[vlc-devel] [PATCH 01/12] vlc_input: add title angles

[Thomas Guillem]

On Fri, Apr 3, 2020, at 10:21, Rémi Denis-Courmont wrote:
> Le perjantaina 3. huhtikuuta 2020, 10.18.26 EEST Thomas Guillem a écrit :
> > On Fri, Apr 3, 2020, at 09:15, Rémi Denis-Courmont wrote:
> > > Le perjantaina 3. huhtikuuta 2020, 9.58.16 EEST Thomas Guillem a écrit :
> > > > On Fri, Apr 3, 2020, at 08:52, Rémi Denis-Courmont wrote:
> > > > > Le torstaina 2. huhtikuuta 2020, 21.40.09 EEST Francois Cartegnie a
> > > > > écrit
> > > > > 
> > > > > > ---
> > > > > > 
> > > > > >  include/vlc_input.h | 3 +++
> > > > > >  1 file changed, 3 insertions(+)
> > > > > 
> > > > > I'm not convinved that angles should be exposed separately. AFAICT,
> > > > > it's
> > > > > not technically different from multiple exclusive video tracks. The
> > > > > fact
> > > > > that they're called angles is just semantics.
> > > > > 
> > > > > As far as this patchset goes, it only concerns DVDs (which don't have
> > > > > multiple video tracks currently), and VLC is pretty much out of free
> > > > > hotkeys at this point.
> > > > 
> > > > The hotkey issue can be addressed in the control module, it can switch
> > > > angles before switching tracks for example.
> > > 
> > > That's even worse than leaving an unassigned pair of hotkeys. With that
> > > approach, all VLC UIs, and any LibVLC app that want to do the same, has to
> > > implement the same bespoke track handling to cover tracks and angles.
> > 
> > We can add this helper in the player API then (like it's already done for
> > few complicated things that are only done from control/interfaces).
> 
> And the point of that is what exactly? At this point, we're telling everybody 
> to treat angles as video tracks. Might as well skip the reverse abstraction 
> and treat angles as video tracks from the ground up then.
> 
> Besides, this "helper" assumes that an input cnanot have multiple video tracks 
> and multiple angles simultaneously. The assumption is questionable due to 
> slave inputs, whose handling is completely left out of this patchset (which is 
> a problem of its own) and unspecified. And second, this fails to address the 
> underlying question of what's the difference between angles and exclusive video 
> tracks.

OK you got a valid point.
I think we should mix both of your solutions.

- Keep ANGLE like francois did in input.c/demux.c
- Fix player angle implementation to create "fake" video tracks for each angles.

I think it is like ADM I'm working on (totally WIP/notready): an audio track can have multiple presentations (English, French, with commentary...). We should keep one ES audio track (so one decoder) that can output multiple presentations. For each presentations, the player create a new "fake" track. Selecting a "fake" track will just select a presentation on the decoder side.

> 
> Back when video tracks were always inclusive, there was a clear case for 
> angles, but not anymore.
> 
> -- 
> Реми Дёни-Курмон
> http://www.remlab.net/
> 
> 
> 
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