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Bug#717076: marked as done (tech-ctte: Decide what jpeg library the Debian project will use)

Your message dated Thu, 31 Jul 2014 19:24:29 -0700
with message-id <20140801022429.GE12356@teltox.donarmstrong.com>
and subject line [CTTE #717076] Default libjpeg implementation in Debian
has caused the Debian Bug report #717076,
regarding tech-ctte: Decide what jpeg library the Debian project will use
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

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-- 
717076: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=717076
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems
--- Begin Message --- 
Package: tech-ctte
Severity: normal

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Hash: SHA1

Dear Technical Committee,

I have raised the question of libjpeg8 vs. jpeg-turbo as a default
libjpeg library for Debian in debian-devel[1], but we were not able to
reach a consensus.  I spoke to our DPL and he recommended to fill a
tech-ctte bug, since this is exactly the kind of problems the
tech-ctte should have final word.

1. <CALjhHG9iNiA6kXfo0M+vgo-+xGZjpiX8jNXJguXv=REc9deGew@mail.gmail.com>

The current libjpeg* world looks like this (Bill please correct me
if I made a mistake somewhere).

There's a IJG libjpeg implementation (where IJG has nothing to do with
former IJG which created libjpeg6).  The current maintainer (Guido
Vollbeding) of IJG libjpeg is adding library features not blessed by
JPEG commitee and he seems to add new features he pushes without
coordination of ISO (SmartScale).  Also it seems that current IJG is
not very healthy open-source project - the upstream maintainer seems
to be hostile and there's no bug tracker, no mailing list, no online
repository, no instructions how to propose new feature, where to send
bugfixes etc.

See my unanswered questions in:
<CALjhHG-6u1y0V50ZxUzn-2ZCgoMxy0dg5Qb7cQSyc2M1ZLZ7eg@mail.gmail.com>

Also the ISO committe has rejected the changes made by libjpeg8:
http://mail.kde.org/pipermail/digikam-devel/2013-January/066256.html

The other implementation - libjpeg-turbo[2] is a green field 2-4 times
faster reimplementation of libjpeg62 (with added support for libjpeg8
ABI).  Most of other Linux distributions (Fedora[3], Ubuntu and SuSE,
maybe others).  My view is that libjpeg-turbo is much conservative
when adding new features to it.

2. http://libjpeg-turbo.virtualgl.org/
3. https://lists.fedoraproject.org/pipermail/devel/2013-January/176299.html

Since the release team (and I understand them) doesn't want to have
more than one libjpeg library in Debian this needs to be decided by
independent party, since Bill has declared he wants to have IJG
libjpeg as default (and bump the SONAME yet again to libjpeg9).

My proposal is to switch the default libjpeg library to libjpeg-turbo
to achieve several goals:

1. to have faster libjpeg implementation
2. to have upstream which is community driven and community friendly
3. to align with other distros
4. to not have upstream which bumps SONAME to push his own new features
   incompatible with ISO JPEG standard

I think we can use the libjpeg8 compatibility layer of libjpeg-turbo.

Although I am not sure if it is really needed as there was only one
package needing new API from libjpeg8 I have heard and that should be
trivial to fix.

Ondrej

- -- System Information:
Debian Release: 7.1
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.2.0-4-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

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--- End Message ---
--- Begin Message --- 
The technical committee was asked in #717076 to decide whether
libjpeg8 or libjpeg-turbo would be the default libjpeg implementation.
The decision is below:

==== RESOLUTION ====

Whereas:

 1. There is a dispute between Developers about whether libjpeg8/9 or
    libjpeg-turbo should be the default libjpeg implementation in
    Debian.  The release team does not want to have more than one
    libjpeg implementation.

 2. The Debian libjpeg8 maintainer does not see libjpeg-turbo as a
    suitable replacement, and notes that it does not implement the
    full libjpeg8/9 ABI.

 3. libjpeg8 adds new features to the JPEG image format.  These have
    however been rejected from the ISO standard, and their
    contributions to image quality and compression appear to be widely
    disputed.

 4. libjpeg-turbo is reported to have significantly better performance
    than libjpeg, and to be API/ABI-compatible with libjpeg6b.

 5. libjpeg-turbo is in use by several other distributions (at least
    Fedora, Gentoo, openSUSE, Ubuntu) and browser projects (WebKit,
    Blink, Gecko).

 6. The former organiser of the IJG advised Fedora of his opinion that
    libjpeg8 was a "dead end" due to fragmentation.

 7. The libjpeg-turbo packages in Debian are not yet in a state where
    they could be a drop-in replacement for libjpeg8.  However,
    similar work has been done in Ubuntu and could be adopted.

 8. In general it does not appear that other Debian packages require
    the libjpeg8 API.  The sole exception appears to be a "decode from
    memory buffer" interface (jpeg_mem_src/jpeg_mem_dest), which is
    implemented by libjpeg-turbo unless configured
    --without-mem-srcdst.

 9. While libjpeg-turbo can be configured with support for much of the
    newer interfaces in libjpeg8, it does not support the SmartScale
    API.  However, images with this extension may have
    interoperability problems.  Those developers advocating
    libjpeg-turbo generally suggest disabling the libjpeg7/libjpeg8
    APIs there.

Therefore:

10. The Technical Committee resolves that libjpeg-turbo should
    become the libjpeg implementation in Debian, using its power
    under 6.1(2) to decide on technical matters of overlapping
    jurisdiction.

11. The prospective libjpeg-turbo maintainer should propose an appropriate
    transition plan for this change, and, after a reasonable period for
    comment, prepare tested packages for upload.  The transition
    plan should state the timescales for the relevant changes.

12. Implementing the decision in 10 above will require removing
    "Provides: libjpeg-dev" from libjpeg8, since such a virtual
    package must be provided by only one real package at a time.
    Therefore the Provides should be removed from the libjpeg8
    package - in accordance with the transition plan -
    notwithstanding the libjpeg8 maintainer's preference that
    libjpeg8 should remain as the default libjpeg.  This change
    should be made by the libjpeg8 maintainer; if the change is not
    made within a reasonable time it should be done in an NMU by the
    libjpeg-turbo maintainer.

==== END OF RESOLUTION ====



Please see http://bugs.debian.org/717076 for discussion of
this bug.

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