## Re: why does normalizing a file make compression less efficient?

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Reply #6 –

Do you have some evidence that your variation could produce a perceptible difference?

if the sample is quiet enough and is still quiet enough after amplification, yes, why not.

but since we're talking about file sizes, it doesn't even matter if this is perceptible, because it's obviously big difference in file size after FLAC encoding, therefore the difference is significant.

you can try it yourself easy with this sample:

# bigger file

ffmpeg -i sample.flac -af volume=6dB sample_6db.flac

# smaller file if using exact integer gain

ffmpeg -i sample.flac -af volume=2 sample_2x.flac

...and if you replace 6dB with 6.020599913279624dB, you get exactly the same output as with 2x multiplication (as expected). Not sure how many decimal digits are enough to produce the same result with 16 bit audio, and tbh I'm not really interested, I just wanted to show that 6dB is indeed far enough from 2x multiplication, even though it's a common misconception