/* 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. */ /** * SECTION:element-avisubtitle * * <refsect2> * <para> * Parses the subtitle stream from an avi file. * </para> * <title>Example launch line</title> * <para> * <programlisting> * gst-launch-1.0 filesrc location=subtitle.avi ! avidemux name=demux ! queue ! avisubtitle ! subparse ! textoverlay name=overlay ! videoconvert ! autovideosink demux. ! queue ! decodebin ! overlay. * </programlisting> * This plays an avi file with a video and subtitle stream. * </para> * </refsect2> * * Last reviewed on 2008-02-01 */ /* 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, GstObject * parent, GstBuffer * buffer); static GstStateChangeReturn gst_avi_subtitle_change_state (GstElement * element, GstStateChange transition); static gboolean gst_avi_subtitle_send_event (GstElement * element, GstEvent * event); #define gst_avi_subtitle_parent_class parent_class G_DEFINE_TYPE (GstAviSubtitle, gst_avi_subtitle, 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 = NULL; gchar *data; GstMapInfo map; gst_buffer_map (buffer, &map, GST_MAP_READ); data = (gchar *) (map.data + offset); if (len >= (3 + 1) && IS_BOM_UTF8 (data) && g_utf8_validate (data + 3, len - 3, NULL)) { ret = gst_buffer_copy_region (buffer, GST_BUFFER_COPY_ALL, 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_copy_region (buffer, GST_BUFFER_COPY_ALL, offset, len); } else { /* we could fall back to gst_tag_freeform_to_utf8() here */ GST_WARNING_OBJECT (sub, "unspecified encoding, and not UTF-8"); ret = NULL; goto done; } g_return_val_if_fail (ret != NULL || input_enc != NULL, NULL); if (input_enc) { GError *err = NULL; gchar *utf8; gsize slen; 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); ret = NULL; goto done; } ret = gst_buffer_new (); slen = strlen (utf8); gst_buffer_append_memory (ret, gst_memory_new_wrapped (0, utf8, slen, 0, slen, utf8, g_free)); GST_BUFFER_OFFSET (ret) = 0; } done: gst_buffer_unmap (buffer, &map); 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) { gst_pad_push_event (sub->src, gst_event_new_tag (gst_tag_list_new (GST_TAG_TITLE, title, NULL))); } static GstFlowReturn gst_avi_subtitle_parse_gab2_chunk (GstAviSubtitle * sub, GstBuffer * buf) { gchar *name_utf8; guint name_length; guint file_length; GstMapInfo map; gst_buffer_map (buf, &map, GST_MAP_READ); /* check the magic word "GAB2\0", and the next word must be 2 */ if (map.size < 12 || memcmp (map.data, "GAB2\0\2\0", 5 + 2) != 0) goto wrong_magic_word; /* read 'name' of subtitle */ name_length = GST_READ_UINT32_LE (map.data + 5 + 2); GST_LOG_OBJECT (sub, "length of name: %u", name_length); if (map.size <= 17 + name_length) goto wrong_name_length; name_utf8 = g_convert ((gchar *) map.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 (map.data + 11 + name_length) != 0x4) goto wrong_fixed_word_2; file_length = GST_READ_UINT32_LE (map.data + 13 + name_length); GST_LOG_OBJECT (sub, "length srt/ssa file: %u", file_length); if (map.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; gst_buffer_unmap (buf, &map); return GST_FLOW_OK; /* ERRORS */ wrong_magic_word: { GST_ELEMENT_ERROR (sub, STREAM, DECODE, (NULL), ("Wrong magic word")); gst_buffer_unmap (buf, &map); return GST_FLOW_ERROR; } wrong_name_length: { GST_ELEMENT_ERROR (sub, STREAM, DECODE, (NULL), ("name doesn't fit in buffer (%" G_GSIZE_FORMAT " < %d)", map.size, 17 + name_length)); gst_buffer_unmap (buf, &map); 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 (map.data + 11 + name_length))); gst_buffer_unmap (buf, &map); return GST_FLOW_ERROR; } wrong_total_length: { GST_ELEMENT_ERROR (sub, STREAM, DECODE, (NULL), ("buffer size is wrong: need %d bytes, have %" G_GSIZE_FORMAT " bytes", 17 + name_length + file_length, map.size)); gst_buffer_unmap (buf, &map); return GST_FLOW_ERROR; } extract_failed: { GST_ELEMENT_ERROR (sub, STREAM, DECODE, (NULL), ("could not extract subtitles")); gst_buffer_unmap (buf, &map); return GST_FLOW_ERROR; } } static GstFlowReturn gst_avi_subtitle_chain (GstPad * pad, GstObject * parent, GstBuffer * buffer) { GstAviSubtitle *sub = GST_AVI_SUBTITLE (parent); GstFlowReturn ret; if (sub->subfile != NULL) { GST_WARNING_OBJECT (sub, "Got more buffers than expected, dropping"); ret = GST_FLOW_EOS; 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_class_init (GstAviSubtitleClass * klass) { GstElementClass *gstelement_class = (GstElementClass *) klass; GST_DEBUG_CATEGORY_INIT (avisubtitle_debug, "avisubtitle", 0, "parse avi subtitle stream"); gstelement_class->change_state = GST_DEBUG_FUNCPTR (gst_avi_subtitle_change_state); gstelement_class->send_event = GST_DEBUG_FUNCPTR (gst_avi_subtitle_send_event); gst_element_class_add_pad_template (gstelement_class, gst_static_pad_template_get (&sink_template)); gst_element_class_add_pad_template (gstelement_class, gst_static_pad_template_get (&src_template)); gst_element_class_set_static_metadata (gstelement_class, "Avi subtitle parser", "Codec/Parser/Subtitle", "Parse avi subtitle stream", "Thijs Vermeir <thijsvermeir@gmail.com>"); } static void gst_avi_subtitle_init (GstAviSubtitle * self) { GstCaps *caps; 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)); caps = gst_static_pad_template_get_caps (&src_template); gst_pad_set_caps (self->src, caps); gst_caps_unref (caps); gst_pad_use_fixed_caps (self->src); 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; }