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387 lines
12 KiB
C
387 lines
12 KiB
C
/* GStreamer AVI GAB2 subtitle parser
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* Copyright (C) <2007> Thijs Vermeir <thijsvermeir@gmail.com>
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* Copyright (C) <2007> Tim-Philipp Müller <tim centricular net>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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/**
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* SECTION:element-avisubtitle
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* @title: avisubtitle
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*
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* Parses the subtitle stream from an avi file.
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*
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* ## Example launch line
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*
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* |[
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* gst-launch-1.0 filesrc location=subtitle.avi ! avidemux name=demux ! queue ! avisubtitle ! subparse ! textoverlay name=overlay ! videoconvert ! autovideosink demux. ! queue ! decodebin ! overlay.
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* ]|
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* This plays an avi file with a video and subtitle stream.
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*
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*/
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/* example of a subtitle chunk in an avi file
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* 00000000: 47 41 42 32 00 02 00 10 00 00 00 45 00 6e 00 67 GAB2.......E.n.g
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* 00000010: 00 6c 00 69 00 73 00 68 00 00 00 04 00 8e 00 00 .l.i.s.h........
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* 00000020: 00 ef bb bf 31 0d 0a 30 30 3a 30 30 3a 30 30 2c ....1..00:00:00,
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* 00000030: 31 30 30 20 2d 2d 3e 20 30 30 3a 30 30 3a 30 32 100 --> 00:00:02
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* 00000040: 2c 30 30 30 0d 0a 3c 62 3e 41 6e 20 55 54 46 38 ,000..<b>An UTF8
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* 00000050: 20 53 75 62 74 69 74 6c 65 20 77 69 74 68 20 42 Subtitle with B
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* 00000060: 4f 4d 3c 2f 62 3e 0d 0a 0d 0a 32 0d 0a 30 30 3a OM</b>....2..00:
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* 00000070: 30 30 3a 30 32 2c 31 30 30 20 2d 2d 3e 20 30 30 00:02,100 --> 00
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* 00000080: 3a 30 30 3a 30 34 2c 30 30 30 0d 0a 53 6f 6d 65 :00:04,000..Some
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* 00000090: 74 68 69 6e 67 20 6e 6f 6e 41 53 43 49 49 20 2d thing nonASCII -
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* 000000a0: 20 c2 b5 c3 b6 c3 a4 c3 bc c3 9f 0d 0a 0d 0a ..............
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <string.h>
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#include "gstavisubtitle.h"
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GST_DEBUG_CATEGORY_STATIC (avisubtitle_debug);
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#define GST_CAT_DEFAULT avisubtitle_debug
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static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
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GST_PAD_SINK,
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GST_PAD_ALWAYS,
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GST_STATIC_CAPS ("application/x-subtitle-avi")
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);
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static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
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GST_PAD_SRC,
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GST_PAD_ALWAYS,
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GST_STATIC_CAPS ("application/x-subtitle")
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);
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static void gst_avi_subtitle_title_tag (GstAviSubtitle * sub, gchar * title);
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static GstFlowReturn gst_avi_subtitle_chain (GstPad * pad, GstObject * parent,
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GstBuffer * buffer);
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static GstStateChangeReturn gst_avi_subtitle_change_state (GstElement * element,
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GstStateChange transition);
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static gboolean gst_avi_subtitle_send_event (GstElement * element,
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GstEvent * event);
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#define gst_avi_subtitle_parent_class parent_class
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G_DEFINE_TYPE (GstAviSubtitle, gst_avi_subtitle, GST_TYPE_ELEMENT);
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#define IS_BOM_UTF8(data) ((GST_READ_UINT32_BE(data) >> 8) == 0xEFBBBF)
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#define IS_BOM_UTF16_BE(data) (GST_READ_UINT16_BE(data) == 0xFEFF)
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#define IS_BOM_UTF16_LE(data) (GST_READ_UINT16_LE(data) == 0xFEFF)
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#define IS_BOM_UTF32_BE(data) (GST_READ_UINT32_BE(data) == 0xFEFF)
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#define IS_BOM_UTF32_LE(data) (GST_READ_UINT32_LE(data) == 0xFEFF)
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static GstBuffer *
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gst_avi_subtitle_extract_file (GstAviSubtitle * sub, GstBuffer * buffer,
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guint offset, guint len)
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{
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const gchar *input_enc = NULL;
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GstBuffer *ret = NULL;
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gchar *data;
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GstMapInfo map;
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gst_buffer_map (buffer, &map, GST_MAP_READ);
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data = (gchar *) (map.data + offset);
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if (len >= (3 + 1) && IS_BOM_UTF8 (data) &&
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g_utf8_validate (data + 3, len - 3, NULL)) {
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ret =
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gst_buffer_copy_region (buffer, GST_BUFFER_COPY_ALL, offset + 3,
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len - 3);
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} else if (len >= 2 && IS_BOM_UTF16_BE (data)) {
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input_enc = "UTF-16BE";
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data += 2;
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len -= 2;
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} else if (len >= 2 && IS_BOM_UTF16_LE (data)) {
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input_enc = "UTF-16LE";
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data += 2;
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len -= 2;
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} else if (len >= 4 && IS_BOM_UTF32_BE (data)) {
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input_enc = "UTF-32BE";
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data += 4;
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len -= 4;
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} else if (len >= 4 && IS_BOM_UTF32_LE (data)) {
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input_enc = "UTF-32LE";
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data += 4;
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len -= 4;
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} else if (g_utf8_validate (data, len, NULL)) {
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/* not specified, check if it's UTF-8 */
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ret = gst_buffer_copy_region (buffer, GST_BUFFER_COPY_ALL, offset, len);
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} else {
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/* we could fall back to gst_tag_freeform_to_utf8() here */
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GST_WARNING_OBJECT (sub, "unspecified encoding, and not UTF-8");
