/* GStreamer * Copyright (C) <1999> Erik Walthinsen * Copyright (C) 2004 Ronald S. Bultje * Copyright (C) 2006 Tim-Philipp Müller * Copyright (C) <2015> British Broadcasting Corporation * * 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. */ /** * SECTION:element-ttmlparse * @title: ttmlparse * * Parses timed text subtitle files described using Timed Text Markup Language * (TTML). Currently, only the EBU-TT-D profile of TTML, designed for * distribution of subtitles over IP, is supported. * * The parser outputs a #GstBuffer for each scene in the input TTML file, a * scene being a period of time during which a static set of subtitles should * be visible. The parser places each text element within a scene into its own * #GstMemory within the scene's buffer, and attaches metadata to the buffer * describing the styling and layout associated with all the contained text * elements. A downstream renderer element uses this information to correctly * render the text on top of video frames. * * ## Example launch lines * |[ * gst-launch-1.0 filesrc location= ! video/quicktime ! qtdemux name=q ttmlrender name=r q. ! queue ! h264parse ! avdec_h264 ! autovideoconvert ! r.video_sink filesrc location= blocksize=16777216 ! queue ! ttmlparse ! r.text_sink r. ! ximagesink q. ! queue ! aacparse ! avdec_aac ! audioconvert ! alsasink * ]| Parse and render TTML subtitles contained in a single XML file over an * MP4 stream containing H.264 video and AAC audio. * */ #include #include #include #include #include #include "gstttmlelements.h" #include "gstttmlparse.h" #include "ttmlparse.h" GST_DEBUG_CATEGORY (ttmlparse_debug); #define GST_CAT_DEFAULT ttmlparse_debug #define DEFAULT_ENCODING NULL static GstStaticPadTemplate sink_templ = GST_STATIC_PAD_TEMPLATE ("sink", GST_PAD_SINK, GST_PAD_ALWAYS, GST_STATIC_CAPS ("application/ttml+xml") ); static GstStaticPadTemplate src_templ = GST_STATIC_PAD_TEMPLATE ("src", GST_PAD_SRC, GST_PAD_ALWAYS, GST_STATIC_CAPS ("text/x-raw(meta:GstSubtitleMeta)") ); static gboolean gst_ttml_parse_src_event (GstPad * pad, GstObject * parent, GstEvent * event); static gboolean gst_ttml_parse_src_query (GstPad * pad, GstObject * parent, GstQuery * query); static gboolean gst_ttml_parse_sink_event (GstPad * pad, GstObject * parent, GstEvent * event); static GstStateChangeReturn gst_ttml_parse_change_state (GstElement * element, GstStateChange transition); static GstFlowReturn gst_ttml_parse_chain (GstPad * sinkpad, GstObject * parent, GstBuffer * buf); static gboolean gst_element_ttmlparse_init (GstPlugin * plugin); #define gst_ttml_parse_parent_class parent_class G_DEFINE_TYPE (GstTtmlParse, gst_ttml_parse, GST_TYPE_ELEMENT); GST_ELEMENT_REGISTER_DEFINE_CUSTOM (ttmlparse, gst_element_ttmlparse_init); static void gst_ttml_parse_dispose (GObject * object) { GstTtmlParse *ttmlparse = GST_TTML_PARSE (object); GST_DEBUG_OBJECT (ttmlparse, "cleaning up subtitle parser"); g_free (ttmlparse->encoding); ttmlparse->encoding = NULL; g_free (ttmlparse->detected_encoding); ttmlparse->detected_encoding = NULL; if (ttmlparse->adapter) { g_object_unref (ttmlparse->adapter); ttmlparse->adapter = NULL; } if (ttmlparse->textbuf) { g_string_free (ttmlparse->textbuf, TRUE); ttmlparse->textbuf = NULL; } GST_CALL_PARENT (G_OBJECT_CLASS, dispose, (object)); } static void gst_ttml_parse_class_init (GstTtmlParseClass * klass) { GObjectClass *object_class = G_OBJECT_CLASS (klass); GstElementClass *element_class = GST_ELEMENT_CLASS (klass); object_class->dispose = gst_ttml_parse_dispose; gst_element_class_add_pad_template (element_class, gst_static_pad_template_get (&sink_templ)); gst_element_class_add_pad_template (element_class, gst_static_pad_template_get (&src_templ)); gst_element_class_set_static_metadata (element_class, "TTML subtitle parser", "Codec/Decoder/Subtitle", "Parses TTML subtitle files", "GStreamer maintainers , " "Chris Bass "); element_class->change_state = gst_ttml_parse_change_state; } static void gst_ttml_parse_init (GstTtmlParse * ttmlparse) { ttmlparse->sinkpad = gst_pad_new_from_static_template (&sink_templ, "sink"); gst_pad_set_chain_function (ttmlparse->sinkpad, GST_DEBUG_FUNCPTR (gst_ttml_parse_chain)); gst_pad_set_event_function (ttmlparse->sinkpad, GST_DEBUG_FUNCPTR (gst_ttml_parse_sink_event)); gst_element_add_pad (GST_ELEMENT (ttmlparse), ttmlparse->sinkpad); ttmlparse->srcpad = gst_pad_new_from_static_template (&src_templ, "src"); gst_pad_set_event_function (ttmlparse->srcpad, GST_DEBUG_FUNCPTR (gst_ttml_parse_src_event)); gst_pad_set_query_function (ttmlparse->srcpad, GST_DEBUG_FUNCPTR (gst_ttml_parse_src_query)); gst_element_add_pad (GST_ELEMENT (ttmlparse), ttmlparse->srcpad); ttmlparse->textbuf = g_string_new (NULL); gst_segment_init (&ttmlparse->segment, GST_FORMAT_TIME); ttmlparse->need_segment = TRUE; ttmlparse->encoding = g_strdup (DEFAULT_ENCODING); ttmlparse->detected_encoding = NULL; ttmlparse->adapter = gst_adapter_new (); } /* * Source pad functions. */ static gboolean gst_ttml_parse_src_query (GstPad * pad, GstObject * parent, GstQuery * query) { GstTtmlParse *self = GST_TTML_PARSE (parent); gboolean ret = FALSE; GST_DEBUG ("Handling %s query", GST_QUERY_TYPE_NAME (query)); switch (GST_QUERY_TYPE (query)) { case GST_QUERY_POSITION:{ GstFormat fmt; gst_query_parse_position (query, &fmt, NULL); if (fmt != GST_FORMAT_TIME) { ret = gst_pad_peer_query (self->sinkpad, query); } else { ret = TRUE; gst_query_set_position (query, GST_FORMAT_TIME, self->segment.position); } break; } case GST_QUERY_SEEKING: { GstFormat fmt; gboolean seekable = FALSE; ret = TRUE; gst_query_parse_seeking (query, &fmt, NULL, NULL, NULL); if (fmt == GST_FORMAT_TIME) { GstQuery *peerquery = gst_query_new_seeking (GST_FORMAT_BYTES); seekable = gst_pad_peer_query (self->sinkpad, peerquery); if (seekable) gst_query_parse_seeking (peerquery, NULL, &seekable, NULL, NULL); gst_query_unref (peerquery); } gst_query_set_seeking (query, fmt, seekable, seekable ? 0 : -1, -1); break; } default: ret = gst_pad_query_default (pad, parent, query); break; } return ret; } static gboolean gst_ttml_parse_src_event (GstPad * pad, GstObject * parent, GstEvent * event) { GstTtmlParse *self = GST_TTML_PARSE (parent); gboolean ret = FALSE; GST_DEBUG ("Handling %s event", GST_EVENT_TYPE_NAME (event)); switch (GST_EVENT_TYPE (event)) { case GST_EVENT_SEEK: { GstFormat format; GstSeekFlags flags; GstSeekType start_type, stop_type; gint64 start, stop; gdouble rate; gboolean update; gst_event_parse_seek (event, &rate, &format, &flags, &start_type, &start, &stop_type, &stop); if (format != GST_FORMAT_TIME) { GST_WARNING_OBJECT (self, "we only support seeking in TIME format"); gst_event_unref (event); goto beach; } /* Convert that seek to a seeking in bytes at position 0, FIXME: could use an index */ ret = gst_pad_push_event (self->sinkpad, gst_event_new_seek (rate, GST_FORMAT_BYTES, flags, GST_SEEK_TYPE_SET, 0, GST_SEEK_TYPE_NONE, 0)); if (ret) { /* Apply the seek to our segment */ gst_segment_do_seek (&self->segment, rate, format, flags, start_type, start, stop_type, stop, &update); GST_DEBUG_OBJECT (self, "segment after seek: %" GST_SEGMENT_FORMAT, &self->segment); self->need_segment = TRUE; } else { GST_WARNING_OBJECT (self, "seek to 0 bytes failed"); } gst_event_unref (event); break; } default: ret = gst_pad_event_default (pad, parent, event); break; } beach: return ret; } static gchar * gst_convert_to_utf8 (const gchar * str, gsize len, const gchar * encoding, gsize * consumed, GError ** err) { gchar *ret = NULL; *consumed = 0; /* The char cast is necessary in glib < 2.24 */ ret = g_convert_with_fallback (str, len, "UTF-8", encoding, (char *) "*", consumed, NULL, err); if (ret == NULL) return ret; /* + 3 to skip UTF-8 BOM if it was added */ len = strlen (ret); if (len >= 3 && (guint8) ret[0] == 0xEF && (guint8) ret[1] == 0xBB && (guint8) ret[2] == 0xBF) memmove (ret, ret + 3, len + 1 - 3); return ret; } static gchar * detect_encoding (const gchar * str, gsize