Added support for PNG/XMP. Indentation. And fixed pull mode to parse the file.

Original commit message from CVS:
Added support for PNG/XMP. Indentation. And fixed pull mode to parse the file.

17 files changed, 530 insertions, 153 deletions

diff --git a/ext/metadata/Makefile.am b/ext/metadata/Makefile.am
index 88596b42..095a3996 100644
--- a/ext/metadata/Makefile.am
+++ b/ext/metadata/Makefile.am
@@ -4,6 +4,7 @@ libgstmetadata_la_SOURCES =	gstmetadata.c       \
 				gstmetadataparse.c  \
 				metadataparse.c     \
 				metadataparsejpeg.c \
+				metadataparsepng.c  \
 				metadataparseexif.c \
 				metadataparseiptc.c \
 				metadataparsexmp.c  \
@@ -16,6 +17,7 @@ libgstmetadata_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS)
 noinst_HEADERS = 	gstmetadataparse.h  \
 			metadataparse.h     \
 			metadataparsejpeg.h \
+			metadataparsepng.h  \
 			metadataparseexif.h \
 			metadataparseiptc.h \
 			metadataparsexmp.h  \
diff --git a/ext/metadata/gstmetadataparse.c b/ext/metadata/gstmetadataparse.c
index cb828f29..be1e0d43 100644
--- a/ext/metadata/gstmetadataparse.c
+++ b/ext/metadata/gstmetadataparse.c
@@ -146,6 +146,8 @@ static gboolean gst_metadata_parse_activate (GstPad * pad);
 static gboolean
 gst_metadata_parse_element_activate_src_pull (GstPad * pad, gboolean active);
 
+static gboolean gst_metadata_parse_pull_range_parse (GstMetadataParse * filter);
+
 static void gst_metadata_parse_init_members (GstMetadataParse * filter);
 static void gst_metadata_parse_dispose_members (GstMetadataParse * filter);
 
@@ -486,7 +488,7 @@ gst_metadata_parse_dispose_members (GstMetadataParse * filter)
 static void
 gst_metadata_parse_init_members (GstMetadataParse * filter)
 {
-  filter->need_send_tag = TRUE;
+  filter->need_send_tag = FALSE;
   filter->exif = TRUE;
   filter->iptc = TRUE;
   filter->xmp = TRUE;
@@ -708,6 +710,7 @@ gst_metadata_parse_parse (GstMetadataParse * filter, const guint8 * buf,
   } else {
     filter->state = MT_STATE_PARSED;
     filter->need_more_data = FALSE;
+    filter->need_send_tag = TRUE;
   }
 
   if (filter->img_type != PARSE_DATA_IMG_TYPE (filter->parse_data)) {
@@ -807,22 +810,14 @@ done:
 }
 
 static gboolean
-gst_metadata_parse_activate (GstPad * pad)
+gst_metadata_parse_pull_range_parse (GstMetadataParse * filter)
 {
-  GstMetadataParse *filter = NULL;
+
+  int res;
   gboolean ret = TRUE;
+  guint32 offset = 0;
   gint64 duration = 0;
   GstFormat format = GST_FORMAT_BYTES;
-  int res;
-  guint32 offset = 0;
-
-  filter = GST_METADATA_PARSE (GST_PAD_PARENT (pad));
-
-  if (!gst_pad_check_pull_range (pad) ||
-      !gst_pad_activate_pull (filter->sinkpad, TRUE)) {
-    /* nothing to be done by now, activate push mode */
-    return gst_pad_activate_push (pad, TRUE);
-  }
 
   if (!(ret =
           gst_pad_query_peer_duration (filter->sinkpad, &format, &duration))) {
@@ -836,7 +831,6 @@ gst_metadata_parse_activate (GstPad * pad)
     goto done;
   }
 
-  /* try to parse */
   do {
     GstFlowReturn flow;
     GstBuffer *buf = NULL;
@@ -872,6 +866,32 @@ gst_metadata_parse_activate (GstPad * pad)
 
 done:
 
+  return ret;
+
+}
+
+static gboolean
+gst_metadata_parse_activate (GstPad * pad)
+{
+  GstMetadataParse *filter = NULL;
+  gboolean ret = TRUE;
+
+
+  filter = GST_METADATA_PARSE (GST_PAD_PARENT (pad));
+
+  if (!gst_pad_check_pull_range (pad) ||
+      !gst_pad_activate_pull (filter->sinkpad, TRUE)) {
+    /* nothing to be done by now, activate push mode */
+    return gst_pad_activate_push (pad, TRUE);
+  }
+
+  /* try to parse */
+  if (filter->state == MT_STATE_NULL) {
+    ret = gst_metadata_parse_pull_range_parse (filter);
+  }
+
+done:
+
   if (ret) {
     gst_pad_activate_pull (pad, FALSE);
     gst_pad_activate_push (filter->srcpad, FALSE);
@@ -911,6 +931,10 @@ gst_metadata_parse_element_activate_src_pull (GstPad * pad, gboolean active)
 
   ret = gst_pad_activate_pull (filter->sinkpad, active);
 
