A Ripper that will provide "Level Input"
Reply #20 – 2008-08-10 00:32:15
Is this the reason why people are hesitant to say there is no quality loss when using mp3gain?http://www.hydrogenaudio.org/forums/index....st&p=578702 Hmm, maybe. Or maybe there's the technical possibility that some signal may sink into the noise, even though it's almost certainly inaudible. Putting scalefactors out of bounds doesn't seem to be a problem with mp3, and I think mp3gain wraps around if it happens (the tags it puts in record the max and min scalefactors show the there's a huge range downward left on all the files I've looked at), and you wouldn't wish to increase gain of loud-mastered albums, as they're already at the limit of clipping. Trying to find an album with modern loud mastering that I had applied mp3gain to, here's an example: EAC/REACT2 // LAME 3.97 -V2 --vbr-new --noreplaygain --nohist Scissor Sisters / Ta-Dah (with Bonus Track) MP3GAIN_ALBUM_MINMAX = 135,249 MP3GAIN_UNDO = +006,+006,N Basically, it has had -9.0 dB of Album Gain applied by mp3gain, so originally had max scalefactors of 255 on the album and could not be made louder by mp3gain (target volume would have to be 98.1 dB to try this). However, the lowest scalefactor was originally 141, and can go as low as 0 before it's no longer allowed and would wrap to 255 instead. Think about it: 256 x 1.505 dB steps is about over 385.3 dB of range, which is just huge! I made a copy and applied Constant Gain of +21 dB then reverted (peak was over 4.0). Comparing the original to the copy, fb2k bit compare found no differences As for losing quality through the psymodel, things like the ATH model tend to keep more information in louder music, so loud music turned down after encoding should have more quiet parts encoded than a file that is pre-scaled before encoding by LAME. Most other things are relative, like signal to mask ratios, so should remain unaffected. I have no qualms about using mp3gain, or using pre-scaling (usually through fb2k's converter, via 24-bit input to LAME, but sometimes through LAME --scale 0.xx)