If you only want to adjust the gain, and will be using a player that supports MP3Gain metadata, then better (and quicker) to use MP3Gain.ĭoes Audacity use the ReplayGain algorithm for both the “Normalize” effect and the “Loudness Normalize” effect?
Audacity does this for all file types that are not already PCM.ĭecoding MP3 is essentially lossless - it’s the encoding that loses quality.Īs the Import and Output conversion will introduce losses would it be best to use MP3Gain, rather than Audacity? On Import, does audacity convert the mp3 file to PCM (plus edit codes)? In practice, I doubt that the tiny amount of clipping would be audible, but interesting nonetheless (I wish I could find that article again ) Unfortunately that was an article that I found on-line and I didn’t bookmark it and haven’t found it again since then. Most of them (even expensive models) showed measurable signs of clipping close to 0 dB. The article was looking at “measurable” distortion rather than “audible” distortion. I read an article a while back that tested a range of CD players and found that very few of them handled 0 dB very well.
#Real mp3 gain full#
I am assuming the DAC would be designed to cope with the full +/- 32k If so then there is no ADC involved?Īt the output end, is there a standard output level corresponding to 0dB. The tracks I have been trying are ripped from a CD using Audiograbber (without using the normalizing option) using LAME at 192kbps constant bitrate.ĬD is a digital format, so am I right in thinking it is converted to mp3 without being converted to analogue. Thanks for this very detailed explanation Doug. The 89dB default is a compromise that works with more files If you make it lower, MP3Gain has “more room to work” and fewer files will clip. Again, you are limited to volume adjustment (or normalization) in 1.5dB steps There are special purpose MP3 editors (like MP3DirectCut) that can do some limited editing without decompressing/re-compressing. It’s best to work with a lossless format (if possible) and convert ONCE to MP3. If you re-export as MP3 you are going through another generation of lossy compression and some “damage” does accumulate. When you open an MP3 in Audacity (or any “normal” audio editor) it gets decompressed. MP3 can only be adjusted losslessly in 1.5dB steps and since MP3Gain works losslessly it can only adjust in 1.5dB steps. Or if you have a truly-clipped file you can reduce the volume so the peaks are below 0dB (which of course doesn’t fix the clipped wave shape) and Audacity won’t show it as clipped. It’s just looking for samples over 0dB, or a few 0dB samples in a row. Audacity isn’t looking at the wave shape. Regular WAV files, audio CDs, digital-to-analog converters (playback) and analog-to-digital converters (recording) all all hard-limited to 0dB and they will clip if you try to go over.Īudacity shows potential clipping (red). In that case, the actual audio will only be clipped if you feed it to your digital-to-analog converter at (or near) full-digital volume.
MP3 can go over 0dB without clipping so your file might not really be clipped. The 89dB default is a compromise that works with more files. If you make the target loudness higher you are more likely to clip (or find more files that can’t hit the target without clipping). That won’t change when you normalize because the ratio between loudness and peak doesn’t change. If you don’t allow clipping it will only adjust it as much as it can. The other two clip(Track) and clip(Album) are just warning you of clipping if you adjust to the target loudness. But it usually only peaks about 1dB higher.
If you normalize to 0dB and export as MP3, the MP3 peaks may go over 0dB and if you re-import the MP3 Audacity may “show red”. …MP3 is lossy so it does change the wave shape and some peaks often get higher. That shouldn’t show clipping if you’ve normalized to -3 or -6dB. I have just tried it from the original file to -6dB, and MP3Gain gives the same clipping levels, between 4 and 6dB too highĬlipping tells you if it currently goes over 0dB.
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