[LAU] keeping same perceived level on mp3 files

[Atte André Jensen]

On 10/06/2012 01:51 PM, Georg Holzmann wrote:

> That's great - now you only have to bring all your files to the same
> loudness!
> For example, let's say you want all files to be at 13 LU.
> You can apply a simple gain on all files:
> -0.7 dB for the first file (13.7LU), 0dB for the second, +7dB for the
> third (6LU) and so on ...
>
> I think you can do that with sox - and maybe it's also good to use an
> additional limiter (at -1dBFS or lower), to avoid clipping!
> AFAIK sox has the compad effect, which can do that ...

Thanks for the help! That's great.

Now I started looking for an sox alternative that could do gain 
adjustment without having to decode/reencode the mp3, since I seemed to 
remember such a tool existed.

This led me to mp3gain. Reading it's man page:

"mp3gain can analyze and adjust mp3 files so that they have the same 
volume."

Hmmmm. Now I'm thinking, isn't this exactly what I wanted in the first 
place?

After running "mp3gain -r *.mp3" on the same files as I tested with in 
the original mail, and checking them with ebur128, it seems that the two 
programs do not agree how to measure the perceived loudness. mp3gain 
uses the replay gain algorithm, what ever that means. Any ideas whether 
mp3gains measurements should fare worse than ebur128?

The reason I ask is, that I'm tempted to just use "mp3gain -r *.mp3" :-)

-- 
Atte

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