Corrupt Thumbnails

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Chris Wood
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Corrupt Thumbnails

Post by Chris Wood » 23 Jul 2004 05:20

OS: WindowsME

Reproducibility: Every time (only in a particular directory)

Steps to Reproduce:
1. Enter thumbnail mode
2. Copy an image with a thumbnail from one folder to another

What happens:
Thumbnail of image in new folder is corrupted

This only happens in one directory on my computer (that I've found so far) - a directory containing only .png, .jpg and .gif files.

Some other uncopied files in the directory also have corrupted thumbnails.
test everything. hold on to the good.

admin
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Re: Corrupt Thumbnails

Post by admin » 23 Jul 2004 11:27

Chris Wood wrote:Thumbnail of image in new folder is corrupted.
What do you mean by corrupted?
Are you using the cache, and if yes, have you tried to Ctrl+F5 (Refresh thumbs cache)?

Chris Wood
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Re: Corrupt Thumbnails

Post by Chris Wood » 23 Jul 2004 12:54

admin wrote:What do you mean by corrupted?
Image
admin wrote:Are you using the cache, and if yes, have you tried to Ctrl+F5 (Refresh thumbs cache)?
Yes, yes, restores some images but corrupts new ones.

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Re: Corrupt Thumbnails

Post by admin » 23 Jul 2004 13:21

Chris Wood wrote:This only happens in one directory on my computer
... which is strange. Any idea what could be so special about this directory? What happens when you move the same files to another directory?

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Re: Corrupt Thumbnails

Post by Chris Wood » 25 Jul 2004 04:24

admin wrote:Any idea what could be so special about this directory?
It seems to happen only in folders with large numbers of largish images.

The above directory was fixed when I upgraded to the latest beta, but other directories show corruption:
Image

admin wrote:What happens when you move the same files to another directory?
They look normal.

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Re: Corrupt Thumbnails

Post by admin » 25 Jul 2004 11:35

Chris Wood wrote:It seems to happen only in folders with large numbers of largish images.
Can you specify large and largish?

Does it happen from a specific picture position onwards, say for example from the 65th pic in the directory? (Turn line numbers on to easily read position)

Chris Wood
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Post by Chris Wood » 26 Jul 2004 08:42

I've spent a lot of time testing this bug - hopefully it helps:

The number of thumbnails is variable, and so is the number of bytes processed. But the big problem certainly happens to all thumbnails after a particular point (although not only then - once I found a single uncorrupted thumbs in a long way into the corrupted thumbs, and once a single corrupt thumb in the middle of an uncorrupt directory).

Here's some stats I've compiled, in the format: Directory number (for reference), # images in directory, size of directory, # of partially-corrupt thumbnail (see tripgoth.jpg above), combined size of thumbnails below partially-corrupt thumbnail

1. 32, 852.69Kb, 31, 749.5Kb
2. 133, 1.16Mb, 29, 249.79Kb
3. 180, 16.13Mb, 39, 3.56Mb

It seems to be an error in the cache: I viewed the above directories in order. Directory 1:

Image

Now, in directory 2, thumbnail #29 has a chunk of what appears to be #30 from directory 1. Thumbnails #33 onwards all look similar to #45 (a bunch of similarly spaced lines):

Image

Directory 3 is like directory 2:

Image

The thumbnails are corrupted on creation (I can see them created in corrupted form, it's not a later viewing error).


While testing this bug, I also found another: Directories with a certain number of images always recache (this may be something to do with the corrupt thumbnails, but there are directories with corrupt thumbnails with ~30 images which don't exhibit this behaviour). It happens in a directory with 180 images, and one with 133 images. However, I came across strange behaviour when I attempted to determine the exact number of images:

When I moved some files from the directory with 133 images, I found the directory continued to always recache, even when there were only 15 images! Then I moved another 6, and the remaining 7 didn't recache. Adding back 4, and it did recache. Then, I moved files one at a time, and the directory still recached with 5 images (4 didn't recache).

Interestingly, after all this moving around, I moved all the images back into the same directory again. Now all the images *before* #86 are corrupt. Then I do a manual recache (CTRL-F5) and #29 onwards are again corrupted, except for #86 onwards.

Doesn't look like I'm going to get much more useful information.
test everything. hold on to the good.

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Post by admin » 26 Jul 2004 11:31

Hmm, very strange! You know, I never saw this type of problem here even in the very first stages of the cache development. The cache always worked 100% perfect, and I tested much larger image directories. I don't think the cache is the source of the problem.
Looking at your screenshots, it appears to me that it's always one specific image where the problems start: No. 30! Could you send me that image?! I'm almost sure that it's internally corrupted...

tnx for testing!
Donald

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Post by Chris Wood » 27 Jul 2004 05:40

Image

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Post by admin » 27 Jul 2004 09:54

The image is ok. So, now I'm out of ideas how to help you with that problem, though I'm still convinced it's not the cache but something else that is causing it.
You've not by chance set your system to a reduced color-depth, say 8-bit (256 colors)?

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Post by Chris Wood » 28 Jul 2004 03:00

Nope, 32-bit (1152x864).

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Post by admin » 28 Jul 2004 11:17

Could you send me the image after no. 30, i.e. the first one that comes out totally corrupted?

Gandolf
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Post by Gandolf » 28 Jul 2004 13:00

Another thought. Since you have a largish display is there sufficient video memory or is the system grabbing conventional memory when it needs more video memory? I didn't think that modern video drivers did that but I know it was something that was done with earlier video cards that did not have sufficient memory.

I don't remember seeing you mention the memory size or the processor speed. It's not an AMD by any chance is it? There were all sorts of problems with them some years ago. My previous 350Mhz laptop was an AMD and when it got hot programs would just crash without any warning. The system was perfect when cold.

Dave.

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Post by admin » 28 Jul 2004 13:53

Chris, just to be sure: you see this problem only with caching enabled?

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