X-Git-Url: http://git.maemo.org/git/?p=mafwsubrenderer;a=blobdiff_plain;f=gst-plugins-base-subtitles0.10%2Fgst%2Fencoding%2Fgstsmartencoder.c;fp=gst-plugins-base-subtitles0.10%2Fgst%2Fencoding%2Fgstsmartencoder.c;h=ed0e42bd5cdd5ebf790e06ebd35d582ba9f1ba90;hp=0000000000000000000000000000000000000000;hb=57ba96e291a055f69dbfd4ae9f1ae2390e36986e;hpb=be2c98fb83895d10ac44af7b9a9c3e00ca54bf49

diff --git a/gst-plugins-base-subtitles0.10/gst/encoding/gstsmartencoder.c b/gst-plugins-base-subtitles0.10/gst/encoding/gstsmartencoder.c
new file mode 100644
index 0000000..ed0e42b
--- /dev/null
+++ b/gst-plugins-base-subtitles0.10/gst/encoding/gstsmartencoder.c
@@ -0,0 +1,701 @@
+/* GStreamer Smart Video Encoder element
+ * Copyright (C) <2010> Edward Hervey <bilboed@gmail.com>
+ *
+ * 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.
+ */
+
+/* TODO:
+ * * Implement get_caps/set_caps (store/forward caps)
+ * * Adjust template caps to the formats we can support
+ **/
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <string.h>
+#include "gstsmartencoder.h"
+
+GST_DEBUG_CATEGORY_STATIC (smart_encoder_debug);
+#define GST_CAT_DEFAULT smart_encoder_debug
+
+/* FIXME : Update this with new caps */
+/* WARNING : We can only allow formats with closed-GOP */
+#define ALLOWED_CAPS "video/x-h263;video/x-intel-h263;"\
+  "video/mpeg,mpegversion=(int)1,systemstream=(boolean)false;"\
+  "video/mpeg,mpegversion=(int)2,systemstream=(boolean)false;"
+
+static GstStaticPadTemplate src_template =
+GST_STATIC_PAD_TEMPLATE ("src", GST_PAD_SRC,
+    GST_PAD_ALWAYS,
+    GST_STATIC_CAPS (ALLOWED_CAPS)
+    );
+
+static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
+    GST_PAD_SINK,
+    GST_PAD_ALWAYS,
+    GST_STATIC_CAPS (ALLOWED_CAPS)
+    );
+
+static GQuark INTERNAL_ELEMENT;
+
+/* GstSmartEncoder signals and args */
+enum
+{
+  /* FILL ME */
+  LAST_SIGNAL
+};
+
+enum
+{
+  ARG_0
+      /* FILL ME */
+};
+
+static void
+_do_init (void)
+{
+  INTERNAL_ELEMENT = g_quark_from_string ("internal-element");
+};
+
+G_DEFINE_TYPE_EXTENDED (GstSmartEncoder, gst_smart_encoder, GST_TYPE_ELEMENT, 0,
+    _do_init ());
+
+static void gst_smart_encoder_dispose (GObject * object);
+
+static gboolean setup_recoder_pipeline (GstSmartEncoder * smart_encoder);
+
+static GstFlowReturn gst_smart_encoder_chain (GstPad * pad, GstBuffer * buf);
+static gboolean smart_encoder_sink_event (GstPad * pad, GstEvent * event);
+static GstCaps *smart_encoder_sink_getcaps (GstPad * pad);
+static GstStateChangeReturn
+gst_smart_encoder_change_state (GstElement * element,
+    GstStateChange transition);
+
+static void
+gst_smart_encoder_class_init (GstSmartEncoderClass * klass)
+{
+  GObjectClass *gobject_class;
+  GstElementClass *element_class;
+
+  element_class = (GstElementClass *) klass;
+  gobject_class = G_OBJECT_CLASS (klass);
+
+  gst_smart_encoder_parent_class = g_type_class_peek_parent (klass);
+
+  gst_element_class_add_pad_template (element_class,
+      gst_static_pad_template_get (&src_template));
+  gst_element_class_add_pad_template (element_class,
+      gst_static_pad_template_get (&sink_template));
