From 49caa0a775be06539a7cd30875f1c80368a7ac55 Mon Sep 17 00:00:00 2001
From: Rudolf Polzer <divVerent@xonotic.org>
Date: Fri, 1 Nov 2013 13:15:59 +0100
Subject: sd_ass, sd_lavc: use the input video's pixel aspect for scaling
 subtitles.

The previous code used the output video's pixel aspect for stretching
purposes, breaking rendering with e.g. -vf scale in the chain. Now
subtitles are stretched using the input video's pixel aspect only,
matching the intentions of the original subtitle author.
---
 sub/sd_ass.c  |  5 ++++-
 sub/sd_lavc.c | 24 +++++++++++++++++++++---
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/sub/sd_ass.c b/sub/sd_ass.c
index 591f9d5105..fd545cdbda 100644
--- a/sub/sd_ass.c
+++ b/sub/sd_ass.c
@@ -142,7 +142,10 @@ static void get_bitmaps(struct sd *sd, struct mp_osd_res dim, double pts,
     if (!ctx->is_converted && (!opts->ass_style_override ||
                                opts->ass_vsfilter_aspect_compat))
     {
-        scale = scale * dim.video_par;
+        // Let's use the original video PAR for vsfilter compatibility:
+        scale = scale
+            * (ctx->video_params.d_w / (double)ctx->video_params.d_h)
+            / (ctx->video_params.w   / (double)ctx->video_params.h);
     }
     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 b03861025d..2cce6ea4cd 100644
--- a/sub/sd_lavc.c
+++ b/sub/sd_lavc.c
@@ -26,6 +26,7 @@
 #include "mpvcore/av_common.h"
 #include "mpvcore/options.h"
 #include "demux/stheader.h"
+#include "video/mp_image.h"
 #include "sd.h"
 #include "dec_sub.h"
 #include "sub.h"
@@ -41,6 +42,7 @@ struct sd_lavc_priv {
     bool bitmaps_changed;
     double pts;
     double endpts;
+    struct mp_image_params video_params;
 };
 
 static bool supports_format(const char *format)
@@ -223,10 +225,13 @@ static void get_bitmaps(struct sd *sd, struct mp_osd_res d, double pts,
     double yscale = (double)vidh / inh;
     if (priv->avctx->codec_id == AV_CODEC_ID_DVD_SUBTITLE) {
         // For DVD subs, try to keep the subtitle PAR at display PAR.
-        if (d.video_par > 1.0) {
-            xscale /= d.video_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 *= d.video_par;
+            yscale *= video_par;
         }
     }
     int cx = vidw / 2 - (int)(inw * xscale) / 2;
@@ -268,12 +273,25 @@ static void uninit(struct sd *sd)
     talloc_free(priv);
 }
 
+static int control(struct sd *sd, enum sd_ctrl cmd, void *arg)
+{
+    struct sd_lavc_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_lavc = {
     .name = "lavc",
     .supports_format = supports_format,
     .init = init,
     .decode = decode,
     .get_bitmaps = get_bitmaps,
+    .control = control,
     .reset = reset,
     .uninit = uninit,
 };
-- 
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