I have been exploring some problems I have been having with Images in various programs at the byte level and have come across something with may be a 'very subtle' bug or may just be my lack of understanding of the topic. I hope someone will help clear it up for me.
When adding cover art using MP3Tag (ID3v2.4) it appears that 4 extra bytes are being added to the APIC header which I cannot account for between the Frame ID and the MIME Type. I have attached a screen print of what I am seeing, but this is found in all of the mp3 files I have experimented with.
My understand of the specification is the following: APIC (4 bytes) Size (4) Flags (2) Text Encoding (1) followed by 'image/jpeg' for a total of 11 bytes before 'image/jpeg'
In the attached screen print, I count 15 and I cannot figure out what the other 4 bytes are for. Any explaination (education) greatly appreciated.