+
+  gst_element_class_set_details_simple (element_class, "Smart Video Encoder",
+      "Codec/Recoder/Video",
+      "Re-encodes portions of Video that lay on segment boundaries",
+      "Edward Hervey <bilboed@gmail.com>");
+
+  gobject_class->dispose = (GObjectFinalizeFunc) (gst_smart_encoder_dispose);
+  element_class->change_state = gst_smart_encoder_change_state;
+
+  GST_DEBUG_CATEGORY_INIT (smart_encoder_debug, "smartencoder", 0,
+      "Smart Encoder");
+}
+
+static void
+smart_encoder_reset (GstSmartEncoder * smart_encoder)
+{
+  gst_segment_init (smart_encoder->segment, GST_FORMAT_UNDEFINED);
+
+  if (smart_encoder->encoder) {
+    /* Clean up/remove elements */
+    gst_element_set_state (smart_encoder->encoder, GST_STATE_NULL);
+    gst_element_set_state (smart_encoder->decoder, GST_STATE_NULL);
+    gst_element_set_bus (smart_encoder->encoder, NULL);
+    gst_element_set_bus (smart_encoder->decoder, NULL);
+    gst_pad_set_active (smart_encoder->internal_srcpad, FALSE);
+    gst_pad_set_active (smart_encoder->internal_sinkpad, FALSE);
+    gst_object_unref (smart_encoder->encoder);
+    gst_object_unref (smart_encoder->decoder);
+    gst_object_unref (smart_encoder->internal_srcpad);
+    gst_object_unref (smart_encoder->internal_sinkpad);
+
+    smart_encoder->encoder = NULL;
+    smart_encoder->decoder = NULL;
+    smart_encoder->internal_sinkpad = NULL;
+    smart_encoder->internal_srcpad = NULL;
+  }
+
+  if (smart_encoder->newsegment) {
+    gst_event_unref (smart_encoder->newsegment);
+    smart_encoder->newsegment = NULL;
+  }
+}
+
+
+static void
+gst_smart_encoder_init (GstSmartEncoder * smart_encoder)
+{
+  smart_encoder->sinkpad =
+      gst_pad_new_from_static_template (&sink_template, "sink");
+  gst_pad_set_chain_function (smart_encoder->sinkpad, gst_smart_encoder_chain);
+  gst_pad_set_event_function (smart_encoder->sinkpad, smart_encoder_sink_event);
+  gst_pad_set_getcaps_function (smart_encoder->sinkpad,
+      smart_encoder_sink_getcaps);
+  gst_element_add_pad (GST_ELEMENT (smart_encoder), smart_encoder->sinkpad);
+
+  smart_encoder->srcpad =
+      gst_pad_new_from_static_template (&src_template, "src");
+  gst_pad_use_fixed_caps (smart_encoder->srcpad);
+  gst_element_add_pad (GST_ELEMENT (smart_encoder), smart_encoder->srcpad);
+
+  smart_encoder->segment = gst_segment_new ();
+
+  smart_encoder_reset (smart_encoder);
+}
+
+void
+gst_smart_encoder_dispose (GObject * object)
+{
+  GstSmartEncoder *smart_encoder = (GstSmartEncoder *) object;
+
+  if (smart_encoder->segment)
+    gst_segment_free (smart_encoder->segment);
+  smart_encoder->segment = NULL;
+  if (smart_encoder->available_caps)
+    gst_caps_unref (smart_encoder->available_caps);
+  smart_encoder->available_caps = NULL;
+  G_OBJECT_CLASS (gst_smart_encoder_parent_class)->dispose (object);
+}
+
+static GstFlowReturn
+gst_smart_encoder_reencode_gop (GstSmartEncoder * smart_encoder)
+{
+  GstFlowReturn res = GST_FLOW_OK;
+  GList *tmp;
+
+  if (smart_encoder->encoder == NULL) {
+    if (!setup_recoder_pipeline (smart_encoder))
+      return GST_FLOW_ERROR;
+  }
+