+  if (ret && filter->state == MT_STATE_NULL) {
+    ret = gst_metadata_parse_pull_range_parse (filter);
+  }
+
   gst_object_unref (filter);
 
   return ret;
diff --git a/ext/metadata/gstmetadataparse.h b/ext/metadata/gstmetadataparse.h
index 5ae49cb3..eb1f802d 100644
--- a/ext/metadata/gstmetadataparse.h
+++ b/ext/metadata/gstmetadataparse.h
@@ -49,7 +49,6 @@
 #include "metadataparse.h"
 
 G_BEGIN_DECLS
-
 /* #defines don't like whitespacey bits */
 #define GST_TYPE_METADATA_PARSE \
   (gst_metadata_parse_get_type())
@@ -61,13 +60,12 @@ G_BEGIN_DECLS
   (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_METADATA_PARSE))
 #define GST_IS_METADATA_PARSE_CLASS(klass) \
   (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_METADATA_PARSE))
-
-typedef struct _GstMetadataParse      GstMetadataParse;
+typedef struct _GstMetadataParse GstMetadataParse;
 typedef struct _GstMetadataParseClass GstMetadataParseClass;
 
-typedef enum _tag_MetadataState {
-  MT_STATE_NULL,    /* still need to check media type */
-  MT_STATE_READING,
+typedef enum _tag_MetadataState
+{
+  MT_STATE_NULL,                /* still need to check media type */
   MT_STATE_PARSED
 } MetadataState;
 
@@ -85,7 +83,7 @@ struct _GstMetadataParse
 
   GstTagList *taglist;
   ParseData parse_data;
-  GstAdapter * adapter;
+  GstAdapter *adapter;
   guint32 next_offset;
   guint32 next_size;
   ImageType img_type;
@@ -98,17 +96,14 @@ struct _GstMetadataParse
 
 };
 
-struct _GstMetadataParseClass 
+struct _GstMetadataParseClass
 {
   GstElementClass parent_class;
 };
 
-extern GType
-gst_metadata_parse_get_type (void);
+extern GType gst_metadata_parse_get_type (void);
 
-extern gboolean
-gst_metadata_parse_plugin_init (GstPlugin * plugin);
+extern gboolean gst_metadata_parse_plugin_init (GstPlugin * plugin);
 
 G_END_DECLS
-
 #endif /* __GST_METADATA_PARSE_H__ */
diff --git a/ext/metadata/metadataparse.c b/ext/metadata/metadataparse.c
index 9c7dfa84..8a16bcf3 100644
--- a/ext/metadata/metadataparse.c
+++ b/ext/metadata/metadataparse.c
@@ -43,9 +43,6 @@
 
 #include "metadataparse.h"
 
-#include "metadataparsejpeg.h"
-
-
 /*
  *static declarations
  */
@@ -103,7 +100,9 @@ metadataparse_parse (ParseData * parse_data, const guint8 * buf,
           (guint8 *) buf, &bufsize, &next_start, next_size);
       break;
     case IMG_PNG:
-      ret = 0;
+      ret =
+          metadataparse_png_parse (&parse_data->format_data.png,
+          (guint8 *) buf, &bufsize, &next_start, next_size);
       break;
     default:
       /* unexpected */
@@ -131,6 +130,9 @@ metadataparse_dispose (ParseData * parse_data)
     case IMG_JPEG:
       metadataparse_jpeg_dispose (&parse_data->format_data.jpeg);
       break;
+    case IMG_PNG:
+      metadataparse_png_dispose (&parse_data->format_data.png);
+      break;
   }
 
   if (parse_data->adpt_xmp) {
@@ -169,13 +171,12 @@ metadataparse_parse_none (ParseData * parse_data, const guint8 * buf,
 
   parse_data->img_type = IMG_NONE;
 
-  if (*bufsize < 4) {
-    *next_size = 4;
+  if (*bufsize < 3) {
+    *next_size = 3;
     ret = 1;
     goto done;
   }
 
-  ret = 0;
   if (parse_data->option & PARSE_OPT_EXIF)
     adpt_exif = &parse_data->adpt_exif;
   if (parse_data->option & PARSE_OPT_IPTC)
@@ -186,12 +187,25 @@ metadataparse_parse_none (ParseData * parse_data, const guint8 * buf,
   if (buf[0] == 0xFF && buf[1] == 0xD8 && buf[2] == 0xFF) {
     metadataparse_jpeg_init (&parse_data->format_data.jpeg, adpt_exif,
         adpt_iptc, adpt_xmp);
+    ret = 0;
     parse_data->img_type = IMG_JPEG;
-  } else if (buf[0] == 0x89 && buf[1] == 0x50 && buf[2] == 0x4e
-      && buf[3] == 0x47) {
+    goto done;
+  }
+
+  if (*bufsize < 8) {
+    *next_size = 8;
+    ret = 1;
+    goto done;
+  }
+
+  if (buf[0] == 0x89 && buf[1] == 0x50 && buf[2] == 0x4E && buf[3] == 0x47 &&
+      buf[4] == 0x0D && buf[5] == 0x0A && buf[6] == 0x1A && buf[7] == 0x0A) {
+    metadataparse_png_init (&parse_data->format_data.png, adpt_exif,
+        adpt_iptc, adpt_xmp);
+    ret = 0;
     parse_data->img_type = IMG_PNG;
-  } else
-    ret = -1;
+    goto done;
+  }
 
 done:
 
diff --git a/ext/metadata/metadataparse.h b/ext/metadata/metadataparse.h
index fde0a8b8..4534f12a 100644
--- a/ext/metadata/metadataparse.h
+++ b/ext/metadata/metadataparse.h
@@ -47,35 +47,41 @@
 #include <gst/base/gstadapter.h>
 
