gst/subparse/gstssaparse.c - mtk-gst-plugins-base - Git at Google

 /* GStreamer SSA subtitle parser
  * Copyright (c) 2006 Tim-Philipp Müller <tim centricular net>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library 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
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public
  * License along with this library; if not, write to the
  * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */

 /* Super-primitive SSA parser - we just want the text and ignore
  * everything else like styles and timing codes etc. for now */

 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif

 #include <stdlib.h>             /* atoi() */
 #include <string.h>

 #include "gstssaparse.h"

 GST_DEBUG_CATEGORY_STATIC (ssa_parse_debug);
 #define GST_CAT_DEFAULT ssa_parse_debug

 static GstStaticPadTemplate sink_templ = GST_STATIC_PAD_TEMPLATE ("sink",
     GST_PAD_SINK,
     GST_PAD_ALWAYS,
     GST_STATIC_CAPS ("application/x-ssa; application/x-ass")
     );

 static GstStaticPadTemplate src_templ = GST_STATIC_PAD_TEMPLATE ("src",
     GST_PAD_SRC,
     GST_PAD_ALWAYS,
     GST_STATIC_CAPS ("text/x-raw, format=pango-markup")
     );

 #define gst_ssa_parse_parent_class parent_class
 G_DEFINE_TYPE (GstSsaParse, gst_ssa_parse, GST_TYPE_ELEMENT);

 static GstStateChangeReturn gst_ssa_parse_change_state (GstElement *
     element, GstStateChange transition);
 static gboolean gst_ssa_parse_setcaps (GstPad * sinkpad, GstCaps * caps);
 static gboolean gst_ssa_parse_src_event (GstPad * pad, GstObject * parent,
     GstEvent * event);
 static gboolean gst_ssa_parse_sink_event (GstPad * pad, GstObject * parent,
     GstEvent * event);
 static GstFlowReturn gst_ssa_parse_chain (GstPad * sinkpad, GstObject * parent,
     GstBuffer * buf);

 static void
 gst_ssa_parse_dispose (GObject * object)
 {
   GstSsaParse *parse = GST_SSA_PARSE (object);

   g_free (parse->ini);
   parse->ini = NULL;

   GST_CALL_PARENT (G_OBJECT_CLASS, dispose, (object));
 }

 static void
 gst_ssa_parse_init (GstSsaParse * parse)
 {
   parse->sinkpad = gst_pad_new_from_static_template (&sink_templ, "sink");
   gst_pad_set_chain_function (parse->sinkpad,
       GST_DEBUG_FUNCPTR (gst_ssa_parse_chain));
   gst_pad_set_event_function (parse->sinkpad,
       GST_DEBUG_FUNCPTR (gst_ssa_parse_sink_event));
   gst_element_add_pad (GST_ELEMENT (parse), parse->sinkpad);

   parse->srcpad = gst_pad_new_from_static_template (&src_templ, "src");
   gst_pad_set_event_function (parse->srcpad,
       GST_DEBUG_FUNCPTR (gst_ssa_parse_src_event));
   gst_element_add_pad (GST_ELEMENT (parse), parse->srcpad);
   gst_pad_use_fixed_caps (parse->srcpad);

   parse->ini = NULL;
   parse->framed = FALSE;
   parse->send_tags = FALSE;
 }

 static void
 gst_ssa_parse_class_init (GstSsaParseClass * klass)
 {
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
   GstElementClass *element_class = GST_ELEMENT_CLASS (klass);

   object_class->dispose = gst_ssa_parse_dispose;

   gst_element_class_add_static_pad_template (element_class, &sink_templ);
   gst_element_class_add_static_pad_template (element_class, &src_templ);
   gst_element_class_set_static_metadata (element_class,
       "SSA Subtitle Parser", "Codec/Parser/Subtitle",
       "Parses SSA subtitle streams",
       "Tim-Philipp Müller <tim centricular net>");

