Re: Ascertaining UDF and ISO CD time zone?

From: Pieter-Bas IJdens <pieter-bas(at)ijdens.com>
Date: Mon Dec 16 2002 - 06:09:36 EST

> My coworker who is putting together the tutorial on UDF and ISO CD-ROM

The following code can be used to decode timezones as specified by the UDF specification.

    UINT16 UtcOffset; /* 12-bit signed number in twos complement */     UtcOffset = (TypeAndTimezone & 0x7FF);     if ((TypeAndTimezone & 0x800) == 0x800)     {
      UtcOffset = -1 * (0x800 - UtcOffset);     }

The timestamp you described, 0x0FC4 because of big endian recording, is in fact:

TYPE 0
TIMZEONE: FC4 [12 bit signed number] = -60

This is not a legal timestamp for UDF because of the following quote from the specification (below). However, I think the person writing this volume tried to indicate that the stamp has an offstet of -1 hour (1 hour east of) the UTC zone.

<quote>
2.1.4.1 Uint16 TypeAndTimezone;

For the following descriptions Type refers to the most significant 4 bits of this field, and TimeZone refers to the least significant 12 bits of this field, which is interpreted as a signed 12-bit number in two's complement form.

(ON READ) The time within the structure shall be interpreted as Local

          Time since Type shall be equal to ONE for OSTA UDF compliant
          media.     ^^^^^^^^^^^^^^^^^^^^^^^^^^

(ON WRITE) Type shall be set to ONE to indicate Local Time.
           ^^^^^^^^^^^^^^^^^^^^^^^^

</quote>

Kind regards,

  Pieter-Bas

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This list is provided by the SecurityFocus ARIS analyzer service. For more information on this free incident handling, management and tracking system please see: http://aris.securityfocus.com Received on Thu Dec 19 12:06:28 2002