#51 Mp3 Volume Normalization: (mp3gain ?)

[Vathek]

Hi,
is it possible to include in ml_ipod a feature that
normalize all the volume levels of songs on ipod?

Normalization consists on analyze the volume of songs
on the ipod and making them at the same peak level...
(so that switching from Vivaldi to Metallica could be
possible without constantly modifying volume wheel)

Actually I'm using mp3gain
(http://mp3gain.sourceforge.net/) to scan all file on
my ipod and then normalize the volumes...

Mp3Gain works by adding some information tags about the
original and wanted (read normalized) volume level to
the mp3s (this is the first step called "analyze").

Then the second step is to actually normalize (changing
the mp3 volume) the songs... (called "Normalize" feature)

All this method is completely tunable and reversible as
normalization keeps the original volume level tag so
that is always possible to undo everything...

In my opinion it could be possibile to add such a
feature in "Tools" or maybe just before the transfer...

Anyway it seems to me to be not so different from
transcoding (already implement) so ... give it a look :)

Thank you :)
(Mp3Gain was also supported by EuPod, because is also
avaiable a nice mp3gain command line executable)

[Achim Bursian]

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Just to make it clearer: You would like to have it that way:

When a file is transfered to the iPod, it should be copied
to a temporary place first, then mp3gain exe should edit
it, and then we write the edited file to the iPod. Correct?

[Vathek]

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Ok, normalization could be done either before or after
transfer .

As normalization step requires the analysis one, and two
steps require about 10second for track, I think the best way
is to add a command that do the normalization directly on
the ipod...

(Obviously normalization should be done only on new songs,
but I think that this task is already done by mp3gain itself)

Hope it's more clear now :)
Thanks!

[Achim Bursian]

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Ok, thanks for the clarification.
I have a new test version up on the website. It does
mp3gain on all songs (There is an option in the tools menu)

No prefs page yet, it simply uses the standards. And
mp3gain must be correctly installed (with the installer).

On my nano, it takes ages, I guess this is because of the
slow read/write speed on the flash memory. Could you give
it a try on your iPod (which model do you have?)

Is that ok this way?

[Vathek]

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I have a 4MB Mini version... I'll test your new version
immediatly..

Anyway did you try to test processing time by running
mp3gain on a dozen of tracks either on hard disk and on your
nano flash?

High timing could be due to a very slow cpu...
I'm using a P4 3,2Ghz and it takes approximatively the same
time on my mini and on my hard disk)

[Vathek]

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OK! It works good with my ipod mini.
Actually I ran it only for normalyzing task (as I already
did the analysis with mp3gain original program) and it takes
15-20 tracks per minute, so it's quite the same speed as the
original mp3gain.

Anyway I also found some strange little flaws:

1) I found that it normalizes all tracks to 91dB. It's
strange since mp3gain default value should be 89dB? (Is it
intentional or it's a problem of mine?)

2) I found that tracks of 15minutes are not being
normalized, I don't really know why as original mp3gain
normalises them without any problem...

Hope it helps :)

[Achim Bursian]

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Thanks for reporting that it's working fine.
The two flaws are actually implemented that way: The 91dB
just to see if other dB settings work, and the 15min limit
that very long tracks (audiobooks) get excluded. 15min is
hardcoded at the moment. That will go into a prefs page.
Don't you think that this limit is a good idea?

[Vathek]

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Ok, preference page it's a good idea.
Just include dB and time limit in the user settings and the
feature will be perfect. :)

For default values I think 89dB (maybe 90?) and 15min are ok!

Thanks!

[Vathek]

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I've just tried v1.40p10 and it's look very very good...

However at this point I'm thinking about a pair of
additional features that could make it better:
1) Is it possibile to show in winamp ipod plugin the volumes
tag as it happens with original mp3gain? (In the column near
the id3 tags as size or bitrate for example)
Mp3Gain tags are in APEv2 format.

2) While normalizing I can't know how much time process will
require, is it possible to add an estimation of time needed
to complete? (As it happens with transfer process?)

Thanks a lot, you're making an excellent plugin! (Maybe
better than iTunes itself!)

[Achim Bursian]

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Ok, to your questions:
1) No, ml_ipod does not read ANY tags from the file. That
would be too much work to add. At the moment, it only
displays what it gets from the ML interface, and there are
no APE2 tags available.
2)No again. I don't know in advance how long it will take,
only how many files I have to process. For files that have
been procesed already, it takes milliseconds until mp3gain
returns control. But for those that have to be analyzed or
changed, it takes several seconds. And I leave it to
mp3gain to detect which ones it has to analyze.

To support what you request, it would be necessary to scan
all files in advance to see whether processing is
necessary. That takes time again. I think it's not worth
the effort.

[Vathek]

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Ok for the first topic, but for the second one I think it
could be possible to give an estimation based on the mean
value of processing time for a track.

I mean that just after have processed one track I have a
mean value identical to processing time for that track.
Then after two tracks I will take half of the total time for
mean processing time.
So after N tracks I will take total time elapsed divided by N...

At this point if there are T-N tracks remaining I always
could estimate the remaining time applying mean value to the
remaining tracks.
So a simple formula to do this is:

(TOTAL_TRACKS-N)*(TIME_ELAPSED/N)
where N is the number of tracks allready normalized.

Simple, isnt'it? :)

[Achim Bursian]

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You were right if there was something like an average time.
But imagine: You have 5000 tracks, all normalized already.
Now you upload 100 new ones, which will take average 8
seconds per track. The 5000 first ones will be analyzed in
a second or so, so the calculation will always
say "estimated time left 1sek". Even after normalizing some
of the new files, the average time will be very small, so
no real estimation can be done.
And I don't want to keep track of what has been normalized
already, besides the tags that mp3gain writes.

Surely it would be possible to do something about that, but
as you know, I do this in my spare time only. And I've got
a regular job, that takes most time, too. So from my point
of view, it would be just too much effort for something
that is only "nice to have", but definitely no improved
functionality.

I waste too much time for ml_ipod anyway... my family needs
more of it.

[Vathek]

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Ok, ok... no problem...