I aplogize if my questions have already been discussed in another topic.
I discovered that an MP3 file can contain a cover image, which is not showed in MP3Tag. Also most audio players do not show the cover image, but some audio players do.
So what is going on?
I found out that the cover is in a comments field, which is not part of id3v2. It is nowhere showed in MP3Tag. I checked everything, also "Extended Tags..."
My first question: Could it be that I need to change a setting in MP3Tag to be able to see the cover?
So how do I know the cover is in a "comments" field?
I wrote my own audio player which uses getid3 (see https://getid3.sourceforge.net/ ). With this libary you can retreive file info (id3v2 tags) from audio files. It also reads comments from audio files, which are not part of the id3v2 tags and some MP3 files have covers hidden in these "comments".
If I read the fileinfo with getid3,I see an asccoiated array $fileinfo and one of the keys is 'comments'.
$fileinfo['comments'] is an associated array with the following keys: picture, album, artist, band, title, text, lastweek, weeks, year, genre, comment.
Element $fileinfo['comments']['picture'] contains the picture data and the image mime type.
My next question is: Can covers being part of "comments" be handled by MP3Tag?
Because I could not use MP3Tag to remove the cover from the "comments", I had to find anothe way to remove the cover from the file. For this I used:
ffmpeg -i tagged.mp3 -map_metadata -1 untagged.mp3
This also works:
ffmpeg -i tagged.mp3 -map 0:a -c:a copy -map_metadata -1 untagged.mp3
After that I could edit the MP3 file with MP3Tag, add all the tags again, with a normal album cover.
My last question: Can you/somebody provide more information about these 'hidden covers'?
PS: If you need a MP3 file with a cover in the 'comments', I can provide it of course.