Quote:
Originally posted by xeen
If you look at the original one, it looks like your normal wave (although a loud one). But after I made it less loud, it looks more like a rectangle than a wave. So my question is does the de-amplification process degrade quality by causing distortion? Or is it perfectly safe for me to lower the volume of my audio tracks before I encode them?
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The top wave is pretty rectangular too. The bottom wave is what I'd expect see if you reduced the top to 80%. A lot of popular music (I use the term in the broadest sense) is heavily processed to get it as loud as possible, and it's sadly all too common to see it looking (and sounding) distorted like that. De-amplification shouldn't cause any distortion like that.
Quote:
Originally posted by xeen
My second question is about the reverse process. Say I want to extract a piece of audio from a DVD and save it as an mp3. DVD audio tracks are usually not very loud for some reason (I mean the songs, not the speech). So after I extract it, but before I save as mp3, I like to amplify it some to make it the same loudness as my other mp3s. Does this cause any quality degradation? I understand that of course it does if I amplify it by too much, but does anything happen from an amplification of say, up to 200% ?
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Use besweet to convert AC3 to MP3 and tell it to normalize. Besweet's hybridgain option is a normalizing method and is recomend for AC3 to MP3 conversion by many people (including me) due to it's speed. Normalizing [to 100%] will make it as loud as possible without causing any distortion. I may have misunderstood jorel but he looks to be confusing normalization with dynamic range compression. Normalizing [to 100%] will not cause distortion.
Once you've finished encoding you can use something like MP3Gain to automatically adjust the volume of your entire MP3 collection so it all at approximately the same loudness.