[vlc-devel] [PATCH v2 1/7] clock: handle the normal play time (npt) from the input

[Alexandre Janniaux]

Hi,

Sure it is needed, but the NPT value represents the whole NPT
state and is used to display the time to the user on the GUI,
so it´s racy by design, so an atomic should be enough rather
than a mutex here.

Regards,
--
Alexandre Janniaux
Videolabs

On Wed, Apr 07, 2021 at 11:10:27AM +0200, Thomas Guillem wrote:
> Yes, that was I did first, but then you have to add an extra mutex.
>
> ClockUpdate() can be called by any out thread.
>
>
> On Wed, Apr 7, 2021, at 10:31, Alexandre Janniaux wrote:
> > On Wed, Apr 07, 2021 at 09:53:08AM +0200, Thomas Guillem wrote:
> > >
> > >
> > > On Sat, Apr 3, 2021, at 10:22, Rémi Denis-Courmont wrote:
> > > > Le torstaina 1. huhtikuuta 2021, 18.30.06 EEST Thomas Guillem a écrit :
> > > > > vlc_clock_t will send corrected update points directly.
> > > > >
> > > > > The player won't have to fetch the normal_time from the demux and fix
> > > > > its timer accordingly.
> > > >
> > > > I'm not convinced that the clock should know/care about NPT.
> > >
> > > The clock doesn't use it for any calculation. It is just used when passing the pts/system_date points to the clock listener (the player) and only for information purpose.
> > >
> >
> > If the clock doesn´t use it, maybe it can be sent directly
> > from the es_out to the player there:
> >
> >     static void ClockUpdate(vlc_tick_t system_ts, vlc_tick_t ts, double rate,
> >                             unsigned frame_rate, unsigned frame_rate_base,
> >                             void *data)
> >     {
> >         es_out_id_t *es = data;
> >         es_out_sys_t *p_sys = container_of(es->out, es_out_sys_t, out);
> >
> >         input_SendEventOutputClock(p_sys->p_input, &es->id, es->master,
> > system_ts,
> >                                    ts, rate, frame_rate,
> > frame_rate_base);
> >     }
> >
> > Thus, you´d just have to store the NPT in the es_out, where
> > it should mostly make sense, and the player won´t have to
> > fetch it from the demux itself either.
> >
> > > >
> > > > And if we need to track NPT per group, that seems rather problematic, because
> > > > there will be multiple NPTs for a single clock...
> > >
> > > Yes, NPT are per group, but there is also one vlc_clock_main per group, so if there are multiple NPTs, they will be handled by their respective clock (main).
> > >
> > > >
> > > > --
> > > > 雷米‧德尼-库尔蒙
> > > > http://www.remlab.net/
> > > >
> > > >
> > > >
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