AC3 -> IEC958 (S/PDIF) framer, based on Martin Soto's 0.8 plugin

Original commit message from CVS:
AC3 -> IEC958 (S/PDIF) framer, based on Martin Soto's 0.8 plugin

7 files changed, 823 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 0ca5976b..e168c183 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,17 @@
+2005-09-01  Michael Smith <msmith@fluendo.com>
+
+	* configure.ac:
+	* gst/iec958/Makefile.am:
+	* gst/iec958/ac3_padder.c: (ac3p_init), (ac3p_push_data),
+	(ac3p_parse):
+	* gst/iec958/ac3_padder.h:
+	* gst/iec958/ac3iec.c: (ac3iec_get_type), (ac3iec_base_init),
+	(ac3iec_class_init), (ac3iec_init), (ac3iec_finalize),
+	(ac3iec_set_property), (ac3iec_get_property), (ac3iec_chain),
+	(ac3iec_change_state), (plugin_init):
+	* gst/iec958/ac3iec.h:
+	  AC3 -> IEC958 (S/PDIF) framer, port of Martin Soto's 0.8 plugin.
+
 2005-09-01  Wim Taymans  <wim@fluendo.com>
 
 	* gst/dvdlpcmdec/gstdvdlpcmdec.c: (gst_dvdlpcmdec_setcaps),
diff --git a/configure.ac b/configure.ac
index 3d399411..7eb0ed25 100644
--- a/configure.ac
+++ b/configure.ac
@@ -215,6 +215,7 @@ AC_SUBST(GST_PLUGIN_LDFLAGS)
 dnl these are all the gst plug-ins, compilable without additional libs
 GST_PLUGINS_ALL="\
 		dvdlpcmdec \
+                iec958 \
 		mpegaudioparse \
 		realmedia \
                 "
@@ -382,6 +383,7 @@ AC_CONFIG_FILES(
 Makefile
 gst/Makefile
 gst/dvdlpcmdec/Makefile
+gst/iec958/Makefile
 gst/mpegaudioparse/Makefile
 gst/realmedia/Makefile
 ext/Makefile
diff --git a/gst/iec958/Makefile.am b/gst/iec958/Makefile.am
new file mode 100644
index 00000000..a83dce94
--- /dev/null
+++ b/gst/iec958/Makefile.am
@@ -0,0 +1,9 @@
+plugin_LTLIBRARIES = libiec958.la
+
+libiec958_la_SOURCES = ac3iec.c ac3_padder.c
+libiec958_la_CFLAGS = $(GLIB_CFLAGS) $(GST_CFLAGS) \
+    $(GSTLIBS_CFLAGS) $(EXTRA_CFLAGS)
+libiec958_la_LIBADD = $(GLIB_LIBS) $(GST_LIBS) $(GSTLIBS_LIBS)
+libiec958_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS)
+
+noinst_HEADERS = ac3_padder.h ac3iec.h 
diff --git a/gst/iec958/ac3_padder.c b/gst/iec958/ac3_padder.c
new file mode 100644
index 00000000..9ec551de
--- /dev/null
+++ b/gst/iec958/ac3_padder.c
@@ -0,0 +1,250 @@
+/* GStreamer
+ * Copyright (C) 2003, 2004 Martin Soto <martinsoto@users.sourceforge.net>
+ *
+ * ac3_padder.c: Pad AC3 frames for use with an SPDIF interface.
