1 files changed, 121 insertions, 0 deletions
diff --git a/demux/demux_libass.c b/demux/demux_libass.c
new file mode 100644
index 0000000000..cbc85b3abe
--- /dev/null
+++ b/demux/demux_libass.c
@@ -0,0 +1,121 @@
+/*
+ * This file is part of mpv.
+ *
+ * mpv 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.
+ *
+ * mpv 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 mpv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+// Note: just wraps libass, and makes the subtitle track available though
+//       sh_sub->track. It doesn't produce packets and doesn't support seeking.
+
+#include <ass/ass.h>
+#include <ass/ass_types.h>
+
+#include "core/options.h"
+#include "core/mp_msg.h"
+#include "core/charset_conv.h"
+#include "stream/stream.h"
+#include "demux.h"
+
+#define PROBE_SIZE (8 * 1024)
+
+struct priv {
+    ASS_Track *track;
+};
+
+static int d_check_file(struct demuxer *demuxer)
+{
+    const char *user_cp = demuxer->opts->sub_cp;
+    struct stream *s = demuxer->stream;
+    // Older versions of libass will behave strange if renderer and track
+    // library handles mismatch, so make sure everything uses a global handle.
+    ASS_Library *lib = demuxer->params ? demuxer->params->ass_library : NULL;
+    if (!lib)
+        return 0;
+
+    // Probe by loading a part of the beginning of the file with libass.
+    // Incomplete scripts are usually ok, and we hope libass is not verbose
+    // when dealing with (from its perspective) completely broken binary
+    // garbage.
+
+    bstr buf = stream_peek(s, PROBE_SIZE);
+    // Older versions of libass will overwrite the input buffer, and despite
+    // passing length, expect a 0 termination.
+    void *tmp = talloc_size(NULL, buf.len + 1);
+    memcpy(tmp, buf.start, buf.len);
+    buf.start = tmp;
+    buf.start[buf.len] = '\0';
+    bstr cbuf =
+        mp_charset_guess_and_conv_to_utf8(buf, user_cp,  MP_ICONV_ALLOW_CUTOFF);
+    if (cbuf.start == NULL)
+        cbuf = buf;
+    ASS_Track *track = ass_read_memory(lib, cbuf.start, cbuf.len, NULL);
+    if (cbuf.start != buf.start)
+        talloc_free(cbuf.start);
+    talloc_free(buf.start);
+    if (!track)
+        return 0;
+    ass_free_track(track);
+
+    // Actually load the full thing.
+
+    buf = stream_read_complete(s, NULL, 100000000);
+    if (!buf.start) {
+        mp_tmsg(MSGT_ASS, MSGL_ERR, "Refusing to load subtitle file "
+                "larger than 100 MB: %s\n", demuxer->filename);
+        return 0;
+    }
+    cbuf = mp_charset_guess_and_conv_to_utf8(buf, user_cp,  MP_ICONV_VERBOSE);
+    if (cbuf.start == NULL)
+        cbuf = buf;
+    track = ass_read_memory(lib, cbuf.start, cbuf.len, NULL);
+    if (cbuf.start != buf.start)
+        talloc_free(cbuf.start);
+    talloc_free(buf.start);
+    if (!track)
+        return 0;
+
+    track->name = strdup(demuxer->filename);
+
+    struct priv *p = talloc_ptrtype(demuxer, p);
+    *p = (struct priv) {
+        .track = track,
+    };
+
+    struct sh_stream *sh = new_sh_stream(demuxer, STREAM_SUB);
+    sh->sub->track = track;
+    sh->codec = "ass";
+
+    return DEMUXER_TYPE_LIBASS;
+}
+
+static void d_close(struct demuxer *demuxer)
+{
+    struct priv *p = demuxer->priv;
+    if (p) {
+        if (p->track)
+            ass_free_track(p->track);
+    }
+}
+
+const struct demuxer_desc demuxer_desc_libass = {
+    .info = "Read subtitles with libass",
+    .name = "libass",
+    .shortdesc = "ASS/SSA subtitles (libass)",
+    .author = "",
+    .comment = "",
+    .safe_check = 1,
+    .type = DEMUXER_TYPE_LIBASS,
+    .check_file = d_check_file,
+    .close = d_close,
+};