[mb-bugs] [MusicBrainz Bug Tracker] #4841: patched_MultiSpec_write function prevents iTunes SoundCheck tag from being read from shared music library

[MusicBrainz Bug Tracker]

#4841: patched_MultiSpec_write function prevents iTunes SoundCheck tag from being
read from shared music library
------------------------------------------------+---------------------------
 Reporter:  paraquat@...                  |        Type:  bug          
   Status:  new                                 |    Priority:  normal      
Milestone:                                      |   Component:  Picard Tagger
  Version:  Picard 0.11                         |    Keywords:              
  Browser:  Netscape, Firefox, Mozilla (Gecko)  |          Os:  Windows Vista
------------------------------------------------+---------------------------
 This is a pretty esoteric bug, but here goes anyway:

 I use a music server called Firefly Media Server to host my music as an
 iTunes share, which I play using my laptop.  iTunes has a feature called
 SoundCheck which basically stores volume normalization information in a
 special comment tag so that each track has a consistent volume.  The issue
 I've been having for quite some time is that after saving MP3 files with
 Picard, the SoundCheck information is no longer available to iTunes.  A
 workaround I've been using is to re-save the tags using a program called
 Mp3tag, after which point the files work properly.

 I finally had some free time to investigate.  At first I suspected that
 the Mutagen tagging library had some incompatibilities, but eventually I
 found that re-saving the files with the mutagen tool mid3v2 fixed the
 files as well.  A binary diff tool showed differences in tag structure
 between the picard-saved file and the mutagen-saved file.

 I finally tracked it down to the function patched_MultiSpec_write in
 picard/formats/id3.py, line 42.  After I commented out the function, my
 local copy of Picard saved the files byte-for-byte exactly the same as
 mutagen, and the SoundCheck information worked properly.

 I don't know why that function was patched originally, or what problem it
 was meant to solve, but maybe it could be an option to turn on or off that
 null-termination functionality?

 Actually, upon further inspection of the differences between the release
 Picard tags and the Mp3tag program tags, the bug may be more subtle.  It
 seems from looking at the hex editor that Mp3tag only null-terminates the
 COMM tag but none of the others.  Mutagen by default appears to null-
 terminate every tag.

--
Ticket URL: <http://bugs.musicbrainz.org/ticket/4841>
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[MusicBrainz Bug Tracker]

#4841: patched_MultiSpec_write function prevents iTunes SoundCheck tag from being
read from shared music library
-------------------------------------------------+--------------------------
  Reporter:  paraquat@...                  |       Owner:              
      Type:  bug                                 |      Status:  new          
  Priority:  normal                              |   Milestone:              
 Component:  Picard Tagger                       |     Version:  Picard 0.11  
Resolution:                                      |    Keywords:              
   Browser:  Netscape, Firefox, Mozilla (Gecko)  |          Os:  Windows Vista
-------------------------------------------------+--------------------------
Comment (by luks):

 If you still have the files, could you please send me the working and not-
 working files to lalinsky@...?

 The hack was added specifically for iTunes -- it likes to display the null
 characters after titles in some font/encoding combinations.

--
Ticket URL: <http://bugs.musicbrainz.org/ticket/4841#comment:1>
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[MusicBrainz Bug Tracker]

#4841: patched_MultiSpec_write function prevents iTunes SoundCheck tag from being
read from shared music library
-------------------------------------------------+--------------------------
  Reporter:  paraquat@...                  |       Owner:              
      Type:  bug                                 |      Status:  new          
  Priority:  normal                              |   Milestone:              
 Component:  Picard Tagger                       |     Version:  Picard 0.11  
Resolution:                                      |    Keywords:              
   Browser:  Netscape, Firefox, Mozilla (Gecko)  |          Os:  Windows Vista
-------------------------------------------------+--------------------------
Comment (by paraquat@...):

 Sure, I will send you 3 files via e-mail.  I reproduced the issue with a
 file that has no cover art, since it makes it easier to look at the tags
 without a giant block of JPG data in the middle.  All of these are with
 ID3 2.4, UTF8.

 01 - The Fox.picard.mp3

 Saved with Picard 0.11.  Does not work.

 01 - The Fox.mid3v2.mp3

 Saved with mid3v2 from Mutagen 1.15.  Does work.

 01 - The Fox.mp3tag.mp3

 Saved with Mp3tag 2.42.  Does work.

