Added element to rewrite vorbiscomments embedded in flac files. It currently doesn't honour the tag merge mode setting.

Original commit message from CVS:
Added element to rewrite vorbiscomments embedded in flac files. It currently
doesn't honour the tag merge mode setting.
Changed application/x-flac to audio/x-flac in gstflacenc.c

1 files changed, 432 insertions, 0 deletions

diff --git a/ext/flac/gstflactag.c b/ext/flac/gstflactag.c
new file mode 100644
index 00000000..539c98af
--- /dev/null
+++ b/ext/flac/gstflactag.c
@@ -0,0 +1,432 @@
+/* GStreamer
+ * Copyright (C) 2003 Christophe Fergeau <teuf@gnome.org>
+ *
+ * gstflactag.c: plug-in for reading/modifying vorbis comments in flac files
+ *
+ * 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.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+#include <gst/gsttaginterface.h>
+#include <gst/tags/gsttagediting.h>
+#include <string.h>
+
+#define GST_TYPE_FLAC_TAG (gst_flac_tag_get_type())
+#define GST_FLAC_TAG(obj) (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_FLAC_TAG, GstFlacTag))
+#define GST_FLAC_TAG_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_FLAC_TAG, GstFlacTag))
+#define GST_IS_FLAC_TAG(obj) (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_FLAC_TAG))
+#define GST_IS_FLAC_TAG_CLASS(obj) (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_FLAC_TAG))
+
+typedef struct _GstFlacTag GstFlacTag;
+typedef struct _GstFlacTagClass GstFlacTagClass;
+
+static inline 
+gint min (gint a, gint b) {
+  if (a < b) {
+    return a;
+  } else {
+    return b;
+  }
+}
+  
+
+typedef enum {
+  GST_FLAC_TAG_STATE_INIT,
+  GST_FLAC_TAG_STATE_METADATA_BLOCKS,
+  GST_FLAC_TAG_STATE_WRITING_METADATA_BLOCK,
+  GST_FLAC_TAG_STATE_SKIP_METADATA_BLOCK,
+  GST_FLAC_TAG_STATE_ADD_VORBIS_COMMENT,
+  GST_FLAC_TAG_STATE_AUDIO_DATA
+} GstFlacTagState;
+
+
+struct _GstFlacTag {
+  GstElement	 element;
+
+  /* pads */
+  GstPad *		sinkpad;
+  GstPad *		srcpad;
+
+  GstFlacTagState       state;
+
+  GstBuffer *		buffer;
+
+  guint                 metadata_bytes_remaining;
+  gboolean              metadata_last_block;  
+  gboolean              metadata_append_vc_block;
+};
+
+struct _GstFlacTagClass {
+  GstElementClass parent_class;
+};
+
+/* elementfactory information */
+static GstElementDetails gst_flac_tag_details = GST_ELEMENT_DETAILS (
+  "flac rettager",
+  "Tag",
+  "Rewrite tags in a FLAC file",
+  "Christope Fergeau <teuf@gnome.org>"
+);
+
+
+/* signals and args */
+enum {
+  /* FILL ME */
+  LAST_SIGNAL
+};
+
+enum {
+  ARG_0,
+  /* FILL ME */
+};
+
+GST_PAD_TEMPLATE_FACTORY (flac_tag_src_template_factory,
+  "src",
+  GST_PAD_SRC,
+  GST_PAD_ALWAYS,
+  GST_CAPS_NEW (
+    "flac_tag_tag_src",
+    "audio/x-flac",
+    NULL
+    )
+)
+
+GST_PAD_TEMPLATE_FACTORY (flac_tag_sink_template_factory,
+  "sink",
+  GST_PAD_SINK,
+  GST_PAD_ALWAYS,
+  GST_CAPS_NEW (
+    "flac_tag_data_sink",
+    "audio/x-flac",
+    NULL
+  )
+)
+
+
+static void		gst_flac_tag_base_init	(gpointer		g_class);
+static void		gst_flac_tag_class_init	(GstFlacTagClass *	klass);
+static void		gst_flac_tag_init	(GstFlacTag *		tag);
+
+static void		gst_flac_tag_chain	(GstPad *		pad,
+						 GstData *		data);
+
+static GstElementStateReturn gst_flac_tag_change_state	(GstElement * element);