+ *
+ * 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 <stdio.h>
+#include <string.h>
+
+#include "ac3_padder.h"
+
+#define IEC61937_DATA_TYPE_AC3 1
+
+struct frmsize_s
+{
+  unsigned short bit_rate;
+  unsigned short frm_size[3];
+};
+
+
+static const struct frmsize_s frmsizecod_tbl[64] = {
+  {32, {64, 69, 96}},
+  {32, {64, 70, 96}},
+  {40, {80, 87, 120}},
+  {40, {80, 88, 120}},
+  {48, {96, 104, 144}},
+  {48, {96, 105, 144}},
+  {56, {112, 121, 168}},
+  {56, {112, 122, 168}},
+  {64, {128, 139, 192}},
+  {64, {128, 140, 192}},
+  {80, {160, 174, 240}},
+  {80, {160, 175, 240}},
+  {96, {192, 208, 288}},
+  {96, {192, 209, 288}},
+  {112, {224, 243, 336}},
+  {112, {224, 244, 336}},
+  {128, {256, 278, 384}},
+  {128, {256, 279, 384}},
+  {160, {320, 348, 480}},
+  {160, {320, 349, 480}},
+  {192, {384, 417, 576}},
+  {192, {384, 418, 576}},
+  {224, {448, 487, 672}},
+  {224, {448, 488, 672}},
+  {256, {512, 557, 768}},
+  {256, {512, 558, 768}},
+  {320, {640, 696, 960}},
+  {320, {640, 697, 960}},
+  {384, {768, 835, 1152}},
+  {384, {768, 836, 1152}},
+  {448, {896, 975, 1344}},
+  {448, {896, 976, 1344}},
+  {512, {1024, 1114, 1536}},
+  {512, {1024, 1115, 1536}},
+  {576, {1152, 1253, 1728}},
+  {576, {1152, 1254, 1728}},
+  {640, {1280, 1393, 1920}},
+  {640, {1280, 1394, 1920}}
+};
+
+
+
+/* Go one byte forward in the input buffer. */
+#define ac3p_in_fw(padder) ((padder)->in_ptr++, (padder)->remaining--)
+
+/* Go one byte forward in the output buffer. */
+#define ac3p_out_fw(padder) ((padder)->out_ptr++, (padder)->bytes_to_copy--)
+
+
+/**
+ * ac3p_init
+ * @padder: The padder structure to initialize.
+ *
+ * Initializes an AC3 stream padder.  This structure can be
+ * subsequently used to parse an AC3 stream and convert it to IEC958
+ * (S/PDIF) padded packets.
+ */
+extern void
+ac3p_init (ac3_padder * padder)
+{
+  const char sync[4] = { 0x72, 0xF8, 0x1F, 0x4E };
+
+  padder->state = AC3P_STATE_SYNC1;
+
+  /* No material to read yet. */
+  padder->remaining = 0;
+
+  /* Initialize the sync bytes in the frame. */
+  memcpy (padder->frame.header, sync, 4);
+}
+
+
+/**
+ * ac3_push_data
+ * @padder The padder structure.
+ * @data A pointer to a buffer with new data to parse.  This should 
+ * correspond to a new piece of a stream containing raw AC3 data.
+ * @size The number of available bytes in the buffer.
+ *
+ * Pushes a new buffer of data to be parsed by the ac3 padder.  The
+ * ac3_parse() function will actually parse the data and report when
+ * new frames are found.  This funcion should only be called once at
+ * the beginning of the parsing process, or when the ac3_parse()
+ * function returns the %AC3P_EVENT_PUSH event.
+ */
+extern void
+ac3p_push_data (ac3_padder * padder, guchar * data, guint size)
+{
+  padder->in_ptr = data;
+  padder->remaining = size;
+}
+
+
+/**
+ * ac3p_parse
+ * @padder The padder structure.
+ * 
+ * Parses the bytes already pushed into the padder structure (see
+ * ac3p_push_data()) and returns an event value depending on the
+ * results of the parsing.
+ *
+ * Returns: %AC3P_EVENT_FRAME to indicate that a new AC3 was found and
+ * padded for IEC958 transmission.  This frame can be read inmediatly
+ * with ac3p_frame(). %AC3P_EVENT_PUSH to indicate that new data from
+ * the input stream must be pushed into the padder using
+ * ac3p_push_data().  This function should be called again after
+ * pushing the data.
