matroska: add kate subtitle support to matroska muxer and demuxer

See #525743.

gst/matroska/matroska-demux.c

@@ -121,7 +121,8 @@ static GstStaticPadTemplate subtitle_src_templ =
     GST_PAD_SOMETIMES,
     GST_STATIC_CAPS ("text/plain; application/x-ssa; application/x-ass; "
         "application/x-usf; video/x-dvd-subpicture; "
-        "subpicture/x-pgs; " "application/x-subtitle-unknown")
+        "subpicture/x-pgs; subtitle/x-kate; "
+        "application/x-subtitle-unknown")
     );
 
 static GstFlowReturn gst_matroska_demux_parse_contents (GstMatroskaDemux *
@@ -5771,6 +5772,9 @@ gst_matroska_demux_subtitle_caps (GstMatroskaTrackSubtitleContext *
     ((GstMatroskaTrackContext *) subtitlecontext)->send_dvd_event = TRUE;
   } else if (!strcmp (codec_id, GST_MATROSKA_CODEC_ID_SUBTITLE_HDMVPGS)) {
     caps = gst_caps_new_simple ("subpicture/x-pgs", NULL);
+  } else if (!strcmp (codec_id, GST_MATROSKA_CODEC_ID_SUBTITLE_KATE)) {
+    caps = gst_caps_new_simple ("subtitle/x-kate", NULL);
+    context->send_xiph_headers = TRUE;
   } else {
     GST_DEBUG ("Unknown subtitle stream: codec_id='%s'", codec_id);
     caps = gst_caps_new_simple ("application/x-subtitle-unknown", NULL);

gst/matroska/matroska-ids.h

@@ -379,6 +379,7 @@
 #define GST_MATROSKA_CODEC_ID_SUBTITLE_VOBSUB    "S_VOBSUB"
 #define GST_MATROSKA_CODEC_ID_SUBTITLE_HDMVPGS   "S_HDMV/PGS"
 #define GST_MATROSKA_CODEC_ID_SUBTITLE_BMP       "S_IMAGE/BMP"
+#define GST_MATROSKA_CODEC_ID_SUBTITLE_KATE      "S_KATE"
 
 /*
  * Matroska tags. Strings.

gst/matroska/matroska-mux.c

@@ -228,6 +228,8 @@ static gboolean vorbis_streamheader_to_codecdata (const GValue * streamheader,
     GstMatroskaTrackContext * context);
 static gboolean speex_streamheader_to_codecdata (const GValue * streamheader,
     GstMatroskaTrackContext * context);
+static gboolean kate_streamheader_to_codecdata (const GValue * streamheader,
+    GstMatroskaTrackContext * context);
 static gboolean flac_streamheader_to_codecdata (const GValue * streamheader,
     GstMatroskaTrackContext * context);
 
@@ -897,6 +899,109 @@ skip_details:
   return FALSE;
 }
 
+/* N > 0 to expect a particular number of headers, negative if the
+   number of headers is variable */
+static gboolean
+xiphN_streamheader_to_codecdata (const GValue * streamheader,
+    GstMatroskaTrackContext * context, GstBuffer ** p_buf0, int N)
+{
+  GstBuffer **buf = NULL;
+  GArray *bufarr;
+  guint8 *priv_data;
+  guint bufi, i, offset, priv_data_size;
+
+  if (streamheader == NULL)
+    goto no_stream_headers;
+
+  if (G_VALUE_TYPE (streamheader) != GST_TYPE_ARRAY)
+    goto wrong_type;
+
+  bufarr = g_value_peek_pointer (streamheader);
+  if (bufarr->len <= 0 || bufarr->len > 255)    /* at least one header, and count stored in a byte */
+    goto wrong_count;
+  if (N > 0 && bufarr->len != N)
+    goto wrong_count;
+
+  context->xiph_headers_to_skip = bufarr->len;
+
+  buf = (GstBuffer **) g_malloc0 (sizeof (GstBuffer *) * bufarr->len);
+  for (i = 0; i < bufarr->len; i++) {
+    GValue *bufval = &g_array_index (bufarr, GValue, i);
+
+    if (G_VALUE_TYPE (bufval) != GST_TYPE_BUFFER) {
+      g_free (buf);
+      goto wrong_content_type;
+    }
+
+    buf[i] = g_value_peek_pointer (bufval);
+  }
+
+  priv_data_size = 1;
+  if (bufarr->len > 0) {
+    for (i = 0; i < bufarr->len - 1; i++) {
+      priv_data_size += GST_BUFFER_SIZE (buf[i]) / 0xff + 1;
+    }
+  }
+
+  for (i = 0; i < bufarr->len; ++i) {
+    priv_data_size += GST_BUFFER_SIZE (buf[i]);
+  }
+
+  priv_data = g_malloc0 (priv_data_size);
+
+  priv_data[0] = bufarr->len - 1;
+  offset = 1;
+
+  if (bufarr->len > 0) {
+    for (bufi = 0; bufi < bufarr->len - 1; bufi++) {
+      for (i = 0; i < GST_BUFFER_SIZE (buf[bufi]) / 0xff; ++i) {
+        priv_data[offset++] = 0xff;
+      }
+      priv_data[offset++] = GST_BUFFER_SIZE (buf[bufi]) % 0xff;
+    }
+  }
+
+  for (i = 0; i < bufarr->len; ++i) {
+    memcpy (priv_data + offset, GST_BUFFER_DATA (buf[i]),
+        GST_BUFFER_SIZE (buf[i]));
+    offset += GST_BUFFER_SIZE (buf[i]);
+  }
+
+  context->codec_priv = priv_data;
+  context->codec_priv_size = priv_data_size;
+
+  if (p_buf0)
+    *p_buf0 = gst_buffer_ref (buf[0]);
+
+  g_free (buf);
+
+  return TRUE;
+
+/* ERRORS */
+no_stream_headers:
+  {
+    GST_WARNING ("required streamheaders missing in sink caps!");
+    return FALSE;
+  }
+wrong_type:
+  {
+    GST_WARNING ("streamheaders are not a GST_TYPE_ARRAY, but a %s",
+        G_VALUE_TYPE_NAME (streamheader));
+    return FALSE;
+  }
+wrong_count:
+  {
+    GST_WARNING ("got %u streamheaders, not 3 as expected", bufarr->len);
+    return FALSE;
+  }
+wrong_content_type:
+  {
+    GST_WARNING ("streamheaders array does not contain GstBuffers");
+    return FALSE;
+  }
+}
+
+/* FIXME: after release make all code use xiph3_streamheader_to_codecdata() */
 static gboolean
 xiph3_streamheader_to_codecdata (const GValue * streamheader,
     GstMatroskaTrackContext * context, GstBuffer ** p_buf0)
@@ -994,6 +1099,7 @@ vorbis_streamheader_to_codecdata (const GValue * streamheader,
 {
   GstBuffer *buf0 = NULL;
 
