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Re: [OM] Card(s) download Q --Paging Dr. C.F. Card

Subject: Re: [OM] Card(s) download Q --Paging Dr. C.F. Card
From: Moose <olymoose@xxxxxxxxx>
Date: Mon, 04 Oct 2010 14:06:08 -0700
  On 10/4/2010 12:58 PM, Chuck Norcutt wrote:
> ...
>
> Anyhow, your statement that the downloader did know the files had already 
> been downloaded caused me to think a bit harder.  I haven't had to think 
> about internal FAT file structures since about 1987 but I just
> realized how the downloader must work in order to recognize that the file has 
> already been downloaded.  I had completely forgotten about the "archive bit" 
> in the FAT file system.  Each file has one byte available
> for file attributes and one of the bits is called the archive bit.  I looked 
> up this tidbit to refresh my memory.

Got it in one. I'd just taken a few shots when I came in and read this post. 
Looking at the CF card, it's clear you are 
right. For other reasons, I've been shooting RAW+the smallest pixel size JPEGs. 
All of today's' images have the archive 
bit set. Prior day's images have it unset on the JPGs, but not the CR2s. I 
suppose ZB uses the JPGs as the key when both 
are shot?

Just erased a couple of the new JPGs on the card, for shots that didn't work, 
then downloaded using ZB. This time, it 
unset all the CR2 file archive bits and left the JPGs set. It's internal logic 
is odd, but to the user, it just works.

This leaves open the question of that the .ctg files may be. A quick search 
unearths:
-----------------------------------------------
CTG file extension - Canon Digital Camera Catalog File

CTG files are found on Canon digital camera memory cards and operate as data 
indexes for the image folders stored on the 
memory card. The indexed information is changed as the pictures that the 
information references are removed from the 
camera; the CTG file is removed completely when the folder containing the 
pictures is removed.

These files are proprietary and the information that they store is not known ...
-----------------------------------------------
It appears that ctg files only appear when the camera creates more than one 
image folder on a card.

Moose
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