ext/xvid/: xvid plugin to support more capabilities of XviD codec.

Original commit message from CVS:
Patch by: Mark Nauwelaerts <manauw at skynet dot be>
* ext/xvid/gstxvid.c: (gst_xvid_init), (gst_xvid_structure_to_csp),
(gst_xvid_csp_to_caps), (gst_xvid_image_get_size),
(gst_xvid_image_fill):
* ext/xvid/gstxvid.h:
* ext/xvid/gstxviddec.c: (gst_xviddec_class_init),
(gst_xviddec_init), (gst_xviddec_reset), (gst_xviddec_unset),
(gst_xviddec_handle_sink_event), (gst_xviddec_setup),
(gst_xviddec_add_par), (gst_xviddec_negotiate),
(gst_xviddec_decode), (gst_xviddec_chain),
(gst_xviddec_flush_buffers), (gst_xviddec_src_getcaps),
(gst_xviddec_src_link), (gst_xviddec_setcaps),
(gst_xviddec_change_state):
* ext/xvid/gstxviddec.h:
* ext/xvid/gstxvidenc.c: (gst_xvidenc_profile_get_type),
(gst_xvidenc_quant_type_get_type), (gst_xvidenc_pass_get_type),
(gst_xvidenc_get_type), (gst_xvidenc_base_init),
(gst_xvidenc_class_init), (gst_xvidenc_init),
(gst_xvidenc_finalize), (gst_xvidenc_handle_sink_event),
(gst_xvidenc_setup), (gst_xvidenc_setcaps), (gst_xvidenc_encode),
(gst_xvidenc_chain), (gst_xvidenc_flush_buffers),
(gst_xvidenc_set_property), (gst_xvidenc_get_property),
(gst_xvidenc_change_state):
* ext/xvid/gstxvidenc.h:
xvid plugin to support more capabilities of XviD codec.
Fixes #339462.
Some more cleanups here and there.

1 files changed, 435 insertions, 112 deletions

diff --git a/ext/xvid/gstxviddec.c b/ext/xvid/gstxviddec.c
index 5825dcb0..5aa59b09 100644
--- a/ext/xvid/gstxviddec.c
+++ b/ext/xvid/gstxviddec.c
@@ -1,5 +1,6 @@
 /* GStreamer xvid decoder plugin
  * Copyright (C) 2003 Ronald Bultje <rbultje@ronald.bitfreak.net>
+ *           (C) 2006 Mark Nauwelaerts <manauw@skynet.be>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ -17,6 +18,7 @@
  * Boston, MA 02111-1307, USA.
  */
 
+
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
@@ -39,7 +41,7 @@ static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
     GST_PAD_ALWAYS,
     GST_STATIC_CAPS ("video/x-xvid, "
         "width = (int) [ 0, MAX ], "
-        "height = (int) [ 0, MAX ], " "framerate = (fraction) [0/1, MAX]")
+        "height = (int) [ 0, MAX ], " "framerate = (fraction) [ 0/1, MAX ]")
     );
 
 static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
@@ -68,19 +70,32 @@ enum
       /* FILL ME */
 };
 
+GST_DEBUG_CATEGORY_STATIC (xviddec_debug);
+#define GST_CAT_DEFAULT xviddec_debug
+
 static void gst_xviddec_base_init (GstXvidDecClass * klass);
 static void gst_xviddec_class_init (GstXvidDecClass * klass);
 static void gst_xviddec_init (GstXvidDec * xviddec);
+static void gst_xviddec_reset (GstXvidDec * xviddec);
+static gboolean gst_xviddec_handle_sink_event (GstPad * pad, GstEvent * event);
 static GstFlowReturn gst_xviddec_chain (GstPad * pad, GstBuffer * buf);
 static gboolean gst_xviddec_setcaps (GstPad * pad, GstCaps * caps);
-static gboolean gst_xviddec_negotiate (GstXvidDec * xviddec);
+static void gst_xviddec_flush_buffers (GstXvidDec * xviddec, gboolean send);
+
+#if 0
+static GstPadLinkReturn
+gst_xviddec_src_link (GstPad * pad, const GstCaps * vscapslist);
+*/static GstCaps *gst_xviddec_src_getcaps (GstPad * pad);
+#endif
 static GstStateChangeReturn gst_xviddec_change_state (GstElement * element,
     GstStateChange transition);
 