+  /* FIXME: change to use xiphN_streamheader_to_codecdata() after release */
   if (!xiph3_streamheader_to_codecdata (streamheader, context, &buf0))
     return FALSE;
 
@@ -1023,6 +1129,7 @@ theora_streamheader_to_codecdata (const GValue * streamheader,
 {
   GstBuffer *buf0 = NULL;
 
+  /* FIXME: change to use xiphN_streamheader_to_codecdata() after release */
   if (!xiph3_streamheader_to_codecdata (streamheader, context, &buf0))
     return FALSE;
 
@@ -1074,6 +1181,27 @@ theora_streamheader_to_codecdata (const GValue * streamheader,
   return TRUE;
 }
 
+static gboolean
+kate_streamheader_to_codecdata (const GValue * streamheader,
+    GstMatroskaTrackContext * context)
+{
+  GstBuffer *buf0 = NULL;
+
+  if (!xiphN_streamheader_to_codecdata (streamheader, context, &buf0, -1))
+    return FALSE;
+
+  if (buf0 == NULL || GST_BUFFER_SIZE (buf0) < 64) {    /* Kate ID header is 64 bytes */
+    GST_WARNING ("First kate header too small, ignoring");
+  } else if (memcmp (GST_BUFFER_DATA (buf0), "\200kate\0\0\0", 8) != 0) {
+    GST_WARNING ("First header not a kate identification header, ignoring");
+  }
+
+  if (buf0)
+    gst_buffer_unref (buf0);
+
+  return TRUE;
+}
+
 static gboolean
 flac_streamheader_to_codecdata (const GValue * streamheader,
     GstMatroskaTrackContext * context)
@@ -1538,6 +1666,57 @@ gst_matroska_mux_subtitle_pad_setcaps (GstPad * pad, GstCaps * caps)
    * no single subtitle creation element in GStreamer,
    * neither do I know how subtitling works at all. */
 
+  /* There is now (at least) one such alement (kateenc), and I'm going
+     to handle it here and claim it works when it can be piped back
+     through GStreamer and VLC */
+
+  GstMatroskaTrackContext *context = NULL;
+  GstMatroskaTrackSubtitleContext *scontext;
+  GstMatroskaMux *mux;
+  GstMatroskaPad *collect_pad;
+  const gchar *mimetype;
+  GstStructure *structure;
+
+  mux = GST_MATROSKA_MUX (GST_PAD_PARENT (pad));
+
+  /* find context */
+  collect_pad = (GstMatroskaPad *) gst_pad_get_element_private (pad);
+  g_assert (collect_pad);
+  context = collect_pad->track;
+  g_assert (context);
+  g_assert (context->type == GST_MATROSKA_TRACK_TYPE_SUBTITLE);
+  scontext = (GstMatroskaTrackSubtitleContext *) context;
+
+  structure = gst_caps_get_structure (caps, 0);
+  mimetype = gst_structure_get_name (structure);
+
+  /* general setup */
+  scontext->check_utf8 = 1;
+  scontext->invalid_utf8 = 0;
+  context->default_duration = 0;
+
+  /* TODO: - other format than Kate */
+
+  if (!strcmp (mimetype, "subtitle/x-kate")) {
+    const GValue *streamheader;
+
+    context->codec_id = g_strdup (GST_MATROSKA_CODEC_ID_SUBTITLE_KATE);
+
+    if (context->codec_priv != NULL) {
+      g_free (context->codec_priv);
+      context->codec_priv = NULL;
+      context->codec_priv_size = 0;
+    }
+
+    streamheader = gst_structure_get_value (structure, "streamheader");
+    if (!kate_streamheader_to_codecdata (streamheader, context)) {
+      GST_ELEMENT_ERROR (mux, STREAM, MUX, (NULL),
+          ("kate stream headers missing or malformed"));
+      return FALSE;
+    }
+    return TRUE;
+  }
+
   return FALSE;
 }