I’m trying to create a fan-made music video for a song I downloaded from Amazon.com, but when I open the MP3 in Audacity, I see that it has a lot of apparent clipping. This seems really bizarre to me, so I was hoping if you guys could answer a couple of questions for me.
Why would a song that was professionally recorded and produced have so much distortion?
Are there any other programs out there that would allow me to see and modify the ‘real’ soundpeaks of the song, even those that Audacity would consider ‘clipped’?
(I’m using Audacity2.0 on Windows 7 64-bit, if that helps.)
It probably isn’t distorted, unless it sounds distorted (which I assume is not the case).
The current fashion for most commercial recordings is to make them as loud as possible (see: http://en.wikipedia.org/wiki/Loudness_war).
To do this, the peaks are “limited” to 0 dB (see: http://en.wikipedia.org/wiki/Dynamic_range_compression#Limiting).
MP3 is an inexact format (it uses lossy compression) so peaks that were 0 dB before conversion to MP3 will often come out a little over 0 dB when decoded to 32 bit float, or very slightly clipped if decoded to 16 bit or 24 bit format.
Although this looks ugly it is not generally anything to worry about because the amount of clipping is usually just single samples so there is no audible effect to this clipping.
Applying the Amplify effect with default settings will bring the audio back down to within the “valid” range of 0 dB. You may still see occasional red lines where the waveform touches 0 dB.
Personally I prefer to leave a little headroom when encoding to MP3 so as to avoid this ugliness.
(that example is nowhere near as bad as some that I’ve seen)
