[LAU] Batch normalising wav files

Q lists at quirq.ukfsn.org
Fri Dec 24 17:07:48 UTC 2010


Jörn Nettingsmeier wrote:
> On 12/24/2010 02:53 PM, Q wrote:
>> Hello
>>
>> I'm wanting to batch process a bunch of wav files, normalising them all
>> to -0.3 dBFS.
> 
> that's high! you will almost certainly get distortion in the analog
> stages of cheaper playback equipment with a signal that hot. think
> inter-sample peaks.

I got the impression most masters were peak normalised to 0 dBFS these 
days and less frequently to slightly under to avoid playback issues. The 
original files were all done to 0 and Rezound showed a pink clip line in 
one or two of the files, which is why I opted for slightly below for the 
ones I processed.

Anyway, playback on cheap equipment will not be an issue for these files 
-- they won't be played on music players.

Out of interest, how high can intersample peaks get above the highest 
peaks in a file?

> 
>> I thought I could do this with normalize/normalize-audio, but it doesn't
>> look to be possible. The man page suggests that simply analysing the
>> file and raising the level so the loudest peak is 0 dBFS isn't
>> normalising, which is news to me:
> 
> depends. that's peak normalisation. what you probably want is loudness
> normalisation, which adjusts the levels so that the perceived loudness
> is constant across tracks.

No, peak normalisation is what I'm after; this isn't a CD collection I'm 
processing.

> 
> in a presentation i heard recently, the presenter played a metallica
> single, in direct comparison to pink noise at full scale. the metallica
> mix was significantly louder. go figure...
>

I'd rather listen to pink noise any day!

>> " --peak
>> Adjust using peak levels instead of RMS levels. Each file  will be
>> adjusted so that its maximum sample is at full scale. This just gives a
>> file the maximum volume possible without clipping; no normalization is
>> done."
> 
> that is a funny definition of normalisation.

I get the impression that the term normalisation has taken on another 
meaning among non-music producers to mean replay gain normalisation for 
whole albums or music collections. Doesn't replay gain either peak 
normalise the loudest track and raise all the others by the same amount 
(to preserve inter-song dynamics), or in some case do loudness 
normalisation? Personally, I don't bother with such things, volume knobs 
are what we evolved fingers for!

> 
>> That would be okay, except I want them normalising to something other
>> than full scale.
>>
>> Is there a quick and easy way to do this?
> 
> like julien suggested, use a standard peak normalizer and then attenuate
> by 0.3dB )(if you are sure that's what you want to do).
> 
When you put it as simply as that it's blindingly obvious! I can't 
believe it didn't occur to me and one extra step when batch processing 
is not a big deal at all. Blame the cold weather and a brain freeze!

Thanks again

Q


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