Animated GIF displays flickering

[johng]

I like to use irfanview to display animated GIFs that I have downloaded (and some that I have constructed myself).

Most of these display perfectly well, but a small number display an annoying flicker - a sort of momentary black band (covering some - or sometimes it may even be all - of the image) that lasts a very short time.

I have established to my own satisfaction that this flicker appears only when the image is repeating automatically - as if the action of returning to the first image is taking just a little too long and the black image (or part image) interferes.

In some cases, the image I download is moving much too fast, and I have used online GIF editors (ezgif and gifcreator.me) to change the delay times to a more appropriate value. It occurred to me that I could use these to change the delay time of the last image - in the GIFs that flicker - to a larger value, to allow more time to go "back" to the first image. In some cases this does seem to have worked, but not in all.

I also "think" that this may be dependent on the processing speed of the PC. I suspect that the flicker is more noticeable on an older PC with a slower CPU running Win XP than on my newest PC which has a faster CPU and is running Win 10.

However, the strange thing is that I NEVER see the flicker when I display the GIFs using other software - e.g. Windows Picture and Fax Viewer, Internet Explorer, Google Chrome - but ONLY using irfanview... which suggests to me that there is something in this particular viewer that is causing the flicker.

I really do want to keep using irfanview - for its slideshow feature and its option to scale an image to the screen regardless of its original size.

Has anyone else encountered this? If so, is there some way to correct it?

[Bhikkhu Pesala]

Yes GIFs always give troubles. They play at different speeds, some flicker, some don't. some programs crash. I think GIF authors do crazy, non-standard stuff.

If you're into animations, IrfanView is not much use. It cannot edit them, or build them. Use something designed for the job.

[Mij]

There was a new hotkey that might help, introduced in Irfanview v4.40

- New hotkey: CTRL + SHIFT and '+' or '-' to change GIF/ANI/PNG animation speed

[johng]

Thank you for your response, but I was not asking about using Irfanview to edit or build GIFs, only to view them, because it seemed to be only Irfanview that shows the flickering I was getting.

In case you're interested, I found a website that describes the structure of GIFs; after studying that for a while, I decided on a hunch to try editing one of the GIFs that was bothering me using a HEX editor. Strangely enough, my hunch came off!

I can now get rid of the flicker simply by entering zero into the first data byte in what is called the Graphic Control Extension of the first image of an animated GIF; sometimes this means changing just one bit in the whole GIF!

Now none of the GIFs I want to view flicker at all.

[Dabble]

Question about GIF animation

I notice that even in the latest version (4.50) there are still issues with a blinking black/incomplete display of some short animated GIF. So my question is if there is some setting I'm missing here to fix that?
Other viewers don't have the issue with the same GIF files so it's not a fundamental issue with my graphics card or some such.
And the animated PNG's don't have that issue I have to add, and it's also an issue more applicable to very short GIF files, like 2 frames or such.

[Dabble]

Oh, OK, so it's a I_view bug for sure. Well there must be a fix if all other players don't have the bug, the only issue being to find the specific cause.
When you think about it it does seem that as I said it's short GIF and it's like there is a black screen in the buffer, so I would think it might be a buffering issue, where with short length there is an error in reserving the space.
I'm sure if Irfan spends some time on it he'd be able to fix it, so I'll just give it time, and in the meantime use another GIF viewer, although now that I_view has that control, the 'g' to stop and scrolling through it and reducing speed it becomes hard to use a viewer that doesn't have that functionality, and let's face it, most just play without control.
So if anybody knows of a viewer with some control that's good for GIF alone please post the name.

As for Johng's suggestion, I don't find it convenient to hex edit every damn GIF I need to play, after I first study how to id the structures mentioned. But perhaps if there was a drop&drag utility I might occasionally go that route, but then again there are already utilities to convert them to APNG which has the same effect, although of course pretty slow in comparison to flipping a bit or two, plus the idea of having 'fake' APNG sort of irks me (fake in that they are originating in 256 color palette images from a GIF).

OK I did a search and found gifsicle.exe from a link in the documentation on the ImageMagick site, and running gifs through its optimize function seems to fix them, so now I only need a batch file to make it drag and drop.

Edit: here's the batch file line I ended up with:
gifsicle --optimize %1 -o "%~n1-fix.gif"

Put it in a textfile with the extension .bat. drop the gifsicle.exe somewhere where windows can find it (in the 'path' set), then drop gifs on the .bat to get a fixed one with the same name with an added -fix to it.

[Dabble]

One small addition: I noticed that with those GIF files that have the issue the flickering is also there if I do the manual flipping with the scrollwheel, so that is interesting in terms of finding the issue.
Oh and in regards to that batch file, you can also set that as an external program in irfanview and hotkey that to fix a GIF you have open in irfanview (works in most cases although I did find a GIF that gave an error message and was never converted).

[imagefixer]

Bhikkhu Pesala--

I'm interested in making and editing gifs. Can you recommend a free program?

I don't know how to change my profile under my username.