+  /* Activate elements */
+  /* Set elements to PAUSED */
+  gst_element_set_state (smart_encoder->encoder, GST_STATE_PAUSED);
+  gst_element_set_state (smart_encoder->decoder, GST_STATE_PAUSED);
+
+  GST_INFO ("Pushing Flush start/stop to clean decoder/encoder");
+  gst_pad_push_event (smart_encoder->internal_srcpad,
+      gst_event_new_flush_start ());
+  gst_pad_push_event (smart_encoder->internal_srcpad,
+      gst_event_new_flush_stop ());
+
+  /* push newsegment */
+  GST_INFO ("Pushing newsegment %" GST_PTR_FORMAT, smart_encoder->newsegment);
+  gst_pad_push_event (smart_encoder->internal_srcpad,
+      gst_event_ref (smart_encoder->newsegment));
+
+  /* Push buffers through our pads */
+  GST_DEBUG ("Pushing pending buffers");
+
+  for (tmp = smart_encoder->pending_gop; tmp; tmp = tmp->next) {
+    GstBuffer *buf = (GstBuffer *) tmp->data;
+
+    res = gst_pad_push (smart_encoder->internal_srcpad, buf);
+    if (G_UNLIKELY (res != GST_FLOW_OK))
+      break;
+  }
+
+  if (G_UNLIKELY (res != GST_FLOW_OK)) {
+    GST_WARNING ("Error pushing pending buffers : %s", gst_flow_get_name (res));
+    /* Remove pending bfufers */
+    for (tmp = smart_encoder->pending_gop; tmp; tmp = tmp->next) {
+      gst_buffer_unref ((GstBuffer *) tmp->data);
+    }
+  } else {
+    GST_INFO ("Pushing out EOS to flush out decoder/encoder");
+    gst_pad_push_event (smart_encoder->internal_srcpad, gst_event_new_eos ());
+  }
+
+  /* Activate elements */
+  /* Set elements to PAUSED */
+  gst_element_set_state (smart_encoder->encoder, GST_STATE_NULL);
+  gst_element_set_state (smart_encoder->decoder, GST_STATE_NULL);
+
+  g_list_free (smart_encoder->pending_gop);
+  smart_encoder->pending_gop = NULL;
+
+  return res;
+}
+
+static GstFlowReturn
+gst_smart_encoder_push_pending_gop (GstSmartEncoder * smart_encoder)
+{
+  gint64 cstart, cstop;
+  GList *tmp;
+  GstFlowReturn res = GST_FLOW_OK;
+
+  GST_DEBUG ("Pushing pending GOP (%" GST_TIME_FORMAT " -- %" GST_TIME_FORMAT
+      ")", GST_TIME_ARGS (smart_encoder->gop_start),
+      GST_TIME_ARGS (smart_encoder->gop_stop));
+
+  /* If GOP is entirely within segment, just push downstream */
+  if (gst_segment_clip (smart_encoder->segment, GST_FORMAT_TIME,
+          smart_encoder->gop_start, smart_encoder->gop_stop, &cstart, &cstop)) {
+    if ((cstart != smart_encoder->gop_start)
+        || (cstop != smart_encoder->gop_stop)) {
+      GST_DEBUG ("GOP needs to be re-encoded from %" GST_TIME_FORMAT " to %"
+          GST_TIME_FORMAT, GST_TIME_ARGS (cstart), GST_TIME_ARGS (cstop));
+      res = gst_smart_encoder_reencode_gop (smart_encoder);
+    } else {
+      /* The whole GOP is within the segment, push all pending buffers downstream */
+      GST_DEBUG ("GOP doesn't need to be modified, pushing downstream");
+      for (tmp = smart_encoder->pending_gop; tmp; tmp = tmp->next) {
+        GstBuffer *buf = (GstBuffer *) tmp->data;
+        res = gst_pad_push (smart_encoder->srcpad, buf);
+        if (G_UNLIKELY (res != GST_FLOW_OK))
+          break;
+      }
+    }
+  } else {
+    /* The whole GOP is outside the segment, there's most likely