+
 static GstElementClass *parent_class = NULL;
 
 /* static guint gst_xviddec_signals[LAST_SIGNAL] = { 0 }; */
 
+
 GType
 gst_xviddec_get_type (void)
 {
@@ -121,25 +136,31 @@ gst_xviddec_base_init (GstXvidDecClass * klass)
 static void
 gst_xviddec_class_init (GstXvidDecClass * klass)
 {
-  GstElementClass *gstelement_class = GST_ELEMENT_CLASS (klass);
+  GstElementClass *gstelement_class = (GstElementClass *) klass;
 
   parent_class = g_type_class_peek_parent (klass);
 
-  gstelement_class->change_state = gst_xviddec_change_state;
+  GST_DEBUG_CATEGORY_INIT (xviddec_debug, "xviddec", 0, "XviD decoder");
+
+  gstelement_class->change_state = GST_DEBUG_FUNCPTR (gst_xviddec_change_state);
 }
 
+
 static void
 gst_xviddec_init (GstXvidDec * xviddec)
 {
-  gst_xvid_init ();
-
   /* create the sink pad */
   xviddec->sinkpad =
       gst_pad_new_from_template (gst_static_pad_template_get (&sink_template),
       "sink");
   gst_element_add_pad (GST_ELEMENT (xviddec), xviddec->sinkpad);
-  gst_pad_set_chain_function (xviddec->sinkpad, gst_xviddec_chain);
-  gst_pad_set_setcaps_function (xviddec->sinkpad, gst_xviddec_setcaps);
+
+  gst_pad_set_chain_function (xviddec->sinkpad,
+      GST_DEBUG_FUNCPTR (gst_xviddec_chain));
+  gst_pad_set_setcaps_function (xviddec->sinkpad,
+      GST_DEBUG_FUNCPTR (gst_xviddec_setcaps));
+  gst_pad_set_event_function (xviddec->sinkpad,
+      GST_DEBUG_FUNCPTR (gst_xviddec_handle_sink_event));
 
   /* create the src pad */
   xviddec->srcpad =
@@ -148,129 +169,380 @@ gst_xviddec_init (GstXvidDec * xviddec)
   gst_element_add_pad (GST_ELEMENT (xviddec), xviddec->srcpad);
   gst_pad_use_fixed_caps (xviddec->srcpad);
 
+  gst_xviddec_reset (xviddec);
+}
+
+
+static void
+gst_xviddec_reset (GstXvidDec * xviddec)
+{
   /* size, etc. */
   xviddec->width = xviddec->height = xviddec->csp = -1;
+  xviddec->fps_n = xviddec->par_n = -1;
+  xviddec->fps_d = xviddec->par_d = 1;
+  xviddec->next_ts = xviddec->next_dur = GST_CLOCK_TIME_NONE;
 
   /* set xvid handle to NULL */
   xviddec->handle = NULL;
+
+  /* no delayed timestamp to start with */
+  xviddec->have_ts = FALSE;
+
+  /* need keyframe to get going */
+  xviddec->waiting_for_key = TRUE;
 }
 
 
 static void
 gst_xviddec_unset (GstXvidDec * xviddec)
 {
-  /* unref this instance */
+  /* release XviD decoder */
   xvid_decore (xviddec->handle, XVID_DEC_DESTROY, NULL, NULL);
   xviddec->handle = NULL;
 }
 
