gstreamer/gst/avi/gstavisubtitle.c

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/* GStreamer AVI GAB2 subtitle parser
* Copyright (C) <2007> Thijs Vermeir <thijsvermeir@gmail.com>
* Copyright (C) <2007> 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., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/* FIXME: documentation */
/* example of a subtitle chunk in an avi file
* 00000000: 47 41 42 32 00 02 00 10 00 00 00 45 00 6e 00 67 GAB2.......E.n.g
* 00000010: 00 6c 00 69 00 73 00 68 00 00 00 04 00 8e 00 00 .l.i.s.h........
* 00000020: 00 ef bb bf 31 0d 0a 30 30 3a 30 30 3a 30 30 2c ....1..00:00:00,
* 00000030: 31 30 30 20 2d 2d 3e 20 30 30 3a 30 30 3a 30 32 100 --> 00:00:02
* 00000040: 2c 30 30 30 0d 0a 3c 62 3e 41 6e 20 55 54 46 38 ,000..<b>An UTF8
* 00000050: 20 53 75 62 74 69 74 6c 65 20 77 69 74 68 20 42 Subtitle with B
* 00000060: 4f 4d 3c 2f 62 3e 0d 0a 0d 0a 32 0d 0a 30 30 3a OM</b>....2..00:
* 00000070: 30 30 3a 30 32 2c 31 30 30 20 2d 2d 3e 20 30 30 00:02,100 --> 00
* 00000080: 3a 30 30 3a 30 34 2c 30 30 30 0d 0a 53 6f 6d 65 :00:04,000..Some
* 00000090: 74 68 69 6e 67 20 6e 6f 6e 41 53 43 49 49 20 2d thing nonASCII -
* 000000a0: 20 c2 b5 c3 b6 c3 a4 c3 bc c3 9f 0d 0a 0d 0a ..............
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <string.h>
#include "gstavisubtitle.h"
GST_DEBUG_CATEGORY_STATIC (avisubtitle_debug);
#define GST_CAT_DEFAULT avisubtitle_debug
static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
GST_PAD_SINK,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("application/x-subtitle-avi")
);
static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
GST_PAD_SRC,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("application/x-subtitle")
);
static void gst_avi_subtitle_title_tag (GstAviSubtitle * sub, gchar * title);
static GstFlowReturn gst_avi_subtitle_chain (GstPad * pad, GstBuffer * buffer);
static GstStateChangeReturn gst_avi_subtitle_change_state (GstElement * element,
GstStateChange transition);
static gboolean gst_avi_subtitle_send_event (GstElement * element,
GstEvent * event);
GST_BOILERPLATE (GstAviSubtitle, gst_avi_subtitle, GstElement,
GST_TYPE_ELEMENT);
#define IS_BOM_UTF8(data) ((GST_READ_UINT32_BE(data) >> 8) == 0xEFBBBF)
#define IS_BOM_UTF16_BE(data) (GST_READ_UINT16_BE(data) == 0xFEFF)
#define IS_BOM_UTF16_LE(data) (GST_READ_UINT16_LE(data) == 0xFEFF)
#define IS_BOM_UTF32_BE(data) (GST_READ_UINT32_BE(data) == 0xFEFF)
#define IS_BOM_UTF32_LE(data) (GST_READ_UINT32_LE(data) == 0xFEFF)
static GstBuffer *
gst_avi_subtitle_extract_file (GstAviSubtitle * sub, GstBuffer * buffer,
guint offset, guint len)
{
const gchar *input_enc = NULL;
GstBuffer *ret;
gchar *data;
data = (gchar *) GST_BUFFER_DATA (buffer) + offset;
if (len >= (3 + 1) && IS_BOM_UTF8 (data) &&
g_utf8_validate (data + 3, len - 3, NULL)) {
ret = gst_buffer_create_sub (buffer, offset + 3, len - 3);
} else if (len >= 2 && IS_BOM_UTF16_BE (data)) {
input_enc = "UTF-16BE";
data += 2;
len -= 2;
} else if (len >= 2 && IS_BOM_UTF16_LE (data)) {
input_enc = "UTF-16LE";
data += 2;
len -= 2;
} else if (len >= 4 && IS_BOM_UTF32_BE (data)) {
input_enc = "UTF-32BE";
data += 4;
len -= 4;
} else if (len >= 4 && IS_BOM_UTF32_LE (data)) {
input_enc = "UTF-32LE";
