the chain).


If on the other hand, you routed all of those tracks directly to the main outputs, the Master Fader clip light would RED, as you are now leaving floating point world, and any clipping is permanent.


At least, that seems to be the behaviour I've observed...

[critictalk]

Correct me if I'm wrong, since PT 11, it comes with 32bit floating point meter design, you may not see any 'red' clipping in the track meter. You better insert a good meter plugin or route your signal to outboard meter to see what happen. Of course, train your ear. Also, make sure you have select correct meter type inside PT. There are VU, classic, sample peak, etc.

[bugnut]

Thanks CK. Great explanation!

[zedhed]

This is a good video for Calibrating your PT11 system.

http://www.groove3.com/str/player.ph...roductid=16493

[DTM]

Hi Guys,

I'm a little confused at this, check my video here.

It shows a normal recording level, then I push the input to distortion, shouldn't it indicate with a red or yellow box that clipping occurs on the input ?

Here it just squares the waveform off without an indication.

https://youtu.be/QWbYbr6CPHw

[Darryl Ramm]

[QUOTE=Carl Kolchak;2178320]I don't think it's a bug - it's a technically accurate feature (can't remember if it's new to Pro Tools 11, or goes back maybe as far as PT9).

Pro Tools 9 definitely shows a classic meter clip indication. This change was after that, I can't remember if in 10 or 11.

[Darryl Ramm]

Originally Posted by DTM

Hi Guys,

I'm a little confused at this, check my video here.

It shows a normal recording level, then I push the input to distortion, shouldn't it indicate with a red or yellow box that clipping occurs on the input ?

Here it just squares the waveform off without an indication.

https://youtu.be/QWbYbr6CPHw

An *input* meter not clipping when you have true digital clipping, that behavior is just a bug as far as I'm concerned. Pro Tools knows this is coming in from a interface at 0dbFS and is therefore digitally clipping. It really should be using the usual way of digital clip detection (looking for actual digital input clipping on multiple sequential samples, maybe with some filtering), as well as maybe optionally allow that level to be lowered in a softer clip type indication.

And that is exactly how it is supposed to work. From the PT 11 Reference Guide....

"Audio track clip indicators display red under the following circumstances, otherwise they display yellow:
• When an audio track is record enabled or set to input monitoring and the input assignment is set to a physical input signal that exceeds 0 dBFS causing clipping at the converters."

In other words, yep a bug.

The intermediate mixing happens with such huge headroom due to the 32-bit/64-bit floating point processing/mixing and there should not be any clipping until you get to the master fader, where there should be similar behavior to the input... it knows when it is digitally clipping.