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ret = NULL;
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goto done;
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}
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g_return_val_if_fail (ret != NULL || input_enc != NULL, NULL);
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if (input_enc) {
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GError *err = NULL;
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gchar *utf8;
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gsize slen;
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GST_DEBUG_OBJECT (sub, "converting subtitles from %s to UTF-8", input_enc);
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utf8 = g_convert (data, len, "UTF-8", input_enc, NULL, NULL, &err);
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if (err != NULL) {
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GST_WARNING_OBJECT (sub, "conversion to UTF-8 failed : %s", err->message);
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g_error_free (err);
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ret = NULL;
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goto done;
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}
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ret = gst_buffer_new ();
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slen = strlen (utf8);
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gst_buffer_append_memory (ret,
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gst_memory_new_wrapped (0, utf8, slen, 0, slen, utf8, g_free));
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GST_BUFFER_OFFSET (ret) = 0;
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}
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done:
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gst_buffer_unmap (buffer, &map);
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return ret;
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}
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/**
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* gst_avi_subtitle_title_tag:
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* @sub: subtitle element
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* @title: the title of this subtitle stream
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*
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* Send an event to the srcpad of the @sub element with the title
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* of the subtitle stream as a GST_TAG_TITLE
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*/
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static void
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gst_avi_subtitle_title_tag (GstAviSubtitle * sub, gchar * title)
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{
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gst_pad_push_event (sub->src,
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gst_event_new_tag (gst_tag_list_new (GST_TAG_TITLE, title, NULL)));
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}
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static GstFlowReturn
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gst_avi_subtitle_parse_gab2_chunk (GstAviSubtitle * sub, GstBuffer * buf)
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{
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gchar *name_utf8;
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guint name_length;
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guint file_length;
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GstMapInfo map;
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gst_buffer_map (buf, &map, GST_MAP_READ);
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/* check the magic word "GAB2\0", and the next word must be 2 */
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if (map.size < 12 || memcmp (map.data, "GAB2\0\2\0", 5 + 2) != 0)
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goto wrong_magic_word;
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/* read 'name' of subtitle */
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name_length = GST_READ_UINT32_LE (map.data + 5 + 2);
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GST_LOG_OBJECT (sub, "length of name: %u", name_length);
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if (map.size <= 17 + name_length)
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goto wrong_name_length;
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name_utf8 =
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g_convert ((gchar *) map.data + 11, name_length, "UTF-8", "UTF-16LE",
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NULL, NULL, NULL);
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if (name_utf8) {
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GST_LOG_OBJECT (sub, "subtitle name: %s", name_utf8);
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gst_avi_subtitle_title_tag (sub, name_utf8);
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g_free (name_utf8);
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}
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/* next word must be 4 */
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if (GST_READ_UINT16_LE (map.data + 11 + name_length) != 0x4)
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goto wrong_fixed_word_2;
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file_length = GST_READ_UINT32_LE (map.data + 13 + name_length);
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GST_LOG_OBJECT (sub, "length srt/ssa file: %u", file_length);
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if (map.size < (17 + name_length + file_length))
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goto wrong_total_length;
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/* store this, so we can send it again after a seek; note that we shouldn't
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* assume all the remaining data in the chunk is subtitle data, there may
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* be padding at the end for some reason, so only parse file_length bytes */
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sub->subfile =
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gst_avi_subtitle_extract_file (sub, buf, 17 + name_length, file_length);
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if (sub->subfile == NULL)
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goto extract_failed;
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gst_buffer_unmap (buf, &map);
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return GST_FLOW_OK;
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/* ERRORS */
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wrong_magic_word:
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{
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GST_ELEMENT_ERROR (sub, STREAM, DECODE, (NULL), ("Wrong magic word"));
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gst_buffer_unmap (buf, &map);
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return GST_FLOW_ERROR;
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}
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wrong_name_length:
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{
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GST_ELEMENT_ERROR (sub, STREAM, DECODE, (NULL),
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("name doesn't fit in buffer (%" G_GSIZE_FORMAT " < %d)", map.size,
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17 + name_length));
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gst_buffer_unmap (buf, &map);
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return GST_FLOW_ERROR;
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}
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wrong_fixed_word_2:
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{
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GST_ELEMENT_ERROR (sub, STREAM, DECODE, (NULL),
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("wrong fixed word: expected %u, got %u", 4,
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GST_READ_UINT16_LE (map.data + 11 + name_length)));
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gst_buffer_unmap (buf, &map);
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return GST_FLOW_ERROR;
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}
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wrong_total_length:
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{
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GST_ELEMENT_ERROR (sub, STREAM, DECODE, (NULL),
