sub/osd: use atomic for osd_state.force_video_pts

this field is used only in a special vo draining edge case.

switching to an atomic reduces osd->lock contention
between the mpv core (in write_video) and vo threads
which are managing osd rendering manually (such as vo_rpi).

Signed-off-by: Aman Karmani <aman@tmm1.net>

1 files changed, 6 insertions, 10 deletions

diff --git a/sub/osd.c b/sub/osd.c
index 297ad88fe8..6892925e25 100644
--- a/sub/osd.c
+++ b/sub/osd.c
@@ -124,7 +124,7 @@ struct osd_state *osd_create(struct mpv_global *global)
         .opts_cache = m_config_cache_alloc(osd, global, &mp_osd_render_sub_opts),
         .global = global,
         .log = mp_log_new(osd, global->log, "osd"),
-        .force_video_pts = MP_NOPTS_VALUE,
+        .force_video_pts = ATOMIC_VAR_INIT(MP_NOPTS_VALUE),
         .stats = stats_ctx_create(osd, global, "osd"),
     };
     pthread_mutex_init(&osd->lock, NULL);
@@ -210,17 +210,12 @@ void osd_set_render_subs_in_filter(struct osd_state *osd, bool s)
 
 void osd_set_force_video_pts(struct osd_state *osd, double video_pts)
 {
-    pthread_mutex_lock(&osd->lock);
-    osd->force_video_pts = video_pts;
-    pthread_mutex_unlock(&osd->lock);
+    atomic_store(&osd->force_video_pts, video_pts);
 }
 
 double osd_get_force_video_pts(struct osd_state *osd)
 {
-    pthread_mutex_lock(&osd->lock);
-    double pts = osd->force_video_pts;
-    pthread_mutex_unlock(&osd->lock);
-    return pts;
+    return atomic_load(&osd->force_video_pts);
 }
 
 void osd_set_progbar(struct osd_state *osd, struct osd_progbar_state *s)
@@ -335,8 +330,9 @@ struct sub_bitmap_list *osd_render(struct osd_state *osd, struct mp_osd_res res,
     list->w = res.w;
     list->h = res.h;
 
-    if (osd->force_video_pts != MP_NOPTS_VALUE)
-        video_pts = osd->force_video_pts;
+    double force_video_pts = atomic_load(&osd->force_video_pts);
+    if (force_video_pts != MP_NOPTS_VALUE)
+        video_pts = force_video_pts;
 
     if (draw_flags & OSD_DRAW_SUB_FILTER)
         draw_flags |= OSD_DRAW_SUB_ONLY;