diff --git a/sub/sd_ass.c b/sub/sd_ass.c
index 4b0c3024c8..8b6f1f1554 100644
--- a/sub/sd_ass.c
+++ b/sub/sd_ass.c
@@ -19,6 +19,7 @@
 #include <stdlib.h>
 #include <assert.h>
 #include <string.h>
+#include <math.h>
 
 #include <libavutil/common.h>
 #include <ass/ass.h>
@@ -142,9 +143,11 @@ static void get_bitmaps(struct sd *sd, struct mp_osd_res dim, double pts,
                                opts->ass_vsfilter_aspect_compat))
     {
         // Let's use the original video PAR for vsfilter compatibility:
-        scale = scale
+        double par = scale
             * (ctx->video_params.d_w / (double)ctx->video_params.d_h)
             / (ctx->video_params.w   / (double)ctx->video_params.h);
+        if (isnormal(par))
+            scale = par;
     }
     mp_ass_configure(renderer, opts, &dim);
     ass_set_aspect_ratio(renderer, scale, 1);
diff --git a/sub/sd_lavc.c b/sub/sd_lavc.c
index 7fa798dd66..f0fa183419 100644
--- a/sub/sd_lavc.c
+++ b/sub/sd_lavc.c
@@ -17,6 +17,7 @@
 
 #include <stdlib.h>
 #include <assert.h>
+#include <math.h>
 
 #include <libavcodec/avcodec.h>
 #include <libavutil/common.h>
@@ -233,9 +234,11 @@ static void get_bitmaps(struct sd *sd, struct mp_osd_res d, double pts,
     if (priv->avctx->codec_id == AV_CODEC_ID_DVD_SUBTITLE &&
             opts->stretch_dvd_subs) {
         // For DVD subs, try to keep the subtitle PAR at display PAR.
-        video_par =
+        double par =
               (priv->video_params.d_w / (double)priv->video_params.d_h)
             / (priv->video_params.w   / (double)priv->video_params.h);
+        if (isnormal(par))
+            video_par = par;
     }
     int insize[2];
     get_resolution(sd, insize);
diff --git a/sub/sd_spu.c b/sub/sd_spu.c
index 3a7bf09127..fbc80b7f1f 100644
--- a/sub/sd_spu.c
+++ b/sub/sd_spu.c
@@ -26,7 +26,6 @@
 
 struct sd_spu_priv {
     void *spudec;
-    struct mp_image_params video_params;
 };
 
 static bool is_dvd_sub(const char *t)
@@ -72,22 +71,8 @@ static void get_bitmaps(struct sd *sd, struct mp_osd_res d, double pts,
     spudec_set_forced_subs_only(priv->spudec, opts->forced_subs_only);
     spudec_heartbeat(priv->spudec, pts * 90000);
 
-    if (spudec_visible(priv->spudec)) {
-        double xscale = 1;
-        double yscale = 1;
-        if (opts->stretch_dvd_subs) {
-            // For DVD subs, try to keep the subtitle PAR at display PAR.
-            double video_par =
-                  (priv->video_params.d_w / (double)priv->video_params.d_h)
-                / (priv->video_params.w   / (double)priv->video_params.h);
-            if (video_par > 1.0) {
-                xscale /= video_par;
-            } else {
-                yscale *= video_par;
-            }
-        }
-        spudec_get_indexed(priv->spudec, &d, xscale, yscale, res);
-    }
+    if (spudec_visible(priv->spudec))
+        spudec_get_indexed(priv->spudec, &d, 1, 1, res);
 }
 
 static void reset(struct sd *sd)
@@ -105,25 +90,12 @@ static void uninit(struct sd *sd)
     talloc_free(priv);
 }
 
-static int control(struct sd *sd, enum sd_ctrl cmd, void *arg)
-{
-    struct sd_spu_priv *priv = sd->priv;
-    switch (cmd) {
-    case SD_CTRL_SET_VIDEO_PARAMS:
-        priv->video_params = *(struct mp_image_params *)arg;
-        return CONTROL_OK;
-    default:
-        return CONTROL_UNKNOWN;
-    }
-}
-
 const struct sd_functions sd_spu = {
     .name = "spu",
     .supports_format = supports_format,
     .init = init,
     .decode = decode,
     .get_bitmaps = get_bitmaps,
-    .control = control,
     .reset = reset,
     .uninit = uninit,
 };