   GST_DEBUG_CATEGORY_INIT (ssa_parse_debug, "ssaparse", 0,
       "SSA subtitle parser");

   element_class->change_state = GST_DEBUG_FUNCPTR (gst_ssa_parse_change_state);
 }

 static gboolean
 gst_ssa_parse_src_event (GstPad * pad, GstObject * parent, GstEvent * event)
 {
   return gst_pad_event_default (pad, parent, event);
 }

 static gboolean
 gst_ssa_parse_sink_event (GstPad * pad, GstObject * parent, GstEvent * event)
 {
   gboolean res;

   switch (GST_EVENT_TYPE (event)) {
     case GST_EVENT_CAPS:
     {
       GstCaps *caps;

       gst_event_parse_caps (event, &caps);
       res = gst_ssa_parse_setcaps (pad, caps);
       gst_event_unref (event);
       break;
     }
     default:
       res = gst_pad_event_default (pad, parent, event);
       break;
   }
   return res;
 }

 static gboolean
 gst_ssa_parse_setcaps (GstPad * sinkpad, GstCaps * caps)
 {
   GstSsaParse *parse = GST_SSA_PARSE (GST_PAD_PARENT (sinkpad));
   GstCaps *outcaps;
   const GValue *val;
   GstStructure *s;
   const guchar bom_utf8[] = { 0xEF, 0xBB, 0xBF };
   const gchar *end;
   GstBuffer *priv;
   GstMapInfo map;
   gchar *ptr;
   gsize left, bad_offset;
   gboolean ret;

   s = gst_caps_get_structure (caps, 0);
   val = gst_structure_get_value (s, "codec_data");
   if (val == NULL) {
     parse->framed = FALSE;
     GST_ERROR ("Only SSA subtitles embedded in containers are supported");
     return FALSE;
   }

   parse->framed = TRUE;
   parse->send_tags = TRUE;

   priv = (GstBuffer *) g_value_get_boxed (val);
   g_return_val_if_fail (priv != NULL, FALSE);

   gst_buffer_ref (priv);

   if (!gst_buffer_map (priv, &map, GST_MAP_READ)) {
     gst_buffer_unref (priv);
     return FALSE;
   }

   GST_MEMDUMP_OBJECT (parse, "init section", map.data, map.size);

   ptr = (gchar *) map.data;
   left = map.size;

   /* skip UTF-8 BOM */
   if (left >= 3 && memcmp (ptr, bom_utf8, 3) == 0) {
     ptr += 3;
     left -= 3;
   }

   if (!strstr (ptr, "[Script Info]"))
     goto invalid_init;

   if (!g_utf8_validate (ptr, left, &end)) {
     bad_offset = (gsize) (end - ptr);
     GST_WARNING_OBJECT (parse, "Init section is not valid UTF-8. Problem at "
         "byte offset %" G_GSIZE_FORMAT, bad_offset);
     /* continue with valid UTF-8 data */
     left = bad_offset;
   }

   /* FIXME: parse initial section */
   if (parse->ini)
     g_free (parse->ini);
   parse->ini = g_strndup (ptr, left);
   GST_LOG_OBJECT (parse, "Init section:\n%s", parse->ini);

   gst_buffer_unmap (priv, &map);
   gst_buffer_unref (priv);

   outcaps = gst_caps_new_simple ("text/x-raw",
       "format", G_TYPE_STRING, "pango-markup", NULL);

   ret = gst_pad_set_caps (parse->srcpad, outcaps);
   gst_caps_unref (outcaps);

   return ret;

   /* ERRORS */
 invalid_init:
   {
     GST_WARNING_OBJECT (parse, "Invalid Init section - no Script Info header");
     gst_buffer_unmap (priv, &map);
     gst_buffer_unref (priv);
     return FALSE;
   }
 }

 static gboolean
 gst_ssa_parse_remove_override_codes (GstSsaParse * parse, gchar * txt)
 {
   gchar *t, *end;
   gboolean removed_any = FALSE;

   while ((t = strchr (txt, '{'))) {
     end = strchr (txt, '}');
     if (end == NULL) {
       GST_WARNING_OBJECT (parse, "Missing { for style override code");
       return removed_any;
     }
     /* move terminating NUL character forward as well */
     memmove (t, end + 1, strlen (end + 1) + 1);
     removed_any = TRUE;
   }

