From cab544889a6ce2dd48a5859b54ccfd807518bd92 Mon Sep 17 00:00:00 2001
From: Dudemanguy <random342@airmail.cc>
Date: Sat, 15 Jul 2023 12:57:31 -0500
Subject: [PATCH] sd_ass: don't reconfigure ass on every frame

dbc5d7b7db70f898dcd5cbbba76ffed38e5371ee seems to have originally
introduced this behavior. At the time, wm4 simply reconfigured ass on
every frame in order to accommodate runtime changes in sub options. This
certainly works, but these libass API calls are not free and there is at
least one known performance regression due to a change in libass*.
Regardless of whether or not the libass change is good/bad, there is no
need for mpv to constantly reconfigure this. When wm4 made that commit,
there was no notification mechanism for options changing that could
easily be used so he didn't really have any other choice. But it's
nearly 10 years later now and internally we have all the necessary
pieces to only configure ass again when we need to: on option changes or
resizes. So go ahead and implement that in this commit which simply uses
the already existing SD_CTRL_UPDATE_OPTS and compares osd_res sizes to
determine whether or not an ass configure is needed.

*: https://github.com/libass/libass/issues/698
---
 sub/sd_ass.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/sub/sd_ass.c b/sub/sd_ass.c
index fa52056862..2189f0cebe 100644
--- a/sub/sd_ass.c
+++ b/sub/sd_ass.c
@@ -43,6 +43,7 @@ struct sd_ass_priv {
     struct ass_renderer *ass_renderer;
     struct ass_track *ass_track;
     struct ass_track *shadow_track; // for --sub-ass=no rendering
+    bool ass_configured;
     bool is_converted;
     struct lavc_conv *converter;
     struct sd_filter **filters;
@@ -54,6 +55,7 @@ struct sd_ass_priv {
     char last_text[500];
     struct mp_image_params video_params;
     struct mp_image_params last_params;
+    struct mp_osd_res osd;
     int64_t *seen_packets;
     int num_seen_packets;
     bool duration_unknown;
@@ -537,6 +539,10 @@ static struct sub_bitmaps *get_bitmaps(struct sd *sd, struct mp_osd_res dim,
     ASS_Renderer *renderer = ctx->ass_renderer;
     struct sub_bitmaps *res = &(struct sub_bitmaps){0};
 
+    // Always update the osd_res
+    struct mp_osd_res old_osd = ctx->osd;
+    ctx->osd = dim;
+
     if (pts == MP_NOPTS_VALUE || !renderer)
         goto done;
 
@@ -555,7 +561,10 @@ static struct sub_bitmaps *get_bitmaps(struct sd *sd, struct mp_osd_res dim,
         if (isnormal(par))
             scale *= par;
     }
-    configure_ass(sd, &dim, converted, track);
+    if (!ctx->ass_configured || !osd_res_equals(old_osd, ctx->osd)) {
+        configure_ass(sd, &dim, converted, track);
+        ctx->ass_configured = true;
+    }
     ass_set_pixel_aspect(renderer, scale);
     if (!converted && (!opts->ass_style_override ||
                        opts->ass_vsfilter_blur_compat))
@@ -831,6 +840,7 @@ static int control(struct sd *sd, enum sd_ctrl cmd, void *arg)
             assobjects_destroy(sd);
             assobjects_init(sd);
         }
+        ctx->ass_configured = false; // ass always needs to be reconfigured
         return CONTROL_OK;
     }
     default: