Very serious Consolidate issue in Live 4.1.1!

raapie · Post by **raapie** » Wed Mar 23, 2005 7:51 pm

I am working on a track and I recorded large audio tracks. When consolidating the audio is changed, even quiet parts contain a bit of noise. I really can't explain why.

Please check out these screenshots:
before:

after consolidate:

???

raapie · Post by **raapie** » Wed Mar 23, 2005 7:54 pm

forget to mention: happened on WindowsXPsp2 machine

brecht · Post by **brecht** » Thu Mar 24, 2005 4:06 am

hey raapie,

not sure why you're trying to consolidate silence, but...

I'm pretty sure that consolidate normalizes the volume of the track when rendering. it then changes the clip volume to approximate the volume of the original unconsolidated version. so when you consolidate silence, you're amplifying the background noise.

Ben

raapie · Post by **raapie** » Thu Mar 24, 2005 7:03 am

I made this example so I could show it in a simple way. I consolidate the whole track and everything was changed. so then I tried a part with less noise and this was the result.

It shouldn't normalize. I need headroom when arranging and mixing. I will only normalize at the end of the proces.

Thanks for you reply.

madlab · Post by **madlab** » Thu Mar 24, 2005 7:32 am

I neither don't understand why we would need a normalization in the consolidate process. Anyone from Ableton on this ?

raapie · Post by **raapie** » Thu Mar 24, 2005 7:43 am

I had contact with Ulf yesterday about another bug (also normalizing related btw) and I send him a link to this thread. He probably will respond soon.

Support of Ableton is great I have to say. They are on it! But well fingers crossed when this will be solved.

Post by **Alex** » Thu Mar 24, 2005 1:45 pm

Hi folks,

well, I think it's not a bug, it's a feature (sorry, love to say that

)

In Live a consolidated clip will be normalized (I explain later why). To compensate the volume change trough the normalizing the clip's gain is adjusted.

Example:
----------------------------
1) Put an audio clip into Live's arranger.
2) Select a small part in the middle of the clip and consolidate it
3) Now you have 3 clips. You will notice that the waveform view of the consolidated clip looks different as the same part in the original clip before.
4) But now compare the gain settings of these clips. The gain of the consolidated clip is lowered to compensate the normalization.

So because the consolidated clip is normalized, you see the a different amplitude in the waveform as before.

But why the normalize?
----------------------------
This was already an issue during the beta period of Live 4.0. So I will quote something Bernd already wrote concerning this issue:

Here is a misunderstanding. Live does *not* change the relative amplitudes through consolidate. *But* we need to change the clip volume *because* Live makes quite an effort so that consolidate does change as less as possible in terms of the resulting audio.

So why do we need to change the volume? Some examples:

1) We have a clip with a sample that is normalized means it uses the whole resolution that lets say a 16 bit sample file offers. And now you raise the gain of that clip. What happens? That clip creates audio that is above 0 db. If we would write this to a file it would result in a sound file with clipping. So we need to normalize the audio before writing it to the file. But now we need to lower the gain of the consolidated clip to ensure that this clip will not create loader audio.

2) Internally the audio engine calculates in 32 bit float resolution. So every convertion of a intermediate signal to a 16 or even 24 bit resolution - and that is what happens when you consolidate - will result in a reduction of resolution - by definition, no matter of you use dithering or not. So if you now consolidate a very quiet part of a sample and Live would write it back to the file as it is, the sound would even loose more resolution.

So for all this and some other reasons Live always normalizes the audio before writing it to disk when consolidating to keep as much resolution as possible. This can result in a clip that has a gain different from the original clip, but again, it never results in a different amplitude of the resulting audio.

Kind regards, Bernd.

regards,
Alex

supster · Post by **supster** » Thu Mar 24, 2005 2:02 pm

Alex wrote: This can result in a clip that has a gain different from the original clip, but again, it never results in a different amplitude of the resulting audio.

hey alex, thanks for adressing this

excuse me for not remembering the engineering difference between 'gain' and 'amplitude' .. could you explain this quote further so we know exaclty what he means by that?

.

raapie · Post by **raapie** » Thu Mar 24, 2005 2:09 pm

thanks Alex (and Bernd). it makes sense to me now since I didn't notice the gain reduction on the clip/part.

Post by **Alex** » Thu Mar 24, 2005 2:09 pm

Hi supster,

with "gain" I referred just to the gain slider (right of the transpose knob) in sample settings of any audio clip in Live.

regards,
Alex

conny · Post by **conny** » Thu Mar 24, 2005 2:13 pm

OK, fair enough.
Does this mean
1 - if I consolidate a region composed of part of a previois consolidated region and part of a non consolidated region,
that the resulting clip will compensate both parts
so there will be no "double" normalizing on part of the new clip?
(Test I did shows this is handled correct by just one tiny test.)
2 - that in theory a series of consolidations will go from one resolution
to another in every step and that some sound information may be
lost/altered in the process?

// C

Post by **Alex** » Thu Mar 24, 2005 2:30 pm

Hi conny,

1) In the end, yes because to normalize an already normalized clip odes not make a difference.

2) Simply, yes. Probably this is not a problem in most cases but in cases where for some reason you want to avoid this conversations and normalizing stuff you should instead resample by recording from Master out.

regards,
Alex