Volume Normalization

[sredmyer]

I have a library of flac files that I want to convert to mp3 for a portable player. I also want to apply volume normalization to the converted (mp3) files so that any track from the entire list can be played without the constant need to adjust the volume.

I am familiar with the program Mp3Gain for doing this. My questions are this:
1) Is the Volume Normalization dsp ReplayGain (track gain) the same as Mp3Gain in track gain (as opposed to album gain) mode?
2) Does dmc write the undo information to the tags like Mp3Gain?
3) Can the Mp3Gain application be used to reverse the ReplayGain done by dmc?

Thanks,

[LtData]

Re: Volume Normalization

1. No
2. No, the actual files are altered in a non-reversible manner
3. No

[sredmyer]

Re: Volume Normalization

1. No
2. No, the actual files are altered in a non-reversible manner
3. No

1) Then is there an option in dmc which produces similar results?

2) Mp3Gain also alters the actual files...but it then writes what alteration was made to a custom tag. The user can then "undo" the normalization and get back to the original mp3 amplitude by running the app again.

2a) Does dmc not offer any such feature?

[LtData]

Re: Volume Normalization

1) Volume Normalize in ReplayGain mode should produce a consistent gain when used in track mode, I believe, though Spoon would have to verify. Sorry, I misunderstood your question.
2) I was under the impression mp3Gain writes a gain value at the start of each frame or something similar, so that the actual audio data isn't altered.
3) See #2, RG and mp3Gain function in different ways.

[xoas]

Re: Volume Normalization

I would like to add that the Volume Normalization dsp in dBpowerAMP Music Converter (dMC) is irreversible. dMC does have a ReplayGain dsp although the results of this require a player that can read ReplayGain. The changes produced by the ReplayGain dsp are reversible. The Volume Normalization dsp in ReplayGain mode is NOT reversible but can be played by any player.

My understanding is that Mp3Gain can reverse Mp3Gain files (and I do believe that it does function as LtData suggests it does). I am sure apply Mp3Gain to files that have have been ripped with Volume Normalization dsp in dMC (whether in ReplayGain mode or any other mode). But this would not necessarily undo the effects of applying the original Volume Normalization dsp, it would merely apply the effects of Mp3Gain to the altered file.

Best wishes,
Bill

[a.wright]

Re: Volume Normalization

Although not a direct answer to your question I spent ages trying to decide the best way to go about normalising my files.

In the end I decided to go with MP3 Gain because then I have freedom to change what I have done and all players will play the files at the correct volume, determined by me. If for example I decided I wanted to apply Album Gain instead of Track Gain or vice versa, I can just undo the gain changes and redo them again. It's dead easy to load a whole list of files in and let MP3Gain work through them.

Curiously given how MP3Gain is supposed to work (i.e. it writes tags in APE format to hold the Undo information but actually alters the file) there still apear to be Replaygain tags written, which should not be needed. I have no idea what effect this has on players that don't support Replaygain but I assume they would just ignore them.

All I know is that in all the various players/devices I have, the MP3 files play at the right volume so it must work!

[sredmyer]

Re: Volume Normalization

a.wright,

The tags written by Mp3Gain are what is used by the app to "undo" the changes made. In other words if the gain calcualted and applied by Mp3Gain is +1.5 (not this value is applied to each frame), that value will be written to the files tag. Then when/if you want to revert to the original you simply run Mp3Gain again and specify undo. It will read this value and modify the file apropriately. This implies (though I am not sure of this) that if you adjust the volume again without first reverting to the original you would then lose the ability to get back to the original and only be able to get back to what it was prior to last adjustment.

My original question was if dmc ReplayGain dsp also created this same type of "undo" tag and could therefore be used in a similar manner (reversable). It appears though that although both Mp3Gain and dmc Replay gain do alter the actual audio data, dmc does not create any undo tag value.

Bottom line
Mp3Gain is reversable (only a single level though)
dmc with ReplayGain is not reversable

[a.wright]

Re: Volume Normalization

The tags written by Mp3Gain are what is used by the app to "undo" the changes made.

