Encoding from FLAC to MP3 with -1db normalization error

[GavSalkeld]

Ive been encoding FLAC files to MP3s for years now, with the DSP volume normalize function on -1db (to avoid clipping). But suddenly now, today, when I check the files back in Adobe Audition, it is encoding all my MP3 files fully normalized and then applying a -1db reduction. So quiet tracks are now loud and hissy.

Ive removed the DSP effect and re-added it, but nothing is working. Anyone got any thoughts? :S

[Spoon-]

Re: Encoding from FLAC to MP3 with -1db normalization error

The DSP effect cannot be applied after encoding, it is simply not possible in dBpoweramp, if you have the effect it is happening Decode >> Effect >> Encode

[GavSalkeld]

Re: Encoding from FLAC to MP3 with -1db normalization error

Oh I know how to use it, I right click and Convert To and add it to the effects at the bottom. Its worked for years but yesterday it was being weird and normalizing audion -I had no normalization added anywhere, so why is this?

[Spoon-]

Re: Encoding from FLAC to MP3 with -1db normalization error

Set it to something like -12db so it is obvious if being applied.

[GavSalkeld]

Re: Encoding from FLAC to MP3 with -1db normalization error

But this doesnt explain the issue. For years I used these settings:



...which encoded everything with a 1db drop.

However now, I am having to use this setting to achieve the same effect:



...which doesnt make sense. Why would it suddenly mess up like this?

[Spoon-]

Re: Encoding from FLAC to MP3 with -1db normalization error

First I would encode to WAV, this eliminates the issue being in a later mp3 encoder (mp3 can scale up peaks over clipping, it is how any lossy designed codec works).

[GavSalkeld]

Re: Encoding from FLAC to MP3 with -1db normalization error

OK but I shouldnt have to do that. All I would like to know is, a) why did it suddenly start doing this and b) how do we stop it?

[Spoon-]

Re: Encoding from FLAC to MP3 with -1db normalization error

You have to do it as a test to find where the difference is from. Until you investigate you will not have a clue what is going on.

Encode a trouble file, to wave with -1db and without -1db then compare in an audio editor and look for the peaks. Then convert both files to mp3 (no DSP effects as already applied) again compare the peaks.

[Spoon-]

Re: Encoding from FLAC to MP3 with -1db normalization error

For all we know the mp3 decoder in adobe might be the thing which has changed...

[GavSalkeld]

Re: Encoding from FLAC to MP3 with -1db normalization error

OK I did as you said converting two files to WAV; one using my old method of putting -1dB under Desired Volume, which always used to work, and encoding one without any DSP effect.

The one with -1dB applied was again normalized to -1db and the one without any DSP effects was the same. Encoding them both to MP3 without any DSP effects left the volumes identical.

[Spoon-]

Re: Encoding from FLAC to MP3 with -1db normalization error

Makes sense now, the Peak to Peak if was less than -1db off clipping in the original would not normalize, so your fixed option will always take -1db off. With mp3 it is possible to get clipping at these levels I am sure (-1db).

[GavSalkeld]

Re: Encoding from FLAC to MP3 with -1db normalization error

Makes sense now, the Peak to Peak if was less than -1db off clipping in the original would not normalize

Sorry, forgive me, I dont follow?

[Spoon-]

Re: Encoding from FLAC to MP3 with -1db normalization error

See:

http://www.hydrogenaudio.org/forums/index.php?showtopic=82112

Here are samples which need -5dB to stop clipping (watch the animation).

I was saying, the option -1dB peak to peak, will leave the file untouched if it is already -1dB off the peak.

[GavSalkeld]

Re: Encoding from FLAC to MP3 with -1db normalization error

I was saying, the option -1dB peak to peak, will leave the file untouched if it is already -1dB off the peak.

Thats not true, the test file I encoded was quite quiet and the Peak to Peak normalized it to -1db. Ive encoded similar quiet files (ambient music, for example) using the exact same method for years and it has not normalized them in this way.

I see no reason why one day dbPowerAmp would suddenly start doing this one day. Ive never had to use Fixed Amplitude at all, until the other day...

[Spoon-]

Re: Encoding from FLAC to MP3 with -1db normalization error

I was referring to normalizing down, if over the -1db, if the signal was -12dB off peak then it would be normalized upto -1db off peak.

If your file was close to -1dB you would see no change, where-as if you apply -1db fixed, then it would then be -2db