 
 static gboolean
+gst_xviddec_handle_sink_event (GstPad * pad, GstEvent * event)
+{
+  GstXvidDec *xviddec = GST_XVIDDEC (GST_PAD_PARENT (pad));
+
+  switch (GST_EVENT_TYPE (event)) {
+    case GST_EVENT_EOS:
+      gst_xviddec_flush_buffers (xviddec, TRUE);
+      break;
+    case GST_EVENT_FLUSH_STOP:
+      gst_xviddec_flush_buffers (xviddec, FALSE);
+      break;
+    case GST_EVENT_NEWSEGMENT:
+      /* don't really mind about the actual segment info,
+       * but we do need to recover from this possible jump */
+      /* FIXME, NEWSEGMENT is not a discontinuity. A decoder
+       * should clip the output to the segment boundaries.
+       * Also the rate field of the segment can be used to
+       * optimize the decoding, like skipping B frames when
+       * playing at double speed.
+       * The DISCONT flag on buffers should be used to detect
+       * discontinuities. 
+       */
+      xviddec->waiting_for_key = TRUE;
+      break;
+    default:
+      break;
+  }
+
+  return gst_pad_push_event (xviddec->srcpad, event);
+}
+
+
+static gboolean
 gst_xviddec_setup (GstXvidDec * xviddec)
 {
   xvid_dec_create_t xdec;
-  int ret;
+  gint ret;
 
   /* initialise parameters, see xvid documentation */
   gst_xvid_init_struct (xdec);
-  xdec.width = xviddec->width;
-  xdec.height = xviddec->height;
+  /* let the decoder handle this, don't trust the container */
+  xdec.width = 0;
+  xdec.height = 0;
   xdec.handle = NULL;
 
   if ((ret = xvid_decore (NULL, XVID_DEC_CREATE, &xdec, NULL)) < 0) {
-    GST_ELEMENT_ERROR (xviddec, LIBRARY, SETTINGS, (NULL),
-        ("Setting parameters %dx%d@%d failed: %s (%d)",
-            xviddec->width, xviddec->height, xviddec->csp,
-            gst_xvid_error (ret), ret));
+    GST_DEBUG_OBJECT (xviddec,
+        "Initializing xvid decoder with parameters %dx%d@%d failed: %s (%d)",
+        xviddec->width, xviddec->height, xviddec->csp,
+        gst_xvid_error (ret), ret);
     return FALSE;
   }
 