   /* these may occur outside of curly brackets. We don't handle the different
    * wrapping modes yet, so just remove these markers from the text for now */
   while ((t = strstr (txt, "\\n"))) {
     t[0] = ' ';
     t[1] = '\n';
   }
   while ((t = strstr (txt, "\\N"))) {
     t[0] = ' ';
     t[1] = '\n';
   }
   while ((t = strstr (txt, "\\h"))) {
     t[0] = ' ';
     t[1] = ' ';
   }

   return removed_any;
 }

 /**
  * gst_ssa_parse_push_line:
  * @parse: caller element
  * @txt: text to push
  * @start: timestamp for the buffer
  * @duration: duration for the buffer
  *
  * Parse the text in a buffer with the given properties and
  * push it to the srcpad of the @parse element
  *
  * Returns: result of the push of the created buffer
  */
 static GstFlowReturn
 gst_ssa_parse_push_line (GstSsaParse * parse, gchar * txt,
     GstClockTime start, GstClockTime duration)
 {
   GstFlowReturn ret;
   GstBuffer *buf;
   gchar *t, *escaped;
   gint num, i, len;

   num = atoi (txt);
   GST_LOG_OBJECT (parse, "Parsing line #%d at %" GST_TIME_FORMAT,
       num, GST_TIME_ARGS (start));

   /* skip all non-text fields before the actual text */
   t = txt;
   for (i = 0; i < 8; ++i) {
     t = strchr (t, ',');
     if (t == NULL)
       return GST_FLOW_ERROR;
     ++t;
   }

   GST_LOG_OBJECT (parse, "Text : %s", t);

   if (gst_ssa_parse_remove_override_codes (parse, t)) {
     GST_LOG_OBJECT (parse, "Clean: %s", t);
   }

   /* we claim to output pango markup, so we must escape the
    * text even if we don't actually use any pango markup yet */
   escaped = g_markup_printf_escaped ("%s", t);

   len = strlen (escaped);

   /* allocate enough for a terminating NUL, but don't include it in buf size */
   buf = gst_buffer_new_and_alloc (len + 1);
   gst_buffer_fill (buf, 0, escaped, len + 1);
   gst_buffer_set_size (buf, len);
   g_free (escaped);

   GST_BUFFER_TIMESTAMP (buf) = start;
   GST_BUFFER_DURATION (buf) = duration;

   GST_LOG_OBJECT (parse, "Pushing buffer with timestamp %" GST_TIME_FORMAT
       " and duration %" GST_TIME_FORMAT, GST_TIME_ARGS (start),
       GST_TIME_ARGS (duration));

   ret = gst_pad_push (parse->srcpad, buf);

   if (ret != GST_FLOW_OK) {
     GST_DEBUG_OBJECT (parse, "Push of text '%s' returned flow %s", txt,
         gst_flow_get_name (ret));
   }

   return ret;
 }

 static GstFlowReturn
 gst_ssa_parse_chain (GstPad * sinkpad, GstObject * parent, GstBuffer * buf)
 {
   GstFlowReturn ret;
   GstSsaParse *parse = GST_SSA_PARSE (parent);
   GstClockTime ts;
   gchar *txt;
   GstMapInfo map;

   if (G_UNLIKELY (!parse->framed))
     goto not_framed;

   if (G_UNLIKELY (parse->send_tags)) {
     GstTagList *tags;

     tags = gst_tag_list_new_empty ();
     gst_tag_list_add (tags, GST_TAG_MERGE_APPEND, GST_TAG_SUBTITLE_CODEC,
         "SubStation Alpha", NULL);
     gst_pad_push_event (parse->srcpad, gst_event_new_tag (tags));
     parse->send_tags = FALSE;
   }

