player: avoid underrun wakeup loop

The VO underrun detection (just a weak heuristic) added in commit f26dfb
flagged the underrun state every time it was checked, and since the
check happened in every playloop iteration, this caused the playloop to
wake up itself on every iteration. It burned an entire core while in
this state.

Fix this by flagging this condition only once (as it should be), and
requiring that a frame is displayed to trigger it again. This makes it
work similar as the audio underrun check.

The bug report referenced below says --demuxer-thread=no avoided this.
This is because the demuxer layer doesn't do proper underrun reporting
if the reader thread is disabled.

Fixes: #7259

1 files changed, 8 insertions, 1 deletions

diff --git a/player/video.c b/player/video.c
index af795c316f..e92aaf7024 100644
--- a/player/video.c
+++ b/player/video.c
@@ -92,6 +92,7 @@ static void vo_chain_reset_state(struct vo_chain *vo_c)
 {
     vo_seek_reset(vo_c->vo);
     vo_c->underrun = false;
+    vo_c->underrun_signaled = false;
 }
 
 void reset_video_state(struct MPContext *mpctx)
@@ -1013,8 +1014,12 @@ void write_video(struct MPContext *mpctx)
 
     if (r == VD_WAIT) {
         // Heuristic to detect underruns.
-        if (mpctx->video_status == STATUS_PLAYING && !vo_still_displaying(vo))
+        if (mpctx->video_status == STATUS_PLAYING && !vo_still_displaying(vo) &&
+            !vo_c->underrun_signaled)
+        {
             vo_c->underrun = true;
+            vo_c->underrun_signaled = true;
+        }
         // Demuxer will wake us up for more packets to decode.
         return;
     }
@@ -1217,6 +1222,8 @@ void write_video(struct MPContext *mpctx)
             mpctx->max_frames--;
     }
 
+    vo_c->underrun_signaled = false;
+
     screenshot_flip(mpctx);
 
     mp_wakeup_core(mpctx);