Update ffmpeg in F24 to 3.1.x ?

[Nicolas Chauvet]

2016-10-12 2:49 GMT+02:00 Sérgio Basto <sergio at serjux.com>:
> Hi,
> Nicolas, ask me to bring this discussion to the mailing list .
> Nicolas sorry for the delay , I had a big cold, I'm ok now (it just an
> excuse :) )
>
> OK, all story is in
> https://bugzilla.rpmfusion.org/show_bug.cgi?id=4260
> and in https://bugzilla.rpmfusion.org/show_bug.cgi?id=4145
>
> and we have 48 packages depends on ffmpeg-libs.
>
> First, ABI changes of ffmpeg 3.0.x to 3.1.x ?
> "There are no SONAME changes, only new symbols added to the libraries,
> so they're backwards compatible and no rebuild of dependencies should
> be required" . "mpv will break" .
>
> My arguments, I read today
> http://fedoraproject.org/wiki/Updates_Policy#All_other_updates and it
> have one exceptions list, we have some items that can be applied to
> this case, like :
>
> - The update doesn't change ABI/API and nothing needs to be rebuilt
> against the new version. (almost)
>
> - The update fixes serious bugs that many fedora users are
> encountering.
Where thoses serious bugs was reported ? Is there upstream reports ?
What I would expect instead are more features instead, (and even some
features was removed such as libdcadec)
So despite there is no ABI changes, there are some behavior changes.

> ffmpeg-3.0 is a major version that had short duration, it was the first
> version of an major version (3.0.x), so we expect have more bugs, also
> vlc now requires ffmpeg 3.1.x and we have to maintain it about more 9
> months (F24 be an fresh version also counts).
I don't understand what you mean by "we expect to have more bugs..",
so a little history:

Previously ffmpeg upstream didn't provide maintained branches at all.
If one distro packager wanted a rebase to a newer snapshot from
master, there are probably some API changes and very often ABI changes
(along with new bugs and features mixed). Also if one wanted to report
and issue upstream, the first step was to test with a recent git
snapshot. Most likely that our stable ffmpeg packages was contains
known upstream bugs that was unfixed because of that.
So the way we used to have a stabilized version was to periodically
check for api/abi snapshot, get the last commit before an abi break
and stick to this version with adding only patches and backports from
our user base reported issues. On a fedora development cycle, we
updated the newer api/abi snapshot, rebuild (and more likely patch)
all dependent applications and try to fix regression and feedbacks
from our rawhide users.

This was lot of packager work about testing, patching, bisecting for
finding regression and all. And probably that job was done across all
ffmpeg package maintainers. So really see that having maintained
branches upstream as an enormous improvement.
Here the proposition seems to ask to withdraw all that and only pick
the last stable release everywhere. So this sounds to me that we are
going backward on the highway.

I would also notice, that our stabilization process was very little in
the f24 development timeframe, because of the infra issues we had
passed. So I'm expect to have a better stabilization process with f25
and hopes to have lot of feedbacks from branches/rawhide users while
keeping users stable. (There is probably already lot of issue related
to f24 -> f25 system-upgrade migrations).

Now that was rather general about our stabilization process, but now
from a more specific analysis on ffmpeg 3.0x and 3.1x maintained
branches, I see the same kind of fixes between branches. I think there
is just normal bugfix . So not having 3.1x only means missing the 3.1
specific features. So It's probably safe from ffmpeg itslef
perpective.

> I hope have one decision, quickly and close this subject (update ffmpeg
> in F24 to 3.1.x ? ).

So the question is do we update 3.1x in f24 ?, my vote is the following:
+0
It means I don't agree with the proposition, but I won't hold it either.
instead, I expect that people that want this proposition are actively
working on testing the package update and doing the needed QA in
cooperation with each package maintainer if needed.


I also note that I'm way too much busy with internal infra issue to
back this update and the eventual regressions
(on a side note I would like to have a my ffmpeg-nonfree patches
reviewed/merged before any backport to f24 - rfbz#4243)


Thx

-- 
-

Nicolas (kwizart)