From a790009a630ebf12772ead2915ca9d59ee7fdf72 Mon Sep 17 00:00:00 2001
From: wm4 <wm4@nowhere>
Date: Sat, 14 Nov 2015 21:44:59 +0100
Subject: player: account for minor VO underruns

If the player sends a frame with duration==0 to the VO, it can trivially
underrun. Don't panic, but keep the correct time.

Also, returning the absolute time from vo_get_next_frame_start_time()
just to turn it into a float with relative time was silly. Rename it and
make it return what the caller needs.
---
 player/video.c |  4 ++--
 video/out/vo.c | 24 +++++++++++++++---------
 video/out/vo.h |  2 +-
 3 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/player/video.c b/player/video.c
index 043abeb3b1..531ad2ee06 100644
--- a/player/video.c
+++ b/player/video.c
@@ -1025,8 +1025,8 @@ static void handle_display_sync_frame(struct MPContext *mpctx,
 
     // Estimate the video position, so we can calculate a good A/V difference
     // value below. This is used to estimate A/V drift.
-    double time_left = (vo_get_next_frame_start_time(vo) - mp_time_us()) / 1e6;
-    time_left = MPMAX(time_left, 0);
+    double time_left = vo_get_delay(vo);
+
     // We also know that the timing is (necessarily) off, because we have to
     // align frame timings on the vsync boundaries. This is unavoidable, and
     // for the sake of the A/V sync calculations we pretend it's perfect.
diff --git a/video/out/vo.c b/video/out/vo.c
index 81537e80d9..767f6bab7d 100644
--- a/video/out/vo.c
+++ b/video/out/vo.c
@@ -868,8 +868,11 @@ void vo_set_paused(struct vo *vo, bool paused)
     pthread_mutex_lock(&in->lock);
     if (in->paused != paused) {
         in->paused = paused;
-        if (in->paused && in->dropped_frame)
-            in->request_redraw = true;
+        if (in->paused) {
+            if (in->dropped_frame)
+                in->request_redraw = true;
+            in->last_flip = 0;
+        }
     }
     pthread_mutex_unlock(&in->lock);
     vo_control(vo, paused ? VOCTRL_PAUSE : VOCTRL_RESUME, NULL);
@@ -913,11 +916,13 @@ bool vo_want_redraw(struct vo *vo)
 
 void vo_seek_reset(struct vo *vo)
 {
-    pthread_mutex_lock(&vo->in->lock);
+    struct vo_internal *in = vo->in;
+    pthread_mutex_lock(&in->lock);
     forget_frames(vo);
-    vo->in->send_reset = true;
+    in->last_flip = 0;
+    in->send_reset = true;
     wakeup_locked(vo);
-    pthread_mutex_unlock(&vo->in->lock);
+    pthread_mutex_unlock(&in->lock);
 }
 
 // Return true if there is still a frame being displayed (or queued).
@@ -1026,12 +1031,13 @@ int64_t vo_get_vsync_interval(struct vo *vo)
     return res;
 }
 
-// Get the mp_time_us() time at which the currently rendering frame will end
-// (i.e. time of the last flip call needed to display it).
+// Get the time in seconds at after which the currently rendering frame will
+// end. Returns positive values if the frame is yet to be finished, negative
+// values if it already finished.
 // This can only be called while no new frame is queued (after
 // vo_is_ready_for_frame). Returns 0 for non-display synced frames, or if the
 // deadline for continuous display was missed.
-int64_t vo_get_next_frame_start_time(struct vo *vo)
+double vo_get_delay(struct vo *vo)
 {
     struct vo_internal *in = vo->in;
     pthread_mutex_lock(&in->lock);
@@ -1047,7 +1053,7 @@ int64_t vo_get_next_frame_start_time(struct vo *vo)
             res = 0;
     }
     pthread_mutex_unlock(&in->lock);
-    return res;
+    return res ? (res - mp_time_us()) / 1e6 : 0;
 }
 
 int64_t vo_get_delayed_count(struct vo *vo)
diff --git a/video/out/vo.h b/video/out/vo.h
index c7bcccd778..30948e149b 100644
--- a/video/out/vo.h
+++ b/video/out/vo.h
@@ -342,7 +342,7 @@ void vo_set_queue_params(struct vo *vo, int64_t offset_us, bool vsync_timed,
 int vo_get_num_req_frames(struct vo *vo);
 int64_t vo_get_vsync_interval(struct vo *vo);
 double vo_get_display_fps(struct vo *vo);
-int64_t vo_get_next_frame_start_time(struct vo *vo);
+double vo_get_delay(struct vo *vo);
 
 void vo_wakeup(struct vo *vo);
 
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