Correct but on checking the tags after running the files through MP3Gain, it seems to have also written ReplayGain tags in addition to the "undo" tags. This is what seems odd. Why does it need to write ReplayGain tags if it already alters the audio (in whichever way) and has the "undo" tags to change back if necessary?

Bottom line
Mp3Gain is reversable (only a single level though)
dmc with ReplayGain is not reversable

Which is why I went with MP3Gain. Reversable and works with all players, i.e they don't need to support ReplayGain tags.

[xoas]

Re: Volume Normalization

Correct but on checking the tags after running the files through MP3Gain, it seems to have also written ReplayGain tags in addition to the "undo" tags. This is what seems odd. Why does it need to write ReplayGain tags if it already alters the audio (in whichever way) and has the "undo" tags to change back if necessary?


Which is why I went with MP3Gain. Reversable and works with all players, i.e they don't need to support ReplayGain tags.

Just to reiterate. dMC using the ReplayGain dsp IS reversible but it will ONLY work with players that support ReplayGain. ReplayGain can be applied to a wide variety of formats. However, if you convert a file with ReplayGain to a different format (say from flac to mp3) ReplayGain needs to be re-calculated. As I understand it, ReplayGain does NOT touch the original audio qualities of the file. Instead it creates a file that tells the player (assuming it is set up to read this information) how to adjust the volume as the file is played.

dMC using the Volume Normalization dsp (with the ReplayGain setting or with any of the other settings) is NOT reversible but the effect will be audible on any player. It does not need to be re-applied if you convert a file with Volume Normalization from one format to another. The Volume Normalization dsp re-writes the audio file but contains NO tag data that would allow it to be undone.

I don't believe that Mp3Gain can work with many different formats. It will change the audio quality of the files it is applied to but only those frames (and that quality that are specifically) related to gain and it stores information to allow the effect to be undone and thus it allows the original file characteristics to be restored.

I point these things out partly to explain why Mp3Gain and ReplayGain are not interchangeable and how they store different tag information from one another. I also wanted to remind users of the distinction between dMC's ReplayGain dsp and dMC's Volume Normalize dsp with the ReplayGain setting (the first is reversible, the second is not; the first creates tag information, the second does not).

I am not advocating any of these approaches over any other. A strong case can be made for using each of these approaches. Many players also have a volume normalization feature independent of Mp3Gain or ReplayGain, but these tend not to be as powerful in their results as these 3 options.

Best wishes,
Bill

[a.wright]

Re: Volume Normalization

MP3Gain... It will change the audio quality of the files it is applied to but only those frames (and that quality that are specifically) related to gain

I assume you mean that it changes the actual characteristics of the file rather affecting the sound (listening) quality?[quote]

I point these things out partly to explain why Mp3Gain and ReplayGain are not interchangeable and how they store different tag information from one another.

Which is why I was surprised to find files that had been put through MP3Gain contained all the undo tag information in addition to the same ReplayGain tags which I would have expected to see if the files had been run through dMC's Volume Normalize dsp with the ReplayGain setting.

If I right click on the files in explorer and choose audio properties, it specifically notes that ReplayGain has been applied, which I assume it is picking up from the ReplayGain tags and not the MP3Gain Undo tags.

[xoas]

Re: Volume Normalization

Which is why I was surprised to find files that had been put through MP3Gain contained all the undo tag information in addition to the same ReplayGain tags which I would have expected to see if the files had been run through dMC's Volume Normalize dsp with the ReplayGain setting.

If I right click on the files in explorer and choose audio properties, it specifically notes that ReplayGain has been applied, which I assume it is picking up from the ReplayGain tags and not the MP3Gain Undo tags.

