player: always require a future frame with display-sync enabled

We need a frame duration even on start, because the number of vsyncs
the frame is shown is predetermined. (vo_opengl actually makes use of
this property in certain cases.)

1 files changed, 6 insertions, 2 deletions

diff --git a/player/video.c b/player/video.c
index 0aebc6a7e9..430fed530e 100644
--- a/player/video.c
+++ b/player/video.c
@@ -611,10 +611,14 @@ static void shift_frames(struct MPContext *mpctx)
 static int get_req_frames(struct MPContext *mpctx, bool eof)
 {
     // On EOF, drain all frames.
-    // On the first frame, output a new frame as quickly as possible.
-    if (eof || mpctx->video_pts == MP_NOPTS_VALUE)
+    if (eof)
         return 1;
 
+    // On the first frame, output a new frame as quickly as possible.
+    // But display-sync likes to have a correct frame duration always.
+    if (mpctx->video_pts == MP_NOPTS_VALUE)
+        return mpctx->opts->video_sync == VS_DEFAULT ? 1 : 2;
+
     int req = vo_get_num_req_frames(mpctx->video_out);
     return MPCLAMP(req, 2, MP_ARRAY_SIZE(mpctx->next_frames));
 }