CIFF specification -- which is bit 31?

[Archive]

[Originally posted by hippiness on 2006-03-20 22:24:44-08]

Regarding http://xyrion.org/ciff/CIFFspecV1R04.pdf, section 5.4.6, linked from http://www.exiftool.org/canon_raw.html...

I intend to update some files created by my Canon Powershot G2.  I want to set the time zone code and accordingly the `valid time zone code' bit (31) of the time zone info, but I do not know which is meant by `bit 31'.  The majority of my research leads me to believe that it is the most significant bit (MSB), but I would like to be surer before I meddle with the metadata.

Please help.

Thanks for ExifTool, by the way.  It's maaaaaaaaaaaaaaarvellous.  

[Archive]

[Originally posted by exiftool on 2006-03-21 00:24:16-08]

Nice to know somebody actually reads the documentation...

Yes, bit 31 is the most significant bit.  You can set this bit with either of these two commands:

Code:

   exiftool -TimeZoneCode=0x80000000 image.crw
    exiftool -TimeZoneCode=2147483648 image.crw

Personally, I find the hex representation easier to use, but currently ExifTool will print the decimal version when you read it back again.

But now I have a question:  What software do you have that honours this time zone code?

[Archive]

[Originally posted by hippiness on 2006-03-21 09:14:51-08]

Thanks for the speedy response.

I have no software to make sense of this setting of the time zone code; I know of none.  The same goes for the user comments I might apply to some of my images, thanks to your dandy tool.  I'm correcting the time zone code in the metadata in order to make sense of my bizarre meanderings between UTC and local time over recent years.  I had composed text messages explaining my time zone changes and saved them in my image repository; but now, on the occasion of my latest reorganisation, those text files appear to have vanished.  This time, setting a few bytes inside the images themselves will make me happiest.

And it's all thanks to you!  (Et alias.)

Thanks and best wishes.

[Archive]

[Originally posted by exiftool on 2006-03-21 12:42:26-08]

This makes sense.   Please note that I used the wrong tag name in my examples.  It should have been "TimeZoneInfo", not "TimeZoneCode".  As you know "TimeZoneCode" represents the time offset in seconds from GMT.

- Phil