+     * a bug somewhere. */
+    GST_WARNING
+        ("GOP is entirely outside of the segment, upstream gave us too much data");
+    for (tmp = smart_encoder->pending_gop; tmp; tmp = tmp->next) {
+      gst_buffer_unref ((GstBuffer *) tmp->data);
+    }
+  }
+
+  if (smart_encoder->pending_gop) {
+    g_list_free (smart_encoder->pending_gop);
+    smart_encoder->pending_gop = NULL;
+  }
+  smart_encoder->gop_start = GST_CLOCK_TIME_NONE;
+  smart_encoder->gop_stop = GST_CLOCK_TIME_NONE;
+
+  return res;
+}
+
+static GstFlowReturn
+gst_smart_encoder_chain (GstPad * pad, GstBuffer * buf)
+{
+  GstSmartEncoder *smart_encoder;
+  GstFlowReturn res = GST_FLOW_OK;
+  gboolean discont, keyframe;
+
+  smart_encoder = GST_SMART_ENCODER (gst_object_get_parent (GST_OBJECT (pad)));
+
+  discont = GST_BUFFER_IS_DISCONT (buf);
+  keyframe = !GST_BUFFER_FLAG_IS_SET (buf, GST_BUFFER_FLAG_DELTA_UNIT);
+
+  GST_DEBUG ("New buffer %s %s %" GST_TIME_FORMAT,
+      discont ? "discont" : "",
+      keyframe ? "keyframe" : "", GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (buf)));
+
+  if (keyframe) {
+    GST_DEBUG ("Got a keyframe");
+
+    /* If there's a pending GOP, flush it out */
+    if (smart_encoder->pending_gop) {
+      /* Mark gop_stop */
+      smart_encoder->gop_stop = GST_BUFFER_TIMESTAMP (buf);
+
+      /* flush pending */
+      res = gst_smart_encoder_push_pending_gop (smart_encoder);
+      if (G_UNLIKELY (res != GST_FLOW_OK))
+        goto beach;
+    }
+
+    /* Mark gop_start for new gop */
+    smart_encoder->gop_start = GST_BUFFER_TIMESTAMP (buf);
+  }
+
+  /* Store buffer */
+  smart_encoder->pending_gop = g_list_append (smart_encoder->pending_gop, buf);
+  /* Update GOP stop position */
+  if (GST_BUFFER_TIMESTAMP_IS_VALID (buf)) {
+    smart_encoder->gop_stop = GST_BUFFER_TIMESTAMP (buf);
+    if (GST_BUFFER_DURATION_IS_VALID (buf))
+      smart_encoder->gop_stop += GST_BUFFER_DURATION (buf);
+  }
+
+  GST_DEBUG ("Buffer stored , Current GOP : %" GST_TIME_FORMAT " -- %"
+      GST_TIME_FORMAT, GST_TIME_ARGS (smart_encoder->gop_start),
+      GST_TIME_ARGS (smart_encoder->gop_stop));
+
+beach:
+  gst_object_unref (smart_encoder);
+  return res;
+}
+
+static gboolean
+smart_encoder_sink_event (GstPad * pad, GstEvent * event)
+{
+  gboolean res = TRUE;
+  GstSmartEncoder *smart_encoder = GST_SMART_ENCODER (gst_pad_get_parent (pad));
+
+  switch (GST_EVENT_TYPE (event)) {
+    case GST_EVENT_FLUSH_STOP:
+      smart_encoder_reset (smart_encoder);
+      break;
+    case GST_EVENT_NEWSEGMENT:
+    {
+      GstFormat format;
+      gdouble rate, arate;
+      gint64 start, stop, time;
+      gboolean update;
+
+      gst_event_parse_new_segment_full (event, &update, &rate, &arate, &format,
+          &start, &stop, &time);
+      GST_DEBUG_OBJECT (smart_encoder,
+          "newsegment: update %d, rate %g, arate %g, start %" GST_TIME_FORMAT
+          ", stop %" GST_TIME_FORMAT ", time %" GST_TIME_FORMAT,
+          update, rate, arate, GST_TIME_ARGS (start), GST_TIME_ARGS (stop),
+          GST_TIME_ARGS (time));
+      if (format != GST_FORMAT_TIME)
