hi, just a quick question, wondering why certain badly mastered albums lame cant handle

i have tried tests with EAC & foobar both using LAME.exe (3.97) and the v0 switch.

now if i rip the CD as wav or flac, all is fine, the album holds its -0.1db peak

if i encode to V0 the peak goes over 0db (clipping) (playback with vlc/mediaplayer 11 or foobar) and measured using RME's digicheck software on HDSP 9652 card. (extremely accurate)

1 cd im testing with is retail janes addiction - strays (2003) (badly mastered yes, but no clipping on original cd or ripped wavs)

seems to happen with any hotly mastered CD...

ive tried with replaygain on & off, makes no difference.

any help? or is it just a known problem with lame & v0 ?


thanks again
kC_

This is absolutely normal for every lossy encoder (not just MP3). Lossy encoding is called "lossy" because it modifies the signal... if the signal is already near 0dB, it may for short moments go above it.

Besides, the mp3 itself does NOT clip - else it could not go above 0dB. Exactly because such things can happen, MP3 and other lossy formats can store signals above 0dB.... but the dataformat of your soundcard cannot. So, while inside the mp3, the signal is NOT clipped, it will clip when it gets decoded.

Solution? For practical purposes: none necessary, because most probably you cannot spot it in an ABX test. For theretical purposes: replaygain with clipping-prevention or a limiter.

This is a problem with lossy compression (mp3, ogg, aac) in general. Since data is stored in frequency domain with reduced resolution and the waveform is synthesized at playback, heavily dynamic compressed and hot audio can clip because of something like the Gibbs phenomenon. Interestingly, those clippings are hardly ever audible in contrast to bad clipping upon recording.

One possible solution is to use replaygain, where volume is lowered while decoding; and it has an option to "never clip" (which you don't need really if you set your playback gain to reasonable levels). Or you could take the hotness out of the audio before encoding. Or you could live with it because it is really unnoticable most of the time

ok thanks for the explanation