   xviddec->handle = xdec.handle;
+
   return TRUE;
 }
 
+
+static void
+gst_xviddec_add_par (GstStructure * structure,
+    gint mux_par_n, gint mux_par_d, gint dec_par_n, gint dec_par_d)
+{
+  /* muxer wins if decoder has nothing interesting to offer */
+  if (dec_par_n == dec_par_d) {
+    gst_structure_set (structure, "pixel-aspect-ratio", GST_TYPE_FRACTION,
+        mux_par_n, mux_par_d, NULL);
+  } else {
+    gst_structure_set (structure, "pixel-aspect-ratio", GST_TYPE_FRACTION,
+        dec_par_n, dec_par_d, NULL);
+  }
+}
+
+
+/* based on the decoder info, if provided, and xviddec info,
+   construct a caps and send on to src pad */
+static gboolean
+gst_xviddec_negotiate (GstXvidDec * xviddec, xvid_dec_stats_t * xstats)
+{
+  gint par_width, par_height;
+  GstCaps *caps;
+
+  /* note: setcaps call with no xstats info,
+     so definitely need to negotiate then */
+  if (xstats && (xstats->type != XVID_TYPE_VOL
+          || (xstats->type == XVID_TYPE_VOL
+              && xviddec->width == xstats->data.vol.width
+              && xviddec->height == xstats->data.vol.height)))
+    return TRUE;
+
+  switch (xstats ? xstats->data.vol.par : XVID_PAR_11_VGA) {
+    case XVID_PAR_11_VGA:
+      par_width = par_height = 1;
+      break;
+    case XVID_PAR_43_PAL:
+    case XVID_PAR_43_NTSC:
+      par_width = 4;
+      par_height = 3;
+      break;
+    case XVID_PAR_169_PAL:
+    case XVID_PAR_169_NTSC:
+      par_width = 16;
+      par_height = 9;
+      break;
+    case XVID_PAR_EXT:
+    default:
+      par_width = xstats->data.vol.par_width;
+      par_height = xstats->data.vol.par_height;
+  }
+
+  caps = gst_xvid_csp_to_caps (xviddec->csp, xviddec->width, xviddec->height);
+
+  /* can only provide framerate if we received one */
+  if (xviddec->fps_n != -1) {
+    gst_structure_set (gst_caps_get_structure (caps, 0), "framerate",
+        GST_TYPE_FRACTION, xviddec->fps_n, xviddec->fps_d, NULL);
+  }
+
+  gst_xviddec_add_par (gst_caps_get_structure (caps, 0),
+      xviddec->par_n, xviddec->par_d, par_width, par_height);
+
+  return gst_pad_set_caps (xviddec->srcpad, caps);
+}
+
+
+/* decodes frame according to info in xframe;
+   - outbuf must not be NULL
+   - xstats can be NULL, if not, it has been init'ed
+   - output placed in outbuf, which is also allocated if NULL,
+     caller must unref when needed
+   - xvid stats placed in xstats, if not NULL
+   - xvid return code is returned, which is usually the size of the output frame
+*/
+static gint
+gst_xviddec_decode (GstXvidDec * xviddec, xvid_dec_frame_t xframe,
+    GstBuffer ** outbuf, xvid_dec_stats_t * xstats)
+{
+
+  g_return_val_if_fail (outbuf, -1);
+
+  if (!*outbuf) {
+    gint size = gst_xvid_image_get_size (xviddec->csp,
+        xviddec->width, xviddec->height);
+
+    gst_pad_alloc_buffer (xviddec->srcpad, GST_BUFFER_OFFSET_NONE, size,
+        GST_PAD_CAPS (xviddec->srcpad), outbuf);
+  }
+
+  gst_xvid_image_fill (&xframe.output, GST_BUFFER_DATA (*outbuf),
+      xviddec->csp, xviddec->width, xviddec->height);
+
+  GST_DEBUG_OBJECT (xviddec, "decoding into buffer %" GST_PTR_FORMAT
+      ", data %" GST_PTR_FORMAT ", %" GST_PTR_FORMAT, *outbuf,
+      GST_BUFFER_MALLOCDATA (*outbuf), GST_BUFFER_DATA (*outbuf));
+
+  return xvid_decore (xviddec->handle, XVID_DEC_DECODE, &xframe, xstats);
+}
+
 static GstFlowReturn
 gst_xviddec_chain (GstPad * pad, GstBuffer * buf)
 {
-  GstXvidDec *xviddec = GST_XVIDDEC (gst_pad_get_parent (pad));
+  GstXvidDec *xviddec;
   GstBuffer *outbuf = NULL;
   xvid_dec_frame_t xframe;
-  GstFlowReturn ret = GST_FLOW_OK;
-  guint bufsize;
-  int error = 0;
+  xvid_dec_stats_t xstats;
+  gint ret;
+  guint8 *data;
+  guint size;
+  GstFlowReturn fret;
 
-  if (xviddec->handle == NULL) {
-    if (!gst_xviddec_negotiate (xviddec))
-      goto not_negotiated;
-  }
+  xviddec = GST_XVIDDEC (GST_OBJECT_PARENT (pad));
 
-  bufsize = (xviddec->width * xviddec->height * xviddec->bpp / 8);
+  if (!xviddec->handle)
+    goto not_negotiated;
 
-  outbuf = gst_buffer_new_and_alloc (bufsize);
+  fret = GST_FLOW_OK;
 
-  GST_BUFFER_TIMESTAMP (outbuf) = GST_BUFFER_TIMESTAMP (buf);
-  GST_BUFFER_DURATION (outbuf) = GST_BUFFER_DURATION (buf);
-  GST_BUFFER_SIZE (outbuf) = bufsize;
+  GST_DEBUG_OBJECT (xviddec,
+      "Received buffer of time %" GST_TIME_FORMAT ", size %d",
+      GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (buf)), GST_BUFFER_SIZE (buf));
 
