sub: move all subtitle timestamp messing code to a central place

It was split at least across osd.c and sd_ass.c/sd_lavc.c. sd_lavc.c
actually ignored most of the more obscure subtitle timing things.
There's no reason for this - just move it all to dec_sub.c (mostly from
sd_ass.c, because it has some of the most complex stuff).

Now timestamps are transformed as they enter or leave dec_sub.c.

There appear to have been some subtle mismatches about how subtitle
timestamps were transformed, e.g. sd_functions.accepts_packet didn't
apply the subtitle speed to the timestamp. This patch should fix them,
although it's not clear if they caused actual misbehavior.

The semantics of SD_CTRL_SUB_STEP are slightly changed, which is the
reason for the changes in command.c and sd_lavc.c.

1 files changed, 2 insertions, 6 deletions

diff --git a/sub/osd.c b/sub/osd.c
index 0d594cd24d..d2351b7213 100644
--- a/sub/osd.c
+++ b/sub/osd.c
@@ -273,12 +273,8 @@ static void render_object(struct osd_state *osd, struct osd_object *obj,
     check_obj_resize(osd, res, obj);
 
     if (obj->type == OSDTYPE_SUB || obj->type == OSDTYPE_SUB2) {
-        if (obj->sub) {
-            double sub_pts = video_pts;
-            if (sub_pts != MP_NOPTS_VALUE)
-                sub_pts -= opts->sub_delay;
-            sub_get_bitmaps(obj->sub, obj->vo_res, format, sub_pts, out_imgs);
-        }
+        if (obj->sub)
+            sub_get_bitmaps(obj->sub, obj->vo_res, format, video_pts, out_imgs);
     } else if (obj->type == OSDTYPE_EXTERNAL2) {
         if (obj->external2 && obj->external2->format) {
             *out_imgs = *obj->external2;