sd_ass: remove dead code

With the FFmpeg subtitle decoder used for _all_ non-ASS text subtitle
format, this code is simply unused now.

Ironically, the FFmpeg subtitle decoder does not handle things correctly
in a bunch of cases. Should it turn out they actually matter, they will
have to hack back.

The extend_event one is a candidate, although even though there were
allegedly files which need it, I couldn't get samples from the user who
originally reported such files. As such, extend_event was only confirmed
to handle trailing events with no (endless) duration like with MicroDVD
and LRC, but FFmpeg "fudges" these anyway, so no special handling is
needed.

This code also had logic to handle seeking with muxed srt subtitles,
which made the sub-seek command work. But this has been broken before
this commit already. Currently, seeking with muxed srt subs will clear
all subtitles, as the broken FFmpeg ASS format output by the libavcodec
subtitle converters does not check for duplicates. Since the subtitles
are all cleared, ass_step_sub() can not work properly and sub-seek can
not seek to already seen subtitles.

sub/dec_sub.c

@@ -303,8 +303,6 @@ static void add_sub_list(struct dec_sub *sub, struct packet_list *subs)
     struct sd *sd = sub_get_last_sd(sub);
     assert(sd);
 
-    sd->no_remove_duplicates = true;
-
     for (int n = 0; n < subs->num_packets; n++)
         decode_chain_recode(sub, subs->packets[n]);
 
@@ -314,8 +312,6 @@ static void add_sub_list(struct dec_sub *sub, struct packet_list *subs)
     // but this is obviously unwanted in this case.
     if (sd->driver->fix_events)
         sd->driver->fix_events(sd);
-
-    sd->no_remove_duplicates = false;
 }
 
 static void add_packet(struct packet_list *subs, struct demux_packet *pkt)

sub/sd.h

@@ -39,10 +39,6 @@ struct sd {
     struct ass_renderer *ass_renderer;
     pthread_mutex_t *ass_lock;
 
-    // If false, try to remove multiple subtitles.
-    // (Only for decoders which have accept_packets_in_advance set.)
-    bool no_remove_duplicates;
-
     // Set by sub converter
     const char *output_codec;
     char *output_extradata;

sub/sd_ass.c

@@ -43,7 +43,6 @@ struct sd_ass_priv {
     bool on_top;
     struct sub_bitmap *parts;
     bool flush_on_seek;
-    int extend_event;
     char last_text[500];
     struct mp_image_params video_params;
     struct mp_image_params last_params;
@@ -79,12 +78,9 @@ static void mp_ass_add_default_styles(ASS_Track *track, struct MPOpts *opts)
 
 static bool supports_format(const char *format)
 {
-    // ass-text is produced by converters and the subreader.c ssa parser; this
-    // format has ASS tags, but doesn't start with any prelude, nor does it
-    // have extradata.
+    // "ssa" is used for the FFmpeg subtitle converter output
     return format && (strcmp(format, "ass") == 0 ||
-                      strcmp(format, "ssa") == 0 ||
-                      strcmp(format, "ass-text") == 0);
+                      strcmp(format, "ssa") == 0);
 }
 
 static int init(struct sd *sd)
@@ -96,7 +92,6 @@ static int init(struct sd *sd)
     struct sd_ass_priv *ctx = talloc_zero(NULL, struct sd_ass_priv);
     sd->priv = ctx;
 
-    ctx->extend_event = -1;
     ctx->is_converted = sd->converted_from != NULL;
 
     pthread_mutex_lock(sd->ass_lock);
@@ -139,59 +134,16 @@ static void decode(struct sd *sd, struct demux_packet *packet)
 {
     struct sd_ass_priv *ctx = sd->priv;
     ASS_Track *track = ctx->ass_track;
-    long long ipts = packet->pts * 1000 + 0.5;
-    long long iduration = packet->duration * 1000 + 0.5;
     if (strcmp(sd->codec, "ass") == 0) {
+        long long ipts = lrint(packet->pts * 1000);
+        long long iduration = lrint(packet->duration * 1000);
         ass_process_chunk(track, packet->buffer, packet->len, ipts, iduration);
         return;
-    } else if (strcmp(sd->codec, "ssa") == 0) {
-        // broken ffmpeg ASS packet format
+    } else {
+        // "ssa" codec ID
         ctx->flush_on_seek = true;
         ass_process_data(track, packet->buffer, packet->len);
-        return;
     }
-
-    // plaintext subs
-    if (packet->pts == MP_NOPTS_VALUE) {
-        MP_WARN(sd, "Subtitle without pts, ignored\n");
-        return;
-    }
-    if (ctx->extend_event >= 0 && ctx->extend_event < track->n_events) {
-        ASS_Event *event = &track->events[ctx->extend_event];
-        if (event->Start <= ipts)
-            event->Duration = ipts - event->Start;
-        ctx->extend_event = -1;
-    }
-
-    unsigned char *text = packet->buffer;
-    if (!sd->no_remove_duplicates) {
-        for (int i = 0; i < track->n_events; i++) {
-            if (track->events[i].Start == ipts
-                && (track->events[i].Duration == iduration)
-                && strcmp(track->events[i].Text, text) == 0)
-                return;   // We've already added this subtitle
-        }
-    }
-    int eid = ass_alloc_event(track);
-    ASS_Event *event = track->events + eid;
-
-    if (packet->duration == 0) {
-        MP_WARN(sd, "Subtitle without duration or "
-                "duration set to 0 at pts %f.\n", packet->pts);
-    }
-    if (packet->duration < 0) {
-        // Assume unknown duration. The FFmpeg API is very unclear about this.
-        MP_WARN(sd, "Assuming subtitle without duration at pts %f\n", packet->pts);
-        // _If_ there's a next subtitle, the duration will be adjusted again.
-        // If not, show it forever.
-        iduration = INT_MAX;
-        ctx->extend_event = eid;
-    }
-
-    event->Start = ipts;
-    event->Duration = iduration;
-    event->Style = track->default_style;
-    event->Text = strdup(text);
 }
 
 static void configure_ass(struct sd *sd, struct mp_osd_res *dim,
@@ -533,10 +485,8 @@ static void fix_events(struct sd *sd)
 static void reset(struct sd *sd)
 {
     struct sd_ass_priv *ctx = sd->priv;
-    if (ctx->flush_on_seek || sd->opts->sub_clear_on_seek) {
+    if (ctx->flush_on_seek || sd->opts->sub_clear_on_seek)
         ass_flush_events(ctx->ass_track);
-        ctx->extend_event = -1;
-    }
     ctx->flush_on_seek = false;
 }