vo_opengl_cb: better underflow reporting

This applies to unexpected freezes or deadlocks, not e.g. normal
framedrops. The verbose messages also might remind an API user if the
API usage is incorrect, such as not calling mpv_opengl_cb_draw() when a
redraw request was issued.

1 files changed, 12 insertions, 6 deletions

diff --git a/video/out/vo_opengl_cb.c b/video/out/vo_opengl_cb.c
index 15faa36c88..a78b6a7fb7 100644
--- a/video/out/vo_opengl_cb.c
+++ b/video/out/vo_opengl_cb.c
@@ -363,8 +363,10 @@ static void flip_page(struct vo *vo)
 
     // Wait until frame was rendered
     while (p->ctx->next_frame) {
-        if (pthread_cond_timedwait(&p->ctx->wakeup, &p->ctx->lock, &ts))
-            break;
+        if (pthread_cond_timedwait(&p->ctx->wakeup, &p->ctx->lock, &ts)) {
+            MP_VERBOSE(vo, "mpv_opengl_cb_draw() not being called or stuck.\n");
+            goto done;
+        }
     }
 
     // Unblock mpv_opengl_cb_draw().
@@ -377,15 +379,19 @@ static void flip_page(struct vo *vo)
         // Assume the user calls it consistently _if_ it's called at all.
         if (!p->ctx->flip_count)
             break;
-        if (pthread_cond_timedwait(&p->ctx->wakeup, &p->ctx->lock, &ts))
-            break;
+        if (pthread_cond_timedwait(&p->ctx->wakeup, &p->ctx->lock, &ts)) {
+            MP_VERBOSE(vo, "mpv_opengl_cb_report_flip() not being called.\n");
+            goto done;
+        }
     }
 
-    // The API user is not reacting, or is being unusually slow => drop.
+done:
+
+    // Cleanup after the API user is not reacting, or is being unusually slow.
     if (p->ctx->next_frame) {
         talloc_free(p->ctx->next_frame);
         p->ctx->next_frame = NULL;
-        p->ctx->present_count += 1;
+        p->ctx->present_count += 2;
         pthread_cond_signal(&p->ctx->wakeup);
         vo_increment_drop_count(vo, 1);
     }