/* 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., 51 Franklin St, Fifth Floor,

 * Boston, MA 02110-1301, 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>

 */

/* 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..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....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_static_pad_template (gstelement_class, &sink_template);

  gst_element_class_add_static_pad_template (gstelement_class, &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;

}