 #include "metadataparsejpeg.h"
+#include "metadataparsepng.h"
 
 G_BEGIN_DECLS
 
-typedef enum _tag_ParseOption {
+typedef enum _tag_ParseOption
+{
   PARSE_OPT_EXIF = (1 << 0),
   PARSE_OPT_IPTC = (1 << 1),
-  PARSE_OPT_XMP  = (1 << 2),
-  PARSE_OPT_ALL  = (1 << 3) -1
+  PARSE_OPT_XMP = (1 << 2),
+  PARSE_OPT_ALL = (1 << 3) - 1
 } ParseOption;
 
-typedef enum _tag_ParseState {
+typedef enum _tag_ParseState
+{
   STATE_NULL,
   STATE_READING,
   STATE_DONE
 } ParseState;
 
-typedef enum _tag_ImageType {
+typedef enum _tag_ImageType
+{
   IMG_NONE,
   IMG_JPEG,
   IMG_PNG
 } ImageType;
 
-
-typedef struct _tag_ParseData {
+typedef struct _tag_ParseData
+{
   ParseState state;
-  ImageType  img_type;
+  ImageType img_type;
   ParseOption option;
-  union {
+  union
+  {
     JpegData jpeg;
+    PngData png;
   } format_data;
   GstAdapter *adpt_exif;
   GstAdapter *adpt_iptc;
@@ -87,8 +93,7 @@ typedef struct _tag_ParseData {
 #define set_parse_option(p, m) do { (p).option = (p).option | (m); } while(FALSE)
 #define unset_parse_option(p, m) do { (p).option = (p).option & ~(m); } while(FALSE)
 
-extern void
-metadataparse_init(ParseData *parse_data);
+extern void metadataparse_init (ParseData * parse_data);
 
 /*
  * offset: number of bytes to jump (just a hint to jump a chunk)
@@ -98,12 +103,11 @@ metadataparse_init(ParseData *parse_data);
  *    1 -> need more data
  */
 extern int
-metadataparse_parse(ParseData *parse_data, const guint8 *buf, guint32 bufsize, guint32 * next_offset, guint32 * next_size);
+metadataparse_parse (ParseData * parse_data, const guint8 * buf,
+    guint32 bufsize, guint32 * next_offset, guint32 * next_size);
 
 
-extern void
-metadataparse_dispose(ParseData *parse_data);
+extern void metadataparse_dispose (ParseData * parse_data);
 
 G_END_DECLS
-
 #endif /* __METADATAPARSE_H__ */
diff --git a/ext/metadata/metadataparseexif.c b/ext/metadata/metadataparseexif.c
index 204319ac..4b7fd4f1 100644
--- a/ext/metadata/metadataparseexif.c
+++ b/ext/metadata/metadataparseexif.c
@@ -65,7 +65,7 @@ metadataparse_exif_tag_list_add (GstTagList * taglist, GstTagMergeMode mode,
 
   GST_LOG ("EXIF not defined, here I should send just one tag as whole chunk");
 
-  metadataparse_tag_list_add_chunk (taglist, mode, GST_TAG_EXIF, adapter);
+  metadataparse_util_tag_list_add_chunk (taglist, mode, GST_TAG_EXIF, adapter);
 
 }
 
@@ -91,7 +91,7 @@ metadataparse_exif_tag_list_add (GstTagList * taglist, GstTagMergeMode mode,
   }
 
   /* add chunk tag */
-  metadataparse_tag_list_add_chunk (taglist, mode, GST_TAG_EXIF, adapter);
+  metadataparse_util_tag_list_add_chunk (taglist, mode, GST_TAG_EXIF, adapter);
 
   buf = gst_adapter_peek (adapter, size);
 
diff --git a/ext/metadata/metadataparseexif.h b/ext/metadata/metadataparseexif.h
index 4830e5a3..8c6ecb2c 100644
--- a/ext/metadata/metadataparseexif.h
+++ b/ext/metadata/metadataparseexif.h
@@ -48,13 +48,11 @@
 #include <gst/base/gstadapter.h>
 
 G_BEGIN_DECLS
+    extern void
+metadataparse_exif_tag_list_add (GstTagList * taglist, GstTagMergeMode mode,
+    GstAdapter * adapter);
 