+
+
+static GstElementClass *parent_class = NULL;
+/* static guint gst_flac_tag_signals[LAST_SIGNAL] = { 0 }; */
+
+GType
+gst_flac_tag_get_type (void)
+{
+  static GType flac_tag_type = 0;
+
+  if (!flac_tag_type) {
+    static const GTypeInfo flac_tag_info = {
+      sizeof (GstFlacTagClass),
+      gst_flac_tag_base_init,
+      NULL,
+      (GClassInitFunc) gst_flac_tag_class_init,
+      NULL,
+      NULL,
+      sizeof (GstFlacTag),
+      0,
+      (GInstanceInitFunc) gst_flac_tag_init,
+    };
+    static const GInterfaceInfo tag_setter_info = {
+      NULL,
+      NULL,
+      NULL
+    };
+    
+    flac_tag_type = g_type_register_static(GST_TYPE_ELEMENT, "GstFlacTag", &flac_tag_info, 0);
+
+    g_type_add_interface_static (flac_tag_type, GST_TYPE_TAG_SETTER, &tag_setter_info);
+    
+  }
+  return flac_tag_type;
+}
+
+
+static void
+gst_flac_tag_base_init (gpointer g_class)
+{
+  GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
+
+  gst_element_class_set_details (element_class, &gst_flac_tag_details);
+
+  gst_element_class_add_pad_template (element_class,
+		  GST_PAD_TEMPLATE_GET (flac_tag_sink_template_factory));
+  gst_element_class_add_pad_template (element_class,
+		  GST_PAD_TEMPLATE_GET (flac_tag_src_template_factory));
+}
+
+
+static void
+gst_flac_tag_class_init (GstFlacTagClass *klass)
+{
+  GstElementClass *gstelement_class;
+  GObjectClass *gobject_class;
+  
+  gstelement_class = (GstElementClass*) klass;
+  gobject_class = (GObjectClass*) klass;
+
+  parent_class = g_type_class_ref(GST_TYPE_ELEMENT);
+
+  gstelement_class->change_state = gst_flac_tag_change_state;
+}
+
+
+static void
+gst_flac_tag_init (GstFlacTag *tag)
+{
+  /* create the sink and src pads */
+  tag->sinkpad = gst_pad_new_from_template(
+		  GST_PAD_TEMPLATE_GET (flac_tag_sink_template_factory), "sink");
+  gst_element_add_pad (GST_ELEMENT (tag), tag->sinkpad);
+  gst_pad_set_chain_function (tag->sinkpad, GST_DEBUG_FUNCPTR (gst_flac_tag_chain));
+
+  tag->srcpad = gst_pad_new_from_template(
+		  GST_PAD_TEMPLATE_GET (flac_tag_src_template_factory), "src");
+  gst_element_add_pad (GST_ELEMENT (tag), tag->srcpad);
+
+  tag->buffer = NULL;
+}
+
+#define FLAC_MAGIC "fLaC"
+#define FLAC_MAGIC_SIZE (sizeof (FLAC_MAGIC) - 1)
+
+static void
+gst_flac_tag_chain (GstPad *pad, GstData *data)
+{
+  GstBuffer *buffer;
+  GstFlacTag *tag;
+  
+  if (GST_IS_EVENT (data)) {
+    g_print ("Unhandled event\n");
+    return;
+  }
+
+  buffer = GST_BUFFER (data);
+  tag = GST_FLAC_TAG (gst_pad_get_parent (pad));
+
+  if (tag->buffer) {
+    tag->buffer = gst_buffer_merge (tag->buffer, buffer);
+  } else {
+    tag->buffer = buffer;
+  }
+
+
+  /* Initial state, we don't even know if we are dealing with a flac file */
+  if (tag->state == GST_FLAC_TAG_STATE_INIT) {
+    if (GST_BUFFER_SIZE (tag->buffer) < sizeof (FLAC_MAGIC)) {
+      return;
+    }
+
+    if (strncmp (GST_BUFFER_DATA (tag->buffer), FLAC_MAGIC, FLAC_MAGIC_SIZE) == 0) {
+      GstBuffer *sub;
+      tag->state = GST_FLAC_TAG_STATE_METADATA_BLOCKS;
+      sub = gst_buffer_create_sub (tag->buffer, 0, FLAC_MAGIC_SIZE);
+	      
+      gst_pad_push (tag->srcpad, GST_DATA (sub));
+      sub = gst_buffer_create_sub (tag->buffer, FLAC_MAGIC_SIZE, GST_BUFFER_SIZE (tag->buffer) - FLAC_MAGIC_SIZE);
