Re: [gentoo-dev] RFC News item: FFmpeg default

[Ben de Groot]

On 6 April 2015 at 17:35, Michał Górny <mgorny@g.o> wrote:
> Dnia 2015-04-06, o godz. 14:10:12
> Ben de Groot <yngwin@g.o> napisał(a):
>
>> On 30 March 2015 at 00:23, Michał Górny <mgorny@g.o> wrote:
>> > Dnia 2015-03-30, o godz. 00:07:16
>> >
>> > Include example code.
>> >
>>
>> Updated version:
>>
>> Title: FFmpeg default
>> Author: Ben de Groot <yngwin@g.o>
>> Content-Type: text/plain
>> Posted: 2015-04-07
>> Revision: 1
>> News-Item-Format: 1.0
>> Display-If-Installed: media-video/ffmpeg
>> Display-If-Installed: media-video/libav
>>
>> Since the choice between ffmpeg and libav has been made more
>> explicit, there has been a lot of discussion about what the
>> default implementation should be. It can be concluded that
>> media-video/ffmpeg has wider support, and would be somewhat
>> more convenient for most end-users.
>>
>> For this reason the default implementation has been switched
>> back from media-video/libav to media-video/ffmpeg by removing
>> the libav useflag from the base profile.
>
> 'Switched back' is suggesting there was some 'unintentional' switch
> from ffmpeg to libav. Keep this free of politics, and just 'switched'.

No, it does not suggest that. It simply reflects the history of the
issue: once upon a time we had ffmpeg. Then libav was introduced and
at some point made the default implementation. Now we are switching
back to ffmpeg as default implementation. There is no politics in my
statement.

>> If the libav useflag is already globally enabled or disabled
>> in /etc/portage/make.conf, then no further action is required.
>>
>> Users who implicitly relied on libav being enabled in their
>> profile, and who wish to continue using libav, should enable
>> USE=libav in their /etc/portage/make.conf file.
>>
>> > Also please prepare an update to the USE=libav news item to state
>> > updated default.
>>
>> Diff:
>>
>> --- /var/portage/metadata/news/2015-02-01-use-libav/2015-02-01-use-libav.en.txt
>> 2015-02-04 05:31:20.000000000 +0800
>> +++ /home/ben/tmp/2015-02-01-use-libav.en.txt   2015-04-06
>> 14:05:56.982039939 +0800
>> @@ -2,7 +2,7 @@
>>  Author: Michał Górny <mgorny@g.o>
>>  Content-Type: text/plain
>>  Posted: 2015-02-01
>> -Revision: 1
>> +Revision: 2
>>  News-Item-Format: 1.0
>>  Display-If-Installed: media-video/ffmpeg
>>  Display-If-Installed: media-video/libav
>> @@ -20,17 +20,17 @@
>>  However, whenever appropriate additional USE=libav will be introduced to
>>  control the preference of one implementation over the other.
>>
>> -Users who currently use libav (the Gentoo default) do not have to
>> -perform any action since USE=libav is enabled by default. It should be
>> -noted that the users still need to enable USE=ffmpeg on packages with
>> -optional libav support as well. Users who want to use ffmpeg instead
>> -need to specify USE=-libav in make.conf explicitly.
>> +Users who currently use libav need to enable USE=libav in
>> +/etc/portage/make.conf. It should be noted that users still need to
>> +enable USE=ffmpeg on packages with optional libav support as well.
>> +Users who currently use ffmpeg need to take no action.
>>
>>  Please also note that some packages support only one of the two
>>  implementations. An attempt to install one of those packages may result
>>  in blockers requiring the user changes the global USE=libav state.
>>  The most notable example of such package is media-video/mplayer.
>> -media-video/mpv may be used as a replacement for users who prefer libav.
>> +media-video/mpv may be used as a replacement for users who prefer libav,
>> +even though upstream mpv developers recommend using ffmpeg.
>
> This is off-topic, and strongly biased.

The original statement may give the impression that mpv is to libav
what mplayer is to ffmpeg. Many users were surprised to find out that
mpv upstream actually recommends ffmpeg, and that some of mpv's
features do not work with libav. If we are going to specifically
recommend mpv, then it is something users need to be aware of.

We could change it to: media-video/mpv works with both ffmpeg and
libav, though some of its features require ffmpeg. Or something along
those lines.

>>  Please do not alter the state of 'libav' flag on a per-package basis
>>  (e.g. via package.use). The flag needs to be set globally to have
>
> FYI: since Council's meeting in one week, I have added this to
> the agenda. I'm really concerned about Gentoo's PR when users suffer
> due to developers ping-ponging implementations/defaults.

It's not so much ping-ponging as stumbling upon what is the best
solution for our users. Some years ago libav was made a soft default.
And if I recall correctly, that was done with very little discussion.
Recently this default was made harder by adding USE=libav to the base
profile. This resulted in quite a backlash from users.

Moreover, many upstreams of consuming packages actually prefer ffmpeg.
Add to that the upstream ffmpeg policy of merging in changes from
libav.

All in all, from an end-user point of view it makes more sense to have
ffmpeg as default. And when users were asked, they overwhelmingly
expressed support for changing the default to ffmpeg.

I see no reason to stick with libav as default, except political
(which I'm trying to avoid here).

-- 
Cheers,

Ben | yngwin
Gentoo developer