+ */
+extern int
+ac3p_parse (ac3_padder * padder)
+{
+  while (padder->remaining > 0) {
+    switch (padder->state) {
+      case AC3P_STATE_SYNC1:
+        if (*(padder->in_ptr) == 0x0b) {
+          /* The first sync byte was found.  Go to the next state. */
+          padder->frame.sync_byte1 = 0x0b;
+          padder->state = AC3P_STATE_SYNC2;
+        }
+        ac3p_in_fw (padder);
+        break;
+
+      case AC3P_STATE_SYNC2:
+        if (*(padder->in_ptr) == 0x77) {
+          /* The second sync byte was seen right after the first.  Go to
+             the next state. */
+          padder->frame.sync_byte2 = 0x77;
+          padder->state = AC3P_STATE_HEADER;
+
+          /* Skip one byte. */
+          ac3p_in_fw (padder);
+
+          /* Prepare for reading the header. */
+          padder->out_ptr = (guchar *) & (padder->frame.crc1);
+          /* Discount the 2 sync bytes from the header size. */
+          padder->bytes_to_copy = AC3P_AC3_HEADER_SIZE - 2;
+        } else {
+          /* The second sync byte was not seen.  Go back to the
+             first state. */
+          padder->state = AC3P_STATE_SYNC1;
+        }
+        break;
+
+      case AC3P_STATE_HEADER:
+        if (padder->bytes_to_copy > 0) {
+          /* Copy one byte. */
+          *(padder->out_ptr) = *(padder->in_ptr);
+          ac3p_in_fw (padder);
+          ac3p_out_fw (padder);
+        } else {
+          int fscod;
+
+          /* The header is ready: */
+
+          fscod = (padder->frame.code >> 6) & 0x03;
+
+          /* Calculate the frame size. */
+          padder->ac3_frame_size =
+              2 * frmsizecod_tbl[padder->frame.code & 0x3f].frm_size[fscod];
+
+          /* Set up the IEC header. */
+          if (padder->ac3_frame_size > 0) {
+            padder->frame.header[4] = IEC61937_DATA_TYPE_AC3;
+          } else {
+            /* Don't know what it is, better be careful. */
+            padder->state = AC3P_STATE_SYNC1;
+            break;
+          }
+          padder->frame.header[5] = 0x00;
+          padder->frame.header[6] = (padder->ac3_frame_size * 8) & 0xFF;
+          padder->frame.header[7] = ((padder->ac3_frame_size * 8) >> 8) & 0xFF;
+
+          /* Prepare for reading the body. */
+          padder->bytes_to_copy = padder->ac3_frame_size - AC3P_AC3_HEADER_SIZE;
+          padder->state = AC3P_STATE_CONTENT;
+        }
+        break;
+
+      case AC3P_STATE_CONTENT:
+        if (padder->bytes_to_copy > 0) {
+          /* Copy one byte. */
+          *(padder->out_ptr) = *(padder->in_ptr);
+          ac3p_in_fw (padder);
+          ac3p_out_fw (padder);
+        } else {
+          guint16 *ptr, i;
+
+          /* Frame ready.  Prepare for output: */
+
+          /* Zero the non AC3 portion of the padded frame. */
+          memset (&(padder->frame.sync_byte1) + padder->ac3_frame_size, 0,
+              AC3P_IEC_FRAME_SIZE - AC3P_IEC_HEADER_SIZE -
+              padder->ac3_frame_size);
+
+          /* Fix the byte order in the AC3 portion: */
+          ptr = (guint16 *) & (padder->frame.sync_byte1);
+          i = padder->ac3_frame_size / 2;
+          while (i > 0) {
+            *ptr = GUINT16_TO_BE (*ptr);
+            ptr++;
+            i--;
+          }
+
+          /* Start over again. */
+          padder->state = AC3P_STATE_SYNC1;
+
+          return AC3P_EVENT_FRAME;
+        }
+        break;
+    }
+  }
+
+  return AC3P_EVENT_PUSH;
+}
diff --git a/gst/iec958/ac3_padder.h b/gst/iec958/ac3_padder.h
new file mode 100644
index 00000000..032f41fb
--- /dev/null
+++ b/gst/iec958/ac3_padder.h
@@ -0,0 +1,138 @@
+/* GStreamer
+ * Copyright (C) 2003 Martin Soto <martinsoto@users.sourceforge.net>
+ *
+ * ac3_padder.h: Pad AC3 frames for use with an SPDIF interface. 
