Yesterday I found out that the file size doesn't actually decrease if you delete an embedded album cover image in a FLAC file with MP3tag and if you've changed the image several times the file size increased every time. Apparently this happens because MP3tag just overwrites the file with random data instead of deleting it or something like that. I tried using metaflac but it only removes the padding and picture if the file is still embedded, if you have already tried deleting it with Mp3tag before it won't work. So my music library is now full of FLAC files that contain useless junk data that has accumulated in some cases because i had changed the album cover several times with MP3tag and it seems that this data can't be removed except by re-encoding the FLAC file. Is there any way to remove it without re-encoding, does re-encoding have a risk of corrupting or slightly changing the audio data and why does MP3tag allow "removing" embedded images in FLAC files if it leads to such problems or not at least display some kind of warning?
That's just the metaflac command I had already tried in a batch file. If you run it as is it just adds a bit padding, if you change "--block-type=PADDING" to "--block-type=PADDING,PICTURE" it also removes embedded images but it doesn't remove the data that stems from the images that have been "removed" with MP3tag before.
Mp3tag does not believe it is causing problems, but rather that is is providing a service!
However, I share your concern about file sizes.
And re-encoding can be time consuming.
I wonder if reducing file sizes increases unused space on the disk? I dunno.
Another question: re-encoding vs copying vs bit-rot. ???
flac --no-padding -o "F:\1Hold\TEST\Experiment\2KB raw + 5 KB album art - Art removed by Mp3tag - re-encoded with no padding by FLAC.flac" "F:\1Hold\TEST\Experiment\2KB raw + 5 KB album art - Art removed by Mp3tag.flac"