Normalise Bug in Chain?[SOLVED]

[Shaky]

I'll send you the link via PM, Steve. Thanks for your help.

[steve]

I think I've found the problem.
As a workaround, set the following Preference and I think Normalize will work correctly:
Edit menu > Preferences > Import/Export
"When importing audio files" > "Make a copy"

[Shaky]

I think I've found the problem.
As a workaround, set the following Preference and I think Normalize will work correctly:
Edit menu > Preferences > Import/Export
"When importing audio files" > "Make a copy"

Thanks Steve, that certainly fixed the issue on the problem file.

Can you elaborate a little further on the problem and perhaps how common it might be? Also whether it is something that might be patched in future?

Would just like to understand the probabilities of this issue cropping up again if I process a bunch of files I couldn't realistically check exhaustively.

[steve]

Can you elaborate a little further on the problem and perhaps how common it might be? Also whether it is something that might be patched in future?

It's a pretty obscure bug that requires a specific series of conditions (hence it took me a while to pin down how to reproduce the issue).
I've added a bug report and the details are here: http://bugzilla.audacityteam.org/show_bug.cgi?id=489 so the bug will be picked up and fixed in due course.

Unless you are frequently working on very long audio files it is probably best to leave the Preference setting to "When importing audio files" > "Make a copy". Not only will that work around this bug but it is a generally safer option.

[Shaky]

Thanks again, Steve; sorry to create more work for you but I appreciate the further info.

I guess what is troubling me is that the the Normalise function appears to work properly as a standalone function, suggesting to my inexperienced eye there may be something broader wrong with the way Chains are initialised.

Anyway, I think I'll proceed with caution for now and see what the developers come up with.

[steve]

I don't think the problem is with "the way Chains are initialised".
The fact that you saw the problem with the first file in the batch was a red herring.

The conditions that make the issue occur are:

• "Read Directly" is selected in Preferences.
• The warning message for importing uncompressed audio is disabled.
• The imported file is in an uncompressed format (for example .WAV)
• The file is long enough that it is not automatically copied.
• The original peak level is not 0 dB (otherwise the bug is invisible).
• The Normalize effect is used in a Chain.
• The Chain is applied to files (not the current project)

What I think is happening (or rather "not happening") is that the Chain command is failing to pass the peak level to the Normalize effect, so Normalize assumes a default peak level of 0 dB. The Chains code was updated a while back and I suspect that the developer simply forgot about passing this data to Normalize. I think that Normalize is the only effect that actually needs to know the peak level of the audio. The only other effect that I think may possibly have a similar problem is the Noise Removal effect but I would imagine that it will be obvious to the developer if this is the case or not when they re-examine the code.

[Gale Andrews]

This should be fixed in 2.0.1. The problem turned out to be that Normalize was not waiting for On-Demand Loading to complete computing the waveform before starting its analysis.


Gale