APNG crashes: incomplete fix

[DOS386]

Fixed:
* APNG - viewtopic.php?f=36&t=17939 & viewtopic.php?f=36&t=18283
* APNG - viewtopic.php?f=36&t=18683

The fix is incomplete.

I can confirm that old versions of XN securely crash on all those 3 and the latest displays them well. Also old NC (unsurprisingly) crashes and the latest survives.

But neither latest XN nor NC can extract frames correctly: the frames are either greyscale, completely black, or contain garbage areas. I tested minimally over 1 year ago here: http://newsgroup.xnview.com/viewtopic.php?f=57&t=15836 and seemed to work, but IIRC I had 2 APNG's available at most at that time.

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(no crash)

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Another interesting point is that the 3 "evil" APNG's also securely hang some older APNG-unaware versions of FireFOX, a fact that somewhat defeats the "backward compatibility".

[xnview]

But neither latest XN nor NC can extract frames correctly: the frames are either greyscale, completely black, or contain garbage areas.

'Extract frame' extract the stored frame, not the displayed frame

[DOS386]

'Extract frame' extract the stored frame, not the displayed frame

This doesn't really resolve the issue. That only "stored frames" or "differential frames" are extracted, is a thing I had discovered and pointed over 1 year ago in the other thread, it's a flaw but not a BUG.

But now I'm getting really bad frames, not just "differential frames". Do you get satisfying results from the 4 APNG's above ?

Of course, being able to select whether to extract "differential frames" or "full frames" would be an enhancement request

[xnview]

Ok, so it's more a suggestion than a bug

[DOS386]

Ok, so it's more a suggestion than a bug

It's both. It's a suggestion (extract full frames) and a BUG - because currently not even the differential frames are always extracted correctly.

[MaxSt]

But neither latest XN nor NC can extract frames correctly: the frames are either greyscale, completely black, or contain garbage areas.

'Extract frame' extract the stored frame, not the displayed frame

But stored frames should be using palette if in mode3, right? Not grayscale?

I'm talking about last two examples.

[MaxSt]

Another interesting point is that the 3 "evil" APNG's also securely hang some older APNG-unaware versions of FireFOX, a fact that somewhat defeats the "backward compatibility".

Even Firefox 3.5.5 is somewhat buggy. You can see it on Santa's bag.

[Jaff]

Even Firefox 3.5.5 is somewhat buggy. You can see it on Santa's bag.

Opera v10.10 browser rules

[DOS386]

But stored frames should be using palette if in mode3, right? Not grayscale? I'm talking about last two examples.

YES, they should. But to simplify the problem, one could design the AGIF and APNG frame extraction to output always 32bpp BMP RGBA, irrespective how many colors are actually used and whether there is some transparency (full A channel or just trans index) or not. This would avoid the output color conversion mess, reduce bug risk and testing "cost" and allow to reuse existing (?) code working for viewing.

Even Firefox 3.5.5 is somewhat buggy. You can see it on Santa's bag.

I don't see any BAG on Santa's bug ... oops, this is indeed Opera

[MaxSt]

Just so it's clear what we are talking about.

Two identical animation, in GIF and in APNG:

xnview_apng.png (16.34 KiB) Viewed 5325 times

xnview_agif.png (15.6 KiB) Viewed 5324 times