len) { if (len >= 3 && (guint8) str[0] == 0xEF && (guint8) str[1] == 0xBB && (guint8) str[2] == 0xBF) return g_strdup ("UTF-8"); if (len >= 2 && (guint8) str[0] == 0xFE && (guint8) str[1] == 0xFF) return g_strdup ("UTF-16BE"); if (len >= 2 && (guint8) str[0] == 0xFF && (guint8) str[1] == 0xFE) return g_strdup ("UTF-16LE"); if (len >= 4 && (guint8) str[0] == 0x00 && (guint8) str[1] == 0x00 && (guint8) str[2] == 0xFE && (guint8) str[3] == 0xFF) return g_strdup ("UTF-32BE"); if (len >= 4 && (guint8) str[0] == 0xFF && (guint8) str[1] == 0xFE && (guint8) str[2] == 0x00 && (guint8) str[3] == 0x00) return g_strdup ("UTF-32LE"); return NULL; } static gchar * convert_encoding (GstTtmlParse * self, const gchar * str, gsize len, gsize * consumed) { const gchar *encoding; GError *err = NULL; gchar *ret = NULL; *consumed = 0; /* First try any detected encoding */ if (self->detected_encoding) { ret = gst_convert_to_utf8 (str, len, self->detected_encoding, consumed, &err); if (!err) return ret; GST_WARNING_OBJECT (self, "could not convert string from '%s' to UTF-8: %s", self->detected_encoding, err->message); g_free (self->detected_encoding); self->detected_encoding = NULL; g_error_free (err); } /* Otherwise check if it's UTF8 */ if (self->valid_utf8) { if (g_utf8_validate (str, len, NULL)) { GST_LOG_OBJECT (self, "valid UTF-8, no conversion needed"); *consumed = len; return g_strndup (str, len); } GST_INFO_OBJECT (self, "invalid UTF-8!"); self->valid_utf8 = FALSE; } /* Else try fallback */ encoding = self->encoding; if (encoding == NULL || *encoding == '\0') { /* if local encoding is UTF-8 and no encoding specified * via the environment variable, assume ISO-8859-15 */ if (g_get_charset (&encoding)) { encoding = "ISO-8859-15"; } } ret = gst_convert_to_utf8 (str, len, encoding, consumed, &err); if (err) { GST_WARNING_OBJECT (self, "could not convert string from '%s' to UTF-8: %s", encoding, err->message); g_error_free (err); /* invalid input encoding, fall back to ISO-8859-15 (always succeeds) */ ret = gst_convert_to_utf8 (str, len, "ISO-8859-15", consumed, NULL); } GST_LOG_OBJECT (self, "successfully converted %" G_GSIZE_FORMAT " characters from %s to UTF-8" "%s", len, encoding, (err) ? " , using ISO-8859-15 as fallback" : ""); return ret; } static GstCaps * gst_ttml_parse_get_src_caps (GstTtmlParse * self) { GstCaps *caps; GstCapsFeatures *features = gst_caps_features_new_static_str ("meta:GstSubtitleMeta", NULL); caps = gst_caps_new_empty_simple ("text/x-raw"); gst_caps_set_features (caps, 0, features); return caps; } static void feed_textbuf (GstTtmlParse * self, GstBuffer * buf) { gboolean discont; gsize consumed; gchar *input = NULL; const guint8 *data; gsize avail; discont = GST_BUFFER_IS_DISCONT (buf); if (GST_BUFFER_OFFSET_IS_VALID (buf) && GST_BUFFER_OFFSET (buf) != self->offset) { self->offset = GST_BUFFER_OFFSET (buf); discont = TRUE; } if (discont) { GST_INFO ("discontinuity"); /* flush the parser state */ g_string_truncate (self->textbuf, 0); gst_adapter_clear (self->adapter); /* we could set a flag to make sure that the next buffer we push out also * has the DISCONT flag set, but there's no point really given that it's * subtitles which are discontinuous by nature. */ } self->offset += gst_buffer_get_size (buf); gst_adapter_push (self->adapter, buf); avail = gst_adapter_available (self->adapter); data = gst_adapter_map (self->adapter, avail); input = convert_encoding (self, (const gchar *) data, avail, &consumed); if (input && consumed > 0) { if (!self->textbuf) self->textbuf = g_string_new (input); else self->textbuf = g_string_append (self->textbuf, input); gst_adapter_unmap (self->adapter); gst_adapter_flush (self->adapter, consumed); } else { gst_adapter_unmap (self->adapter); } g_free (input); } static GstFlowReturn handle_buffer (GstTtmlParse * self, GstBuffer * buf) { GstFlowReturn ret = GST_FLOW_OK; GstCaps *caps = NULL; GList *subtitle_list = NULL; GList *iter; GstClockTime begin = GST_BUFFER_PTS (buf); GstClockTime duration = GST_BUFFER_DURATION (buf); guint consumed; if (self->first_buffer) { GstMapInfo map; gst_buffer_map (buf, &map, GST_MAP_READ); self->detected_encoding = detect_encoding ((gchar *) map.data, map.size); gst_buffer_unmap (buf, &map); self->first_buffer = FALSE; } feed_textbuf (self, buf); if (!