Revert "player: reset av state on speed changes"

Ended up being too flawed and caused trouble in other areas. There's
other approaches to trying to solve the issue this meant to address in
the works that should be better, so let's wait on that. Fixes mpv-player#13613 and
fixes mpv-player#13622.

This reverts commit e3af545.

player/command.c

@@ -7246,7 +7246,6 @@ void mp_option_change_callback(void *ctx, struct m_config_option *co, int flags,
 
     if (opt_ptr == &opts->playback_speed) {
         update_playback_speed(mpctx);
-        reset_av_state(mpctx);
         mp_wakeup_core(mpctx);
     }
 

player/core.h

@@ -637,7 +637,6 @@ void update_osd_msg(struct MPContext *mpctx);
 bool update_subtitles(struct MPContext *mpctx, double video_pts);
 
 // video.c
-void reset_av_state(struct MPContext *mpctx);
 void reset_video_state(struct MPContext *mpctx);
 int init_video_decoder(struct MPContext *mpctx, struct track *track);
 void reinit_video_chain(struct MPContext *mpctx);

player/video.c

@@ -45,8 +45,6 @@
 #include "command.h"
 #include "screenshot.h"
 
-#define MIN_PAST_FRAMES 10
-
 enum {
     // update_video() - code also uses: <0 error, 0 eof, >0 progress
     VD_ERROR = -1,
@@ -97,17 +95,6 @@ static void vo_chain_reset_state(struct vo_chain *vo_c)
     vo_c->underrun_signaled = false;
 }
 
-void reset_av_state(struct MPContext *mpctx)
-{
-    mpctx->delay = 0;
-    mpctx->display_sync_drift_dir = 0;
-    mpctx->display_sync_error = 0;
-    mpctx->last_av_difference = 0;
-    mpctx->logged_async_diff = -1;
-    mpctx->num_past_frames = 0;
-    mpctx->total_avsync_change = 0;
-}
-
 void reset_video_state(struct MPContext *mpctx)
 {
     if (mpctx->vo_chain) {
@@ -606,9 +593,7 @@ static void update_avsync_before_frame(struct MPContext *mpctx)
 
     if (mpctx->video_status < STATUS_READY) {
         mpctx->time_frame = 0;
-    } else if (mpctx->display_sync_active || vo->opts->video_sync == VS_NONE ||
-               mpctx->num_past_frames <= MIN_PAST_FRAMES)
-    {
+    } else if (mpctx->display_sync_active || vo->opts->video_sync == VS_NONE) {
         // don't touch the timing
     } else if (mpctx->audio_status == STATUS_PLAYING &&
                mpctx->video_status == STATUS_PLAYING &&
@@ -742,7 +727,7 @@ static double compute_audio_drift(struct MPContext *mpctx, double vsync)
     // audio desync for y. Assume speed didn't change for the frames we're
     // looking at for simplicity. This also should actually use the realtime
     // (minus paused time) for x, but use vsync scheduling points instead.
-    if (mpctx->num_past_frames <= MIN_PAST_FRAMES)
+    if (mpctx->num_past_frames <= 10)
         return NAN;
     int num = mpctx->num_past_frames - 1;
     double sum_x = 0, sum_y = 0, sum_xy = 0, sum_xx = 0;
@@ -847,9 +832,6 @@ static void handle_display_sync_frame(struct MPContext *mpctx,
     if (resample && using_spdif_passthrough(mpctx))
         return;
 
-    if (mpctx->num_past_frames <= MIN_PAST_FRAMES)
-        return;
-
     double vsync = vo_get_vsync_interval(vo) / 1e9;
     if (vsync <= 0)
         return;