gstreamer/ext/ttml/gstttmlparse.c

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/* GStreamer
* Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
* Copyright (C) 2004 Ronald S. Bultje <rbultje@ronald.bitfreak.net>
* Copyright (C) 2006 Tim-Philipp Müller <tim centricular net>
* Copyright (C) <2015> British Broadcasting Corporation <dash@rd.bbc.co.uk>
*
* 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=<media file location> ! video/quicktime ! qtdemux name=q ttmlrender name=r q. ! queue ! h264parse ! avdec_h264 ! autovideoconvert ! r.video_sink filesrc location=<subtitle file 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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <glib.h>
#include "gstttmlparse.h"
#include "ttmlparse.h"
GST_DEBUG_CATEGORY_EXTERN (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);
#define gst_ttml_parse_parent_class parent_class
G_DEFINE_TYPE (GstTtmlParse, gst_ttml_parse, GST_TYPE_ELEMENT);
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/Parser/Subtitle",
"Parses TTML subtitle files",
"GStreamer maintainers <gstreamer-devel@lists.sourceforge.net>, "
"Chris Bass <dash@rd.bbc.co.uk>");
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 ("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;
}