   /* make double-sure it's 0-terminated and all */
   gst_buffer_map (buf, &map, GST_MAP_READ);
   txt = g_strndup ((gchar *) map.data, map.size);
   gst_buffer_unmap (buf, &map);

   if (txt == NULL)
     goto empty_text;

   ts = GST_BUFFER_TIMESTAMP (buf);
   ret = gst_ssa_parse_push_line (parse, txt, ts, GST_BUFFER_DURATION (buf));

   if (ret != GST_FLOW_OK && GST_CLOCK_TIME_IS_VALID (ts)) {
     GstSegment segment;

     /* just advance time without sending anything */
     gst_segment_init (&segment, GST_FORMAT_TIME);
     segment.start = ts;
     segment.time = ts;
     gst_pad_push_event (parse->srcpad, gst_event_new_segment (&segment));
     ret = GST_FLOW_OK;
   }

   gst_buffer_unref (buf);
   g_free (txt);

   return ret;

 /* ERRORS */
 not_framed:
   {
     GST_ELEMENT_ERROR (parse, STREAM, FORMAT, (NULL),
         ("Only SSA subtitles embedded in containers are supported"));
     gst_buffer_unref (buf);
     return GST_FLOW_NOT_NEGOTIATED;
   }
 empty_text:
   {
     GST_ELEMENT_WARNING (parse, STREAM, FORMAT, (NULL),
         ("Received empty subtitle"));
     gst_buffer_unref (buf);
     return GST_FLOW_OK;
   }
 }

 static GstStateChangeReturn
 gst_ssa_parse_change_state (GstElement * element, GstStateChange transition)
 {
   GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
   GstSsaParse *parse = GST_SSA_PARSE (element);

   switch (transition) {
     case GST_STATE_CHANGE_READY_TO_PAUSED:
       break;
     default:
       break;
   }

   ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
   if (ret == GST_STATE_CHANGE_FAILURE)
     return ret;

   switch (transition) {
     case GST_STATE_CHANGE_PAUSED_TO_READY:
       g_free (parse->ini);
       parse->ini = NULL;
       parse->framed = FALSE;
       break;
     default:
       break;
   }

   return ret;
 }
	/* GStreamer SSA subtitle parser
	* Copyright (c) 2006 Tim-Philipp Müller <tim centricular net>
	*
	* This library is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Library General Public
	* License as published by the Free Software Foundation; either
	* version 2 of the License, or (at your option) any later version.
	*
	* This library 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
	* Library General Public License for more details.
	*
	* You should have received a copy of the GNU Library General Public
	* License along with this library; if not, write to the
	* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
	* Boston, MA 02110-1301, USA.
	*/

	/* Super-primitive SSA parser - we just want the text and ignore
	* everything else like styles and timing codes etc. for now */

	#ifdef HAVE_CONFIG_H
	#include "config.h"
	#endif

	#include <stdlib.h> /* atoi() */
	#include <string.h>

	#include "gstssaparse.h"

	GST_DEBUG_CATEGORY_STATIC (ssa_parse_debug);
	#define GST_CAT_DEFAULT ssa_parse_debug

	static GstStaticPadTemplate sink_templ = GST_STATIC_PAD_TEMPLATE ("sink",
	GST_PAD_SINK,
	GST_PAD_ALWAYS,
	GST_STATIC_CAPS ("application/x-ssa; application/x-ass")
	);

	static GstStaticPadTemplate src_templ = GST_STATIC_PAD_TEMPLATE ("src",
	GST_PAD_SRC,
	GST_PAD_ALWAYS,
	GST_STATIC_CAPS ("text/x-raw, format=pango-markup")
	);

	#define gst_ssa_parse_parent_class parent_class
	G_DEFINE_TYPE (GstSsaParse, gst_ssa_parse, GST_TYPE_ELEMENT);

	static GstStateChangeReturn gst_ssa_parse_change_state (GstElement *
	element, GstStateChange transition);
	static gboolean gst_ssa_parse_setcaps (GstPad * sinkpad, GstCaps * caps);
	static gboolean gst_ssa_parse_src_event (GstPad * pad, GstObject * parent,
	GstEvent * event);
	static gboolean gst_ssa_parse_sink_event (GstPad * pad, GstObject * parent,
	GstEvent * event);
	static GstFlowReturn gst_ssa_parse_chain (GstPad * sinkpad, GstObject * parent,
	GstBuffer * buf);

	static void
	gst_ssa_parse_dispose (GObject * object)
	{
	GstSsaParse *parse = GST_SSA_PARSE (object);

	g_free (parse->ini);
	parse->ini = NULL;