-  /* decode and so ... */
-  gst_xvid_init_struct (xframe);
-  xframe.general = XVID_LOWDELAY;
-  xframe.bitstream = (void *) GST_BUFFER_DATA (buf);
-  xframe.length = GST_BUFFER_SIZE (buf);
-  xframe.output.csp = xviddec->csp;
-  if (xviddec->width == xviddec->stride) {
-    xframe.output.plane[0] = GST_BUFFER_DATA (outbuf);
-    xframe.output.plane[1] =
-        xframe.output.plane[0] + (xviddec->width * xviddec->height);
-    xframe.output.plane[2] =
-        xframe.output.plane[1] + (xviddec->width * xviddec->height / 4);
-    xframe.output.stride[0] = xviddec->width;
-    xframe.output.stride[1] = xviddec->width / 2;
-    xframe.output.stride[2] = xviddec->width / 2;
-  } else {
-    xframe.output.plane[0] = GST_BUFFER_DATA (outbuf);
-    xframe.output.stride[0] = xviddec->stride;
-  }
+  data = GST_BUFFER_DATA (buf);
+  size = GST_BUFFER_SIZE (buf);
+
+  do {                          /* loop needed because xvidcore may return vol information */
+    /* decode and so ... */
+    gst_xvid_init_struct (xframe);
+    xframe.general = XVID_LOWDELAY;
+    xframe.bitstream = (void *) data;
+    xframe.length = size;
+
+    gst_xvid_init_struct (xstats);
+
+    if ((ret = gst_xviddec_decode (xviddec, xframe, &outbuf, &xstats)) < 0)
+      goto decode_error;
+
+    GST_DEBUG_OBJECT (xviddec, "xvid produced output, type %d, consumed %d",
+        xstats.type, ret);
+
+    if (xstats.type == XVID_TYPE_VOL)
+      gst_xviddec_negotiate (xviddec, &xstats);
 
-  if ((error =
-          xvid_decore (xviddec->handle, XVID_DEC_DECODE, &xframe, NULL)) < 0) {
-    goto not_decoding;
+    data += ret;
+    size -= ret;
+  } while (xstats.type <= 0 && size > 0);
+
+  if (size > 1)                 /* 1 byte is frequently left over */
+    GST_WARNING_OBJECT (xviddec,
+        "xvid decoder returned frame without consuming all input");
+
+  /* FIXME, reflow the multiple return exit points */
+  if (xstats.type > 0) {        /* some real output was produced */
+    if (G_UNLIKELY (xviddec->waiting_for_key)) {
+      if (xstats.type != XVID_TYPE_IVOP)
+        goto dropping;
+
+      xviddec->waiting_for_key = FALSE;
+    }
+    /* bframes can cause a delay in frames being returned
+       non keyframe timestamps can permute a bit between
+       encode and display order, but should match for keyframes */
+    if (xviddec->have_ts) {
+      GST_BUFFER_TIMESTAMP (outbuf) = xviddec->next_ts;
+      GST_BUFFER_DURATION (outbuf) = xviddec->next_dur;
+      xviddec->next_ts = GST_BUFFER_TIMESTAMP (buf);
+      xviddec->next_dur = GST_BUFFER_DURATION (buf);
+    } else {
+      GST_BUFFER_TIMESTAMP (outbuf) = GST_BUFFER_TIMESTAMP (buf);
+      GST_BUFFER_DURATION (outbuf) = GST_BUFFER_DURATION (buf);
+    }
+    gst_buffer_set_caps (outbuf, GST_PAD_CAPS (xviddec->srcpad));
+
+    fret = gst_pad_push (xviddec->srcpad, outbuf);
+
+  } else {                      /* no real output yet, delay in frames being returned */
+    if (G_UNLIKELY (xviddec->have_ts)) {
+      GST_WARNING_OBJECT (xviddec,
+          "xvid decoder produced no output, but timestamp %" GST_TIME_FORMAT
+          " already queued", GST_TIME_ARGS (xviddec->next_ts));
+    } else {
+      xviddec->have_ts = TRUE;
+      xviddec->next_ts = GST_BUFFER_TIMESTAMP (buf);
+      xviddec->next_dur = GST_BUFFER_TIMESTAMP (buf);
+    }
+    gst_buffer_unref (outbuf);
   }
 