+        GST_ERROR
+            ("smart_encoder can not handle streams not specified in GST_FORMAT_TIME");
+
+      /* now configure the values */
+      gst_segment_set_newsegment_full (smart_encoder->segment, update,
+          rate, arate, format, start, stop, time);
+
+      /* And keep a copy for further usage */
+      if (smart_encoder->newsegment)
+        gst_event_unref (smart_encoder->newsegment);
+      smart_encoder->newsegment = gst_event_ref (event);
+    }
+      break;
+    case GST_EVENT_EOS:
+      GST_DEBUG ("Eos, flushing remaining data");
+      gst_smart_encoder_push_pending_gop (smart_encoder);
+      break;
+    default:
+      break;
+  }
+
+  res = gst_pad_push_event (smart_encoder->srcpad, event);
+
+  gst_object_unref (smart_encoder);
+  return res;
+}
+
+static GstCaps *
+smart_encoder_sink_getcaps (GstPad * pad)
+{
+  GstCaps *peer, *tmpl, *res;
+  GstSmartEncoder *smart_encoder = GST_SMART_ENCODER (gst_pad_get_parent (pad));
+
+  /* Try getting it from downstream */
+  peer = gst_pad_peer_get_caps_reffed (smart_encoder->srcpad);
+
+  /* Use computed caps */
+  if (smart_encoder->available_caps)
+    tmpl = gst_caps_ref (smart_encoder->available_caps);
+  else
+    tmpl = gst_static_pad_template_get_caps (&src_template);
+
+  if (peer == NULL) {
+    res = tmpl;
+  } else {
+    res = gst_caps_intersect (peer, tmpl);
+    gst_caps_unref (peer);
+    gst_caps_unref (tmpl);
+  }
+
+  gst_object_unref (smart_encoder);
+  return res;
+}
+
+/*****************************************
+ *    Internal encoder/decoder pipeline  *
+ ******************************************/
+
+static GstElementFactory *
+get_decoder_factory (GstCaps * caps)
+{
+  GstElementFactory *fact = NULL;
+  GList *decoders, *tmp;
+
+  tmp =
+      gst_element_factory_list_get_elements (GST_ELEMENT_FACTORY_TYPE_DECODER,
+      GST_RANK_MARGINAL);
+  decoders = gst_element_factory_list_filter (tmp, caps, GST_PAD_SINK, FALSE);
+  gst_plugin_feature_list_free (tmp);
+
+  for (tmp = decoders; tmp; tmp = tmp->next) {
+    /* We just pick the first one */
+    fact = (GstElementFactory *) tmp->data;
+    gst_object_ref (fact);
+    break;
+  }
+
+  gst_plugin_feature_list_free (decoders);
+
+  return fact;
+}
+
+static GstElementFactory *
+get_encoder_factory (GstCaps * caps)
+{
+  GstElementFactory *fact = NULL;
+  GList *encoders, *tmp;
+
+  tmp =
+      gst_element_factory_list_get_elements (GST_ELEMENT_FACTORY_TYPE_ENCODER,
+      GST_RANK_MARGINAL);
+  encoders = gst_element_factory_list_filter (tmp, caps, GST_PAD_SRC, FALSE);
+  gst_plugin_feature_list_free (tmp);
+
+  for (tmp = encoders; tmp; tmp = tmp->next) {
+    /* We just pick the first one */
+    fact = (GstElementFactory *) tmp->data;
+    gst_object_ref (fact);
+    break;
+  }
+
+  gst_plugin_feature_list_free (encoders);
+
+  return fact;
+}
+
+static GstElement *
+get_decoder (GstCaps * caps)
+{
+  GstElementFactory *fact = get_decoder_factory (caps);
+  GstElement *res = NULL;
+
+  if (fact) {
+    res = gst_element_factory_create (fact, "internal-decoder");
+    gst_object_unref (fact);
+  }
+  return res;
