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Author Topic: convolution "normalize filter volume" bug  (Read 1824 times)

pgruebele

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convolution "normalize filter volume" bug
« on: July 05, 2014, 01:28:10 pm »

I am using convolution filters created by DRCDesigner (WAV files).  Things work very well except for 2 volume issues:

1. Enabling convolution (with "normalize filter volume" option off), the volume drops about 10 dB
2. If I then enable "normalize filter volume", this decreases the volume about another 4 dB

This makes for a total drop of about 14dB which is not usable in my setup.  I would expect the "normalize filter volume" option to decrease the volume by 6 dB total (relative to disabling convolution), not 14 dB.

Is this a bug?  I know some other people who are having similar issues.  These volume numbers are just measured by ear using an Audiophilleo volume control, which is in dB, so they are about right.

Cheers
Philip
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audiotweak

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Re: convolution "normalize filter volume" bug
« Reply #1 on: July 05, 2014, 01:55:51 pm »

Hi guys,

I can confirm this with DRC as well.
Please test the attached DRC "filter" WAV file?

FYI, my version of JRiver is Media Center 19.0.146

Thanks
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Matt

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Re: convolution "normalize filter volume" bug
« Reply #2 on: July 23, 2014, 08:32:25 am »

There's a right way to apply convolution and Media Center does it.  The volume is baked into the convolution file.  You can use "Normalize filter volume" but since a convolution file has a large theoretical peak it'll be conservative.

To build on the theoretical peak, consider a short convolution sample: -1 1 -1 1 -1 1 -1 1.  It would have a theoretical peak level of 8, even though it would be unlikely to ever encounter that.  The option "Normalize filter volume" is a compromise between real world and theoretical peaks.
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Matt Ashland, JRiver Media Center

audiotweak

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Re: convolution "normalize filter volume" bug
« Reply #3 on: July 23, 2014, 03:10:55 pm »

The loss in volume or output is significant, before normalizing or without, not conservative I'm afraid.
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Matt

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Re: convolution "normalize filter volume" bug
« Reply #4 on: July 23, 2014, 03:14:55 pm »

Then make the convolution sample have more volume.
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Matt Ashland, JRiver Media Center

audiotweak

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Re: convolution "normalize filter volume" bug
« Reply #5 on: July 27, 2014, 05:45:55 am »

Perhaps with Audacity, after the convolution file has been generated via DRC?
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