	GST_CALL_PARENT (G_OBJECT_CLASS, dispose, (object));
	}

	static void
	gst_ssa_parse_init (GstSsaParse * parse)
	{
	parse->sinkpad = gst_pad_new_from_static_template (&sink_templ, "sink");
	gst_pad_set_chain_function (parse->sinkpad,
	GST_DEBUG_FUNCPTR (gst_ssa_parse_chain));
	gst_pad_set_event_function (parse->sinkpad,
	GST_DEBUG_FUNCPTR (gst_ssa_parse_sink_event));
	gst_element_add_pad (GST_ELEMENT (parse), parse->sinkpad);

	parse->srcpad = gst_pad_new_from_static_template (&src_templ, "src");
	gst_pad_set_event_function (parse->srcpad,
	GST_DEBUG_FUNCPTR (gst_ssa_parse_src_event));
	gst_element_add_pad (GST_ELEMENT (parse), parse->srcpad);
	gst_pad_use_fixed_caps (parse->srcpad);

	parse->ini = NULL;
	parse->framed = FALSE;
	parse->send_tags = FALSE;
	}

	static void
	gst_ssa_parse_class_init (GstSsaParseClass * klass)
	{
	GObjectClass *object_class = G_OBJECT_CLASS (klass);
	GstElementClass *element_class = GST_ELEMENT_CLASS (klass);

	object_class->dispose = gst_ssa_parse_dispose;

	gst_element_class_add_static_pad_template (element_class, &sink_templ);
	gst_element_class_add_static_pad_template (element_class, &src_templ);
	gst_element_class_set_static_metadata (element_class,
	"SSA Subtitle Parser", "Codec/Parser/Subtitle",
	"Parses SSA subtitle streams",
	"Tim-Philipp Müller <tim centricular net>");

	GST_DEBUG_CATEGORY_INIT (ssa_parse_debug, "ssaparse", 0,
	"SSA subtitle parser");

	element_class->change_state = GST_DEBUG_FUNCPTR (gst_ssa_parse_change_state);
	}

	static gboolean
	gst_ssa_parse_src_event (GstPad * pad, GstObject * parent, GstEvent * event)
	{
	return gst_pad_event_default (pad, parent, event);
	}

	static gboolean
	gst_ssa_parse_sink_event (GstPad * pad, GstObject * parent, GstEvent * event)
	{
	gboolean res;

	switch (GST_EVENT_TYPE (event)) {
	case GST_EVENT_CAPS:
	{
	GstCaps *caps;

	gst_event_parse_caps (event, &caps);
	res = gst_ssa_parse_setcaps (pad, caps);
	gst_event_unref (event);
	break;
	}
	default:
	res = gst_pad_event_default (pad, parent, event);
	break;
	}
	return res;
	}

	static gboolean
	gst_ssa_parse_setcaps (GstPad * sinkpad, GstCaps * caps)
	{
	GstSsaParse *parse = GST_SSA_PARSE (GST_PAD_PARENT (sinkpad));
	GstCaps *outcaps;
	const GValue *val;
	GstStructure *s;
	const guchar bom_utf8[] = { 0xEF, 0xBB, 0xBF };
	const gchar *end;
	GstBuffer *priv;
	GstMapInfo map;
	gchar *ptr;
	gsize left, bad_offset;
	gboolean ret;

	s = gst_caps_get_structure (caps, 0);
	val = gst_structure_get_value (s, "codec_data");
	if (val == NULL) {
	parse->framed = FALSE;
	GST_ERROR ("Only SSA subtitles embedded in containers are supported");
	return FALSE;
	}

	parse->framed = TRUE;
	parse->send_tags = TRUE;

	priv = (GstBuffer *) g_value_get_boxed (val);
	g_return_val_if_fail (priv != NULL, FALSE);

	gst_buffer_ref (priv);

	if (!gst_buffer_map (priv, &map, GST_MAP_READ)) {
	gst_buffer_unref (priv);
	return FALSE;
	}

