Import Audio - bit depth changed?

[joachim]

Originally Posted by eheilner

So is there any way of ...Getting horizontal lines to show across the track display so it's easy to see where I'm close to 0 db?

Just an umcomfortable, actually very cumbersome workaround and because you wrote "any way...".:
create a send to an unused bus on the track,
set send level to +9.2dB,
set track view to that send,
one can see the send level line (representing a 0dBfs peak line) and the underlaying waveform.
Does work obviously only, if the waveform height is set to default.

[The Weed]

Is it merely a difference in the height of the waveform DISLPAY, rather than the actual headroom available? I can make my waveforms as small or large as I like, but it doesn't change the peaks/headroom in the audio itself, just the distance away from the top of the track.

If there were a horizontal line in the track that denoted 0dB or a value of our choosing, the waveform height displayed would have to remain constant, or the line would have to move when the waveform display height and/or track height changed.

Cheers,

[eheilner]

The horizontal line moves as the display/track height changes. That's how WavePad works and (if memory serves me) the late lamented Peak Pro.

[janmuths]

To sum it up, you're not dealing with messed up bit resolution or modified levels but purely DAW specific graphical differences.

[JFreak]

Originally Posted by john1192

are you saying that that little line in PT is "0" ... ??

Yes. PT leaves some air on top and below of waveform even if it's maxx'd out distortion.

Originally Posted by john1192

would that mean over the line shows overs ??

No, a waveform must always be represented by zeros and ones in audio file so whatever you can read from file can be represented below 0dBFS.

[JFreak]

Originally Posted by eheilner

I've attached screen shot from WavePad showing what I mean.

Opinions do vary, but I find it very counter-productive to use 50% GUI space for the last 6dB (the last bit) so the way PT shows waveforms has always been very natural to me.

There are 24 (fixed-point) bits available so why would I want to use half of the screen space for the last bit and have the useful 23 bits only get another 50% -- beats me.

Just my opinion though.

[LDS]

Originally Posted by Stig Eliassen

Yes, that's what I'm saying. I regard the gap as visual headroom/separation, and I love it, but I have no clue as to why it is so.

It is actually real headroom in the audio as well. Just grab the clip gain slider and increase the audio level and you will see. The floating point mix engine allows 24 bit audio files to escape their usual 144dB theoretical limitation whilst still in the DAW. It is a different story when you take the audio out of the DAW though (through external inserts, or your DAC).

[eheilner]

Janmuths -
That is correct - it is a display issue. The bits are not getting messed with.

JFreak -
Now that you point this out I too am a bit puzzled, since we're dealing w/ roughly 6 DB per bit. So either we are both missing some technical detail - or the scale in WavePad is not accurate since you would expect a vertical leap from -6 to 0 as it jumps that last bit. That said, the wave forms look identical to me in every respect between PT, WavePad, and Audacity. It was the headroom on the PT display that was confusing me. I would still prefer to have some clearer indication that I am running out of headroom.

To everyone who responded -
Thank you. It is gratifying to see that there is a large, enthusiastic, and highly knowledgeable community out there. My first project turned out very nicely.

[LDS]

Originally Posted by eheilner

Janmuths -
That is correct - it is a display issue. The bits are not getting messed with.

JFreak -
Now that you point this out I too am a bit puzzled, since we're dealing w/ roughly 6 DB per bit. So either we are both missing some technical detail - or the scale in WavePad is not accurate since you would expect a vertical leap from -6 to 0 as it jumps that last bit. That said, the wave forms look identical to me in every respect between PT, WavePad, and Audacity. It was the headroom on the PT display that was confusing me. I would still prefer to have some clearer indication that I am running out of headroom.

To everyone who responded -
Thank you. It is gratifying to see that there is a large, enthusiastic, and highly knowledgeable community out there. My first project turned out very nicely.

I think there is a few dots not connected at the moment. I am in the middle of writing a three or four part article for my website about the inner function of bit depth. I will post it when it is done...

But for the time being - the phrase "1 bit equals 6dB" is one of the most misleading statements in audio I think. It definitely had me confused for a while. It is a mathematical statement, not a literal one. There are actually some 700,000 values between -6dBFS and 0dbFS in 24 bit PCM. These are split between the positive and negative peak.

The reason Pro Tools doesn't indicate that 0dBFS is the limit of headroom within the waveform view is because it isn't the limit of headroom. The floating point mix engine provides exponentially more headroom than just the 144dB. I have attached a screenshot to show what I mean. Look at how narrow the 0dBFS indicators are on the left of the waveform.

[janmuths]

When accurate sample-peak levels are important use Audiosuite > Other > Gain > Analyse.
Please note that Gain does not display inter-sample peaks but sample peaks only. The ProLimiters loudness analyser can do that (although not for free)