-  gst_buffer_set_caps (outbuf, GST_PAD_CAPS (xviddec->srcpad));
-  ret = gst_pad_push (xviddec->srcpad, outbuf);
+done:
+  gst_buffer_unref (buf);
 
-  goto cleanup;
+  return fret;
 
+  /* ERRORS */
 not_negotiated:
   {
     GST_ELEMENT_ERROR (xviddec, CORE, NEGOTIATION, (NULL),
         ("format wasn't negotiated before chain function"));
-    ret = GST_FLOW_NOT_NEGOTIATED;
-    goto cleanup;
+    fret = GST_FLOW_NOT_NEGOTIATED;
+    goto done;
   }
-
-not_decoding:
+decode_error:
   {
-    GST_ELEMENT_ERROR (xviddec, STREAM, DECODE, (NULL),
-        ("Error decoding xvid frame: %s (%d)\n", gst_xvid_error (error),
-            error));
-    gst_buffer_unref (outbuf);
-    ret = GST_FLOW_ERROR;
-    goto cleanup;
+    GST_ELEMENT_WARNING (xviddec, STREAM, DECODE, (NULL),
+        ("Error decoding xvid frame: %s (%d)", gst_xvid_error (ret), ret));
+    if (outbuf)
+      gst_buffer_unref (outbuf);
+    goto done;
   }
+dropping:
+  {
+    GST_WARNING_OBJECT (xviddec, "Dropping non-keyframe (seek/init)");
+    if (outbuf)
+      gst_buffer_unref (outbuf);
+    goto done;
+  }
+}
 
-cleanup:
 
-  gst_buffer_unref (buf);
-  gst_object_unref (xviddec);
-  return ret;
+/* flush xvid encoder buffers caused by bframe usage;
+   not well tested */
+static void
+gst_xviddec_flush_buffers (GstXvidDec * xviddec, gboolean send)
+{
+#if 0
+  gint ret;
+  GstBuffer *outbuf = NULL;
+  xvid_dec_frame_t xframe;
+  xvid_dec_stats_t xstats;
+#endif
+
+  GST_DEBUG_OBJECT (xviddec, "flushing buffers with send %d, have_ts %d",
+      send, xviddec->have_ts);
+
+  /* no need to flush if there is no delayed time-stamp */
+  if (!xviddec->have_ts)
+    return;
+
+  /* flushing must reset the timestamp keeping */
+  xviddec->have_ts = FALSE;
+
+  /* also no need to flush if no handle */
+  if (!xviddec->handle)
+    return;
 
+  /* unlike encoder, decoder does not seem to like flushing, disable for now */
+#if 0
+  gst_xvid_init_struct (xframe);
+  gst_xvid_init_struct (xstats);
+
+  /* init a fake frame to force flushing */
+  xframe.bitstream = NULL;
+  xframe.length = -1;
+
+  ret = gst_xviddec_decode (xviddec, xframe, &outbuf, &xstats);
+  GST_DEBUG_OBJECT (xviddec, "received frame when flushing, type %d, size %d",
+      xstats.type, ret);
+
+  if (ret > 0 && send) {
+    /* we have some valid return frame, give it the delayed timestamp and send */
+    GST_BUFFER_TIMESTAMP (outbuf) = xviddec->next_ts;
+    GST_BUFFER_DURATION (outbuf) = xviddec->next_dur;
+
+    gst_buffer_set_caps (outbuf, GST_PAD_CAPS (xviddec->srcpad));
+    gst_pad_push (xviddec->srcpad, outbuf);
+    return;
+  }
+
+  if (outbuf)
+    gst_buffer_unref (outbuf);
+#else
+  return;
+#endif
 }
 