-extern void
-metadataparse_exif_tag_list_add (GstTagList *taglist, GstTagMergeMode mode, GstAdapter * adapter);
-
-extern void
-metadataparse_exif_tags_register (void);
+extern void metadataparse_exif_tags_register (void);
 
 G_END_DECLS
-
 #endif /* __GST_METADATAPARSE_EXIF_H__ */
diff --git a/ext/metadata/metadataparseiptc.c b/ext/metadata/metadataparseiptc.c
index 3f3e5eab..ed4f803e 100644
--- a/ext/metadata/metadataparseiptc.c
+++ b/ext/metadata/metadataparseiptc.c
@@ -65,7 +65,7 @@ metadataparse_iptc_tag_list_add (GstTagList * taglist, GstTagMergeMode mode,
 
   GST_LOG ("IPTC not defined, here I should send just one tag as whole chunk");
 
-  metadataparse_tag_list_add_chunk (taglist, mode, GST_TAG_IPTC, adapter);
+  metadataparse_util_tag_list_add_chunk (taglist, mode, GST_TAG_IPTC, adapter);
 
 }
 
@@ -89,7 +89,7 @@ metadataparse_iptc_tag_list_add (GstTagList * taglist, GstTagMergeMode mode,
   }
 
   /* add chunk tag */
-  metadataparse_tag_list_add_chunk (taglist, mode, GST_TAG_IPTC, adapter);
+  metadataparse_util_tag_list_add_chunk (taglist, mode, GST_TAG_IPTC, adapter);
 
   buf = gst_adapter_peek (adapter, size);
 
diff --git a/ext/metadata/metadataparseiptc.h b/ext/metadata/metadataparseiptc.h
index 29bb559c..e45d350f 100644
--- a/ext/metadata/metadataparseiptc.h
+++ b/ext/metadata/metadataparseiptc.h
@@ -50,11 +50,10 @@
 G_BEGIN_DECLS
 
 extern void
-metadataparse_iptc_tag_list_add (GstTagList *taglist, GstTagMergeMode mode, GstAdapter * adapter);
+metadataparse_iptc_tag_list_add (GstTagList * taglist, GstTagMergeMode mode,
+    GstAdapter * adapter);
 
-extern void
-metadataparse_iptc_tags_register (void);
+extern void metadataparse_iptc_tags_register (void);
 
 G_END_DECLS
-
 #endif /* __GST_METADATAPARSE_IPTC_H__ */
diff --git a/ext/metadata/metadataparsejpeg.c b/ext/metadata/metadataparsejpeg.c
index 753d436a..1a3acb4b 100644
--- a/ext/metadata/metadataparsejpeg.c
+++ b/ext/metadata/metadataparsejpeg.c
@@ -51,12 +51,6 @@ static int
 metadataparse_jpeg_reading (JpegData * jpeg_data, guint8 ** buf,
     guint32 * bufsize, guint8 ** next_start, guint32 * next_size);
 
-
-static int
-metadataparse_jpeg_hold_chunk (JpegData * jpeg_data, guint8 ** buf,
-    guint32 * bufsize, guint8 ** next_start,
-    guint32 * next_size, GstAdapter ** adapter);
-
 static int
 metadataparse_jpeg_exif (JpegData * jpeg_data, guint8 ** buf,
     guint32 * bufsize, guint8 ** next_start, guint32 * next_size);
@@ -245,7 +239,9 @@ metadataparse_jpeg_reading (JpegData * jpeg_data, guint8 ** buf,
 
           if (jpeg_data->adpt_xmp) {
             if (0 == memcmp (XmpHeader, *buf, 29)) {
-              jpeg_data->read = chunk_size - 2;
+              *buf += 29;
+              *bufsize -= 29;
+              jpeg_data->read = chunk_size - 2 - 29;
               ret = 0;
               jpeg_data->state = JPEG_XMP;
               goto done;
@@ -292,43 +288,17 @@ done:
 }
 
 static int
-metadataparse_jpeg_hold_chunk (JpegData * jpeg_data, guint8 ** buf,
-    guint32 * bufsize, guint8 ** next_start,
-    guint32 * next_size, GstAdapter ** adapter)
+metadataparse_jpeg_exif (JpegData * jpeg_data, guint8 ** buf,
+    guint32 * bufsize, guint8 ** next_start, guint32 * next_size)
 {
   int ret;
 
-  if (jpeg_data->read > *bufsize) {
-    *next_start = *buf;
-    *next_size = jpeg_data->read;
-    ret = 1;
-  } else {
-    GstBuffer *gst_buf;
-
-    if (NULL == *adapter) {
-      *adapter = gst_adapter_new ();
-    }
-    gst_buf = gst_buffer_new_and_alloc (jpeg_data->read);
-    memcpy (GST_BUFFER_DATA (gst_buf), *buf, jpeg_data->read);
-    gst_adapter_push (*adapter, gst_buf);
-
-    *next_start = *buf + jpeg_data->read;
-    *buf += jpeg_data->read;
-    *bufsize -= jpeg_data->read;
+  ret = metadataparse_util_hold_chunk (&jpeg_data->read, buf,
+      bufsize, next_start, next_size, jpeg_data->adpt_exif);
+  if (ret == 0) {
     jpeg_data->state = JPEG_READING;
-    ret = 0;
   }
-
   return ret;
-}
-
-static int
-metadataparse_jpeg_exif (JpegData * jpeg_data, guint8 ** buf,
-    guint32 * bufsize, guint8 ** next_start, guint32 * next_size)
-{
-
-  return metadataparse_jpeg_hold_chunk (jpeg_data, buf,
-      bufsize, next_start, next_size, jpeg_data->adpt_exif);
 