data += 4;
len -= 4;
} else if (g_utf8_validate (data, len, NULL)) {
/* not specified, check if it's UTF-8 */
ret = gst_buffer_create_sub (buffer, offset, len);
} else {
/* we could fall back to gst_tag_freeform_to_utf8() here */
GST_WARNING_OBJECT (sub, "unspecified encoding, and not UTF-8");
return NULL;
}
if (input_enc) {
GError *err = NULL;
gchar *utf8;
GST_DEBUG_OBJECT (sub, "converting subtitles from %s to UTF-8", input_enc);
utf8 = g_convert (data, len, "UTF-8", input_enc, NULL, NULL, &err);
if (err != NULL) {
GST_WARNING_OBJECT (sub, "conversion to UTF-8 failed : %s", err->message);
g_error_free (err);
return NULL;
}
ret = gst_buffer_new ();
GST_BUFFER_DATA (ret) = (guint8 *) utf8;
GST_BUFFER_MALLOCDATA (ret) = (guint8 *) utf8;
GST_BUFFER_SIZE (ret) = strlen (utf8);
GST_BUFFER_OFFSET (ret) = 0;
}
GST_BUFFER_CAPS (ret) = gst_caps_new_simple ("application/x-subtitle", NULL);
return ret;
}
/**
* gst_avi_subtitle_title_tag:
* @sub: subtitle element
* @title: the title of this subtitle stream
*
* Send an event to the srcpad of the @sub element with the title
* of the subtitle stream as a GST_TAG_TITLE
*/
static void
gst_avi_subtitle_title_tag (GstAviSubtitle * sub, gchar * title)
{
GstTagList *temp_list = gst_tag_list_new ();
gst_tag_list_add (temp_list, GST_TAG_MERGE_APPEND, GST_TAG_TITLE, title,
NULL);
gst_pad_push_event (sub->src, gst_event_new_tag (temp_list));
}
static GstFlowReturn
gst_avi_subtitle_parse_gab2_chunk (GstAviSubtitle * sub, GstBuffer * buf)
{
const guint8 *data;
gchar *name_utf8;
guint name_length;
guint file_length;
guint size;
data = GST_BUFFER_DATA (buf);
size = GST_BUFFER_SIZE (buf);
/* check the magic word "GAB2\0", and the next word must be 2 */
if (size < 12 || memcmp (data, "GAB2\0\2\0", 5 + 2) != 0)
goto wrong_magic_word;
/* read 'name' of subtitle */
name_length = GST_READ_UINT32_LE (data + 5 + 2);
GST_LOG_OBJECT (sub, "length of name: %u", name_length);
if (size <= 17 + name_length)
goto wrong_name_length;
name_utf8 = g_convert ((gchar *) data + 11, name_length, "UTF-8", "UTF-16LE",
NULL, NULL, NULL);
if (name_utf8) {
GST_LOG_OBJECT (sub, "subtitle name: %s", name_utf8);
gst_avi_subtitle_title_tag (sub, name_utf8);
g_free (name_utf8);
}
/* next word must be 4 */
if (GST_READ_UINT16_LE (data + 11 + name_length) != 0x4)
goto wrong_fixed_word_2;
file_length = GST_READ_UINT32_LE (data + 13 + name_length);
GST_LOG_OBJECT (sub, "length srt/ssa file: %u", file_length);
if (size < (17 + name_length + file_length))
goto wrong_total_length;
/* store this, so we can send it again after a seek; note that we shouldn't
* assume all the remaining data in the chunk is subtitle data, there may
* be padding at the end for some reason, so only parse file_length bytes */
sub->subfile =
gst_avi_subtitle_extract_file (sub, buf, 17 + name_length, file_length);
if (sub->subfile == NULL)
goto extract_failed;
return GST_FLOW_OK;
/* ERRORS */
wrong_magic_word:
{
GST_ELEMENT_ERROR (sub, STREAM, DECODE, (NULL), ("Wrong magic word"));
return GST_FLOW_ERROR;
}
wrong_name_length:
{
GST_ELEMENT_ERROR (sub, STREAM, DECODE, (NULL),
("name doesn't fit in buffer (%d < %d)", size, 17 + name_length));
return GST_FLOW_ERROR;
}
wrong_fixed_word_2:
{
