diff --git a/player/sub.c b/player/sub.c
index 059dbdc2fd..e1e411e2ec 100644
--- a/player/sub.c
+++ b/player/sub.c
@@ -152,12 +152,12 @@ static void reinit_subdec(struct MPContext *mpctx, struct track *track)
     if (sub_is_initialized(dec_sub))
         return;
 
+    sub_init(dec_sub, track->demuxer, track->stream);
+
     struct sh_video *sh_video =
         mpctx->d_video ? mpctx->d_video->header->video : NULL;
-    float fps = sh_video ? sh_video->fps : 25;
-
-    sub_set_video_fps(dec_sub, fps);
-    sub_init(dec_sub, track->demuxer, track->stream);
+    double fps = sh_video ? sh_video->fps : 25;
+    sub_control(dec_sub, SD_CTRL_SET_VIDEO_DEF_FPS, &fps);
 
     // Don't do this if the file has video/audio streams. Don't do it even
     // if it has only sub streams, because reading packets will change the
diff --git a/sub/dec_sub.c b/sub/dec_sub.c
index a1f72d432b..1a2c170596 100644
--- a/sub/dec_sub.c
+++ b/sub/dec_sub.c
@@ -113,13 +113,6 @@ bool sub_is_initialized(struct dec_sub *sub)
     return r;
 }
 
-void sub_set_video_fps(struct dec_sub *sub, double fps)
-{
-    pthread_mutex_lock(&sub->lock);
-    sub->init_sd.video_fps = fps;
-    pthread_mutex_unlock(&sub->lock);
-}
-
 static int sub_init_decoder(struct dec_sub *sub, struct sd *sd)
 {
     sd->driver = NULL;
diff --git a/sub/dec_sub.h b/sub/dec_sub.h
index f1f738b695..e202438777 100644
--- a/sub/dec_sub.h
+++ b/sub/dec_sub.h
@@ -8,11 +8,8 @@
 
 struct demuxer;
 struct sh_stream;
-struct ass_track;
 struct mpv_global;
 struct demux_packet;
-struct ass_library;
-struct ass_renderer;
 
 struct dec_sub;
 struct sd;
@@ -22,6 +19,7 @@ enum sd_ctrl {
     SD_CTRL_SET_VIDEO_PARAMS,
     SD_CTRL_GET_RESOLUTION,
     SD_CTRL_SET_TOP,
+    SD_CTRL_SET_VIDEO_DEF_FPS,
 };
 
 struct dec_sub *sub_create(struct mpv_global *global);
@@ -29,7 +27,6 @@ void sub_destroy(struct dec_sub *sub);
 void sub_lock(struct dec_sub *sub);
 void sub_unlock(struct dec_sub *sub);
 
-void sub_set_video_fps(struct dec_sub *sub, double fps);
 void sub_init(struct dec_sub *sub, struct demuxer *demuxer, struct sh_stream *sh);
 
 bool sub_is_initialized(struct dec_sub *sub);
diff --git a/sub/sd.h b/sub/sd.h
index ce312cca70..26f9d4149f 100644
--- a/sub/sd.h
+++ b/sub/sd.h
@@ -19,7 +19,6 @@ struct sd {
 
     struct demuxer *demuxer;
     struct sh_stream *sh;
-    double video_fps;
 };
 
 struct sd_functions {
diff --git a/sub/sd_ass.c b/sub/sd_ass.c
index 869d8eaf1f..d798b1f4f4 100644
--- a/sub/sd_ass.c
+++ b/sub/sd_ass.c
@@ -48,7 +48,7 @@ struct sd_ass_priv {
     char last_text[500];
     struct mp_image_params video_params;
     struct mp_image_params last_params;
-    double sub_speed;
+    double sub_speed, video_fps, frame_fps;
     int64_t *seen_packets;
     int num_seen_packets;
 };
@@ -147,6 +147,24 @@ static void enable_output(struct sd *sd, bool enable)
     }
 }
 
+static void update_subtitle_speed(struct sd *sd)
+{
+    struct MPOpts *opts = sd->opts;
+    struct sd_ass_priv *ctx = sd->priv;
+    ctx->sub_speed = 1.0;
+
+    if (ctx->video_fps > 0 && ctx->frame_fps > 0) {
+        MP_VERBOSE(sd, "Frame based format, dummy FPS: %f, video FPS: %f\n",
+                   ctx->frame_fps, ctx->video_fps);
+        ctx->sub_speed *= ctx->frame_fps / ctx->video_fps;
+    }
+
+    if (opts->sub_fps && ctx->video_fps)
+        ctx->sub_speed *= opts->sub_fps / ctx->video_fps;
+
+    ctx->sub_speed *= opts->sub_speed;
+}
+
 static int init(struct sd *sd)
 {
     struct MPOpts *opts = sd->opts;
@@ -187,18 +205,8 @@ static int init(struct sd *sd)
 
     mp_ass_add_default_styles(ctx->ass_track, opts);
 
-    ctx->sub_speed = 1.0;
-
-    if (sd->video_fps && sd->sh && sd->sh->sub->frame_based > 0) {
-        MP_VERBOSE(sd, "Frame based format, dummy FPS: %f, video FPS: %f\n",
-                   sd->sh->sub->frame_based, sd->video_fps);
-        ctx->sub_speed *= sd->sh->sub->frame_based / sd->video_fps;
-    }
-
-    if (opts->sub_fps && sd->video_fps)
-        ctx->sub_speed *= opts->sub_fps / sd->video_fps;
-
-    ctx->sub_speed *= opts->sub_speed;
+    ctx->frame_fps = sd->sh->sub->frame_based;
+    update_subtitle_speed(sd);
 
     enable_output(sd, true);
 
@@ -613,6 +621,10 @@ static int control(struct sd *sd, enum sd_ctrl cmd, void *arg)
     case SD_CTRL_SET_TOP:
         ctx->on_top = *(bool *)arg;
         return CONTROL_OK;
+    case SD_CTRL_SET_VIDEO_DEF_FPS:
+        ctx->video_fps = *(double *)arg;
+        update_subtitle_speed(sd);
+        return CONTROL_OK;
     default:
         return CONTROL_UNKNOWN;
     }