 }
 
@@ -339,7 +309,7 @@ metadataparse_jpeg_iptc (JpegData * jpeg_data, guint8 ** buf,
 
   int ret;
 
-  ret = metadataparse_jpeg_hold_chunk (jpeg_data, buf,
+  ret = metadataparse_util_hold_chunk (&jpeg_data->read, buf,
       bufsize, next_start, next_size, jpeg_data->adpt_iptc);
 
 
@@ -350,6 +320,8 @@ metadataparse_jpeg_iptc (JpegData * jpeg_data, guint8 ** buf,
     unsigned int iptc_len;
     int res;
 
+    jpeg_data->state = JPEG_READING;
+
     size = gst_adapter_available (*jpeg_data->adpt_iptc);
     buf = gst_adapter_peek (*jpeg_data->adpt_iptc, size);
 
@@ -383,32 +355,22 @@ static int
 metadataparse_jpeg_xmp (JpegData * jpeg_data, guint8 ** buf,
     guint32 * bufsize, guint8 ** next_start, guint32 * next_size)
 {
+  int ret;
 
-  return metadataparse_jpeg_hold_chunk (jpeg_data, buf,
+  ret = metadataparse_util_hold_chunk (&jpeg_data->read, buf,
       bufsize, next_start, next_size, jpeg_data->adpt_xmp);
 
+  if (ret == 0) {
+    jpeg_data->state = JPEG_READING;
+  }
+  return ret;
 }
 
 static int
 metadataparse_jpeg_jump (JpegData * jpeg_data, guint8 ** buf,
     guint32 * bufsize, guint8 ** next_start, guint32 * next_size)
 {
-  int ret;
-
-  if (jpeg_data->read > *bufsize) {
-    jpeg_data->read -= *bufsize;
-    *next_size = 2;
-    *next_start = *buf + *bufsize + jpeg_data->read;
-    jpeg_data->read = 0;
-    *bufsize = 0;
-    jpeg_data->state = JPEG_READING;
-    ret = 1;
-  } else {
-    *next_start = *buf + jpeg_data->read;
-    *buf += jpeg_data->read;
-    *bufsize -= jpeg_data->read;
-    jpeg_data->state = JPEG_READING;
-    ret = 0;
-  }
-  return ret;
+  jpeg_data->state = JPEG_READING;
+  return metadataparse_util_jump_chunk (&jpeg_data->read, buf,
+      bufsize, next_start, next_size);
 }
diff --git a/ext/metadata/metadataparsejpeg.h b/ext/metadata/metadataparsejpeg.h
index 67e5ac0e..d7f1660d 100644
--- a/ext/metadata/metadataparsejpeg.h
+++ b/ext/metadata/metadataparsejpeg.h
@@ -48,7 +48,8 @@
 
 G_BEGIN_DECLS
 
-typedef enum  _tag_JpegState {
+typedef enum _tag_JpegState
+{
   JPEG_NULL,
   JPEG_READING,
   JPEG_JUMPING,
@@ -59,7 +60,8 @@ typedef enum  _tag_JpegState {
 } JpegState;
 
 
-typedef struct _tag_JpegData {
+typedef struct _tag_JpegData
+{
   JpegState state;
   GstAdapter **adpt_exif;
   GstAdapter **adpt_iptc;
@@ -69,17 +71,15 @@ typedef struct _tag_JpegData {
 
 
 extern void
-metadataparse_jpeg_init(JpegData *jpeg_data, GstAdapter **adpt_exif, GstAdapter **adpt_iptc, GstAdapter **adpt_xmp);
+metadataparse_jpeg_init (JpegData * jpeg_data, GstAdapter ** adpt_exif,
+    GstAdapter ** adpt_iptc, GstAdapter ** adpt_xmp);
 
-extern void
-metadataparse_jpeg_dispose(JpegData *jpeg_data);
+extern void metadataparse_jpeg_dispose (JpegData * jpeg_data);
 
 
 int
-metadataparse_jpeg_parse(JpegData *jpeg_data, guint8 *buf,
-			 guint32 *bufsize, guint8 ** next_start,
-			 guint32 * next_size);
+metadataparse_jpeg_parse (JpegData * jpeg_data, guint8 * buf,
+    guint32 * bufsize, guint8 ** next_start, guint32 * next_size);
 