+ *
+ * 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 AC3_PADDER_INC
+#define AC3_PADDER_INC
+
+#include <glib.h>
+
+
+/* Size of an IEC958 padded AC3 frame. */
+#define AC3P_IEC_FRAME_SIZE 6144
+/* Size of the IEC958 header. */
+#define AC3P_IEC_HEADER_SIZE 8
+/* Size of the AC3 header. */
+#define AC3P_AC3_HEADER_SIZE 7
+
+
+/* An IEC958 padded AC3 frame. */
+typedef struct {
+  /* IEC header. */
+  guchar header[AC3P_IEC_HEADER_SIZE];
+
+  /* Begin of AC3 header. */
+  guchar sync_byte1;
+  guchar sync_byte2;
+
+  guchar crc1[2];
+  guchar code;
+  guchar bsidmod;
+  guchar acmod;
+  /* End of AC3 header. */
+  
+  unsigned char data[AC3P_IEC_FRAME_SIZE - AC3P_IEC_HEADER_SIZE 
+                     - AC3P_AC3_HEADER_SIZE];
+} ac3p_iec958_burst_frame;
+
+
+/* Possible states for the reading automaton: */
+
+/* Searching for sync byte 1. */
+#define AC3P_STATE_SYNC1 1
+/* Searching for sync byte 2. */
+#define AC3P_STATE_SYNC2 2
+/* Reading AC3 header. */
+#define AC3P_STATE_HEADER 3
+/* Reading packet contents.*/
+#define AC3P_STATE_CONTENT 4
+
+
+/* Events generated by the parse function: */
+
+/* The parser needs new data to be pushed. */
+#define AC3P_EVENT_PUSH 1
+/* There is a new padded frame ready to read from the padder structure. */
+#define AC3P_EVENT_FRAME 2
+
+
+/* The internal state for the padder. */
+typedef struct {
+  guint state;       /* State of the reading automaton. */
+
+  guchar *in_ptr;    /* Input pointer, marking the current
+                        postion in the input buffer. */
+  guint remaining;   /* The number of bytes remaining in the current
+                        reading buffer. */
+
+  guchar *out_ptr;   /* Output pointer, marking the current
+                        position in the output frame. */
+  guint bytes_to_copy;
+                     /* Number of bytes that still must be copied
+                        to the output frame *during this reading
+                        stage*. */
+
+  guint ac3_frame_size;
+                     /* The size in bytes of the pure AC3 portion
+                        of the current frame. */
+
+  ac3p_iec958_burst_frame frame;
+                     /* The current output frame. */
+} ac3_padder;
+
+
+
+extern void
+ac3p_init(ac3_padder *padder);
+
+extern void
+ac3p_push_data(ac3_padder *padder, guchar *data, guint size);
+
+extern int
+ac3p_parse(ac3_padder *padder);
+
+
+/**
+ * ac3p_frame
+ * @padder The padder structure.
+ *
+ * Returns a pointer to the padded frame contained in the padder.
+ */
+#define ac3p_frame(padder) ((guint8 *) &((padder)->frame))
+
+/**
+ * ac3p_frame_size
+ * @padder The padder structure.
+ *
+ * Returns the length in bytes of the last read raw AC3 frame.
+ */
+#define ac3p_frame_size(padder) ((padder)->ac3_frame_size)
+
+/**
+ * ac3p_pending
+ * @padder The padder structure.
+ *
+ * Returns a boolean value telling if there are pending material in
+ * the padder.
+ */
+#define ac3p_pending(padder) ((padder)->remaining > 0)
+
+
+#endif
diff --git a/gst/iec958/ac3iec.c b/gst/iec958/ac3iec.c
new file mode 100644
index 00000000..7707f4d9
--- /dev/null
+++ b/gst/iec958/ac3iec.c
@@ -0,0 +1,331 @@
+/* GStreamer
+ * Copyright (C) 2004 Martin Soto <martinsoto@users.sourceforge.net>
+ *
+ * ac3iec.c: Pad AC3 frames into IEC958 frames for the SP/DIF interface.
