Topic: Does normalize affect sound quality?

[SpareRibs]

I recently purchased a Trey Anastasio download of FLAC files and when I used the Nero software to transfer to CD, I used the Normalize option. Was that fine? Did I diminish the sound quality or no differece?

[sygdwm]

try it both ways, decide for yourself and then post your results.

[Brian Skalinder]

Dre offers good advice regarding whether it's fine, or if diminished the sound quality.  Those are both subjective judgements.  As for any difference, it depends in part on how Nero performs normalization.  If Nero normalizes each file individually (which I suspect it does), then the results will produce individual songs that do not maintain their volume level relative to the entire set.  For example, if one song is quite loud, and has very strong levels, and a second song is very quiet, Nero may normalize the second, quiet song so it sounds as loud as the first.  This kind of normalization will impact the relative dynamic range across the entire song set.  Even if Nero takes into account the entire file set when normalizing (which I doubt), if Nero performs RMS normalization, instead of peak normalization, it may also impact dynamic range.  Personally, I'd leave Nero's normalization off unless / until I understood exactly what it does and how it does it.

[SpareRibs]

Thanks

[PH]

(lookout, long complicated answer below)

You do not want to normalize your files using any sort of program such as this. It will adversly affect quality.
If you do need to normalize any audio, you should do so with 24bit software that is designed to transparently perform that function.
(such as soundforge, wavlab, nuendo, protools, etc....)

When in 16 bit, any sort of volume/gain editing requires the program to perform a complicated set of algorithms and the result doesn't add up evenly, leaving artifacts.
This can be percieved as dullness or lifelessness with the recording. The more edits or actions you perform, the more this is compounded.
It's akin to a large number that is divided by a smaller number and leaves an uneven remainder.

When doing this type of editing, you need to import the 16bit into 24bit program and do the edits in that realm. The errors are dramaticlly less and the chance of these nasty artifacts are greatly diminished.
As a general rule, you should be very sparing with volume adjustments. If needed, use trial and error, and the undo function to find the right level/setting, then do it once and leave it alone.
You will need to dither the 24 bit file back down to 16bit afterwards. After the dither, there should be NO MORE "destructive" edits performed on the audio. If you edit after a file has been dithered, it will scramble the bit quantatization, or in other words, it will make it sound worse.

Most of those above things can and will happen if you use a program like itunes, nero, winamp, foobar, flac, or whatever to normalize your files.
Cheers, Phil

[boojum]

foobar allows applying ReplayGain, like normalizing, to FLAC as a one track at a time or as an album, where relative loudness is considered.  foobar is free.

[PH]

foobar allows applying ReplayGain, like normalizing, to FLAC as a one track at a time or as an album, where relative loudness is considered.  foobar is free.

I hope that I have explained why you do not want to use replay gain or normalizing using these type of quickie/on the fly type of gain adjustments.
This includes foobar. If you care about lossless copies, then you wouldn't consider doing this. If it's for your mp3 collection, then go right ahead, but just know that it will adversely affect the sound quality.

[boojum]

foobar allows applying ReplayGain, like normalizing, to FLAC as a one track at a time or as an album, where relative loudness is considered.  foobar is free.

I hope that I have explained why you do not want to use replay gain or normalizing using these type of quickie/on the fly type of gain adjustments.
This includes foobar. If you care about lossless copies, then you wouldn't consider doing this. If it's for your mp3 collection, then go right ahead, but just know that it will adversely affect the sound quality.

And the reason, in your opinion is . . . . . ?

I read your post just now, and understand your opinion.  Other than anecdotal have you any proof, like a series of ABX tests??  I am a little suspicious of sweeping generalizations like this.  You may be right.  But other than what you believe is there any indication elsewhere that this is true?  I am just curious.

Cheers

[PH]

foobar allows applying ReplayGain, like normalizing, to FLAC as a one track at a time or as an album, where relative loudness is considered.  foobar is free.

I hope that I have explained why you do not want to use replay gain or normalizing using these type of quickie/on the fly type of gain adjustments.
This includes foobar. If you care about lossless copies, then you wouldn't consider doing this. If it's for your mp3 collection, then go right ahead, but just know that it will adversely affect the sound quality.

And the reason, in your opinion is . . . . . ?

I read your post just now, and understand your opinion.  Other than anecdotal have you any proof, like a series of ABX tests??  I am a little suspicious of sweeping generalizations like this.  You may be right.  But other than what you believe is there any indication elsewhere that this is true?  I am just curious.

Cheers

It's audio basics. You can find plenty of information on the subject with a google search.

[StuStu]

I would not personally recommend using the normalize affect in Nero. Normalization (IMO) can improve or degrade audio quality. If you decide to normalize, I would use a respectable "audio" software program such as Sound Forge, Wavelab, etc. Nero is basically an affordable all-in-one program. I run it as well, I'm not knocking it for what it is.

