sub: move subtitle FPS adjustment to sd_ass.c

I feel like it's better there. Note that there is no reduced
functionality, as bitmaps subs (i.e. not handled by sd_ass.c) were never
fully read on init, and thus never went through sub_read_all_packets().

On the other hand, this might lead to confusion, as --sub-fps etc. will
now also affect muxed subtitles (which makes not much sense).

sub/dec_sub.c

@@ -62,7 +62,6 @@ struct dec_sub {
     struct MPOpts *opts;
     struct sd init_sd;
 
-    double video_fps;
     const char *charset;
 
     struct sd *sd[MAX_NUM_SD];
@@ -143,7 +142,7 @@ void sub_set_video_res(struct dec_sub *sub, int w, int h)
 void sub_set_video_fps(struct dec_sub *sub, double fps)
 {
     pthread_mutex_lock(&sub->lock);
-    sub->video_fps = fps;
+    sub->init_sd.video_fps = fps;
     pthread_mutex_unlock(&sub->lock);
 }
 
@@ -208,6 +207,7 @@ void sub_init_from_sh(struct dec_sub *sub, struct sh_stream *sh)
         sub_set_extradata(sub, sh->extradata, sh->extradata_size);
     struct sd init_sd = sub->init_sd;
     init_sd.codec = sh->codec;
+    init_sd.sh = sh;
 
     while (sub->num_sd < MAX_NUM_SD) {
         struct sd *sd = talloc(NULL, struct sd);
@@ -230,6 +230,8 @@ void sub_init_from_sh(struct dec_sub *sub, struct sh_stream *sh)
             .converted_from = sd->codec,
             .extradata = sd->output_extradata,
             .extradata_len = sd->output_extradata_len,
+            .sh = sub->init_sd.sh,
+            .video_fps = sub->init_sd.video_fps,
             .ass_library = sub->init_sd.ass_library,
             .ass_renderer = sub->init_sd.ass_renderer,
             .ass_lock = sub->init_sd.ass_lock,
@@ -335,17 +337,6 @@ static const char *guess_sub_cp(struct mp_log *log, void *talloc_ctx,
     return guess;
 }
 
-static void multiply_timings(struct packet_list *subs, double factor)
-{
-    for (int n = 0; n < subs->num_packets; n++) {
-        struct demux_packet *pkt = subs->packets[n];
-        if (pkt->pts != MP_NOPTS_VALUE)
-            pkt->pts *= factor;
-        if (pkt->duration > 0)
-            pkt->duration *= factor;
-    }
-}
-
 static void add_sub_list(struct dec_sub *sub, int at, struct packet_list *subs)
 {
     struct sd *sd = sub_get_last_sd(sub);
@@ -431,22 +422,6 @@ bool sub_read_all_packets(struct dec_sub *sub, struct sh_stream *sh)
     if (sub->charset && sub->charset[0] && !mp_charset_is_utf8(sub->charset))
         MP_INFO(sub, "Using subtitle charset: %s\n", sub->charset);
 
-    double sub_speed = 1.0;
-
-    if (sub->video_fps && sh->sub->frame_based > 0) {
-        MP_VERBOSE(sub, "Frame based format, dummy FPS: %f, video FPS: %f\n",
-                   sh->sub->frame_based, sub->video_fps);
-        sub_speed *= sh->sub->frame_based / sub->video_fps;
-    }
-
-    if (opts->sub_fps && sub->video_fps)
-        sub_speed *= opts->sub_fps / sub->video_fps;
-
-    sub_speed *= opts->sub_speed;
-
-    if (sub_speed != 1.0)
-        multiply_timings(subs, sub_speed);
-
     add_sub_list(sub, preprocess, subs);
 
     pthread_mutex_unlock(&sub->lock);

sub/sd.h

@@ -22,6 +22,8 @@ struct sd {
     char *extradata;
     int extradata_len;
 
+    struct sh_stream *sh;
+
     // Set to !=NULL if the input packets are being converted from another
     // format.
     const char *converted_from;
@@ -30,6 +32,8 @@ struct sd {
     // the resolution of the VO, nor does it have to be the OSD resolution.
     int sub_video_w, sub_video_h;
 
+    double video_fps;
+
     // Shared renderer for ASS - done to avoid reloading embedded fonts.
     struct ass_library *ass_library;
     struct ass_renderer *ass_renderer;

sub/sd_ass.c

@@ -29,6 +29,7 @@
 #include "options/options.h"
 #include "common/common.h"
 #include "common/msg.h"
+#include "demux/stheader.h"
 #include "video/csputils.h"
 #include "video/mp_image.h"
 #include "dec_sub.h"
@@ -46,6 +47,7 @@ struct sd_ass_priv {
     char last_text[500];
     struct mp_image_params video_params;
     struct mp_image_params last_params;
+    double sub_speed;
 };
 
 static void mangle_colors(struct sd *sd, struct sub_bitmaps *parts);
@@ -117,6 +119,19 @@ static int init(struct sd *sd)
 
     pthread_mutex_unlock(sd->ass_lock);
 
+    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;
+
     return 0;
 }
 
@@ -251,6 +266,8 @@ static long long find_timestamp(struct sd *sd, double pts)
     if (pts == MP_NOPTS_VALUE)
         return 0;
 
+    pts /= priv->sub_speed;
+
     long long ts = llrint(pts * 1000);
 
     if (!sd->opts->sub_fix_timing)
@@ -528,10 +545,11 @@ static int control(struct sd *sd, enum sd_ctrl cmd, void *arg)
     switch (cmd) {
     case SD_CTRL_SUB_STEP: {
         double *a = arg;
-        long long res = ass_step_sub(ctx->ass_track, a[0] * 1000 + 0.5, a[1]);
+        long long ts = llrint(a[0] * (1000.0 / ctx->sub_speed));
+        long long res = ass_step_sub(ctx->ass_track, ts, a[1]);
         if (!res)
             return false;
-        a[0] = res / 1000.0;
+        a[0] = res / (1000.0 / ctx->sub_speed);
         return true;
     }
     case SD_CTRL_SET_VIDEO_PARAMS: