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#55 support replaygain tags
Dear sox hackers,
I am using sox as driver for graveman's mp3/vorbis to
wav conversion. I would like sox to honour replaygain
tags in mp3 and ogg media.
Rendering the same ogg file with once a replaygain tag
absent, once one present results in identical wav files.
obviously, the wav output method of ogg123 behaves the
same, so the behaviour might stem from a library that
sox depends upon.
thank you.
peter
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SoX now has some RG support---is this sufficient?
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I am running a current debian unstable system with SoX v14.0.1. No matter where I put the argument, it does not matter; pity the file does not clip... copy/paste terminal session, what could I have done wrong?
:) $ mp3gain Mongoloid.mp3
Mongoloid.mp3
Recommended "Track" dB change: -6.090000
Recommended "Track" mp3 gain change: -4
Max PCM sample at current gain: 31567.085568
Max mp3 global gain field: 203
Min mp3 global gain field: 150
Recommended "Album" dB change for all files: -6.090000
Recommended "Album" mp3 gain change for all files: -4
:) $
:( $ sox Mongoloid.mp3 a.wav
:) $ sox Mongoloid.mp3 --replay-gain track b.wav
:) $ cmp a.wav b.wav
:) $ sox --replay-gain track Mongoloid.mp3 b.wav
:) $ cmp a.wav b.wav
:) $
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Ah, sorry, should've mentioned this before: RG support is only there for some types (including ogg & flac) but not mp3 at the moment. This is largely due to the seemingly ad hoc ways in which mp3 handles tags.
Does mp3gain represent the standard way to embed RG info in mp3?
Annoyingly, unlike almost every other comment/tagging scheme, it puts the info at the end of the file rather than the beginning.
Also, does the current RG support for ogg do what you need?
Cheers,
Rob
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thank you, when asked to, sox-converting ogg to wav uses replaygain info correctly.
I do not know if mp3gain is widely used to tag mp3s with replaygain info; it can also be used to modify the file, so non-aware players get it right, but the default operation is to just tag: an APE tag gets appended to the end of the file. a comparison of an mp3gained file with the original yields just EOF on this one.
recent lame encoders by default add track replaygain info to the files they create. see http://gabriel.mp3-tech.org/mp3infotag.html how it is stored in the LAME info tag at the start of the file. sox might use that for track-gain.
there is also an ID3v2 replaygain tag, like foobar2000 is said to write; mpg123 seems to use that too: see here how to create it - http://www.hydrogenaudio.org/forums/lofiversion/index.php/t42005.html - sox might use that too.
some complications explained here... http://www.mars.org/mailman/public/mad-dev/2004-February/000993.html