+ *
+ * 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 <string.h>
+
+#include <gst/gst.h>
+
+#include "ac3iec.h"
+
+
+GST_DEBUG_CATEGORY_STATIC (ac3iec_debug);
+#define GST_CAT_DEFAULT (ac3iec_debug)
+
+
+/* The duration of a single IEC958 frame. */
+#define IEC958_FRAME_DURATION (32 * GST_MSECOND)
+
+
+/* ElementFactory information. */
+static GstElementDetails ac3iec_details = {
+  "AC3 to IEC958 filter",
+  "audio/x-ac3",
+  "Pads AC3 frames into IEC958 frames suitable for a raw SP/DIF interface",
+  "Martin Soto <martinsoto@users.sourceforge.net>"
+};
+
+
+/* AC3IEC signals and args */
+enum
+{
+  LAST_SIGNAL,
+};
+
+enum
+{
+  ARG_0,
+};
+
+
+static GstStaticPadTemplate ac3iec_sink_template =
+GST_STATIC_PAD_TEMPLATE ("sink",
+    GST_PAD_SINK,
+    GST_PAD_ALWAYS,
+    GST_STATIC_CAPS ("audio/x-ac3")
+    );
+
+static GstStaticPadTemplate ac3iec_src_template =
+GST_STATIC_PAD_TEMPLATE ("src",
+    GST_PAD_SRC,
+    GST_PAD_ALWAYS,
+#if 1
+    GST_STATIC_CAPS ("audio/x-raw-int, "
+        "law = (int) 0, "
+        "endianness = (int) " G_STRINGIFY (G_LITTLE_ENDIAN) ", "
+        "signed = (boolean) true, "
+        "width = (int) 16, "
+        "depth = (int) 16, " "rate = (int) 48000, " "channels = (int) 2")
+#endif
+#if 0
+    GST_STATIC_CAPS ("audio/x-iec958")
+#endif
+    );
+
+
+static void ac3iec_base_init (gpointer g_class);
+static void ac3iec_class_init (AC3IECClass * klass);
+static void ac3iec_init (AC3IEC * ac3iec);
+static void ac3iec_finalize (GObject * object);
+
+static void ac3iec_set_property (GObject * object,
+    guint prop_id, const GValue * value, GParamSpec * pspec);
+static void ac3iec_get_property (GObject * object,
+    guint prop_id, GValue * value, GParamSpec * pspec);
+
+static GstFlowReturn ac3iec_chain (GstPad * pad, GstBuffer * buf);
+
+static GstElementStateReturn ac3iec_change_state (GstElement * element);
+
+
+static GstElementClass *parent_class = NULL;
+
+/* static guint ac3iec_signals[LAST_SIGNAL] = { 0 }; */
+
+
+GType
+ac3iec_get_type (void)
+{
+  static GType ac3iec_type = 0;
+
+  if (!ac3iec_type) {
+    static const GTypeInfo ac3iec_info = {
+      sizeof (AC3IECClass),
+      ac3iec_base_init,
+      NULL,
+      (GClassInitFunc) ac3iec_class_init,
+      NULL,
+      NULL,
+      sizeof (AC3IEC),
+      0,
+      (GInstanceInitFunc) ac3iec_init,
+    };
+    ac3iec_type = g_type_register_static (GST_TYPE_ELEMENT,
+        "AC3IEC", &ac3iec_info, 0);
+
+    GST_DEBUG_CATEGORY_INIT (ac3iec_debug, "ac3iec", 0,
+        "AC3 to IEC958 padding element");
+  }
+  return ac3iec_type;
+}
+
+
+static void
+ac3iec_base_init (gpointer g_class)
+{
+  GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
+
+  gst_element_class_set_details (element_class, &ac3iec_details);
+  gst_element_class_add_pad_template (element_class,
+      gst_static_pad_template_get (&ac3iec_sink_template));
+  gst_element_class_add_pad_template (element_class,
+      gst_static_pad_template_get (&ac3iec_src_template));
+}
+
+
+static void
+ac3iec_class_init (AC3IECClass * klass)
+{
+  GObjectClass *gobject_class;
