bit depth when routing audio through ableton

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kirky_roger
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Joined: Mon Jan 23, 2012 11:17 am

bit depth when routing audio through ableton

Post by kirky_roger » Sun May 03, 2015 11:14 pm

Hi there

I'm using ableton in a live situation where ableton is a kind of a giant effects-processor. For example I'm routing my guitar into a motu interface, then process it in ableton and then send it FOH. My question is at what bit depth is my audio processed? How I understand it, the bit depth setting is part of the sampling process which happens in the interface. Since my motu is capable of 24 bit, I guess the sampling happens at 24 bit. Then it goes into ableton and that's where I'm a bit lost... In the ableton prefrences you can set the bit depth for recording. Now when this setting is 16 bit and you record the audio, ableton does a bit reduction from 24 to 16 bit, since my interface's bit depth setting is not changed by ableton (so it's still 24 bit), is it? Is this correct?
Now what happens if the setting in ableton is still 16 bit but you don't record the audio but just pass it through ableton, like I do in my setup. Is ableton handeling it as 24 bit audio or 16 bit audio? Or do I have to change the bit depth setting in ableton to 24 bit, in order to get ableton to process the audio in 24 bit?

I hope you understand my question and I thank you for your help!
Cheers

Angstrom
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Joined: Mon Oct 04, 2004 2:22 pm
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Re: bit depth when routing audio through ableton

Post by Angstrom » Sun May 03, 2015 11:50 pm

If you are just routing audio through live there's some tricksy phrasing which covers it.

EDIT: This is the authoritative source - https://www.ableton.com/en/manual/audio-fact-sheet/
Please note that, while 64-bit summing is applied to each single mix point, Live‘s internal processing is still done at 32-bit. Thus, signals that are mixed across multiple summing points may still result in an extremely small amount of signal degradation. This combination of 64-bit summing within a 32-bit architecture strikes an ideal balance between audio quality and CPU/memory consumption.


Essentially at all points where signals are mixed its 64 bit mixing. What that means is at the track outs, where they are routed to "master" or wherever.
As far as I know all other places are 32 bit wordlength, like device into device into device.
So it's a mixture of wordlengths.

My info might be out of date, so I advise anyone really interested to grab a plugin like ozone which shows a "bit depth" meter. IE word length. And try it in different places, you'll soon see the available wordlength in each location(track, group, bus, master, etc.)

If these words don't mean much to you, or you are not sure what the meter means then probably don't do this. You'll just confuse yourself. If so just know "at least 32bit, and often 64 bit"

kirky_roger
Posts: 16
Joined: Mon Jan 23, 2012 11:17 am

Re: bit depth when routing audio through ableton

Post by kirky_roger » Sun May 03, 2015 11:58 pm

Angstrom wrote: If these words don't mean much to you, or you are not sure what the meter means then probably don't do this. You'll just confuse yourself. If so just know "at least 32bit, and often 64 bit"
I do know some of these words :)
I also remember reading somewhere, that ableton (and many other DAW nowadays) are working with 32 bit internally. Didn't know that it even goes to 64 bit though.

So the "real" bit depth of the signal in my case would be 24 bit, since that's what the interface is capable of. Even though ableton internally works with higher bit depths, I obviously won't get higher resolution out of that, since my original ad-conversion is in 24 bit. Correct?

Angstrom
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Re: bit depth when routing audio through ableton

Post by Angstrom » Mon May 04, 2015 1:08 am

Well, it depends how you think of it.
In a way you are getting the benefits of a higher word length processing even if you are taking in 24 bit and are truncating it back to 24 bit on the output.

When you are increasing and decreasing volume, as most effects do (eq is a very specific kind of gain adjustment for example) it's not a direct in to out process. We might have a case for reducing gain in a chain then have a fancy reverb with very quiet tails then boost it all back up to -5db for output. EG perhaps our silly effects chain has a volume pedal in it, and then a distortion, then a reverb, then a compressor with make-up gain.

Without the greater depth to work in we might truncate partway through the signal path then when we boost back up before output we are unknowingly presenting a much less detailed signal at the output.
So with a 32/64 bit signal path we can use a volume pedal to reverb to compressor like a lunatic and still be saved by technology from grainy accidentally truncated output.

This is not a technical explanation.

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