bug#54848: 29.0.50; Emacs doesn't understand certain animated GIFs

bug#54848: 29.0.50; Emacs doesn't understand certain animated GIFs

[Lars Ingebrigtsen]

With the following gif:

https://quimby.gnus.org/s/CoolZanyHuman-max-1mb.gif

Emacs reports "Error reading GIF data" and then displays a black box.
ImageMagick, Firefox and feh are all able to display it, so it's either
a giflib error or we're calling the functions wrong from Emacs.



In GNU Emacs 29.0.50 (build 8, x86_64-pc-linux-gnu, GTK+ Version 3.24.33, cairo version 1.16.0)
 of 2022-04-10 built on xo
Repository revision: 02b521ad7456ae6834b0399ec80f56ee8ca09522
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101003
System Description: Debian GNU/Linux bookworm/sid


-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#54848: 29.0.50; Emacs doesn't understand certain animated GIFs

[Lars Ingebrigtsen]

Googling a bit, it seems like there's GIFs out there now (produced by
some popular tool) that adds some extra blocks and are therefore
"invalid".  But all other parsers than the giflib one just ignores those
bits, apparently.

I wonder -- are there other C libraries for GIF that we could switch to?
Not just because of this, but because the libgif one is pretty slow,
especially with animated images.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#54848: 29.0.50; Emacs doesn't understand certain animated GIFs

[Stephen Berman]

On Mon, 11 Apr 2022 11:26:51 +0200 Lars Ingebrigtsen <larsi@gnus.org> wrote:

> With the following gif:
>
> https://quimby.gnus.org/s/CoolZanyHuman-max-1mb.gif
>
> Emacs reports "Error reading GIF data" and then displays a black box.
> ImageMagick, Firefox and feh are all able to display it, so it's either
> a giflib error or we're calling the functions wrong from Emacs.
>
>
>
> In GNU Emacs 29.0.50 (build 8, x86_64-pc-linux-gnu, GTK+ Version 3.24.33,
> cairo version 1.16.0)
>  of 2022-04-10 built on xo
> Repository revision: 02b521ad7456ae6834b0399ec80f56ee8ca09522
> Repository branch: master
> Windowing system distributor 'The X.Org Foundation', version 11.0.12101003
> System Description: Debian GNU/Linux bookworm/sid

When I visit that URL with EWW, the GIF displays the same as in Firefox.

This is in GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
3.24.33, cairo version 1.17.6) of 2022-04-10 built on strobelfs2
Repository revision: 48cb9c4aaadfe7bd50c13f658a6e8e9e97587867
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101003
System Description: Linux From Scratch r11.0-165

Configured using:
 'configure --with-xinput2 --with-xwidgets 'CFLAGS=-Og -g3'
 PKG_CONFIG_PATH=/opt/qt5/lib/pkgconfig'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBSYSTEMD LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG RSVG
SECCOMP SOUND SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS WEBP X11 XDBE XIM
XINPUT2 XPM XWIDGETS GTK3 ZLIB

Steve Berman

bug#54848: 29.0.50; Emacs doesn't understand certain animated GIFs

[Lars Ingebrigtsen]

Stephen Berman <stephen.berman@gmx.net> writes:

> When I visit that URL with EWW, the GIF displays the same as in Firefox.

Then it sounds like it's a problem with a specific version of libgif, I
guess?  Which version do you have installed?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#54848: 29.0.50; Emacs doesn't understand certain animated GIFs

[Stephen Berman]

On Mon, 11 Apr 2022 12:22:22 +0200 Lars Ingebrigtsen <larsi@gnus.org> wrote:

> Stephen Berman <stephen.berman@gmx.net> writes:
>
>> When I visit that URL with EWW, the GIF displays the same as in Firefox.
>
> Then it sounds like it's a problem with a specific version of libgif, I
> guess?  Which version do you have installed?

giflib-5.2.1

Steve Berman

bug#54848: 29.0.50; Emacs doesn't understand certain animated GIFs

[Lars Ingebrigtsen]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Emacs reports "Error reading GIF data" and then displays a black box.
> ImageMagick, Firefox and feh are all able to display it, so it's either
> a giflib error or we're calling the functions wrong from Emacs.

I've now improved the error message in Emacs 29, anyway:

Error reading GIF data: Image EOF detected before image complete

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#54848: 29.0.50; Emacs doesn't understand certain animated GIFs

[Lars Ingebrigtsen]

Stephen Berman <stephen.berman@gmx.net> writes:

>> Then it sounds like it's a problem with a specific version of libgif, I
>> guess?  Which version do you have installed?
>
> giflib-5.2.1

Thanks.  And I seem to have:

libgif-dev/testing,now 5.1.9-2

So it sounds like this is an error in older giflib versions which has
been fixed now, so I'm closing this bug report.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#54848: 29.0.50; Emacs doesn't understand certain animated GIFs

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Mon, 11 Apr 2022 12:34:51 +0200
> Cc: 54848@debbugs.gnu.org
> 
> Stephen Berman <stephen.berman@gmx.net> writes:
> 
> >> Then it sounds like it's a problem with a specific version of libgif, I
> >> guess?  Which version do you have installed?
> >
> > giflib-5.2.1
> 
> Thanks.  And I seem to have:
> 
> libgif-dev/testing,now 5.1.9-2
> 
> So it sounds like this is an error in older giflib versions which has
> been fixed now, so I'm closing this bug report.

FTR, I have 5.1.0 here, and don't see any problem.  So I guess this
was a regression introduced by some later 5.1.x version and fixed in
5.2.x.

bug#54848: 29.0.50; Emacs doesn't understand certain animated GIFs

[Andreas Schwab]

On Apr 11 2022, Lars Ingebrigtsen wrote:

> Stephen Berman <stephen.berman@gmx.net> writes:
>
>>> Then it sounds like it's a problem with a specific version of libgif, I
>>> guess?  Which version do you have installed?
>>
>> giflib-5.2.1
>
> Thanks.  And I seem to have:
>
> libgif-dev/testing,now 5.1.9-2
>
> So it sounds like this is an error in older giflib versions which has
> been fixed now, so I'm closing this bug report.

FWIW, I don't have that problem with libgif 5.1.4 either.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."