+  GstElementClass *gstelement_class;
+
+  gobject_class = (GObjectClass *) klass;
+  gstelement_class = (GstElementClass *) klass;
+
+  parent_class = g_type_class_ref (GST_TYPE_ELEMENT);
+
+  gobject_class->set_property = ac3iec_set_property;
+  gobject_class->get_property = ac3iec_get_property;
+  gobject_class->finalize = ac3iec_finalize;
+
+  gstelement_class->change_state = ac3iec_change_state;
+}
+
+
+static void
+ac3iec_init (AC3IEC * ac3iec)
+{
+  ac3iec->sink =
+      gst_pad_new_from_template (gst_static_pad_template_get
+      (&ac3iec_sink_template), "sink");
+  gst_element_add_pad (GST_ELEMENT (ac3iec), ac3iec->sink);
+  gst_pad_set_chain_function (ac3iec->sink, ac3iec_chain);
+
+  ac3iec->src =
+      gst_pad_new_from_template (gst_static_pad_template_get
+      (&ac3iec_src_template), "src");
+  gst_element_add_pad (GST_ELEMENT (ac3iec), ac3iec->src);
+
+  ac3iec->cur_ts = GST_CLOCK_TIME_NONE;
+
+  ac3iec->padder = g_malloc (sizeof (ac3_padder));
+}
+
+
+static void
+ac3iec_finalize (GObject * object)
+{
+  AC3IEC *ac3iec = AC3IEC (object);
+
+  g_free (ac3iec->padder);
+}
+
+
+static void
+ac3iec_set_property (GObject * object, guint prop_id,
+    const GValue * value, GParamSpec * pspec)
+{
+  AC3IEC *ac3iec;
+
+  /* it's not null if we got it, but it might not be ours */
+  ac3iec = AC3IEC (object);
+
+  switch (prop_id) {
+    default:
+      break;
+  }
+}
+
+
+static void
+ac3iec_get_property (GObject * object, guint prop_id,
+    GValue * value, GParamSpec * pspec)
+{
+  AC3IEC *ac3iec;
+
+  /* it's not null if we got it, but it might not be ours */
+  g_return_if_fail (GST_IS_AC3IEC (object));
+
+  ac3iec = AC3IEC (object);
+
+  switch (prop_id) {
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+static GstFlowReturn
+ac3iec_chain (GstPad * pad, GstBuffer * buf)
+{
+  GstBuffer *new;
+  AC3IEC *ac3iec;
+  int event;
+  GstFlowReturn ret = GST_FLOW_OK;
+
+  g_return_val_if_fail (pad != NULL, GST_FLOW_ERROR);
+  g_return_val_if_fail (GST_IS_PAD (pad), GST_FLOW_ERROR);
+  g_return_val_if_fail (buf != NULL, GST_FLOW_ERROR);
+
+  ac3iec = AC3IEC (gst_pad_get_parent (pad));
+
+  if (GST_BUFFER_TIMESTAMP (buf) != GST_CLOCK_TIME_NONE) {
+    /* Whoever tells me why it is necessary to add a frame in order to
+       get synchronized sound will get a beer from me. */
+    ac3iec->cur_ts = GST_BUFFER_TIMESTAMP (buf) + IEC958_FRAME_DURATION;
+  }
+
+  /* Push the new data into the padder. */
+  ac3p_push_data (ac3iec->padder, GST_BUFFER_DATA (buf), GST_BUFFER_SIZE (buf));
+
+  /* Parse the data. */
+  event = ac3p_parse (ac3iec->padder);
+  while (event != AC3P_EVENT_PUSH) {
+    if (event == AC3P_EVENT_FRAME) {
+      /* We have a new frame: */
+
+      /* Create a new buffer, and copy the frame data into it. */
+      new = gst_buffer_new_and_alloc (AC3P_IEC_FRAME_SIZE);
+      memcpy (GST_BUFFER_DATA (new), ac3p_frame (ac3iec->padder),
+          AC3P_IEC_FRAME_SIZE);
+
+      /* Set the timestamp. */
+      GST_BUFFER_TIMESTAMP (new) = ac3iec->cur_ts;
+      ac3iec->cur_ts = GST_CLOCK_TIME_NONE;
+
