In ID3v1, a track number is present only if byte 125 is null AND byte 126 is non-null. If the track number is not present, don't add a track number tag with value 0.
In ID3v1, a track number is present only if byte 125 is null AND byte 126 is non-null. If the track number is not present, don't add a track number tag with value 0.