Meter scale

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radio42
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Re: Meter scale

Post by radio42 » 22 Sep 2014 15:30

I will put it on the WishList ... to make all meter level displays 'switchable'...or I might add an extra level meter window which can be customized ;-)

Michiel Bouwmeester
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Re: Meter scale

Post by Michiel Bouwmeester » 22 Sep 2014 16:23

Thank you Bernd! Also for the feedback, very nice to get feedback on request and/or remarks :)

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radio42
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Re: Meter scale

Post by radio42 » 22 Sep 2014 20:59

There should not be any signal above! Check any of the professionally used software (Nuendo, Pro tools and such) None have metering above 0dbfs.
That would be nice ;-) But when using high-resolution 32-bit floating point precision, this can actually happen ;-)
Nuendo, Pro Tools etc. just clip this before in their display; but internally it happens as well, also in Pro Tools, Nuendo etc. - be assured, they just do not visualize it ;-)
Also ProTools etc. are mostly used
I would like to see meters calibrated to 0dbfs
The PF meter is calibrated to 0 dB FS. Meaning a 0 dB value is displayed exactly at 0 dB!
There is actually nothing more to calibrate with a meter display, except that it displays the exact values at an exact position. And this is what the PF meters are doing!
A simple "over" is more then enough
Maybe for you. But not for me and others.
No you calibrate the meters and then adjust the audio processing to the propper level
I guess you are wrong. See above... a meter must display the exact values at an exact position, there is nothing to calibrate with a meter! We are digital here and not analog!
...and people will try to push levels above the 0 dB mark on the current meters
Why should that be? Do you assume any user is dump? I guess almost every user will understand, that ANY LEVEL ABOVE 0 dB MIGHT LEAD TO DISTORTION. It is that simple... people who do NOT understand this should not work for a radio station ! ;-)
And I still disagree, as I have seen many people also pushing a 0 dB FS meter by far!
Why?
Pretty simple: In the analog world most meter have been designed, so that the overload indicator should only lit for a few times to be perfectly leveled...so they do the same with a 0 dB FS meter...they increase the level, so that overload indicator only lits sometimes, but not constant.
BUT in the digital world, this is total wrong! It should NEVER lit at all!
So to my mind a 0 dB FS meter does not solve your problem!
You can only solve your problem by teaching people - that's all.
For the advanced user this might be true, for 95% of the others it is not
Now you are inconsistent with yourself!
Above you say: " in a good setup it simply should never be lit"...but a good setup requires an advanced users!
In my mind this is like this:
ANYONE should be able to level his sound correctly, else he is untrained, inexperienced and should not work at a mixing console (note that in 99% of the times it is not the audio file being leveled incorrectly; but its mostly the MIC being leveled too high!).

So here a meter going above 0 dB helps the un-advanced, but trained DJ!
He knows (must know), that a level should NEVER go above 0 dB ... but often he does not know 'how much' he has to lower his level.
With a meter going above 0 dB, he directly can see this...easy.
With a meter stopping at 0 dB he can not see this and must try and error.

And this MIC leveling must be done every day! I don not know how you do it, but the first thing I learned at a radio was, that EVERYTIME I place myself infront of a MIC, you MUST level your MIC! This because your voice is differently loud everyday, no more! every time you place yourself in front of the MIC!
So the first thing you must do when you sit down at a MIC is: LEVEL your MIC according to your current voice level!

And as you do this 'MIC level calibration' EVERY TIME someone sits down in front of a MIC - my personal opinion is, that a level meter going above 0 dB helps.
But...as said, it is a personal taste...

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Re: Meter scale

Post by radio42 » 26 Sep 2014 12:11

Hi Michael,

I tested a bit more and also implemented a (new) peak level meter using a 0 dB FS scale plus an overload indicator (orange = near overload between -0.2dB and 0.0dB and red = overload above 0.0dB).
While testing all this I must agree, that this level meter was indeed more easy to read/understand and due to the new overload indicator it more clearly showed situations in which the soundcard (output) might clip the audio samples (which might result in distortion).

So I am going to implement these new 0 dB FS level meters into the next version!
So you convinced me... ;-)

Even though, I am pretty sure, that this will add new confusion! ;-)
Why?
Pretty simple, while testing, I noticed, that most modern lossy encoded tracks (e.g. newer iTunes m4a or mp3 tracks) are 'oversampled' - meaning, while decoding them using 32-bit floating point precision (which is the default in ProppFrexx) you'll notice, that they contain sample data above 1.0f resp. below -1.0f (meaning above 0dBFS)!!
And this fact will let the (new) overload indicator lit quite often (even in red).

So before people argue, that this is impossible, incorrect, whatsoever, I must explain, that this is totally correct and unfortunately normal!

Due to the current 'loudness war' most newer encoded tracks are actually mastered and encoded in such a way, that they contain 32-bit floating point sample data (when decoded again), which are above 0dB ! This also means, that they are potentially clipped in your soundcard's output. In most of these cases, the average human ear does not recognize this - that why they are mastered/encoded this way - simply to sound loud...

But here is also the technical background of it:

There can be 2 reasons of spikes going beyond 0 dB FS:
1. Regular digital peaks. 32-bit float or mp3/m4a files can store signals that go beyond 0 dB without immediate clipping!
2. Intersample peaks. Even when all digital samples are limited to 0 dB, the analog waveform may still go 0.2–0.5 dB (or more) beyond that level.

As said most mp3/m4a files contain both (1) and (2) !

As ProppFrexx's internal processing is fully 32-bit floating point precision, crossing 0 dB means there's a headroom above 0 dB - so internally there is no immediate clipping or distortion!
But when send to the final output (soundcard) it might get clipped...

If it is (1), then these peaks are quite important for the sound of the file, because you should then reduce the gain and bring these peaks below 0 dB to avoid clipping in your final output!
If these peaks are only of type (2), then they probably don't affect the sound significantly, because most DACs (in good soundcards) have some headroom (above 0 dB FS) to play them properly.

So do NOT wonder, if you play your mp3/m4a files even without ANY FX/DSP/VST but still see the overload indicator blinking (even in red)!

As a good advice, you might want to enable the ProppFrexx ReplayGain feature and activate the Normalization function with it (set the mode to 'Normalization' or 'ReplayGain+Normalization') - as this automatically applies the gain and bring these peaks to max. 0 dB FS.

Michiel Bouwmeester
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Re: Meter scale

Post by Michiel Bouwmeester » 27 Sep 2014 07:59

Hi Bernd,

I must say you have explained my whole argument in a suburb way here. Respect, I could not have done it like that!
Thank you for making these adjustments!

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Re: Meter scale

Post by radio42 » 30 Sep 2014 12:04

The new v3.0.14.16 now implemented real 0 dB FS scale level meter incl. an overload indicator as explained above!

Michiel Bouwmeester
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Re: Meter scale

Post by Michiel Bouwmeester » 30 Sep 2014 18:15

Suberb job Bernd, thank you!

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