+      gst_buffer_unref (tag->buffer);
+      /* We do a copy because we need a writable buffer, and _create_sub
+       * sets the buffer it uses to read-only
+       */
+      tag->buffer = gst_buffer_copy (sub);
+      gst_buffer_unref (sub);
+    } else {
+      /* FIXME: does that work well with FLAC files containing ID3v2 tags ? */
+      gst_element_error (GST_ELEMENT (tag), "Not a flac stream\n");
+    }
+
+    /* We must know if we'll add a vorbiscomment block as the last metadata
+     * block as soon as possible: if we won't add a block  by ourselves,
+     * we must keep the current vorbiscomment block, and don't change
+     * the "last block" flag when we read it
+     */
+    tag->metadata_append_vc_block = (gst_tag_setter_get_list (GST_TAG_SETTER (tag)) != NULL);
+  }
+
+  /* The fLaC magic string has been skipped, try to detect the beginning
+   * of a metadata block
+   */
+  if (tag->state == GST_FLAC_TAG_STATE_METADATA_BLOCKS) {
+    guint size;
+    guint type;
+    gboolean is_last;
+
+    g_assert (tag->metadata_bytes_remaining == 0);
+    g_assert (tag->metadata_last_block == FALSE);
+
+    /* The header of a flac metadata block is 4 bytes long:
+     * 1st bit: indicates whether this is the last metadata info block
+     * 7 next bits: 4 if vorbis comment block
+     * 24 next bits: size of the metadata to follow (big endian)
+     */
+    if (GST_BUFFER_SIZE (tag->buffer) < 4) {
+      return;
+    }
+    is_last = (((GST_BUFFER_DATA (tag->buffer)[0]) & 0x80) == 0x80);
+    /* If we have metadata set on the element, the last metadata block 
+     * will be the vorbis comment block which we will build ourselves
+     */
+    if ((is_last) && (tag->metadata_append_vc_block)) {
+      (GST_BUFFER_DATA (tag->buffer)[0]) &= (~0x80);
+    }
+
+    type = (GST_BUFFER_DATA (tag->buffer)[0]) & 0x7F;
+    size = 
+      ((GST_BUFFER_DATA (tag->buffer)[1]) << 16) 
+      | ((GST_BUFFER_DATA (tag->buffer)[2]) << 8)
+      | (GST_BUFFER_DATA (tag->buffer)[3]);
+
+    /* The 4 bytes long header isn't included in the metadata size */
+    tag->metadata_bytes_remaining = size + 4;
+    tag->metadata_last_block = is_last;
+
+    /* Metadata blocks of type 4 are vorbis comment blocks */
+    if ((type == 0x04) && (tag->metadata_append_vc_block)) {
+      tag->state = GST_FLAC_TAG_STATE_SKIP_METADATA_BLOCK;
+    } else {
+      tag->state = GST_FLAC_TAG_STATE_WRITING_METADATA_BLOCK;
+    }
+  }
+
+  /* Reads a metadata block */
+  if ((tag->state == GST_FLAC_TAG_STATE_WRITING_METADATA_BLOCK) ||
+  (tag->state == GST_FLAC_TAG_STATE_SKIP_METADATA_BLOCK)) {
+    guint bytes_to_push;
+
+    g_assert (tag->metadata_bytes_remaining != 0);
+
+    bytes_to_push = min (tag->metadata_bytes_remaining, 
+			 GST_BUFFER_SIZE (tag->buffer));
+
+    if (tag->state == GST_FLAC_TAG_STATE_WRITING_METADATA_BLOCK) {
+      GstBuffer *sub;
+      sub = gst_buffer_create_sub (tag->buffer, 0, bytes_to_push);
+      gst_pad_push (tag->srcpad, GST_DATA (sub));
+    }
+    tag->metadata_bytes_remaining -= (bytes_to_push);
+
+    if (GST_BUFFER_SIZE (tag->buffer) > bytes_to_push) {
+      GstBuffer *sub;
+
+      sub = gst_buffer_create_sub (tag->buffer, bytes_to_push, 
