Newbie here. I’ve been updating my music collection from mp3 (320) to FLAC by re-ripping my entire CD collection. In some cases, the waveform appears to be riddled with clipping (red lines.) See below example of Dio - Sacred Heart - Another Lie (track #3):
Looks like a tragedy, right? Well, I applied Effect ->Amplify… → Amplification = -0.1 (which also changed the New Peak Amplitude to -0.1). This is the result below:
So, my assumption is that I have NOT made the track sound any better i.e. removed clipping; all I’ve done here is to keep the clipping points from touching the outermost boundaries (i.e. 1.0 and above, -1.0 and below). Is my assumption correct?
Probably yes, though one thing to keep in mind:
The clipping indicators show where the waveform touches or exceeds the top/bottom of the track (0dB). Integer format audio cannot exceed 0dB, so in most cases, if an imported file shows lots of red lines, then there is probably some irreparable clipping damage, but there are two cases where there can be red lines but not actually any “damage”.
If the imported file was “floating point format” (such as “32-bit float WAV”) rather than an “integer format” (FLAC is always integer format).
Floating point formats can exceed 0 dB without damage, but will still sound distorted because sound cards can’t go over 0 dB. If the only problem with a floating-point format file is that it exceeds 0 dB, then this can be fully corrected by amplifying to below 0 dB.
A lot of modern music is heavily processed to make it sound loud. This can cause a lot of peaks to touch 0 dB (top / bottom of the track) without actually clipping the peaks. In this case, zooming in close on the waveform will show that peaks are still rounded and not clipped flat at the top.
Although there is not actually any “damage” in this case, Audacity will still show red warning lines each time the waveform touches the top or bottom of the track. Also, there may still be a small amount of “damage” on playback because digital to analog converters (DACs) are not always able to go all the way up to 0 dB. It is usually recommended to always allow at least a little headroom between the waveform and the top/bottom of the track.
I generally allow 1 dB headroom for lossless formats (WAV / FLAC /…), and 2 to 3 dB for lossy formats (OGG / MP3 / …).