-static gboolean
-gst_xviddec_negotiate (GstXvidDec * xviddec)
+#if 0
+static GstCaps *
+gst_xviddec_src_getcaps (GstPad * pad)
 {
+  GstXvidDec *xviddec = GST_XVIDDEC (GST_PAD_PARENT (pad));
+  GstCaps *caps;
   gint csp[] = {
     XVID_CSP_I420,
     XVID_CSP_YV12,
@@ -289,75 +561,125 @@ gst_xviddec_negotiate (GstXvidDec * xviddec)
     0
   }, i;
 
+  if (!GST_PAD_CAPS (xviddec->sinkpad)) {
+    GstPadTemplate *templ = gst_static_pad_template_get (&src_template);
+
+    return gst_caps_copy (gst_pad_template_get_caps (templ));
+  }
+
+  caps = gst_caps_new_empty ();
   for (i = 0; csp[i] != 0; i++) {
     GstCaps *one = gst_xvid_csp_to_caps (csp[i], xviddec->width,
-        xviddec->height, xviddec->fps_n, xviddec->fps_d);
+        xviddec->height, xviddec->fps, xviddec->par);
 
-    if (one) {
+    gst_caps_append (caps, one);
+  }
 
-      if (gst_pad_set_caps (xviddec->srcpad, one)) {
-        GstStructure *structure = gst_caps_get_structure (one, 0);
+  return caps;
+}
 
-        xviddec->csp = gst_xvid_structure_to_csp (structure, xviddec->width,
-            &xviddec->stride, &xviddec->bpp);
 
-        if (xviddec->csp < 0) {
-          return FALSE;
-        }
+static GstPadLinkReturn
+gst_xviddec_src_link (GstPad * pad, const GstCaps * vscaps)
+{
+  GstXvidDec *xviddec = GST_XVIDDEC (gst_pad_get_parent (pad));
+  GstStructure *structure = gst_caps_get_structure (vscaps, 0);
 
-        break;
-      }
+  if (!GST_PAD_CAPS (xviddec->sinkpad))
+    return GST_PAD_LINK_DELAYED;
 
-      gst_caps_unref (one);
+  /* if there's something old around, remove it */
+  if (xviddec->handle) {
+    gst_xviddec_unset (xviddec);
+  }
+  xviddec->csp = gst_xvid_structure_to_csp (structure);
 
-    }
+  if (xviddec->csp < 0)
+    return GST_PAD_LINK_REFUSED;
 
-  }
+  if (!gst_xviddec_setup (xviddec))
+    return GST_PAD_LINK_REFUSED;
 
-  gst_xviddec_setup (xviddec);
-  return TRUE;
+  return GST_PAD_LINK_OK;
 }
+#endif
 
 static gboolean
 gst_xviddec_setcaps (GstPad * pad, GstCaps * caps)
 {
-  GstXvidDec *xviddec = GST_XVIDDEC (gst_pad_get_parent (pad));
+  GstXvidDec *xviddec = GST_XVIDDEC (GST_PAD_PARENT (pad));
   GstStructure *structure;
-  const GValue *fps;
-  gboolean ret = FALSE;
+  const GValue *val;
+
+  GST_DEBUG ("setcaps called");
 
   /* if there's something old around, remove it */
   if (xviddec->handle) {
     gst_xviddec_unset (xviddec);
   }
 
-  if (!gst_pad_set_caps (xviddec->srcpad, caps)) {
-    ret = FALSE;
-    goto done;
-  }
-
-  /* if we get here, we know the input is xvid. we
-   * only need to bother with the output colorspace,
-   * which the src_link function takes care of. */
   structure = gst_caps_get_structure (caps, 0);
   gst_structure_get_int (structure, "width", &xviddec->width);
   gst_structure_get_int (structure, "height", &xviddec->height);
 