GST_ELEMENT_ERROR (sub, STREAM, DECODE, (NULL),
("wrong fixed word: expected %u, got %u", 4,
GST_READ_UINT16_LE (data + 11 + name_length)));
return GST_FLOW_ERROR;
}
wrong_total_length:
{
GST_ELEMENT_ERROR (sub, STREAM, DECODE, (NULL),
("buffer size is wrong: need %d bytes, have %d bytes",
17 + name_length + file_length, size));
return GST_FLOW_ERROR;
}
extract_failed:
{
GST_ELEMENT_ERROR (sub, STREAM, DECODE, (NULL),
("could not extract subtitles"));
return GST_FLOW_ERROR;
}
}
static GstFlowReturn
gst_avi_subtitle_chain (GstPad * pad, GstBuffer * buffer)
{
GstAviSubtitle *sub = GST_AVI_SUBTITLE (GST_PAD_PARENT (pad));
GstFlowReturn ret;
if (sub->subfile != NULL) {
GST_WARNING_OBJECT (sub, "Got more buffers than expected, dropping");
ret = GST_FLOW_UNEXPECTED;
goto done;
}
/* we expect exactly one buffer with the whole srt/ssa file in it */
ret = gst_avi_subtitle_parse_gab2_chunk (sub, buffer);
if (ret != GST_FLOW_OK)
goto done;
/* now push the subtitle data downstream */
ret = gst_pad_push (sub->src, gst_buffer_ref (sub->subfile));
done:
gst_buffer_unref (buffer);
return ret;
}
static gboolean
gst_avi_subtitle_send_event (GstElement * element, GstEvent * event)
{
GstAviSubtitle *avisubtitle = GST_AVI_SUBTITLE (element);
gboolean ret = FALSE;
if (GST_EVENT_TYPE (event) == GST_EVENT_SEEK) {
if (avisubtitle->subfile) {
if (gst_pad_push (avisubtitle->src,
gst_buffer_ref (avisubtitle->subfile)) == GST_FLOW_OK)
ret = TRUE;
}
}
gst_event_unref (event);
return ret;
}
static void
gst_avi_subtitle_base_init (gpointer klass)
{
GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
GST_DEBUG_CATEGORY_INIT (avisubtitle_debug, "avisubtitle", 0,
"parse avi subtitle stream");
gst_element_class_add_pad_template (element_class,
gst_static_pad_template_get (&sink_template));
gst_element_class_add_pad_template (element_class,
gst_static_pad_template_get (&src_template));
gst_element_class_set_details_simple (element_class,
"Avi subtitle parser", "Codec/Demuxer", "Parse avi subtitle stream",
"Thijs Vermeir <thijsvermeir@gmail.com>");
}
static void
gst_avi_subtitle_class_init (GstAviSubtitleClass * klass)
{
GstElementClass *gstelement_class = (GstElementClass *) klass;
gstelement_class->change_state =
GST_DEBUG_FUNCPTR (gst_avi_subtitle_change_state);
gstelement_class->send_event =
GST_DEBUG_FUNCPTR (gst_avi_subtitle_send_event);
}
static void
gst_avi_subtitle_init (GstAviSubtitle * self, GstAviSubtitleClass * klass)
{
self->src = gst_pad_new_from_static_template (&src_template, "src");
gst_element_add_pad (GST_ELEMENT (self), self->src);
self->sink = gst_pad_new_from_static_template (&sink_template, "sink");
gst_pad_set_chain_function (self->sink,
GST_DEBUG_FUNCPTR (gst_avi_subtitle_chain));
gst_element_add_pad (GST_ELEMENT (self), self->sink);
self->subfile = NULL;
}
static GstStateChangeReturn
gst_avi_subtitle_change_state (GstElement * element, GstStateChange transition)
{
GstStateChangeReturn ret;
GstAviSubtitle *sub = GST_AVI_SUBTITLE (element);
switch (transition) {
case GST_STATE_CHANGE_NULL_TO_READY:
case GST_STATE_CHANGE_READY_TO_PAUSED:
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:
if (sub->subfile) {
gst_buffer_unref (sub->subfile);
sub->subfile = NULL;
}
break;
default:
break;
}
return ret;
}