[vlc-devel] [PATCH] clock: don't return invalid ts when paused

[Thomas Guillem]

On Thu, Sep 5, 2019, at 10:02, Thomas Guillem wrote:
> This commit is wrong. When unpaused, the vout can request a time to the 
> clock while the clock is still paused (but will soon be unpaused, 
> threading...). In that case, the converted time will be delayed by the 
> pause delay.

Naup, there is a problem but not this one ^^ since the clock will always be resumed before all outputs, cf. es_out.c

It's related to seek/flush while paused.

> 
> On Wed, Sep 4, 2019, at 14:35, Thomas Guillem wrote:
> > vlc_clock_ConvertToSystem() could return INT64_MAX when paused, this was not
> > documented and not handled at all by the aout and the vout.
> > 
> > To fix this issue, I first tried the obvious choice: handling this INT64_T
> > value from both outputs. The problem is that I don't really know how to handle
> > it. Indeed, the main clock and every outputs are requested to pause at the same
> > time, but they all run on different thread and will process this request on
> > their own timeline. Therefore, the output might be still running when the clock
> > is paused. Handling 2 different pause state from the output is not a good idea.
> > 
> > So I decided a simpler fix: the clock will act as it's not paused and will
> > always return valid values. Indeed, both outputs are very likely to be in the
> > pause state anyway and will stop requesting/updating time to the clock.
> > 
> > PS: The pause state from the clock is now only used to apply the pause delay on
> > the reference point.
> > ---
> >  src/clock/clock.c | 7 +------
> >  1 file changed, 1 insertion(+), 6 deletions(-)
> > 
> > diff --git a/src/clock/clock.c b/src/clock/clock.c
> > index 15a6cf68e4..cfaef7b151 100644
> > --- a/src/clock/clock.c
> > +++ b/src/clock/clock.c
> > @@ -227,8 +227,6 @@ static vlc_tick_t 
> > vlc_clock_slave_to_system_locked(vlc_clock_t *clock,
> >                                                     vlc_tick_t ts, 
> > double rate)
> >  {
> >      vlc_clock_main_t *main_clock = clock->owner;
> > -    if (main_clock->pause_date != VLC_TICK_INVALID)
> > -        return INT64_MAX;
> >  
> >      vlc_tick_t system = main_stream_to_system(main_clock, ts);
> >      if (system == VLC_TICK_INVALID)
> > @@ -300,10 +298,7 @@ int vlc_clock_Wait(vlc_clock_t *clock, vlc_tick_t 
> > system_now, vlc_tick_t ts,
> >      while (!main_clock->abort)
> >      {
> >          vlc_tick_t deadline;
> > -        if (main_clock->pause_date != VLC_TICK_INVALID)
> > -            deadline = INT64_MAX;
> > -        else
> > -            deadline = clock->to_system_locked(clock, system_now, ts, 
> > rate);
> > +        deadline = clock->to_system_locked(clock, system_now, ts, 
> > rate);
> >          deadline = __MIN(deadline, max_deadline);
> >  
> >          if (vlc_cond_timedwait(&main_clock->cond, &main_clock->lock, deadline))
> > -- 
> > 2.20.1
> > 
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