-  fps = gst_structure_get_value (structure, "framerate");
-  if (fps != NULL) {
-    xviddec->fps_n = gst_value_get_fraction_numerator (fps);
-    xviddec->fps_d = gst_value_get_fraction_denominator (fps);
+  /* perhaps some fps info */
+  val = gst_structure_get_value (structure, "framerate");
+  if ((val != NULL) && GST_VALUE_HOLDS_FRACTION (val)) {
+    xviddec->fps_n = gst_value_get_fraction_numerator (val);
+    xviddec->fps_d = gst_value_get_fraction_denominator (val);
   } else {
     xviddec->fps_n = -1;
+    xviddec->fps_d = 1;
   }
 
-  ret = gst_xviddec_negotiate (xviddec);
+  /* perhaps some par info */
+  val = gst_structure_get_value (structure, "pixel-aspect-ratio");
+  if ((val != NULL) && GST_VALUE_HOLDS_FRACTION (val)) {
+    xviddec->par_n = gst_value_get_fraction_numerator (val);
+    xviddec->par_d = gst_value_get_fraction_denominator (val);
+  } else {
+    xviddec->par_n = 1;
+    xviddec->par_d = 1;
+  }
 
-done:
-  gst_object_unref (xviddec);
+  if (gst_xviddec_setup (xviddec)) {
+    GstCaps *allowed_caps;
+
+    /* we try to find the preferred/accept csp */
+    allowed_caps = gst_pad_get_allowed_caps (xviddec->srcpad);
+    if (!allowed_caps) {
+      GST_DEBUG_OBJECT (xviddec, "... but no peer, using template caps");
+      /* need to copy because get_allowed_caps returns a ref,
+         and get_pad_template_caps doesn't */
+      allowed_caps =
+          gst_caps_copy (gst_pad_get_pad_template_caps (xviddec->srcpad));
+    }
+    /* pick the first one ... */
+    structure = gst_caps_get_structure (allowed_caps, 0);
+    val = gst_structure_get_value (structure, "format");
+    if (G_VALUE_TYPE (val) == GST_TYPE_LIST) {
+      GValue temp = { 0 };
+      gst_value_init_and_copy (&temp, gst_value_list_get_value (val, 0));
+      gst_structure_set_value (structure, "format", &temp);
+      g_value_unset (&temp);
+    }
 
-  return ret;
+    /* ... and use its info to get the csp */
+    xviddec->csp = gst_xvid_structure_to_csp (structure);
+    if (xviddec->csp == -1) {
+      gchar *sstr = gst_structure_to_string (structure);
 
+      GST_INFO_OBJECT (xviddec,
+          "failed to decide upon csp from caps %s, trying I420", sstr);
+      g_free (sstr);
+      xviddec->csp = XVID_CSP_I420;
+    }
+    gst_caps_unref (allowed_caps);
+
+    return gst_xviddec_negotiate (xviddec, NULL);
+
+  } else                        /* setup did not work out */
+    return FALSE;
 }
 
 static GstStateChangeReturn
@@ -368,28 +690,29 @@ gst_xviddec_change_state (GstElement * element, GstStateChange transition)
 
   switch (transition) {
     case GST_STATE_CHANGE_NULL_TO_READY:
-      break;
-    case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
+      if (!gst_xvid_init ())
+        return GST_STATE_CHANGE_FAILURE;
       break;
     default:
       break;
   }
 
-  ret = parent_class->change_state (element, transition);
+  ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
+  if (ret == GST_STATE_CHANGE_FAILURE)
+    goto done;
 
   switch (transition) {
-    case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
-      break;
     case GST_STATE_CHANGE_PAUSED_TO_READY:
+      gst_xviddec_flush_buffers (xviddec, FALSE);
       if (xviddec->handle) {
         gst_xviddec_unset (xviddec);
       }
-      break;
-    case GST_STATE_CHANGE_READY_TO_NULL:
+      gst_xviddec_reset (xviddec);
       break;
     default:
       break;
   }
 
+done:
   return ret;
 }