[vlc-devel] [PATCH 5/6] vout: handle the case where the clock is paused

[Rémi Denis-Courmont]

Hi,

I don't follow the comments. We need to support rendering when paused, to update OSD (and potentially to handle seeking while paused).

Le 5 septembre 2019 14:40:02 GMT+03:00, Thomas Guillem <thomas at gllm.fr> a écrit :
>This case can happen during a very short timespan, when the clock is
>paused
>before the vout thread processed the pause event.
>
>There are two way to handle it:
>
>- In the prepare step: continue processing the picture but don't
>display it,
>   (keep displaying the old one, that is sys->displayed.current).
>
>- In the render step: make the picture as forced and display it now.
>It's too
>   late to fallback to the previous picture.
>---
> src/video_output/video_output.c | 56 ++++++++++++++++++++++++++++-----
> 1 file changed, 48 insertions(+), 8 deletions(-)
>
>diff --git a/src/video_output/video_output.c
>b/src/video_output/video_output.c
>index 2c63624808..5badb35321 100644
>--- a/src/video_output/video_output.c
>+++ b/src/video_output/video_output.c
>@@ -865,7 +865,8 @@ static void ThreadChangeFilters(vout_thread_t
>*vout,
> 
> 
> /* */
>-static int ThreadDisplayPreparePicture(vout_thread_t *vout, bool
>reuse, bool frame_by_frame)
>+static int ThreadDisplayPreparePicture(vout_thread_t *vout, bool
>reuse,
>+                                       bool frame_by_frame, bool
>*paused)
> {
>bool is_late_dropped = vout->p->is_late_dropped &&
>!vout->p->pause.is_on && !frame_by_frame;
>     vout_thread_sys_t *sys = vout->p;
>@@ -888,7 +889,19 @@ static int
>ThreadDisplayPreparePicture(vout_thread_t *vout, bool reuse, bool fra
>                     const vlc_tick_t system_pts =
>                        vlc_clock_ConvertToSystem(vout->p->clock, date,
>                                             decoded->date, sys->rate);
>-                    const vlc_tick_t late = date - system_pts;
>+
>+                    vlc_tick_t late;
>+                    if (system_pts == INT64_MAX)
>+                    {
>+                        /* The clock is paused, notify it (so that the
>current
>+                         * picture is displayed but not the next one),
>this
>+                         * current picture can't be be late. */
>+                        *paused = true;
>+                        late = 0;
>+                    }
>+                    else
>+                        late = date - system_pts;
>+
>                     vlc_tick_t late_threshold;
> if (decoded->format.i_frame_rate && decoded->format.i_frame_rate_base)
>late_threshold = VLC_TICK_FROM_MS(500) *
>decoded->format.i_frame_rate_base / decoded->format.i_frame_rate;
>@@ -1021,10 +1034,21 @@ static int
>ThreadDisplayRenderPicture(vout_thread_t *vout, bool is_forced)
>     if (sys->pause.is_on)
>         render_subtitle_date = sys->pause.date;
>     else
>+    {
>         render_subtitle_date = filtered->date <= 1 ? system_now :
>      vlc_clock_ConvertToSystem(sys->clock, system_now, filtered->date,
>                                       sys->rate);
> 
>+        /* The clock is paused, it's too late to fallback to the
>previous
>+         * picture, display the current picture anyway and force the
>rendering
>+         * to now. */
>+        if (unlikely(render_subtitle_date == INT64_MAX))
>+        {
>+            render_subtitle_date = system_now;
>+            is_forced = true;
>+        }
>+    }
>+
>     /*
>      * Get the subpicture to be displayed
>      */
>@@ -1154,6 +1178,14 @@ static int
>ThreadDisplayRenderPicture(vout_thread_t *vout, bool is_forced)
>     const vlc_tick_t pts = todisplay->date;
>     vlc_tick_t system_pts = is_forced ? system_now :
>     vlc_clock_ConvertToSystem(sys->clock, system_now, pts, sys->rate);
>+    if (unlikely(system_pts == INT64_MAX))
>+    {
>+        /* The clock is paused, it's too late to fallback to the
>previous
>+         * picture, display the current picture anyway and force the
>rendering
>+         * to now. */
>+        system_pts = system_now;
>+        is_forced = true;
>+    }
> 
>     if (vd->prepare != NULL)
>     vd->prepare(vd, todisplay, do_dr_spu ? subpic : NULL, system_pts);
>@@ -1207,11 +1239,12 @@ static int ThreadDisplayPicture(vout_thread_t
>*vout, vlc_tick_t *deadline)
>     assert(sys->clock);
> 
>     if (first)
>-        if (ThreadDisplayPreparePicture(vout, true, frame_by_frame))
>/* FIXME not sure it is ok */
>+        if (ThreadDisplayPreparePicture(vout, true, frame_by_frame,
>&paused)) /* FIXME not sure it is ok */
>             return VLC_EGENERIC;
> 
>     if (!paused || frame_by_frame)
>-        while (!sys->displayed.next &&
>!ThreadDisplayPreparePicture(vout, false, frame_by_frame))
>+        while (!sys->displayed.next
>+            && !ThreadDisplayPreparePicture(vout, false,
>frame_by_frame, &paused))
>             ;
> 
>     const vlc_tick_t system_now = vlc_tick_now();
>@@ -1224,10 +1257,17 @@ static int ThreadDisplayPicture(vout_thread_t
>*vout, vlc_tick_t *deadline)
>         const vlc_tick_t next_system_pts =
>             vlc_clock_ConvertToSystem(sys->clock, system_now,
>                                 sys->displayed.next->date, sys->rate);
>-
>-        date_next = next_system_pts - render_delay;
>-        if (date_next <= system_now)
>-            drop_next_frame = true;
>+        if (unlikely(next_system_pts == INT64_MAX))
>+        {
>+            /* The clock was just paused, don't display the next frame
>(keep
>+             * the current one). */
>+            paused = true;
>+        }
>+        {
>+            date_next = next_system_pts - render_delay;
>+            if (date_next <= system_now)
>+                drop_next_frame = true;
>+        }
>     }
> 
>     /* FIXME/XXX we must redisplay the last decoded picture (because
>-- 
>2.20.1
>
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