command: add mistimed-frame-count property

Does what the manpage says. This is a replacement incrementing the
dropped frame counter (see previous commit).

DOCS/man/input.rst

@@ -913,6 +913,14 @@ Property list
 ``vo-drop-frame-count``
     Frames dropped by VO (when using ``--framedrop=vo``).
 
+``mistimed-frame-count``
+    Number of video frames that were not timed correctly in display-sync mode
+    for the sake of keeping A/V sync. This does not include external
+    circumstances, such as video rendering being too slow or the graphics
+    driver somehow skipping a vsync. It does not include rounding errors either
+    (which can happen especially with bad source timestamps). For example,
+    using the ``display-desync`` mode should never change this value from 0.
+
 ``percent-pos`` (RW)
     Position in current file (0-100). The advantage over using this instead of
     calculating it out of other properties is that it properly falls back to

player/command.c

@@ -553,8 +553,6 @@ static int mp_property_total_avsync_change(void *ctx, struct m_property *prop,
     return m_property_double_ro(action, arg, mpctx->total_avsync_change);
 }
 
-
-/// Late frames
 static int mp_property_drop_frame_cnt(void *ctx, struct m_property *prop,
                                       int action, void *arg)
 {
@@ -565,6 +563,16 @@ static int mp_property_drop_frame_cnt(void *ctx, struct m_property *prop,
     return m_property_int_ro(action, arg, mpctx->dropped_frames_total);
 }
 
+static int mp_property_mistimed_frame_count(void *ctx, struct m_property *prop,
+                                            int action, void *arg)
+{
+    MPContext *mpctx = ctx;
+     if (!mpctx->d_video || !mpctx->display_sync_active)
+        return M_PROPERTY_UNAVAILABLE;
+
+    return m_property_int_ro(action, arg, mpctx->mistimed_frames_total);
+}
+
 static int mp_property_vo_drop_frame_count(void *ctx, struct m_property *prop,
                                            int action, void *arg)
 {
@@ -3383,6 +3391,7 @@ static const struct m_property mp_properties[] = {
     {"avsync", mp_property_avsync},
     {"total-avsync-change", mp_property_total_avsync_change},
     {"drop-frame-count", mp_property_drop_frame_cnt},
+    {"mistimed-frame-count", mp_property_mistimed_frame_count},
     {"vo-drop-frame-count", mp_property_vo_drop_frame_count},
     {"vo-missed-frame-count", mp_property_vo_missed_frame_count},
     {"percent-pos", mp_property_percent_pos},
@@ -3601,7 +3610,7 @@ static const char *const *const mp_event_property_change[] = {
       "percent-pos", "time-remaining", "playtime-remaining", "playback-time",
       "estimated-vf-fps", "drop-frame-count", "vo-drop-frame-count",
       "total-avsync-change", "audio-speed-correction", "video-speed-correction",
-      "vo-missed-frame-count"),
+      "vo-missed-frame-count", "mistimed-frame-count"),
     E(MPV_EVENT_VIDEO_RECONFIG, "video-out-params", "video-params",
       "video-format", "video-codec", "video-bitrate", "dwidth", "dheight",
       "width", "height", "fps", "aspect", "vo-configured", "current-vo",

player/core.h

@@ -269,6 +269,8 @@ typedef struct MPContext {
     // Timing error (in seconds) due to rounding on vsync boundaries
     double display_sync_error;
     int display_sync_disable_counter;
+    // Number of mistimed frames.
+    int mistimed_frames_total;
     /* Set if audio should be timed to start with video frame after seeking,
      * not set when e.g. playing cover art */
     bool sync_audio_to_video;

player/video.c

@@ -211,6 +211,7 @@ void reset_video_state(struct MPContext *mpctx)
     mpctx->display_sync_disable_counter = 0;
     mpctx->dropped_frames_total = 0;
     mpctx->dropped_frames = 0;
+    mpctx->mistimed_frames_total = 0;
     mpctx->drop_message_shown = 0;
     mpctx->display_sync_drift_dir = 0;
 
@@ -1034,6 +1035,9 @@ static void handle_display_sync_frame(struct MPContext *mpctx,
     // Likewise, we know sync is off, but is going to be compensated.
     time_left += drop_repeat * vsync;
 
+    if (drop_repeat)
+        mpctx->mistimed_frames_total += 1;
+
     mpctx->total_avsync_change = 0;
     update_av_diff(mpctx, time_left);