 The soundcheck data is in a tag that Mp3tag calls "COMMENT ITUNNORM" with
 value:

 " 00001048 00001048 00001048 00001048 00001048 00001048 00001048 00001048
 00001048 00001048"

 (I guess it starts with a leading space for some reason)

 mutagen-inspect lists it as:

 COMM=iTunNORM='eng'= 00001048 00001048 00001048 00001048 00001048 00001048
 00001048 00001048 00001048 00001048

--
Ticket URL: <http://bugs.musicbrainz.org/ticket/4841#comment:2>
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#4841: patched_MultiSpec_write function prevents iTunes SoundCheck tag from being
read from shared music library
---------------------------------+------------------------------------------
  Reporter:  paraquat@...  |       Owner:  nxisgod                          
      Type:  bug                 |      Status:  new                              
  Priority:  normal              |   Milestone:                                    
 Component:  Picard Tagger       |     Version:  Picard 0.11                      
Resolution:                      |    Keywords:                                    
        Os:  Windows Vista       |     Browser:  Netscape, Firefox, Mozilla (Gecko)
---------------------------------+------------------------------------------
Changes (by nxisgod):

  * owner:  => nxisgod

Comment:

 "These 10 values are encoded as
 ASCII Hex values of 8 characters each inside the tag (plus a space as
 prefix)."
 prefix is a big hint.

 I checked with current trunk. It does remove the prefix.

 "The hack was added specifically for iTunes -- it likes to display the
 null characters after titles in some font/encoding combinations." - Itunes
 just reached version 9. Good idea to have a look at whether these issues
 have been resolved.

 I suggest to "comment out" the monkey patch. We can late figure out how to
 prevent it from breaking tags.

--
Ticket URL: <http://bugs.musicbrainz.org/ticket/4841#comment:3>
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[MusicBrainz Bug Tracker]

#4841: patched_MultiSpec_write function prevents iTunes SoundCheck tag from being
read from shared music library
---------------------------------+------------------------------------------
  Reporter:  paraquat@...  |       Owner:  nxisgod    
      Type:  bug                 |      Status:  closed    
  Priority:  normal              |   Milestone:  Picard 0.12
 Component:  Picard Tagger       |     Version:  Picard 0.11
Resolution:  fixed               |    Keywords:            
        Os:                      |     Browser:            
---------------------------------+------------------------------------------
Changes (by nxisgod):

  * status:  new => closed
  * resolution:  => fixed
  * milestone:  => Picard 0.12
  * os:  Windows Vista =>
  * browser:  Netscape, Firefox, Mozilla (Gecko) =>

Comment:

 Fix released and merged.

--
Ticket URL: <http://bugs.musicbrainz.org/ticket/4841#comment:4>
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[MusicBrainz Bug Tracker]

#4841: patched_MultiSpec_write function prevents iTunes SoundCheck tag from being
read from shared music library
---------------------------------+------------------------------------------
  Reporter:  paraquat@...  |       Owner:  nxisgod    
      Type:  bug                 |      Status:  reopened  
  Priority:  normal              |   Milestone:  Picard 0.12
 Component:  Picard Tagger       |     Version:  Picard 0.11
Resolution:                      |    Keywords:            
        Os:                      |     Browser:            
---------------------------------+------------------------------------------
Changes (by paraquat@...):

  * status:  closed => reopened
  * resolution:  fixed =>

Comment:

 With Picard 0.12.1, I can confirm that all comments tags are no longer
 being deleted, however, the original problem is not solved.

 The attempted fix at line 251 is not being executed because the metadata
 variable does not contain any items whose name starts with 'comment:'.  I
 inserted some print statements to try and figure out what's going on.

 Using the same test file as from back in March, at line 195 (the end of
 the _load method), metadata contains:

 {'albumartistsort': [u'Sleater-Kinney'],
 'releasecountry': [u'US'],
 'totaldiscs': [u'1'],
 'genre': [u'Punk;Rock;Indie;Perfect;Riot Grrrl;Indie Rock;Chick
 Rock;Alternative;Animal Songs;Sleater-Kinney;Sleater Kinney;Female
 Vocalists;Alternative Rock'],
 'albumartist': [u'Sleater-Kinney'],
 'musicbrainz_albumartistid': [u'e36e78eb-3ace-4acd-882c-16789e700ab7'],
 '~#sample_rate': [44100],
 'tracknumber':[u'1'],
 'musicbrainz_trackid': [u'6b759dc6-2895-4280-8ab5-580caf5f6e6b'],
 'album': [u'Live at Lollapalooza 2006'],
 'musicbrainz_artistid': [u'e36e78eb-3ace-4acd-882c-16789e700ab7'],
 '~#bitrate': [196.18299999999999],
 'title': [u'The Fox'],'label': [u'Lollapalooza 2006 / IODA'],
 'artistsort': [u'Sleater-Kinney'],
 'musicip_puid': [u'2a50abf2-b2e9-538f-9f97-ac6bfd9eaf50'],
 u'comment:iTunNORM': [u' 00001048 00001048 00001048 00001048 00001048
 00001048 00001048 00001048 0000104800001048'],
 'releasestatus': [u'official'],
 'date': ['2006-09-12'],
 'discnumber': [u'1'],
 'artist': [u'Sleater-Kinney'],
 'releasetype': [u'live'],
 'musicbrainz_albumid': [u'a15b06f1-7246-47ce-b04f-59bd74b6b17e'],
 'totaltracks': [u'3'],
 '~format': ['MPEG-1 Layer 3']}

 (I inserted line breaks to see each key/val easier)

 comment:iTunNORM is there, like you'd expect.