+}
+
+static GstElement *
+get_encoder (GstCaps * caps)
+{
+  GstElementFactory *fact = get_encoder_factory (caps);
+  GstElement *res = NULL;
+
+  if (fact) {
+    res = gst_element_factory_create (fact, "internal-encoder");
+    gst_object_unref (fact);
+  }
+  return res;
+}
+
+static GstFlowReturn
+internal_chain (GstPad * pad, GstBuffer * buf)
+{
+  GstSmartEncoder *smart_encoder =
+      g_object_get_qdata ((GObject *) pad, INTERNAL_ELEMENT);
+
+  return gst_pad_push (smart_encoder->srcpad, buf);
+}
+
+static gboolean
+setup_recoder_pipeline (GstSmartEncoder * smart_encoder)
+{
+  GstPad *tmppad;
+
+  /* Fast path */
+  if (G_UNLIKELY (smart_encoder->encoder))
+    return TRUE;
+
+  GST_DEBUG ("Creating internal decoder and encoder");
+
+  /* Create decoder/encoder */
+  smart_encoder->decoder = get_decoder (GST_PAD_CAPS (smart_encoder->sinkpad));
+  if (G_UNLIKELY (smart_encoder->decoder == NULL))
+    goto no_decoder;
+  gst_element_set_bus (smart_encoder->decoder, GST_ELEMENT_BUS (smart_encoder));
+
+  smart_encoder->encoder = get_encoder (GST_PAD_CAPS (smart_encoder->sinkpad));
+  if (G_UNLIKELY (smart_encoder->encoder == NULL))
+    goto no_encoder;
+  gst_element_set_bus (smart_encoder->encoder, GST_ELEMENT_BUS (smart_encoder));
+
+  GST_DEBUG ("Creating internal pads");
+
+  /* Create internal pads */
+
+  /* Source pad which we'll use to feed data to decoders */
+  smart_encoder->internal_srcpad = gst_pad_new ("internal_src", GST_PAD_SRC);
+  g_object_set_qdata ((GObject *) smart_encoder->internal_srcpad,
+      INTERNAL_ELEMENT, smart_encoder);
+  gst_pad_set_caps (smart_encoder->internal_srcpad,
+      GST_PAD_CAPS (smart_encoder->sinkpad));
+  gst_pad_set_active (smart_encoder->internal_srcpad, TRUE);
+
+  /* Sink pad which will get the buffers from the encoder.
+   * Note: We don't need an event function since we'll be discarding all
+   * of them. */
+  smart_encoder->internal_sinkpad = gst_pad_new ("internal_sink", GST_PAD_SINK);
+  g_object_set_qdata ((GObject *) smart_encoder->internal_sinkpad,
+      INTERNAL_ELEMENT, smart_encoder);
+  gst_pad_set_caps (smart_encoder->internal_sinkpad,
+      GST_PAD_CAPS (smart_encoder->sinkpad));
+  gst_pad_set_chain_function (smart_encoder->internal_sinkpad, internal_chain);
+  gst_pad_set_active (smart_encoder->internal_sinkpad, TRUE);
+
+  GST_DEBUG ("Linking pads to elements");
+
+  /* Link everything */
+  tmppad = gst_element_get_static_pad (smart_encoder->encoder, "src");
+  if (GST_PAD_LINK_FAILED (gst_pad_link (tmppad,
+              smart_encoder->internal_sinkpad)))
+    goto sinkpad_link_fail;
+  gst_object_unref (tmppad);
+
+  if (!gst_element_link (smart_encoder->decoder, smart_encoder->encoder))
+    goto encoder_decoder_link_fail;
+
+  tmppad = gst_element_get_static_pad (smart_encoder->decoder, "sink");
+  if (GST_PAD_LINK_FAILED (gst_pad_link (smart_encoder->internal_srcpad,
+              tmppad)))
+    goto srcpad_link_fail;
+  gst_object_unref (tmppad);
+
+  GST_DEBUG ("Done creating internal elements/pads");
+
+  return TRUE;
+
+no_decoder:
+  {
+    GST_WARNING ("Couldn't find a decoder for %" GST_PTR_FORMAT,
