gstreamer/gst/id3demux/gstid3demux.c

/* -*- Mode: C; tab-width: 2; indent-tabs-mode: t; c-basic-offset: 2 -*- */
/* GStreamer ID3 tag demuxer
 * Copyright (C) 2005 Jan Schmidt <thaytan@mad.scientist.com>
 * Copyright (C) 2003-2004 Benjamin Otte <otte@gnome.org>
 *
 * 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-id3demux
 *
 * id3demux accepts data streams with either (or both) ID3v2 regions at the
 * start, or ID3v1 at the end. The mime type of the data between the tag blocks
 * is detected using typefind functions, and the appropriate output mime type
 * set on outgoing buffers. 
 *
 * The element is only able to read ID3v1 tags from a seekable stream, because
 * they are at the end of the stream. That is, when get_range mode is supported
 * by the upstream elements. If get_range operation is available, id3demux makes
 * it available downstream. This means that elements which require get_range
 * mode, such as wavparse, can operate on files containing ID3 tag information.
 *
 * This id3demux element replaced an older element with the same name which
 * relied on libid3tag from the MAD project.
 *
 * <refsect2>
 * <title>Example launch line</title>
 * |[
 * gst-launch filesrc location=file.mp3 ! id3demux ! fakesink -t
 * ]| This pipeline should read any available ID3 tag information and output it.
 * The contents of the file inside the ID3 tag regions should be detected, and
 * the appropriate mime type set on buffers produced from id3demux.
 * </refsect2>
 */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <gst/gst.h>
#include <gst/gst-i18n-plugin.h>
#include <gst/tag/tag.h>
#include <gst/pbutils/pbutils.h>
#include <string.h>

#include "gstid3demux.h"

enum
{
  ARG_0,
  ARG_PREFER_V1
};

#define DEFAULT_PREFER_V1  FALSE

GST_DEBUG_CATEGORY (id3demux_debug);
#define GST_CAT_DEFAULT (id3demux_debug)

#define ID3V1_TAG_SIZE 128
#define ID3V2_HDR_SIZE GST_TAG_ID3V2_HEADER_SIZE

static GstStaticPadTemplate sink_factory = GST_STATIC_PAD_TEMPLATE ("sink",
    GST_PAD_SINK,
    GST_PAD_ALWAYS,
    GST_STATIC_CAPS ("application/x-id3")
    );

static gboolean gst_id3demux_identify_tag (GstTagDemux * demux,
    GstBuffer * buffer, gboolean start_tag, guint * tag_size);
static GstTagDemuxResult gst_id3demux_parse_tag (GstTagDemux * demux,
    GstBuffer * buffer, gboolean start_tag, guint * tag_size,
    GstTagList ** tags);
static GstTagList *gst_id3demux_merge_tags (GstTagDemux * tagdemux,
    const GstTagList * start_tags, const GstTagList * end_tags);

static void gst_id3demux_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec);
static void gst_id3demux_get_property (GObject * object, guint prop_id,
    GValue * value, GParamSpec * pspec);

#define gst_id3demux_parent_class parent_class
G_DEFINE_TYPE (GstID3Demux, gst_id3demux, GST_TYPE_TAG_DEMUX);

static void
gst_id3demux_class_init (GstID3DemuxClass * klass)
{
  GObjectClass *gobject_class = (GObjectClass *) klass;
  GstElementClass *gstelement_class = (GstElementClass *) klass;
  GstTagDemuxClass *tagdemux_class = (GstTagDemuxClass *) klass;

  gobject_class->set_property = gst_id3demux_set_property;
  gobject_class->get_property = gst_id3demux_get_property;

  g_object_class_install_property (gobject_class, ARG_PREFER_V1,
      g_param_spec_boolean ("prefer-v1", "Prefer version 1 tag",
          "Prefer tags from ID3v1 tag at end of file when both ID3v1 "
          "and ID3v2 tags are present", DEFAULT_PREFER_V1,
          G_PARAM_READWRITE | G_PARAM_CONSTRUCT | G_PARAM_STATIC_STRINGS));

  gst_element_class_add_pad_template (gstelement_class,
      gst_static_pad_template_get (&sink_factory));

  gst_element_class_set_static_metadata (gstelement_class, "ID3 tag demuxer",
      "Codec/Demuxer/Metadata",
      "Read and output ID3v1 and ID3v2 tags while demuxing the contents",
      "Jan Schmidt <thaytan@mad.scientist.com>");

  tagdemux_class->identify_tag = GST_DEBUG_FUNCPTR (gst_id3demux_identify_tag);
  tagdemux_class->parse_tag = GST_DEBUG_FUNCPTR (gst_id3demux_parse_tag);
  tagdemux_class->merge_tags = GST_DEBUG_FUNCPTR (gst_id3demux_merge_tags);

  tagdemux_class->min_start_size = ID3V2_HDR_SIZE;
  tagdemux_class->min_end_size = ID3V1_TAG_SIZE;
}

static void
gst_id3demux_init (GstID3Demux * id3demux)
{
  id3demux->prefer_v1 = DEFAULT_PREFER_V1;
}

static gboolean
gst_id3demux_identify_tag (GstTagDemux * demux, GstBuffer * buf,
    gboolean start_tag, guint * tag_size)
{
  guint8 data[3];

  gst_buffer_extract (buf, 0, data, 3);

  if (start_tag) {
    if (data[0] != 'I' || data[1] != 'D' || data[2] != '3')
      goto no_marker;

