mpa audio normalization on multiple files

[Ryan]

Ok here's the details.


I have a bunch (around 30 or so) audio clips that was demuxed from the video clip. They are mpa's which I assume is the same thing as mpg layer two since that's the audio format of the actual video files.


The problem is these video clips have varing audio levels. Its fustrating to have to change the volume on your tv(or pc) everytime a new clip starts (the clips are actualy music videos).

So is there a way to take all the mpa's at once and normalize the volume so they all are about the same level? Preferably in batch mode. I tried besweet but it don't seem to normalize the audio for a bunch of files but indiviually so i still ened up with major vclume changes.

If the program can convert to ac3 that would be a bonus but not mandatory as mpa (mpeg layer II) was the encoded audio for all the files and why when demuxed they eneded up being mpa i don't know.

So basically i am looking for something to look at say 30 files determine the proper volume level to make them all the same level and then encode/transcode to that.

If you suggest besweet, soulforge, or goldwave, please explain in detail on how to do so cause i couldn't figure it out.


thanks in advance

Ryan

[Ryan]

No one can help? I am going mad trying to figure this out. It can't be this hard.


Ok if there is no program that will normalize the sound of a bunch of mpa files what about other types of files? I can convert these mpa's to probalby anythign else needed (ac3,wav, etc))

So don't let me saying mpa keep you from making suggestions.

the mpa's are dvd labs demuxed audio portain of a video file. The audio is actualy mpeg layer II (all dvd specs).

Hopefully somoen can help.

thanks

Ryan

[Cornucopia]

Even if you normalize them all so that their peak level is 0dB (fullscale), they very likely will NOT all sound the same level. That's because they very likely each have different spectral content and dynamic ranges. To adjust these kinds of things really can't be done well in batch mode.

If you convert them all to WAV's, you could open them all up together in SoundForge, CoolEdit(Audition), or ProTools, or similar, and filter and adjust dynamic range so that they all, say, peak at 0dB, with -12dB RMS(average) level, and with similar spectral (frequency) balance. But even then, there is no magic single button.
Then, of course, you would have to re-encode/compress them (losing a little quality, to boot).

Scott

[DRP]

First thing you need to know is that there is no way to do this losslessly. mp2 audio files do not have a volume information tag in the header like their mp3 cousins, so you cannot change the volume without re-encoding like you can with mp3. If you're fine with knowing that and still want to change their volumes and re-encode to either AC3 or MP2 again then proceed like this:

First you have save all the MP2 files out as WAV. Do this using any audio editor like GoldWave. Just open the MP2 file and select SAVE AS and save it out again as WAVE.

Now, with those 30-odd WAVE files you want to perform ReplayGain on them to make them all sound the same loudness without clipping. That is the same thing that Mp3Gain does losslessly to MP3 files but here you're dealing with WAV files.

The program you want is freeware and called WaveGain. WaveGain along with the nice GUI frontend for it is found over on RareWares http://www.rarewares.org/ in the OTHERS section.

It works *really* well. It does not perform peak normalisation like the previous poster suggested. It performs an algorithm called ReplayGain whose sole purpose is to allow for the way humans perceive loudness. It gets complicated, but the end result is that you won't have to vary the volume control at all between tracks.

WaveGain overwrites the existing WAVE files with the adjusted versions, so then all you have to do is encode them back to your choice of AC3 or MP2 for whatever purpose you need. I don't know how to do all this in a one touch batch mode however.