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("buffer size is wrong: need %d bytes, have %" G_GSIZE_FORMAT " bytes",
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17 + name_length + file_length, map.size));
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gst_buffer_unmap (buf, &map);
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return GST_FLOW_ERROR;
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}
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extract_failed:
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{
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GST_ELEMENT_ERROR (sub, STREAM, DECODE, (NULL),
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("could not extract subtitles"));
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gst_buffer_unmap (buf, &map);
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return GST_FLOW_ERROR;
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}
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}
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static GstFlowReturn
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gst_avi_subtitle_chain (GstPad * pad, GstObject * parent, GstBuffer * buffer)
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{
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GstAviSubtitle *sub = GST_AVI_SUBTITLE (parent);
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GstFlowReturn ret;
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if (sub->subfile != NULL) {
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GST_WARNING_OBJECT (sub, "Got more buffers than expected, dropping");
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ret = GST_FLOW_EOS;
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goto done;
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}
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/* we expect exactly one buffer with the whole srt/ssa file in it */
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ret = gst_avi_subtitle_parse_gab2_chunk (sub, buffer);
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if (ret != GST_FLOW_OK)
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goto done;
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/* now push the subtitle data downstream */
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ret = gst_pad_push (sub->src, gst_buffer_ref (sub->subfile));
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done:
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gst_buffer_unref (buffer);
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return ret;
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}
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static gboolean
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gst_avi_subtitle_send_event (GstElement * element, GstEvent * event)
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{
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GstAviSubtitle *avisubtitle = GST_AVI_SUBTITLE (element);
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gboolean ret = FALSE;
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if (GST_EVENT_TYPE (event) == GST_EVENT_SEEK) {
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if (avisubtitle->subfile) {
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if (gst_pad_push (avisubtitle->src,
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gst_buffer_ref (avisubtitle->subfile)) == GST_FLOW_OK)
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ret = TRUE;
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}
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}
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gst_event_unref (event);
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return ret;
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}
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static void
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gst_avi_subtitle_class_init (GstAviSubtitleClass * klass)
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{
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GstElementClass *gstelement_class = (GstElementClass *) klass;
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GST_DEBUG_CATEGORY_INIT (avisubtitle_debug, "avisubtitle", 0,
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"parse avi subtitle stream");
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gstelement_class->change_state =
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GST_DEBUG_FUNCPTR (gst_avi_subtitle_change_state);
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gstelement_class->send_event =
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GST_DEBUG_FUNCPTR (gst_avi_subtitle_send_event);
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gst_element_class_add_static_pad_template (gstelement_class, &sink_template);
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gst_element_class_add_static_pad_template (gstelement_class, &src_template);
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gst_element_class_set_static_metadata (gstelement_class,
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"Avi subtitle parser", "Codec/Parser/Subtitle",
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"Parse avi subtitle stream", "Thijs Vermeir <thijsvermeir@gmail.com>");
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}
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static void
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gst_avi_subtitle_init (GstAviSubtitle * self)
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{
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GstCaps *caps;
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self->src = gst_pad_new_from_static_template (&src_template, "src");
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gst_element_add_pad (GST_ELEMENT (self), self->src);
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self->sink = gst_pad_new_from_static_template (&sink_template, "sink");
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gst_pad_set_chain_function (self->sink,
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GST_DEBUG_FUNCPTR (gst_avi_subtitle_chain));
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caps = gst_static_pad_template_get_caps (&src_template);
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gst_pad_set_caps (self->src, caps);
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gst_caps_unref (caps);
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gst_pad_use_fixed_caps (self->src);
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gst_element_add_pad (GST_ELEMENT (self), self->sink);
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self->subfile = NULL;
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}
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static GstStateChangeReturn
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gst_avi_subtitle_change_state (GstElement * element, GstStateChange transition)
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{
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GstStateChangeReturn ret;
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GstAviSubtitle *sub = GST_AVI_SUBTITLE (element);
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switch (transition) {
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case GST_STATE_CHANGE_NULL_TO_READY:
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case GST_STATE_CHANGE_READY_TO_PAUSED:
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default:
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break;
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}
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ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
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if (ret == GST_STATE_CHANGE_FAILURE)
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return ret;
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switch (transition) {
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case GST_STATE_CHANGE_PAUSED_TO_READY:
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if (sub->subfile) {
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gst_buffer_unref (sub->subfile);
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sub->subfile = NULL;
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}
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break;
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default:
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break;
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}
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return ret;
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}
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