The Case Of The Unreadable File

[Ray G. Miller]

Greetings Puzzle Solvers,

This is a case of How-To-Backout-Gracefully.

I've a small MC project for a client that creates/reads semi-large
databases with images (specifically ".jpg" photos) stored on CDs. The
number of photos on any given CD range from 3500 to 5000. Each image
file is approximately 150Kb per; nothing really large.

Normally, the photos and the data associated with it are retrieved and
displayed within 35-50 ticks. (I have no control over creation or
quality of the photo CDs. The client does that on a fast WIN machine...
I'm on a Mac, G4, 9.2.2 MOS.)

The problem is that a few of the pix files are unreadable. I've tried
everything: PhotoShop 7.0, ClarisWorks, and Quicktime to prove that it
is not MC. Quicktime, after futzing for a couple of minutes, sez it
can't read it (error:-36.) MetaCard takes between 3000 and 12000 ticks
to give up.

The non-reading is in the following script:

  --••• set the pix path
  put the ticks into theStart
  
 set the fileName of image "thePix"  to thePath  #### where the non read occurs!
  
 if the ticks - theStart > 300 then --•••••••• this is a bad record!
    beep
    # put the ticks - theStart

    put "The picture:" & cr & "“" & thePath & "” "  &\
        "is unreadable and may be corrupted!" & cr & cr &\
        "Delete this record?" into pmt
    answer warning pmt with "Cancel" or "Delete"
    
    if it = "Delete" then
      deleteThisLine gCurrentPixRecordNum
    end if
    break --- ******* bad record!!!!!!
  end if
  
As everyone knows, users get itchy if any operation lasts longer than 4
or 5 seconds. Is there a more elegant way of detecting bad file data or
getting out the operation without resetting the machine? The megabytes
MC uses during the  read failure goes from a nominal 18-20 MB up to
60-80MB! 

Any ideas would be greatly appreciated.

Ray

-- 


Ray G. Miller
----------- 
Turtlelips Productions
4009 Everett Ave.
Oakland, CA 94602
MailTo:rgmiller at pacbell.net
(V) 510.530.1971
(F) 510.482.3491