subtitles: add framework for subtitle decoders

Add a framework for subtitle decoder modules that work more like
audio/video decoders do, and change libass rendering of demuxed
subtitles to use the new framework.

The old subtitle code is messy, with details specific to handling
particular subtitle types spread over high-level code. This should
make it easier to clean things up and fix some bugs/limitations.

sub/dec_sub.c

@@ -0,0 +1,72 @@
+/*
+ * This file is part of MPlayer.
+ *
+ * MPlayer is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * MPlayer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with MPlayer; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <stdlib.h>
+#include <stdbool.h>
+#include <assert.h>
+
+#include "config.h"
+#include "libmpdemux/stheader.h"
+#include "sd.h"
+#include "dec_sub.h"
+#include "options.h"
+
+extern const struct sd_functions sd_ass;
+
+void sub_init(struct sh_sub *sh, struct osd_state *osd)
+{
+    struct MPOpts *opts = sh->opts;
+
+#ifdef CONFIG_ASS
+    if (opts->ass_enabled && is_text_sub(sh->type))
+        sh->sd_driver = &sd_ass;
+#endif
+    if (sh->sd_driver) {
+        sh->sd_driver->init(sh, osd);
+        sh->initialized = true;
+        sh->active = true;
+    }
+}
+
+void sub_decode(struct sh_sub *sh, struct osd_state *osd, void *data,
+                int data_len, double pts, double duration)
+{
+    if (sh->active && sh->sd_driver->decode)
+        sh->sd_driver->decode(sh, osd, data, data_len, pts, duration);
+}
+
+void sub_reset(struct sh_sub *sh, struct osd_state *osd)
+{
+    if (sh->active && sh->sd_driver->reset)
+        sh->sd_driver->reset(sh, osd);
+}
+
+void sub_switchoff(struct sh_sub *sh, struct osd_state *osd)
+{
+    if (sh->active && sh->sd_driver->switch_off)
+        sh->sd_driver->switch_off(sh, osd);
+    sh->active = false;
+}
+
+void sub_uninit(struct sh_sub *sh)
+{
+    assert (!sh->active);
+    if (sh->initialized && sh->sd_driver->uninit)
+        sh->sd_driver->uninit(sh);
+    sh->initialized = false;
+}

sub/dec_sub.h

@@ -0,0 +1,14 @@
+struct sh_sub;
+struct osd_state;
+
+static inline bool is_text_sub(int type)
+{
+    return type == 't' || type == 'm' || type == 'a';
+}
+
+void sub_decode(struct sh_sub *sh, struct osd_state *osd, void *data,
+                int data_len, double pts, double duration);
+void sub_init(struct sh_sub *sh, struct osd_state *osd);
+void sub_reset(struct sh_sub *sh, struct osd_state *osd);
+void sub_switchoff(struct sh_sub *sh, struct osd_state *osd);
+void sub_uninit(struct sh_sub *sh);

sub/sd.h

@@ -0,0 +1,16 @@
+#ifndef MPLAYER_SD_H
+#define MPLAYER_SD_H
+
+struct osd_state;
+struct sh_sub;
+
+struct sd_functions {
+    void (*init)(struct sh_sub *sh, struct osd_state *osd);
+    void (*decode)(struct sh_sub *sh, struct osd_state *osd,
+                   void *data, int data_len, double pts, double duration);
+    void (*reset)(struct sh_sub *sh, struct osd_state *osd);
+    void (*switch_off)(struct sh_sub *sh, struct osd_state *osd);
+    void (*uninit)(struct sh_sub *sh);
+};
+
+#endif

sub/sd_ass.c

@@ -0,0 +1,98 @@
+/*
+ * This file is part of MPlayer.
+ *
+ * MPlayer is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * MPlayer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with MPlayer; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <stdlib.h>
+#include <ass/ass.h>
+#include <assert.h>
+
+#include "talloc.h"
+
+#include "mpcommon.h"
+#include "libmpdemux/stheader.h"
+#include "libvo/sub.h"
+#include "ass_mp.h"
+#include "sd.h"
+
+struct sd_ass_priv {
+    struct ass_track *ass_track;
+};
+
+static void init(struct sh_sub *sh, struct osd_state *osd)
+{
+    struct sd_ass_priv *ctx;
+
+    if (sh->initialized) {
+        ctx = sh->context;
+    } else {
+        ctx = talloc_zero(NULL, struct sd_ass_priv);
+        sh->context = ctx;
+        if (sh->type == 'a') {
+            ctx->ass_track = ass_new_track(ass_library);
+            if (sh->extradata)
+                ass_process_codec_private(ctx->ass_track, sh->extradata,
+                                          sh->extradata_len);
+        } else
+            ctx->ass_track = ass_default_track(ass_library);
+    }
+
+    assert(osd->ass_track == NULL);
+    osd->ass_track = ctx->ass_track;
+}
+
+static void decode(struct sh_sub *sh, struct osd_state *osd, void *data,
+                   int data_len, double pts, double duration)
+{
+    struct sd_ass_priv *ctx = sh->context;
+
+    if (sh->type == 'a') { // ssa/ass subs
+        ass_process_chunk(ctx->ass_track, data, data_len,
+                          (long long)(pts*1000 + 0.5),
+                          (long long)(duration*1000 + 0.5));
+    } else { // plaintext subs
+        if (pts != MP_NOPTS_VALUE) {
+            subtitle tmp_subs = {0};
+            if (duration <= 0)
+                duration = 3;
+            sub_add_text(&tmp_subs, data, data_len, pts + duration);
+            tmp_subs.start = pts * 100;
+            tmp_subs.end = (pts + duration) * 100;
+            ass_process_subtitle(ctx->ass_track, &tmp_subs);
+            sub_clear_text(&tmp_subs, MP_NOPTS_VALUE);
+        }
+    }
+}
+
+static void switch_off(struct sh_sub *sh, struct osd_state *osd)
+{
+    osd->ass_track = NULL;
+}
+
+static void uninit(struct sh_sub *sh)
+{
+    struct sd_ass_priv *ctx = sh->context;
+
+    ass_free_track(ctx->ass_track);
+    talloc_free(ctx);
+}
+
+const struct sd_functions sd_ass = {
+    .init = init,
+    .decode = decode,
+    .switch_off = switch_off,
+    .uninit = uninit,
+};