Hello

I often encode Speeches/Vocals with Lame 3.90.3/4 --alt-preset extreme.

I first record them from AstraDigitalRadio (Musicam, MP2 192 CBR) or from FM onto my PC as Wave. After that, I cut and normalise them with WaveLab, so that I can burn audio-CDs and encode them as MP3.

Unfortunately MP3Gain says that about 50% are clipping! I could now use the function 'album gain' or 'track gain' - but in my eyes this is now too late, because clipping cannot be undone.


So my question is:
- What can/must I do, to prevent clipping MP3s?
- Do I have to normalise them to -XX db?
- Is there a lame commandline option to regain before encoding?


Thanks

Use Wavegain on your wav files before encoding to MP3: http://rarewares.hydrogenaudio.org/files/wavegain.zip

Run a wavegain analysis on the ripped files, then plug in the wavegain scale value into LAME like so:

lame --alt-preset standard --scale x.xxxx

This is how I encode everything. I'd recommend putting the scale value used in the ID3 comment field as well.

Not really.
There are two kinds of clipping regarding MP3 files:

1.- "Intrinsecal" clipping.
This was introduced during the mastering stage of a recording. This you can't do anything about. It will always be too late. In your particular case, when you are doing some mastering of your own, you can try adjusting the volume with Wavegain, as you were suggested, as it is a better method to adjust volume levels while retaining audio dynamics (read more on the FAQ), but it will not do much good if the tracks were already clipping from the source.

2.- "Encoding" clipping.
This is produced by the unaudible noise introduced by the encoder (IIRC, as I am not that "technical"). It is added to the original signal during decoding and can make it clip. This is the one that MP3Gain adresses, and fixes.

So, in a way, you are right. But that is no reason not to use MP3Gain.

same as I do. but remember to set "album gain" in wavgain frontend, and "calculate only, dont apply"


another nice way is to put the wav files in foobar, replaygain(album) them, and use the lame discwriter with foo_lame.dll to convert (use replaygain must be enabled in dicwrite options)

Hello

@Liquid_Predator
Thanks for the URL. I already downloaded the software

@Jebus
Thanks for the hint. I will try it out.

@AtaqueEG
In this case "Encoding"-clipping is the problem I encounter. Normally, the vocals/speeches I encode do not have "Intrinsecal"-clipping.

I know, that Encoding-clipping gets worse, the harder you compress MP3-files. I have done several tests with --alt-preset standard/medium/extreme.

I was looking for a setting for normalising to prevent clipping. But I now have seen, that such is not that easy and has to be done in every case again.

So I will continue normalising to 0 db for buring onto CD and use the recommended software for regaining.

@sony666
Thanks as well.

cu
Etienne