For audio, I run Sound Forge 9 and depending on the specific recording, I either normalize OR adjust the volume.
Generic explanation...
Normalize: The levels are fairly consistent but the recording will sound better with levels raised.
Volume$$$: The recording is inconsisent in its recording levels and to normalize will not accurately improve or accurately reproduce the true sound of the performance. It will sound "unnatural."

$$$: A. This process is a much more time consuming pain in the ass B. The cause of the level indifference can be FOH, equipment related, the music itself, a heavily buzzed level-adjusting tapir , a heavily buzzed level-killing-clapping-wooing-neighbor...etc.

Brian and Phil's above posts are very well said.

YMMV

Stu
         

[bobbygeeWOW]

Just a note on replay-gain mentioned above - applying flac's replay-gain does not affect or alter the actual audio content of a flac file.
Its just a metatag (header) that music playing software can be set up to read. (or not)

The idea is that if you're listening in "random mode" with tracks randomly selected from lots of different sources, volume levels will jump around a lot. To avoid having to dive for your volume knob when a really loud -1db 16-bit track comes on right after that -18db 24-bit tune, the software will read this replay-gain tag and make the adjustment for you on the fly - essentially trying to keep each tune more or less at the same volume level.

I think most flac-supporting players (including my rockboxed ipod) have an option like "use replay-gain when playing randomly, otherwise don't bother".

When listening to a complete show, you want the loud parts loud and the quiet parts quiet, so you don't use replay-gain; but I find it pretty handy when I tell my SB3 to just play random background tracks while I fool around in the house doing stuff.

 -Cheers!

[PH]

I stand corrected on the Flac reply-gain setting since it doesn't alter the actual file, but it would essentially do the same thing as normalization but only for temporary listening.
I used to use this setting occasionly on my Rio Karma, but it's long dead.

What I'm specifically referring to when I talk about normalization being destructive is altering the actual file at the time of ripping or burning, or just to raise the levels to make it louder.
All of those things are ok to do, providing you upsample the audio before doing them to prevent any artifacts as were listed already.

Now, all of that being said, it's really not going to make that much a difference in the overall sound to make quick 16 bit edits, but you should know that it can and will leave artifacts.
If you are striving to preserve the integrity of the files you are ripping, such as Commercial CD's, it would not be advised to alter them in any way until after you have archived them on the hard drive, then alter a copy of the fileset.
Compare the two and there you have it.
Cheers,Phil

[boojum]

foobar allows applying ReplayGain, like normalizing, to FLAC as a one track at a time or as an album, where relative loudness is considered.  foobar is free.

I hope that I have explained why you do not want to use replay gain or normalizing using these type of quickie/on the fly type of gain adjustments.
This includes foobar. If you care about lossless copies, then you wouldn't consider doing this. If it's for your mp3 collection, then go right ahead, but just know that it will adversely affect the sound quality.

And the reason, in your opinion is . . . . . ?

I read your post just now, and understand your opinion.  Other than anecdotal have you any proof, like a series of ABX tests??  I am a little suspicious of sweeping generalizations like this.  You may be right.  But other than what you believe is there any indication elsewhere that this is true?  I am just curious.

Cheers

It's audio basics. You can find plenty of information on the subject with a google search.

Maybe you should have done that search yourself before you suggested it.     The results are mixed with the majority for normalizing.  The untilmate test, outlined in one article is to normalize up ndB and then normalize it back down the same amount and compare it to the original.  Tne author says they are bit-for-bit identical.  So unless there is a mysterious "something" that digital cannot capture - this can be used as an out - it would seem that it process is non-destructive.  In my software, Samplitude Master, it is within the project and applied only at burning time.

Links:

http://en.wikipedia.org/wiki/Audio_normalization

http://en.wikipedia.org/wiki/Replay_Gain

http://audioengineering.tribe.net/thread/a657da50-93d3-4c01-b356-6705c19f97e5

http://www.gearslutz.com/board/music-computers/31828-digital-audio-myths-never-normalize-etc.html

http://www.gearslutz.com/board/music-computers/150128-when-should-you-normalize-if-ever.html

http://www.gearslutz.com/board/low-end-theory/78763-normalize-not-normalize.html

http://www.gearslutz.com/board/music-computers/143280-normalize-function.html

http://recforums.prosoundweb.com/index.php/m/237663/17312/?srch=normalize#msg_237663

[Javier Cinakowski]

I would think that increasing the bit depth to 24, then back down to 16 would be more destructive than simple normailzation of the original 16bit file....

[boojum]

I want to say that I am not trying to be argumentative but to find out what is true and what is not.  Audio, as in other professions and hobbies, has some built in "ideas" that are not always true when subjected to reason and analysis.  This may or may not be the case with normalization.  I would like to know as I use it myself.  I use it in FLAC files (non-destructive there) and MP3's, same as FLAC.  The question, I think, that we are working on here is does Normalizing degrade WAV/PCM files when applied?  If it does, is it noticeable or immeasurable and/or undetectable by ear in ABX testing?

This is a pretty important question.  I, for one, would like to get a definitive answer.  Hopefully we can find it here or on a search of the data on the Internet.

Cheers