	GST_MEMDUMP_OBJECT (parse, "init section", map.data, map.size);

	ptr = (gchar *) map.data;
	left = map.size;

	/* skip UTF-8 BOM */
	if (left >= 3 && memcmp (ptr, bom_utf8, 3) == 0) {
	ptr += 3;
	left -= 3;
	}

	if (!strstr (ptr, "[Script Info]"))
	goto invalid_init;

	if (!g_utf8_validate (ptr, left, &end)) {
	bad_offset = (gsize) (end - ptr);
	GST_WARNING_OBJECT (parse, "Init section is not valid UTF-8. Problem at "
	"byte offset %" G_GSIZE_FORMAT, bad_offset);
	/* continue with valid UTF-8 data */
	left = bad_offset;
	}

	/* FIXME: parse initial section */
	if (parse->ini)
	g_free (parse->ini);
	parse->ini = g_strndup (ptr, left);
	GST_LOG_OBJECT (parse, "Init section:\n%s", parse->ini);

	gst_buffer_unmap (priv, &map);
	gst_buffer_unref (priv);

	outcaps = gst_caps_new_simple ("text/x-raw",
	"format", G_TYPE_STRING, "pango-markup", NULL);

	ret = gst_pad_set_caps (parse->srcpad, outcaps);
	gst_caps_unref (outcaps);

	return ret;

	/* ERRORS */
	invalid_init:
	{
	GST_WARNING_OBJECT (parse, "Invalid Init section - no Script Info header");
	gst_buffer_unmap (priv, &map);
	gst_buffer_unref (priv);
	return FALSE;
	}
	}

	static gboolean
	gst_ssa_parse_remove_override_codes (GstSsaParse * parse, gchar * txt)
	{
	gchar t, end;
	gboolean removed_any = FALSE;

	while ((t = strchr (txt, '{'))) {
	end = strchr (txt, '}');
	if (end == NULL) {
	GST_WARNING_OBJECT (parse, "Missing { for style override code");
	return removed_any;
	}
	/* move terminating NUL character forward as well */
	memmove (t, end + 1, strlen (end + 1) + 1);
	removed_any = TRUE;
	}

	/* these may occur outside of curly brackets. We don't handle the different
	* wrapping modes yet, so just remove these markers from the text for now */
	while ((t = strstr (txt, "\\n"))) {
	t[0] = ' ';
	t[1] = '\n';
	}
	while ((t = strstr (txt, "\\N"))) {
	t[0] = ' ';
	t[1] = '\n';
	}
	while ((t = strstr (txt, "\\h"))) {
	t[0] = ' ';
	t[1] = ' ';
	}

	return removed_any;
	}

	/**
	* gst_ssa_parse_push_line:
	* @parse: caller element
	* @txt: text to push
	* @start: timestamp for the buffer
	* @duration: duration for the buffer
	*
	* Parse the text in a buffer with the given properties and
	* push it to the srcpad of the @parse element
	*
	* Returns: result of the push of the created buffer
	*/
	static GstFlowReturn
	gst_ssa_parse_push_line (GstSsaParse * parse, gchar * txt,
	GstClockTime start, GstClockTime duration)
	{
	GstFlowReturn ret;
	GstBuffer *buf;
	gchar t, escaped;
	gint num, i, len;

	num = atoi (txt);
	GST_LOG_OBJECT (parse, "Parsing line #%d at %" GST_TIME_FORMAT,
	num, GST_TIME_ARGS (start));

	/* skip all non-text fields before the actual text */
	t = txt;
	for (i = 0; i < 8; ++i) {
	t = strchr (t, ',');
	if (t == NULL)
	return GST_FLOW_ERROR;
	++t;
	}

	GST_LOG_OBJECT (parse, "Text : %s", t);

	if (gst_ssa_parse_remove_override_codes (parse, t)) {
	GST_LOG_OBJECT (parse, "Clean: %s", t);
	}

