Boost mp3 volume on iOS

Question

I was looking for information on http://developer.apple.com/library/ios as well as on https://stackoverflow.com/, but could not find a simple and elegant solution.

I will describe the key problems: it takes to get MP3 file from your media library iPod and increase its volume. On receipt of the file and playing key problems arise.

But the questions - which are not resolved:

1. How do I change the volume and re-encode MP3 file - so the volume was changed forever? The solution given in iOS: Create an MP3 on device Xcode, building and dylibs Trouble playing mp3s after id3 image edit not strike me as simple and good.

2. How do I replace the files from your iTunes library to the ones that made ​​my program? The need to force the user to synchronize this device, and manually drag and drop files to the library I razocharovyaet.

Are there any - any comments or suggestions. I would appreciate it.

Answer 1

I'm find in iTunes Music Library.xml key

Volume Adjustment 

I can boost volume on iTunes via this =). This match more better for me, except encode and realization meshanisms of lame/ffmpeg etc.

    2009
    
        Track ID2009
        NameStanding On The Shore
        ArtistEmpire Of The Sun
        Album ArtistEmpire Of The Sun
        AlbumWalking On A Dream
        Genre 
        KindАудиофайл MPEG
        Size10564118
        Total Time263836
        Track Number1
        Date Modified2011-11-26T19:52:01Z
        Date Added2011-09-23T20:59:24Z
        Bit Rate320
        Sample Rate44100
        Volume Adjustment192
        Play Count12
        Play Date3402675506
        Play Date UTC2011-10-28T17:38:26Z
        Skip Count2
        Skip Date2011-11-06T10:15:51Z
        Rating100
        Album Rating60
        Album Rating Computed
        Persistent ID2CF1305AEEF0FCDB
        Track TypeFile
        Locationfile://localhost/Users/wins/Music/iTunes/iTunes%20Media/Music/Empire%20Of%20The%20Sun/Walking%20On%20A%20Dream/01%20Standing%20On%20The%20Shore.mp3
        File Folder Count5
        Library Folder Count1
    

Answer 2

Re-encoding would cause a decrease of the audio quality. The good news is that you don't need to do this: There is a feature called "Sound Check" built into iTunes that ensures that all your songs are played with the same volume. iTunes scans the songs and stores the volume information inside the ID3 tags. For more information on this, read here: http://en.wikipedia.org/wiki/ReplayGain This also tells you how to implement it on iOS if you still want to do it.

However, there is no way to sync your changes back to your iTunes library.