 G_END_DECLS
-
 #endif /* __METADATAPARSE_JPEG_H__ */
diff --git a/ext/metadata/metadataparsepng.c b/ext/metadata/metadataparsepng.c
new file mode 100644
index 00000000..9c3241cf
--- /dev/null
+++ b/ext/metadata/metadataparsepng.c
@@ -0,0 +1,245 @@
+/*
+ * GStreamer
+ * Copyright 2007 Edgard Lima <edgard.lima@indt.org.br>
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Alternatively, the contents of this file may be used under the
+ * GNU Lesser General Public License Version 2.1 (the "LGPL"), in
+ * which case the following provisions apply instead of the ones
+ * mentioned above:
+ *
+ * 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.
+ */
+
+#include "metadataparsepng.h"
+
+#include <string.h>
+
+static int
+metadataparse_png_reading (PngData * png_data, guint8 ** buf,
+    guint32 * bufsize, guint8 ** next_start, guint32 * next_size);
+
+static int
+metadataparse_png_xmp (PngData * png_data, guint8 ** buf,
+    guint32 * bufsize, guint8 ** next_start, guint32 * next_size);
+
+static int
+metadataparse_png_jump (PngData * png_data, guint8 ** buf,
+    guint32 * bufsize, guint8 ** next_start, guint32 * next_size);
+
+#define READ(buf, size) ( (size)--, *((buf)++) )
+
+void
+metadataparse_png_init (PngData * png_data, GstAdapter ** adpt_exif,
+    GstAdapter ** adpt_iptc, GstAdapter ** adpt_xmp)
+{
+  png_data->state = PNG_NULL;
+  png_data->adpt_xmp = adpt_xmp;
+  png_data->read = 0;
+
+  metadataparse_xmp_init ();
+}
+
+void
+metadataparse_png_dispose (PngData * png_data)
+{
+  metadataparse_xmp_dispose ();
+
+  png_data->adpt_xmp = NULL;
+}
+
+int
+metadataparse_png_parse (PngData * png_data, guint8 * buf,
+    guint32 * bufsize, guint8 ** next_start, guint32 * next_size)
+{
+
+  int ret = 0;
+  guint8 mark[8];
+
+  *next_start = buf;
+
+  if (png_data->state == PNG_NULL) {
+
+    if (*bufsize < 8) {
+      *next_size = (buf - *next_start) + 8;
+      ret = 1;
+      goto done;
+    }
+
+    mark[0] = READ (buf, *bufsize);
+    mark[1] = READ (buf, *bufsize);
+    mark[2] = READ (buf, *bufsize);
+    mark[3] = READ (buf, *bufsize);
+    mark[4] = READ (buf, *bufsize);
+    mark[5] = READ (buf, *bufsize);
+    mark[6] = READ (buf, *bufsize);
+    mark[7] = READ (buf, *bufsize);
+
+    if (mark[0] != 0x89 || mark[1] != 0x50 || mark[2] != 0x4E || mark[3] != 0x47
+        || mark[4] != 0x0D || mark[5] != 0x0A || mark[6] != 0x1A
+        || mark[7] != 0x0A) {
+      ret = -1;
+      goto done;
+    }
+
+    png_data->state = PNG_READING;
+
+  }
+
+  while (ret == 0) {
+    switch (png_data->state) {
+      case PNG_READING:
+        ret =
+            metadataparse_png_reading (png_data, &buf, bufsize, next_start,
+            next_size);
+        break;
+      case PNG_JUMPING:
+        ret =
+            metadataparse_png_jump (png_data, &buf, bufsize, next_start,
+            next_size);
+        break;
+      case PNG_XMP:
+        ret =
+            metadataparse_png_xmp (png_data, &buf, bufsize, next_start,
+            next_size);
+        break;
+      case PNG_DONE:
+        goto done;
+        break;
+      default:
+        ret = -1;
+        break;
+    }
+  }
+
+done:
+
+  return ret;
+
+}
+
+
+/* look for markers */
+static int
+metadataparse_png_reading (PngData * png_data, guint8 ** buf,
+    guint32 * bufsize, guint8 ** next_start, guint32 * next_size)
+{
+
+  int ret = -1;
+  guint8 mark[4];
+  guint32 chunk_size = 0;
+
+  static const char XmpHeader[] = "XML:com.adobe.xmp";
+
+  *next_start = *buf;
+
+  if (*bufsize < 8) {
+    *next_size = (*buf - *next_start) + 8;
+    ret = 1;
+    goto done;
+  }
+
+  chunk_size = READ (*buf, *bufsize) << 24;