+        GST_PAD_CAPS (smart_encoder->sinkpad));
+    return FALSE;
+  }
+
+no_encoder:
+  {
+    GST_WARNING ("Couldn't find an encoder for %" GST_PTR_FORMAT,
+        GST_PAD_CAPS (smart_encoder->sinkpad));
+    return FALSE;
+  }
+
+srcpad_link_fail:
+  {
+    gst_object_unref (tmppad);
+    GST_WARNING ("Couldn't link internal srcpad to decoder");
+    return FALSE;
+  }
+
+sinkpad_link_fail:
+  {
+    gst_object_unref (tmppad);
+    GST_WARNING ("Couldn't link encoder to internal sinkpad");
+    return FALSE;
+  }
+
+encoder_decoder_link_fail:
+  {
+    GST_WARNING ("Couldn't link decoder to encoder");
+    return FALSE;
+  }
+}
+
+static GstStateChangeReturn
+gst_smart_encoder_find_elements (GstSmartEncoder * smart_encoder)
+{
+  guint i, n;
+  GstCaps *tmpl, *st, *res;
+  GstElementFactory *dec, *enc;
+  GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
+
+  if (G_UNLIKELY (smart_encoder->available_caps))
+    goto beach;
+
+  /* Iterate over all pad template caps and see if we have both an
+   * encoder and a decoder for those media types */
+  tmpl = gst_static_pad_template_get_caps (&src_template);
+  res = gst_caps_new_empty ();
+  n = gst_caps_get_size (tmpl);
+
+  for (i = 0; i < n; i++) {
+    st = gst_caps_copy_nth (tmpl, i);
+    GST_DEBUG_OBJECT (smart_encoder,
+        "Checking for available decoder and encoder for %" GST_PTR_FORMAT, st);
+    if (!(dec = get_decoder_factory (st))) {
+      gst_caps_unref (st);
+      continue;
+    }
+    gst_object_unref (dec);
+    if (!(enc = get_encoder_factory (st))) {
+      gst_caps_unref (st);
+      continue;
+    }
+    gst_object_unref (enc);
+    GST_DEBUG_OBJECT (smart_encoder, "OK");
+    gst_caps_append (res, st);
+  }
+
+  gst_caps_unref (tmpl);
+
+  if (gst_caps_is_empty (res))
+    ret = GST_STATE_CHANGE_FAILURE;
+  else
+    smart_encoder->available_caps = res;
+
+  GST_DEBUG_OBJECT (smart_encoder, "Done, available_caps:%" GST_PTR_FORMAT,
+      smart_encoder->available_caps);
+
+beach:
+  return ret;
+}
+
+/******************************************
+ *    GstElement vmethod implementations  *
+ ******************************************/
+
+static GstStateChangeReturn
+gst_smart_encoder_change_state (GstElement * element, GstStateChange transition)
+{
+  GstSmartEncoder *smart_encoder;
+  GstStateChangeReturn ret;
+
+  g_return_val_if_fail (GST_IS_SMART_ENCODER (element),
+      GST_STATE_CHANGE_FAILURE);
+
+  smart_encoder = GST_SMART_ENCODER (element);
+
+  switch (transition) {
+    case GST_STATE_CHANGE_NULL_TO_READY:
+      /* Figure out which elements are available  */
+      if ((ret =
+              gst_smart_encoder_find_elements (smart_encoder)) ==
+          GST_STATE_CHANGE_FAILURE)
+        goto beach;
+      break;
+    default:
+      break;
+  }
+
+  ret =
+      GST_ELEMENT_CLASS (gst_smart_encoder_parent_class)->change_state (element,
+      transition);
+
+  switch (transition) {
+    case GST_STATE_CHANGE_PAUSED_TO_READY:
+      smart_encoder_reset (smart_encoder);
+      break;
+    default:
+      break;
+  }
+
+beach:
+  return ret;
+}