+      GST_LOG_OBJECT (ac3iec, "Pushing IEC958 buffer of size %d",
+          GST_BUFFER_SIZE (new));
+      /* Push the buffer to the source pad. */
+      ret = gst_pad_push (ac3iec->src, new);
+    }
+
+    event = ac3p_parse (ac3iec->padder);
+  }
+
+  gst_buffer_unref (buf);
+
+  return ret;
+}
+
+
+static GstElementStateReturn
+ac3iec_change_state (GstElement * element)
+{
+  AC3IEC *ac3iec;
+
+  g_return_val_if_fail (GST_IS_AC3IEC (element), GST_STATE_FAILURE);
+
+  ac3iec = AC3IEC (element);
+
+  switch (GST_STATE_TRANSITION (element)) {
+    case GST_STATE_NULL_TO_READY:
+      break;
+    case GST_STATE_READY_TO_PAUSED:
+      ac3p_init (ac3iec->padder);
+      break;
+    case GST_STATE_PAUSED_TO_PLAYING:
+      break;
+    case GST_STATE_PLAYING_TO_PAUSED:
+      break;
+    case GST_STATE_PAUSED_TO_READY:
+      break;
+    case GST_STATE_READY_TO_NULL:
+      break;
+  }
+
+  if (GST_ELEMENT_CLASS (parent_class)->change_state) {
+    return GST_ELEMENT_CLASS (parent_class)->change_state (element);
+  }
+
+  return GST_STATE_SUCCESS;
+}
+
+
+static gboolean
+plugin_init (GstPlugin * plugin)
+{
+  if (!gst_element_register (plugin, "ac3iec958", GST_RANK_NONE,
+          GST_TYPE_AC3IEC)) {
+    return FALSE;
+  }
+
+  return TRUE;
+}
+
+
+GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
+    GST_VERSION_MINOR,
+    "iec958",
+    "Conversion elements to the iec958 SP/DIF format",
+    plugin_init, VERSION, "LGPL", PACKAGE, "http://seamless.sourceforge.net");
diff --git a/gst/iec958/ac3iec.h b/gst/iec958/ac3iec.h
new file mode 100644
index 00000000..cc91d93c
--- /dev/null
+++ b/gst/iec958/ac3iec.h
@@ -0,0 +1,79 @@
+/* GStreamer
+ * Copyright (C) 2004 Martin Soto <martinsoto@users.sourceforge.net>
+ *
+ * ac3iec.h: Pad AC3 frames into IEC958 frames for the SP/DIF interface.
+ *
+ * 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 __AC3IEC_H__
+#define __AC3IEC_H__
+
+#include <gst/gst.h>
+
+#include "ac3_padder.h"
+
+G_BEGIN_DECLS
+
+
+#define GST_TYPE_AC3IEC \
+  (ac3iec_get_type())
+#define AC3IEC(obj) \
+  (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_AC3IEC,AC3IEC))
+#define AC3IEC_CLASS(klass) \
+  (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_AC3IEC,AC3IECClass))
+#define GST_IS_AC3IEC(obj) \
+  (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_AC3IEC))
+#define GST_IS_AC3IEC_CLASS(obj) \
+  (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_AC3IEC))
+
+
+typedef struct _AC3IEC AC3IEC;
+typedef struct _AC3IECClass AC3IECClass;
+
+
+typedef enum {
+  AC3IEC_OPEN = GST_ELEMENT_FLAG_LAST,
+  AC3IEC_FLAG_LAST
+} Ac3iecFlags;
+
+
+struct _AC3IEC {
+  GstElement element;
+
+  GstPad *sink;
+  GstPad *src;
+
+  GstClockTime cur_ts;		/* Time stamp for the current
+                                   frame. */
+  GstClockTime next_ts;		/* Time stamp for the next frame. */
+
+  ac3_padder *padder;      	/* AC3 to SPDIF padder object. */
+};
+
+
+struct _AC3IECClass {
+  GstElementClass parent_class;
+
+  /* Signals */
+};
+
+
+extern GType	ac3iec_get_type		(void);
+
+G_END_DECLS
+
+#endif /* __AC3IEC_H__ */