(caps = gst_ttml_parse_get_src_caps (self))) return GST_FLOW_EOS; gst_caps_unref (caps); /* Push newsegment if needed */ if (self->need_segment) { GST_LOG_OBJECT (self, "pushing newsegment event with %" GST_SEGMENT_FORMAT, &self->segment); gst_pad_push_event (self->srcpad, gst_event_new_segment (&self->segment)); self->need_segment = FALSE; } do { consumed = ttml_parse (self->textbuf->str, begin, duration, &subtitle_list); if (!consumed) { GST_DEBUG_OBJECT (self, "need more data"); return ret; } self->textbuf = g_string_erase (self->textbuf, 0, consumed); for (iter = subtitle_list; iter; iter = g_list_next (iter)) { GstBuffer *op_buffer = GST_BUFFER (iter->data); self->segment.position = GST_BUFFER_PTS (op_buffer); ret = gst_pad_push (self->srcpad, op_buffer); if (ret != GST_FLOW_OK) { GST_DEBUG_OBJECT (self, "flow: %s", gst_flow_get_name (ret)); break; } } g_list_free (subtitle_list); } while (TRUE); return ret; } static GstFlowReturn gst_ttml_parse_chain (GstPad * sinkpad, GstObject * parent, GstBuffer * buf) { GstTtmlParse *self = GST_TTML_PARSE (parent); return handle_buffer (self, buf); } static gboolean gst_ttml_parse_sink_event (GstPad * pad, GstObject * parent, GstEvent * event) { GstTtmlParse *self = GST_TTML_PARSE (parent); gboolean ret = FALSE; GST_DEBUG ("Handling %s event", GST_EVENT_TYPE_NAME (event)); switch (GST_EVENT_TYPE (event)) { case GST_EVENT_SEGMENT: { const GstSegment *s; gst_event_parse_segment (event, &s); if (s->format == GST_FORMAT_TIME) gst_event_copy_segment (event, &self->segment); GST_DEBUG_OBJECT (self, "newsegment (%s)", gst_format_get_name (self->segment.format)); /* if not time format, we'll either start with a 0 timestamp anyway or * it's following a seek in which case we'll have saved the requested * seek segment and don't want to overwrite it (remember that on a seek * we always just seek back to the start in BYTES format and just throw * away all text that's before the requested position; if the subtitles * come from an upstream demuxer, it won't be able to handle our BYTES * seek request and instead send us a newsegment from the seek request * it received via its video pads instead, so all is fine then too) */ ret = TRUE; self->need_segment = TRUE; gst_event_unref (event); break; } case GST_EVENT_CAPS: { GstCaps *caps; gst_event_unref (event); caps = gst_ttml_parse_get_src_caps (self); event = gst_event_new_caps (caps); gst_caps_unref (caps); ret = gst_pad_push_event (self->srcpad, event); break; } default: ret = gst_pad_event_default (pad, parent, event); break; } return ret; } static GstStateChangeReturn gst_ttml_parse_change_state (GstElement * element, GstStateChange transition) { GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS; GstTtmlParse *self = GST_TTML_PARSE (element); switch (transition) { case GST_STATE_CHANGE_READY_TO_PAUSED: /* format detection will init the parser state */ self->offset = 0; self->valid_utf8 = TRUE; self->first_buffer = TRUE; g_free (self->detected_encoding); self->detected_encoding = NULL; g_string_truncate (self->textbuf, 0); gst_adapter_clear (self->adapter); 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: break; default: break; } return ret; } static gboolean gst_element_ttmlparse_init (GstPlugin * plugin) { guint rank = GST_RANK_NONE; ttml_element_init (plugin); GST_DEBUG_CATEGORY_INIT (ttmlparse_debug, "ttmlparse", 0, "TTML parser"); /* We don't want this autoplugged by default yet for now */ if (g_getenv ("GST_TTML_AUTOPLUG")) { GST_INFO_OBJECT (plugin, "Registering ttml elements with primary rank."); rank = GST_RANK_PRIMARY; } return gst_element_register (plugin, "ttmlparse", rank, GST_TYPE_TTML_PARSE); }