+  chunk_size += READ (*buf, *bufsize) << 16;
+  chunk_size += READ (*buf, *bufsize) << 8;
+  chunk_size += READ (*buf, *bufsize);
+
+  mark[0] = READ (*buf, *bufsize);
+  mark[1] = READ (*buf, *bufsize);
+  mark[2] = READ (*buf, *bufsize);
+  mark[3] = READ (*buf, *bufsize);
+
+  if (mark[0] == 'I' && mark[1] == 'E' && mark[2] == 'N' && mark[3] == 'D') {
+    ret = 0;
+    png_data->state = PNG_DONE;
+    goto done;
+  }
+
+  if (mark[0] == 'i' && mark[1] == 'T' && mark[2] == 'X' && mark[3] == 't') {
+    if (chunk_size >= 22) {     /* "XML:com.adobe.xmp" plus some flags */
+      if (*bufsize < 22) {
+        *next_size = (*buf - *next_start) + 22;
+        ret = 1;
+        goto done;
+      }
+
+      if (png_data->adpt_xmp) {
+        if (0 == memcmp (XmpHeader, *buf, 18)) {
+          *buf += 22;           /* jump "XML:com.adobe.xmp" plus some flags */
+          *bufsize -= 22;
+          png_data->read = chunk_size - 22;     /* four CRC bytes at the end will be jumped after */
+          png_data->state = PNG_XMP;
+          ret = 0;
+          goto done;
+        }
+      }
+    }
+  }
+
+  /* just set jump sise  */
+  png_data->read = chunk_size + 4;      /* four CRC bytes at the end */
+  png_data->state = PNG_JUMPING;
+  ret = 0;
+
+done:
+
+  return ret;
+
+
+}
+
+static int
+metadataparse_png_jump (PngData * png_data, guint8 ** buf,
+    guint32 * bufsize, guint8 ** next_start, guint32 * next_size)
+{
+  png_data->state = PNG_READING;
+  return metadataparse_util_jump_chunk (&png_data->read, buf,
+      bufsize, next_start, next_size);
+}
+
+static int
+metadataparse_png_xmp (PngData * png_data, guint8 ** buf,
+    guint32 * bufsize, guint8 ** next_start, guint32 * next_size)
+{
+  int ret;
+
+  ret = metadataparse_util_hold_chunk (&png_data->read, buf,
+      bufsize, next_start, next_size, png_data->adpt_xmp);
+  if (ret == 0) {
+    /* jump four CRC bytes at the end of chunk */
+    png_data->read = 4;
+    png_data->state = PNG_JUMPING;
+  }
+  return ret;
+
+}
diff --git a/ext/metadata/metadataparsepng.h b/ext/metadata/metadataparsepng.h
new file mode 100644
index 00000000..99f0f7ea
--- /dev/null
+++ b/ext/metadata/metadataparsepng.h
@@ -0,0 +1,81 @@
+/*
+ * GStreamer
+ * Copyright 2007 Edgard Lima <edgard.lima@indt.org.br>
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Alternatively, the contents of this file may be used under the
+ * GNU Lesser General Public License Version 2.1 (the "LGPL"), in
+ * which case the following provisions apply instead of the ones
+ * mentioned above:
+ *
+ * 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.
+ */
+
+#ifndef __METADATAPARSE_PNG_H__
+#define __METADATAPARSE_PNG_H__
+
+#include <gst/base/gstadapter.h>
+
+G_BEGIN_DECLS
+
+typedef enum _tag_PngState
+{
+  PNG_NULL,
+  PNG_READING,
+  PNG_JUMPING,
+  PNG_XMP,
+  PNG_DONE
+} PngState;
+
+
+typedef struct _tag_PngData
+{
+  PngState state;
+  GstAdapter **adpt_xmp;
+  guint32 read;
+} PngData;
+
+
+extern void
+metadataparse_png_init (PngData * png_data, GstAdapter ** adpt_exif,
+    GstAdapter ** adpt_iptc, GstAdapter ** adpt_xmp);
+
+extern void metadataparse_png_dispose (PngData * png_data);
+
+
+int
+metadataparse_png_parse (PngData * png_data, guint8 * buf,
+    guint32 * bufsize, guint8 ** next_start, guint32 * next_size);
+
+G_END_DECLS
+#endif /* __METADATAPARSE_PNG_H__ */
diff --git a/ext/metadata/metadataparseutil.c b/ext/metadata/metadataparseutil.c
index dfab579f..ff1b8826 100644
--- a/ext/metadata/metadataparseutil.c
+++ b/ext/metadata/metadataparseutil.c
@@ -44,8 +44,8 @@
 #include "metadataparseutil.h"
 