	/* we claim to output pango markup, so we must escape the
	* text even if we don't actually use any pango markup yet */
	escaped = g_markup_printf_escaped ("%s", t);

	len = strlen (escaped);

	/* allocate enough for a terminating NUL, but don't include it in buf size */
	buf = gst_buffer_new_and_alloc (len + 1);
	gst_buffer_fill (buf, 0, escaped, len + 1);
	gst_buffer_set_size (buf, len);
	g_free (escaped);

	GST_BUFFER_TIMESTAMP (buf) = start;
	GST_BUFFER_DURATION (buf) = duration;

	GST_LOG_OBJECT (parse, "Pushing buffer with timestamp %" GST_TIME_FORMAT
	" and duration %" GST_TIME_FORMAT, GST_TIME_ARGS (start),
	GST_TIME_ARGS (duration));

	ret = gst_pad_push (parse->srcpad, buf);

	if (ret != GST_FLOW_OK) {
	GST_DEBUG_OBJECT (parse, "Push of text '%s' returned flow %s", txt,
	gst_flow_get_name (ret));
	}

	return ret;
	}

	static GstFlowReturn
	gst_ssa_parse_chain (GstPad * sinkpad, GstObject * parent, GstBuffer * buf)
	{
	GstFlowReturn ret;
	GstSsaParse *parse = GST_SSA_PARSE (parent);
	GstClockTime ts;
	gchar *txt;
	GstMapInfo map;

	if (G_UNLIKELY (!parse->framed))
	goto not_framed;

	if (G_UNLIKELY (parse->send_tags)) {
	GstTagList *tags;

	tags = gst_tag_list_new_empty ();
	gst_tag_list_add (tags, GST_TAG_MERGE_APPEND, GST_TAG_SUBTITLE_CODEC,
	"SubStation Alpha", NULL);
	gst_pad_push_event (parse->srcpad, gst_event_new_tag (tags));
	parse->send_tags = FALSE;
	}

	/* make double-sure it's 0-terminated and all */
	gst_buffer_map (buf, &map, GST_MAP_READ);
	txt = g_strndup ((gchar *) map.data, map.size);
	gst_buffer_unmap (buf, &map);

	if (txt == NULL)
	goto empty_text;

	ts = GST_BUFFER_TIMESTAMP (buf);
	ret = gst_ssa_parse_push_line (parse, txt, ts, GST_BUFFER_DURATION (buf));

	if (ret != GST_FLOW_OK && GST_CLOCK_TIME_IS_VALID (ts)) {
	GstSegment segment;

	/* just advance time without sending anything */
	gst_segment_init (&segment, GST_FORMAT_TIME);
	segment.start = ts;
	segment.time = ts;
	gst_pad_push_event (parse->srcpad, gst_event_new_segment (&segment));
	ret = GST_FLOW_OK;
	}

	gst_buffer_unref (buf);
	g_free (txt);

	return ret;

	/* ERRORS */
	not_framed:
	{
	GST_ELEMENT_ERROR (parse, STREAM, FORMAT, (NULL),
	("Only SSA subtitles embedded in containers are supported"));
	gst_buffer_unref (buf);
	return GST_FLOW_NOT_NEGOTIATED;
	}
	empty_text:
	{
	GST_ELEMENT_WARNING (parse, STREAM, FORMAT, (NULL),
	("Received empty subtitle"));
	gst_buffer_unref (buf);
	return GST_FLOW_OK;
	}
	}

	static GstStateChangeReturn
	gst_ssa_parse_change_state (GstElement * element, GstStateChange transition)
	{
	GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
	GstSsaParse *parse = GST_SSA_PARSE (element);

	switch (transition) {
	case GST_STATE_CHANGE_READY_TO_PAUSED:
	break;
	default:
	break;
	}

	ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
	if (ret == GST_STATE_CHANGE_FAILURE)
	return ret;

	switch (transition) {
	case GST_STATE_CHANGE_PAUSED_TO_READY:
	g_free (parse->ini);
	parse->ini = NULL;
	parse->framed = FALSE;
	break;
	default:
	break;
	}

	return ret;
	}