OK. I think I can see what you're getting at. I'm going to do a little checking up on this in the next few days to try to test some ideas about this. I'll discuss my results and ideas at that time. My thoughts are that the tag information that you are seeing is not necesssarily reliable (that is, that the Mp3Gain tag information may be getting mis-identified as ReplayGain-whether in addition to being identified as having Mp3Gain applied or not). I also would expect that applying Volume Normalization dsp using the ReplayGain setting would not cause the tag information to show that ReplayGain had been applied (whereas using the ReplayGain dsp should show up in the tag information).

I am posting these thoughts in case I have misunderstood your findings or if there are any other details about these glitches that I have overlooked.

Best wishes,
Bill

[a.wright]

Re: Volume Normalization

My thoughts are that the tag information that you are seeing is not necesssarily reliable (that is, that the Mp3Gain tag information may be getting mis-identified as ReplayGain-whether in addition to being identified as having Mp3Gain applied or not).

Possibly!

If I right click properties and display the dbpoweramp audio properties it says:

Contains: Album Art, ReplayGain, ID Tag [APEv2 & ID3V2.3 etc]

If I look at the ID-Tag information I see (as an example) this:

<MP3GAIN_ALBUM_MINMAX> 048,207
<MP3GAIN_MINMAX> 048,207
<MP3GAIN_UNDO> +003,+003,N

and this:

<REPLAYGAIN> -3.675000dB
<REPLAYGAIN> 0.630103
<REPLAYGAIN> -4.405000dB
<REPLAYGAIN> 0.606984

Granted I don't have a clue what it all means but I thought that I should only be seeing the <MP3GAIN> tags?

[LtData]

Re: Volume Normalization

According to the mp3Gain FAQ, they use the Replaygain algorithim: http://mp3gain.sourceforge.net/faq.php

[a.wright]

Re: Volume Normalization

According to the mp3Gain FAQ, they use the Replaygain algorithim: http://mp3gain.sourceforge.net/faq.php

Yes they do but I thought they used the result of using the algorithm to change the file itself and then include the "undo" information as tags not use actual ReplayGain tags to achieve the desired effect.

[xoas]

Re: Volume Normalization

Andrew-
I'm puzzled.

I ripped the same CD four times using dBpowerAMP.
All were ripped to mp3 at -v 1.
One was ripped without any dsp and was left that way.
One was ripped plain and had Mp3Gain run at the default setting of 89 db. and track gain.
One was ripped with the ReplayGain dsp and the track gain setting.
The last was ripped with the Volume Normalize dsp and the ReplayGain setting on track gain.

Looking at the tags, the first and last groups show NO extra tag information.

The tracks that had Mp3Gain applied, the the dB Audio Properties shows the extra APEv2 tag (it does not show here that Mp3Gain has been applied) and the ID Tag window shows Mp3Gain information but no ReplayGain information.

The tracks ripped with ReplayGain only show the ID#v2.3 tag and that ReplayGain has been applied (in the dB Audio Properties window). It shows the ReplayGain data in the ID Tag window.

These results would seem to confirm that ReplayGain and Mp3Gain store their information in different locations.

My results are different from your experience in that my tracks with Mp3Gain applied do not show any ReplayGain information. As to why this may be, perhaps there are a number of possibilities: Perhaps we used different settings within dBpowerAMP Music Converter (dMC) for writing the tag information (I am, I believe, using pretty much the default); perhaps you have other tag editing software (that might allow your system to see more information); Perhaps we are using different Windows versions (I am using XP support pack 3; Perhaps Vista has extra capability here); we might be using different versions of Mp3Gain (mine is version 1.2.5 with Back end version 1.4.6).

The other possibility might be that you inadvertently ripped your tracks using the ReplayGain dsp without knowing it (if you rip a cd with a dsp, that dsp setting will remain each time you rip to the same format unless you manually remove the dsp from the list of dsps applied - once removed, it will remain off the dsp list until that dsp is used again at some later date). You might want to check this last possibility first (this is also the one possibility that I am positive will result in the combination of Mp3Gain and ReplayGain tag information on a single tag that you describe).

If there are other factors to look into, please let me know and I'll poke around a bit more to see if we can mail down this issue.

Best wishes,
Bill