 void
-metadataparse_tag_list_add_chunk (GstTagList * taglist, GstTagMergeMode mode,
-    const gchar * name, GstAdapter * adapter)
+metadataparse_util_tag_list_add_chunk (GstTagList * taglist,
+    GstTagMergeMode mode, const gchar * name, GstAdapter * adapter)
 {
   GstBuffer *buf;
   guint size;
@@ -62,3 +62,57 @@ metadataparse_tag_list_add_chunk (GstTagList * taglist, GstTagMergeMode mode,
   }
 
 }
+
+int
+metadataparse_util_hold_chunk (guint32 * read, guint8 ** buf,
+    guint32 * bufsize, guint8 ** next_start,
+    guint32 * next_size, GstAdapter ** adapter)
+{
+  int ret;
+
+  if (*read > *bufsize) {
+    *next_start = *buf;
+    *next_size = *read;
+    ret = 1;
+  } else {
+    GstBuffer *gst_buf;
+
+    if (NULL == *adapter) {
+      *adapter = gst_adapter_new ();
+    }
+    gst_buf = gst_buffer_new_and_alloc (*read);
+    memcpy (GST_BUFFER_DATA (gst_buf), *buf, *read);
+    gst_adapter_push (*adapter, gst_buf);
+
+    *next_start = *buf + *read;
+    *buf += *read;
+    *bufsize -= *read;
+    *read = 0;
+    ret = 0;
+  }
+
+  return ret;
+}
+
+int
+metadataparse_util_jump_chunk (guint32 * read, guint8 ** buf,
+    guint32 * bufsize, guint8 ** next_start, guint32 * next_size)
+{
+  int ret;
+
+  if (*read > *bufsize) {
+    *read -= *bufsize;
+    *next_size = 2;
+    *next_start = *buf + *bufsize + *read;
+    *read = 0;
+    *bufsize = 0;
+    ret = 1;
+  } else {
+    *next_start = *buf + *read;
+    *buf += *read;
+    *bufsize -= *read;
+    *read = 0;
+    ret = 0;
+  }
+  return ret;
+}
diff --git a/ext/metadata/metadataparseutil.h b/ext/metadata/metadataparseutil.h
index 75129843..5d49b54b 100644
--- a/ext/metadata/metadataparseutil.h
+++ b/ext/metadata/metadataparseutil.h
@@ -50,9 +50,15 @@
 G_BEGIN_DECLS
 
 extern void
-metadataparse_tag_list_add_chunk (GstTagList * taglist, GstTagMergeMode mode,
-				  const gchar * name, GstAdapter * adapter);
+metadataparse_util_tag_list_add_chunk (GstTagList * taglist,
+    GstTagMergeMode mode, const gchar * name, GstAdapter * adapter);
+extern int metadataparse_util_hold_chunk (guint32 * read, guint8 ** buf,
+    guint32 * bufsize, guint8 ** next_start, guint32 * next_size,
+    GstAdapter ** adapter);
 
-G_END_DECLS
+extern int
+metadataparse_util_jump_chunk (guint32 * read, guint8 ** buf,
+    guint32 * bufsize, guint8 ** next_start, guint32 * next_size);
 
+G_END_DECLS
 #endif /* __GST_METADATAPARSE_UTIL_H__ */
diff --git a/ext/metadata/metadataparsexmp.c b/ext/metadata/metadataparsexmp.c
index 9b583002..aa503d35 100644
--- a/ext/metadata/metadataparsexmp.c
+++ b/ext/metadata/metadataparsexmp.c
@@ -65,7 +65,7 @@ metadataparse_xmp_tag_list_add (GstTagList * taglist, GstTagMergeMode mode,
 
   GST_LOG ("XMP not defined, here I should send just one tag as whole chunk");
 
-  metadataparse_tag_list_add_chunk (taglist, mode, GST_TAG_XMP, adapter);
+  metadataparse_util_tag_list_add_chunk (taglist, mode, GST_TAG_XMP, adapter);
 
 }
 
@@ -111,13 +111,10 @@ metadataparse_xmp_tag_list_add (GstTagList * taglist, GstTagMergeMode mode,
   }
 
   /* add chunk tag */
-  metadataparse_tag_list_add_chunk (taglist, mode, GST_TAG_XMP, adapter);
+  metadataparse_util_tag_list_add_chunk (taglist, mode, GST_TAG_XMP, adapter);
 
   buf = gst_adapter_peek (adapter, size);
 
-  buf += 29;                    /* jump "http://ns.adobe.com/xap/1.0/" */
-  size -= 29;
-
   xmp = xmp_new (buf, size);
   if (!xmp)
     goto done;
@@ -128,7 +125,6 @@ metadataparse_xmp_tag_list_add (GstTagList * taglist, GstTagMergeMode mode,
 
   xmp_serialize (xmp, xmp_str, XMP_SERIAL_ENCODEUTF8, 2);
 
-
   GST_LOG (xmp_string_cstr (xmp_str));
 
 done:
diff --git a/ext/metadata/metadataparsexmp.h b/ext/metadata/metadataparsexmp.h
index 07e34a95..80b93a39 100644
--- a/ext/metadata/metadataparsexmp.h
+++ b/ext/metadata/metadataparsexmp.h
@@ -50,17 +50,14 @@
 G_BEGIN_DECLS
 
 extern void
-metadataparse_xmp_tag_list_add (GstTagList *taglist, GstTagMergeMode mode, GstAdapter * adapter);
+metadataparse_xmp_tag_list_add (GstTagList * taglist, GstTagMergeMode mode,
+    GstAdapter * adapter);
 
-extern gboolean
-metadataparse_xmp_init(void);
+extern gboolean metadataparse_xmp_init (void);
 
-extern void
-metadataparse_xmp_dispose(void);
+extern void metadataparse_xmp_dispose (void);
 
-extern void
-metadataparse_xmp_tags_register (void);
+extern void metadataparse_xmp_tags_register (void);
 
 G_END_DECLS
-
 #endif /* __GST_METADATAPARSE_XMP_H__ */