Lossless volume normalization of mp2 files (no reencoding)

[Paco M.]

Can anyone recommend a specific tool for normalizing mp2 audio files, without reencoding? Thanks in advance.

Paco

[johns0]

Cant be done without re-encoding.

[SatStorm]

No

[Paco M.]

I've read there are tools able to normalize without reencoding mp3 files. I hope to find some program to do the same for mp2 files

[drjtech]

I've read there are tools able to normalize without reencoding mp3 files.

Where did you read that?

-drj

[junkmalle]

I've read there are tools able to normalize without reencoding mp3 files.

I think this misperception arises from programs like MusicMatch Jukebox which has a normalization feature which doesn't alter the mp3 file. It simply builds a database of volume levels for each file in its playlist and uses it at playback time to normalize the volume. But of course, only MMJB understands and uses the database.

To actually make volume level changes within the file requires reencoding.

[Paco M.]

Look at http://www.dansmc.com/freestuff/nobucks/mp3.htm for MP3Gain.
At least in theory, this program does for MP3 files what I want to do for mp2 ones.

[drjtech]

Thanks for the link. I had not seen that before.

-drj

[junkmalle]

Look at http://www.dansmc.com/freestuff/nobucks/mp3.htm for MP3Gain.
At least in theory, this program does for MP3 files what I want to do for mp2 ones.

I tried a few Windows based software players and they all supported the feature. I tried my DVD player (which can play mp3 files) and it worked there too. I'll have to try the player in my car later...

A close examination of the files shows that MP3Gain adds a metadata field at the end of the file. I originally thought this was simply an instruction to adjust the gain on playback. But it's just information that can be used to undo the changes. It also changes a few bytes here and there within the file. So maybe each packet within the MP3 file has a gain setting?

I tried the obvious -- renaming an MP2 file to MP3 but MP3Gain wouldn't accept it. Even with the "no check for L1 and L2" option set.

[SaSi]

The structure of the MP2 file (which is not much different to the structure of an MP3) should allow for modifying the average volume and normalizing it. It is just a matter of scaling the encoded stream.

I think I have read something similar in articles and papers on "compressed domain transcoding" but cannot recall the exact site or find the papers now. Having a tool to do that is of course a different matter.

should be an interesting programming effort, though.

[Soopafresh]

http://besweet.notrace.dk/BeSplitv0.9b6.zip

Here's the quick way to normalize the file losslessly (per doom9 faq)

BeSplit -core( -input infile.mp2 -output outfile.mp2 -type mp2 ) -ota( -G max )

Use the Beta version above. Earlier versions don't include this function.

[junkmalle]

After a little reading it looks like MP3Gain manipulates the Global Gain Factor within the MP3 frames. From the horse's mouth:

http://www.iis.fraunhofer.de/amm/techinf/layer3/

[Paco M.]

Thanks a lot for the advice: BeSplit works!