    *tag_size = gst_tag_get_id3v2_tag_size (buf);
  } else {
    if (data[0] != 'T' || data[1] != 'A' || data[2] != 'G')
      goto no_marker;

    *tag_size = ID3V1_TAG_SIZE;
  }

  GST_INFO_OBJECT (demux, "Found ID3v%u marker, tag_size = %u",
      (start_tag) ? 2 : 1, *tag_size);

  return TRUE;

no_marker:
  {
    GST_DEBUG_OBJECT (demux, "No ID3v%u marker found", (start_tag) ? 2 : 1);
    return FALSE;
  }
}

static void
gst_id3demux_add_container_format (GstTagList * tags)
{
  GstCaps *sink_caps;

  sink_caps = gst_static_pad_template_get_caps (&sink_factory);
  gst_pb_utils_add_codec_description_to_tag_list (tags,
      GST_TAG_CONTAINER_FORMAT, sink_caps);
  gst_caps_unref (sink_caps);
}

static GstTagDemuxResult
gst_id3demux_parse_tag (GstTagDemux * demux, GstBuffer * buffer,
    gboolean start_tag, guint * tag_size, GstTagList ** tags)
{
  if (start_tag) {
    *tag_size = gst_tag_get_id3v2_tag_size (buffer);
    *tags = gst_tag_list_from_id3v2_tag (buffer);

    if (G_LIKELY (*tags != NULL)) {
      gst_id3demux_add_container_format (*tags);
      return GST_TAG_DEMUX_RESULT_OK;
    } else {
      return GST_TAG_DEMUX_RESULT_BROKEN_TAG;
    }
  } else {
    GstMapInfo map;

    gst_buffer_map (buffer, &map, GST_MAP_READ);
    *tags = gst_tag_list_new_from_id3v1 (map.data);
    gst_buffer_unmap (buffer, &map);

    if (G_UNLIKELY (*tags == NULL))
      return GST_TAG_DEMUX_RESULT_BROKEN_TAG;

    gst_id3demux_add_container_format (*tags);
    *tag_size = ID3V1_TAG_SIZE;
    return GST_TAG_DEMUX_RESULT_OK;
  }
}

static GstTagList *
gst_id3demux_merge_tags (GstTagDemux * tagdemux, const GstTagList * start_tags,
    const GstTagList * end_tags)
{
  GstID3Demux *id3demux;
  GstTagList *merged;
  gboolean prefer_v1;

  id3demux = GST_ID3DEMUX (tagdemux);

  GST_OBJECT_LOCK (id3demux);
  prefer_v1 = id3demux->prefer_v1;
  GST_OBJECT_UNLOCK (id3demux);

  /* we merge in REPLACE mode, so put the less important tags first */
  if (prefer_v1)
    merged = gst_tag_list_merge (start_tags, end_tags, GST_TAG_MERGE_REPLACE);
  else
    merged = gst_tag_list_merge (end_tags, start_tags, GST_TAG_MERGE_REPLACE);

  GST_LOG_OBJECT (id3demux, "start  tags: %" GST_PTR_FORMAT, start_tags);
  GST_LOG_OBJECT (id3demux, "end    tags: %" GST_PTR_FORMAT, end_tags);
  GST_LOG_OBJECT (id3demux, "merged tags: %" GST_PTR_FORMAT, merged);

  return merged;
}

static void
gst_id3demux_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec)
{
  GstID3Demux *id3demux;

  id3demux = GST_ID3DEMUX (object);

  switch (prop_id) {
    case ARG_PREFER_V1:{
      GST_OBJECT_LOCK (id3demux);
      id3demux->prefer_v1 = g_value_get_boolean (value);
      GST_OBJECT_UNLOCK (id3demux);
      break;
    }
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_id3demux_get_property (GObject * object, guint prop_id,
    GValue * value, GParamSpec * pspec)
{
  GstID3Demux *id3demux;

  id3demux = GST_ID3DEMUX (object);

  switch (prop_id) {
    case ARG_PREFER_V1:
      GST_OBJECT_LOCK (id3demux);
      g_value_set_boolean (value, id3demux->prefer_v1);
      GST_OBJECT_UNLOCK (id3demux);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static gboolean
plugin_init (GstPlugin * plugin)
{
  GST_DEBUG_CATEGORY_INIT (id3demux_debug, "id3demux", 0,
      "GStreamer ID3 tag demuxer");

  gst_tag_register_musicbrainz_tags ();

  return gst_element_register (plugin, "id3demux",
      GST_RANK_PRIMARY, GST_TYPE_ID3DEMUX);
}

GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
    GST_VERSION_MINOR,
    id3demux,
    "Demux ID3v1 and ID3v2 tags from a file",
    plugin_init, VERSION, GST_LICENSE, GST_PACKAGE_NAME, GST_PACKAGE_ORIGIN)