 At line 241, right after tags.delall('TCMP') in _save, metadata contains:

 {'albumartistsort': [u'Sleater-Kinney'],
 'releasecountry': [u'US'],
 'albumartist': [u'Sleater-Kinney'],
 'musicbrainz_albumartistid': [u'e36e78eb-3ace-4acd-882c-16789e700ab7'],
 'tracknumber': ['1'],
 'musicbrainz_trackid': [u'6b759dc6-2895-4280-8ab5-580caf5f6e6b'],
 'album': [u'Live at Lollapalooza 2006'],
 'musicbrainz_artistid': [u'e36e78eb-3ace-4acd-882c-16789e700ab7'],
 'title': [u'The Fox'],
 'label': [u'Lollapalooza 2006 / IODA'],
 'artistsort': [u'Sleater-Kinney'],
 'musicip_puid': [u'2a50abf2-b2e9-538f-9f97-ac6bfd9eaf50'],
 'format': [u'Digital'],
 'releasestatus': [u'official'],
 '~extension': [u'mp3'],
 'date': [u'2006-09-12'],
 'language': [u'eng'],
 'artist': [u'Sleater-Kinney'],
 'script': [u'Latn'],
 'releasetype': [u'live'],
 'musicbrainz_albumid': [u'a15b06f1-7246-47ce-b04f-59bd74b6b17e'],
 'totaltracks': ['3']}

 Notice the lack of comment:iTunNORM, as well as various other pairs.  I
 assume at this point that metadata only contains those tags that are
 intended to be updated by Picard itself, but I haven't found the place in
 the code where metadata actually gets cleared out.

--
Ticket URL: <http://bugs.musicbrainz.org/ticket/4841#comment:5>
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#4841: patched_MultiSpec_write function prevents iTunes SoundCheck tag from being
read from shared music library
---------------------------------+------------------------------------------
  Reporter:  paraquat@...  |       Owner:  nxisgod    
      Type:  bug                 |      Status:  reopened  
  Priority:  normal              |   Milestone:  Picard 0.12
 Component:  Picard Tagger       |     Version:  Picard 0.11
Resolution:                      |    Keywords:            
        Os:                      |     Browser:            
---------------------------------+------------------------------------------
Comment (by paraquat@...):

 Sorry, I should have previewed that before submitting.  I guess the Wiki
 syntax took out my linebreaks, and I don't see any way to edit my previous
 message.  All the info is still there, just with unfortunate markup.

--
Ticket URL: <http://bugs.musicbrainz.org/ticket/4841#comment:6>
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#4841: patched_MultiSpec_write function prevents iTunes SoundCheck tag from being
read from shared music library
---------------------------------+------------------------------------------
  Reporter:  paraquat@...  |       Owner:  nxisgod    
      Type:  bug                 |      Status:  reopened  
  Priority:  normal              |   Milestone:  Picard 0.12
 Component:  Picard Tagger       |     Version:  Picard 0.11
Resolution:                      |    Keywords:            
        Os:                      |     Browser:            
---------------------------------+------------------------------------------
Comment (by outsidecontext):

 Thanks for the feedback. It sounds completely logical that the iTunNorm
 tag is not in the metadata, since once you match a file to a track and
 save it only the new metadata from the track will be saved. And as long as
 you don't set the option to delete all existing tags that should leave the
 existing tags untouched if they are not overwritten by the track metadata.

 Without looking at the source I suppose this issue must be solved in
 mutagen.

--
Ticket URL: <http://bugs.musicbrainz.org/ticket/4841#comment:7>
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#4841: patched_MultiSpec_write function prevents iTunes SoundCheck tag from being
read from shared music library
---------------------------------+------------------------------------------
  Reporter:  paraquat@...  |       Owner:  nxisgod    
      Type:  bug                 |      Status:  reopened  
  Priority:  normal              |   Milestone:  Picard 0.12
 Component:  Picard Tagger       |     Version:  Picard 0.12
Resolution:                      |    Keywords:            
        Os:                      |     Browser:            
---------------------------------+------------------------------------------
Changes (by outsidecontext):

  * version:  Picard 0.11 => Picard 0.12

--
Ticket URL: <http://bugs.musicbrainz.org/ticket/4841#comment:8>
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