+				   GST_BUFFER_SIZE (tag->buffer) - bytes_to_push);
+      gst_buffer_unref (tag->buffer);
+
+      /* We do a copy because we need a writable buffer, and _create_sub
+       * sets the buffer it uses to read-only
+       */
+      tag->buffer = gst_buffer_copy (sub);
+      gst_buffer_unref (sub);
+
+      if (tag->metadata_last_block == FALSE) {
+	tag->state = GST_FLAC_TAG_STATE_METADATA_BLOCKS;
+      } else if (tag->metadata_append_vc_block) {
+	tag->state = GST_FLAC_TAG_STATE_ADD_VORBIS_COMMENT;
+      } else {
+	tag->state = GST_FLAC_TAG_STATE_AUDIO_DATA;
+      }
+    } else if (tag->metadata_bytes_remaining == 0) {
+      tag->state = GST_FLAC_TAG_STATE_METADATA_BLOCKS;
+      tag->buffer = NULL;
+    } else {
+      tag->state = GST_FLAC_TAG_STATE_WRITING_METADATA_BLOCK;
+      tag->buffer = NULL;
+    }
+  }
+
+  /* Creates a vorbis comment block from the metadata which was set
+   * on the gstreamer element, and add it to the flac stream
+   */
+  if (tag->state == GST_FLAC_TAG_STATE_ADD_VORBIS_COMMENT) {
+    guchar header[4];
+    GstBuffer *buffer;
+    gint size;
+    const GstTagList *tags;
+
+    g_assert (tag->metadata_append_vc_block);
+    bzero (header, sizeof (header));
+    header[0] = 0x84; /* 0x80 = Last metadata block, 
+		       * 0x04 = vorbiscomment block
+		       */
+    tags = gst_tag_setter_get_list (GST_TAG_SETTER (tag));
+    buffer = gst_tag_list_to_vorbiscomment_buffer (tags, header, 
+						   sizeof (header), NULL);
+    if (buffer == NULL) {
+      gst_element_error (GST_ELEMENT (tag), "Error filling vorbis comments\n");
+      return;
+    }
+    size = GST_BUFFER_SIZE (buffer) - sizeof (header);
+    if ((size > 0xFFFFFF) || (size < 4)) {
+      /* FLAC vorbis comment blocks are limited to 2^24 bytes, 
+       * while the vorbis specs allow more than that. Shouldn't 
+       * be a real world problem though
+       */
+      gst_element_error (GST_ELEMENT (tag), "Vorbis comment too long\n");
+      return;
+    } 
+    GST_BUFFER_DATA (buffer)[1] = ((size & 0xFF0000) >> 16);
+    GST_BUFFER_DATA (buffer)[2] = ((size & 0x00FF00) >>  8);
+    GST_BUFFER_DATA (buffer)[3] =  (size & 0x0000FF);
+    gst_pad_push (tag->srcpad, GST_DATA (buffer));
+    tag->state = GST_FLAC_TAG_STATE_AUDIO_DATA;
+  }
+
+  /* The metadata blocks have been read, now we are reading audio data */
+  if (tag->state == GST_FLAC_TAG_STATE_AUDIO_DATA) {
+    gst_pad_push (tag->srcpad, GST_DATA (tag->buffer));
+    tag->buffer = NULL;
+  }
+}
+
+
+static GstElementStateReturn
+gst_flac_tag_change_state (GstElement *element)
+{
+  GstFlacTag *tag;
+
+  tag = GST_FLAC_TAG (element);
+
+  switch (GST_STATE_TRANSITION (element)) {
+    case GST_STATE_NULL_TO_READY:
+      break;
+    case GST_STATE_READY_TO_PAUSED:
+      break;
+    case GST_STATE_PAUSED_TO_PLAYING:
+      /* do something to get out of the chain function faster */
+      break;
+    case GST_STATE_PLAYING_TO_PAUSED:
+      break;
+    case GST_STATE_PAUSED_TO_READY:
+      if (tag->buffer) {
+        gst_buffer_unref (tag->buffer);
+	tag->buffer = NULL;
+      }
+      tag->state = GST_FLAC_TAG_STATE_INIT;
+      break;
+    case GST_STATE_READY_TO_NULL:
+      break;
+  }
+
+  return parent_class->change_state (element);
+}