1)Not sure what is displayed by exiftool, it may be offset from file beginning, not from jpeg preview start.
(hard to tell without having the file)
2) tags larger than 4 bytes contains offset (relative to IFD start), not exact value, so one need to seek to this offset to read the data. There is not enough output in your quote to check this.
BTW, I suggest you to not invent the wheel :), but use some exif parser (e.g. exiv2 if you can tolerate GPL licensing)
1)Not sure what is displayed by exiftool, it may be offset from file beginning, not from jpeg preview start.
(hard to tell without having the file)
2) tags larger than 4 bytes contains offset (relative to IFD start), not exact value, so one need to seek to this offset to read the data. There is not enough output in your quote to check this.
BTW, I suggest you to not invent the wheel :), but use some exif parser (e.g. exiv2 if you can tolerate GPL licensing)